CHAPTER 13
COGNITIVE FUNCTIONS
A. Lateralization and Language
The left cerebral cortex hemisphere is primarily associated with the connection to
skin receptors and muscles on the right side of the body, while the right hemisphere is
primarily associated with the connection to skin receptors and muscles on the left side. It
is noteworthy that the trunk muscles and facial muscles are controlled by both
hemispheres. According to research, the left hemisphere of the brain processes
information from the right visual field, while the right hemisphere processes information
from the left visual field. Both hemispheres receive auditory input from both ears, with a
slightly greater emphasis on the contralateral ear. What is the evolutionary reason for the
development of cerebral hemispheric lateralization, where each hemisphere of the brain is
responsible for controlling the opposite side of the body? The answer remains unknown.
The senses of taste and smell are anatomically separate and do not share neural pathways.
According to Stevenson, Miller, and McGrillen (2013), taste information is received by
both hemispheres of the brain from all areas of the tongue. On the other hand, Herz,
McCall, and Cahill (1999) and Homewood and Stevenson (2001) have reported that each
hemisphere of the brain receives smell information from the nostril located on the same
side.
The left hemisphere has been found to be the dominant region for speech
production in over 95% of individuals who are right-handed and approximately 80% of
those who are left-handed, as indicated by fMRI data and other research methods.
According to Flowers and Hudson's (2013) research, while a minority of individuals with
a strong left-handed preference exhibit right-hemisphere dominance for speech, the
majority of left-handers demonstrate either left-hemisphere control or a combination of
left- and right-hemisphere control. According to Huth et al. (2016), while the right
hemisphere is not responsible for speech production, it is capable of comprehending
sentences that hold significance. Subsequently, it will be demonstrated that the right
hemisphere serves additional functions. Lateralization refers to the allocation of tasks
between the two hemispheres. The transfer of information between the left and right
hemispheres occurs via the corpus callosum, anterior commissure, hippocampal
commissure, and other minor commissures.
According to the research conducted by Norman Geschwind and Walter Levitsky
in 1968, it was observed that a particular area of the temporal cortex, known as the
planum temporale (PLAY-num tem-poh-RAH-lee), exhibits a greater size in the left
hemisphere for approximately 65% of individuals. In 1973, Sandra Witelson and Wazir
Pallie conducted a study wherein they analyzed the brains of deceased infants who had
not yet reached the age of 3 months. The study revealed that out of 14 infants, 12 had a
larger left planum temporale. Subsequent studies have exhibited variances even among
premature neonates, as evidenced by the work of Hervé, Zago, Petit, Mazoyer, and
Tzourio-Mazoyer (2013). According to Dehaene-Lambertz et al. (2010), findings from an
fMRI study indicate that infants as young as two months old exhibit greater activation in
the left hemisphere when exposed to speech stimuli, as opposed to music stimuli. The
hemispheres exhibit differences from the outset.
There exists a connection between each hemisphere and half of each eye in the
human anatomy. The visual field, or the area of vision that is perceptible at any given
moment, is processed by the retina in a manner such that light from the right half of the
visual field is projected onto the left half of each retina. Consequently, the left
hemisphere of the brain is responsible for processing the visual information from the
right visual field. Likewise, the visual stimuli presented to the left visual field elicits
neural activity in the right hemisphere due to the anatomical connectivity between the left
visual field and the right half of each retina. The central region of each retina, spanning
approximately 5 degrees of visual arc, is linked to both hemispheres through a slender
vertical strip.
Impairment of the corpus callosum hinders interhemispheric communication. In
some cases, medical professionals have performed corpus callosotomy as a therapeutic
intervention for individuals with severe epilepsy, a neurological disorder marked by
recurrent instances of heightened synchronized neural activity. Over 90% of individuals
diagnosed with epilepsy exhibit a positive response to anti-epileptic medications. In cases
where an individual experiences persistent and intense seizures despite the administration
of medication, medical practitioners may contemplate the possibility of surgically
excising the focal point, which is the specific region in the brain where the seizures
originate. The positioning of the focus exhibits variability across individuals.
Individuals who have undergone surgical intervention to sever the corpus
callosum, commonly known as split-brain patients, exhibit preserved cognitive abilities
and drive, normal gait and speech patterns, and are able to perform coordinated manual
tasks, such as tying shoelaces, with both hands. Nonetheless, individuals encounter
difficulties in coordinating their hands while performing tasks that they have not
previously rehearsed. Individuals with split-brain syndrome exhibit the unique ability to
independently utilize their two hands in a manner that is not typically observed in the
general population. As an illustration, endeavor to sketch the symbol ø utilizing your
non-dominant hand whilst concurrently sketching a period symbol with your dominant
hand. While many individuals may struggle with this particular task, those with split-
brain syndrome are able to perform it effortlessly. An alternative approach is to attempt
the task of concurrently sketching circles with both hands, albeit with a slight variation in
the speed of one hand relative to the other, without doubling the pace. The task at hand is
commonly perceived as challenging, however, individuals with split-brain tendencies
exhibit a natural inclination to draw the circles at varying rates.
The phenomenon whereby the left hemisphere lacks awareness of the reasoning
behind actions performed by the right hemisphere has been observed. From the
perspective of the left hemisphere, the behavior's underlying cause was unconscious.
What is its reaction? Instead of displaying a state of surprise, it formulates a rationale. In
instances where a pleasant or unpleasant stimulus is perceived by the right hemisphere,
the left hemisphere is responsible for processing the resulting emotional response. This
may manifest as verbal expressions such as "What a beautiful wall that is!" or "Right now
you are making me sad." In a particular study, researchers presented distinct visual
stimuli to the left and right hemispheres of participants and instructed them to indicate the
images that corresponded with their perceptual experience. In a particular instance, the
cerebral hemisphere located on the left perceived an image of a chicken claw, while the
cerebral hemisphere located on the right perceived an image of a snow scene.
Subsequently, the dexterous extremity indicated an image of a domestic fowl while the
sinister extremity indicated a tool used for digging. Upon being questioned about the
reason behind his gesture towards a shovel, the individual responded that a shovel would
be a necessary tool for the purpose of cleaning out a chicken coop. Michael Gazzaniga
(2000) formulated the notion of the interpreter based on the aforementioned observations.
This refers to the inclination of the left hemisphere to fabricate and safeguard
justifications for actions, despite the fact that the actual reasons may be subconscious.
This characteristic is not exclusive to individuals with split-brain syndrome.
The right cerebral hemisphere exhibits superior proficiency in processing spatial
relationships compared to the left hemisphere. An instance of a young woman with
impairment to her posterior right hemisphere was observed to experience difficulty in
navigating through even familiar territories. In order to arrive at her intended location, the
individual required precise visual instructions. According to Cai, Van der Haegen, and
Brysbaert's (2013) findings, individuals who exhibit right-hemisphere dominance for
speech also demonstrate left-hemisphere dominance for spatial relationships. According
to Adolphs, Damasio, and Tranel (2002), the right hemisphere exhibits greater sensitivity
towards emotional stimuli as compared to the left hemisphere. This is evident in the
ability to perceive emotions in people's gestures and tone of voice. Individuals who have
incurred injury to the right cerebral hemisphere typically exhibit difficulty
comprehending humorous and sarcastic expressions.
Non-human organisms communicate through various means such as visual,
auditory, tactile, or chemical displays, however, the communicative signals exhibited by
these organisms are relatively rigid in nature. According to Cheney and Seyfarth's
research in 2005, monkeys possess the ability to produce distinct alarm calls to signify
the presence of an eagle in the sky or a snake on the ground. However, they lack the
means to communicate the presence of an eagle on the ground or a snake in a tree. The
distinctiveness of human language lies in its productivity, which enables the creation of
novel combinations of signals for the representation of novel concepts. It is likely that the
development of language did not occur spontaneously. The process of evolution typically
involves the modification of pre-existing structures to develop new features. The wings
of bats, quills of porcupines, and stench of skunks are all examples of modified body
parts. Specifically, bat wings are modified arms, porcupine quills are modified hairs, and
skunk stench is a modified secretion from sweat glands.
The reconstruction of the evolution of language is inherently speculative, as there
is no possibility of utilizing fossil evidence to aid in the analysis. It is highly plausible
that the development of language can be attributed to the use of gestural communication,
as suggested by Corballis. All members of the primate order utilize gestural
communication, including Homo sapiens. During the initial year of life, children
commence gesturing, and their employment of gestures serves as a predictor for the
expeditiousness with which they will acquire spoken language, as per Iverson and
Goldin-Meadow's research in 2005. It is noteworthy that a significant number of adults
tend to utilize gestures in conjunction with their verbal communication, even in situations
where the recipient is unable to visually perceive such gestures, such as during a
telephone conversation. Oral gestures could potentially hold significant importance.
Primates employ a variety of oral gestures to convey messages, among which is a lip-
smacking gesture that exhibits a rhythmic pattern akin to human speech. It is widely
acknowledged that monkeys engage in the observation of each other's mouth movements,
particularly during vocalization. It is conceivable that the amalgamation of sound and
mouth gesture may have served as a precursor to the development of spoken language.
If language is not solely a secondary outcome of general intelligence, it is likely to
have undergone evolutionary development as a distinct neural mechanism. According to
Chomsky (1980) and Pinker (1994), there exists a language acquisition device within the
human cognitive system, which is an innate mechanism facilitating the acquisition of
language. The rapid and effortless acquisition of language in most children may suggest a
biological predisposition towards language learning. Deaf children demonstrate a
remarkable ability to acquire sign language at a rapid pace. In the absence of formal
instruction, they exhibit a proclivity for spontaneously developing and disseminating
their own sign language system.
In 1861, Paul Broca, a French surgeon, provided medical care for a patient who
had been unable to speak for a period of 30 years due to gangrene. Upon the man's
demise five days subsequent to the incident, Broca conducted a postmortem examination
and detected a lesion located in the left frontal cortex. During subsequent years, Broca
conducted examinations on the brains of further patients who suffered from aphasia, a
condition characterized by language impairment. In almost all cases, he observed damage
that encompassed the same region, which is currently referred to as Broca's area. Broca's
aphasia, also known as nonfluent aphasia, is the term used to describe language
production impairment resulting from brain damage, irrespective of the precise site of the
damage.
In 1865, Broca disseminated his findings, which were marginally delayed in
comparison to the accounts of other French medical practitioners, Marc and Gustave Dax.
These practitioners also identified the left hemisphere as the location of language
capabilities. Broca was attributed with the recognition, nevertheless, owing to the fact
that his depiction was more elaborate and persuasive. The initial identification of the
operational role of a specific region of the brain, as evidenced by this finding, served as a
crucial precursor to the development of contemporary neuroscience. Individuals afflicted
with Broca's aphasia exhibit a reduced ability to effectively and efficiently engage in
various forms of linguistic communication, such as verbal expression, written
communication, nonverbal gestures, and sign language. This condition is characterized
by a decreased fluency and proficiency in language usage.
In 1874, Carl Wernicke, a junior assistant at a German hospital, identified that a
distinct form of language impairment resulted from injury to a specific area of the left
temporal cortex. It is worth noting that while most English speakers pronounce his name
as WER-nih-kee, the German pronunciation is VAYR-nih-keh. Despite the fact that
patients possessed the ability to verbally communicate and produce written language,
their comprehension of language was deficient. The occurrence of Wernicke's aphasia is
attributed to harm inflicted upon the region surrounding Wernicke's area, which is
situated in close proximity to the auditory cortex. This condition is typified by inadequate
comprehension of language and a compromised capacity to recollect object names. This
condition is commonly referred to as fluent aphasia, as individuals affected by it are able
to maintain a smooth speaking ability. Similar to Broca's aphasia, the manifestations and
cerebral impairments exhibit heterogeneity, and the impairment typically encompasses
regions beyond the cortex, such as the thalamus and basal ganglia. The pattern of
behavior known as fluent aphasia, or Wernicke's aphasia, is utilized to describe a specific
phenomenon, regardless of the site of injury.
Dyslexia is a condition characterized by a particular difficulty in reading, despite
the individual having sufficient visual acuity, cognitive abilities, educational resources,
and motivation. According to Field et al. (2013), there is a higher prevalence of the
condition in males as compared to females, and it has been associated with various
identified genes. Dyslexia is a prevalent condition in the English language, primarily due
to the abundance of words with irregular spellings. This selection of words includes
phlegm, bivouac, khaki, yacht, choir, physique, and gnat. Dyslexia, irrespective of the
language, is consistently characterized by challenges in the conversion of symbols into
sounds.
B. Conscious and Unconscious Processes
The mind-body or mind-brain problem is brought to the forefront by biological
explanations of behavior. This problem pertains to the relationship between the mind and
the brain. It appears that a significant portion of individuals who are not trained in
scientific fields hold the belief of dualism, which posits that the mind and body are
distinct entities. René Descartes, a prominent French philosopher, espoused the concept
of dualism while acknowledging the challenging matter of how a non-material mind
could exert an impact on a physical brain. The proposal posits that there exists a singular
point of interaction between the mind and brain, specifically located at the pineal gland.
This structure was identified as the smallest unpaired component of the brain.
Monism is a philosophical concept that posits the existence of a singular
substance as the fundamental constituent of the universe, in contrast to dualism.
Materialism is a philosophical perspective that posits the notion that all that exists in the
world is comprised of physical or material substances. As per a particular perspective
known as "eliminative materialism," the existence of mental events is deemed non-
existent, and any form of folk psychology that incorporates the notion of mind or mental
activity is intrinsically erroneous. Nonetheless, a significant portion of individuals
encounter challenges in accepting the notion that their cognitive faculties are mere
products of their mental constructs. A theoretical perspective that posits the possibility of
elucidating all psychological phenomena through exclusively physical explanations is an
alternative iteration of materialism. Mentalism is a philosophical perspective that posits
the existence of minds as the only reality, and asserts that the physical world is dependent
on the awareness of a mind for its existence. The position in question was primarily
defended by the philosopher George Berkeley. Testing this concept poses a significant
challenge. Please attempt to rewrite the provided text in an academic style. The identity
position is a theoretical perspective that posits a correspondence between mental
processes and specific types of brain processes, albeit expressed in distinct terminologies.
Analogously, it is possible to characterize the Mona Lisa as an exceptional artwork or
alternatively, to provide a detailed account of the precise hue and luminosity of every
individual point present on the painting. Despite the apparent dissimilarity between the
two depictions, they pertain to identical entities. According to the identity position, the
mind can be defined as the activity of the brain. Similar to how fire is not a tangible
entity but rather a phenomenon that occurs to a substance, mental activity can be
understood as the occurrence within the brain.
Despite the lack of a sound hypothesis regarding the existence of consciousness, it
may be possible to address certain subsidiary inquiries pertaining to consciousness. The
primary challenge in conducting research on consciousness lies in the inability to directly
observe it. Defining it can be a challenging task. In practical terms, scholars utilize this
operational definition: If an individual who exhibits cooperative behavior reports being
cognizant of one stimulus but not the other, it can be inferred that they were conscious of
the former and not the latter. This definition is not applicable to individuals who lack the
ability to communicate verbally, such as non-human animals and infants. Consequently,
the investigation of consciousness is restricted to adult individuals who are typically
healthy and willing to participate in research. Following this definition, the subsequent
procedure involves the presentation of a specific stimulus in two distinct conditions, with
the anticipation that an observer will perceive it in one condition but not in the other.
Subsequently, the brain responses in both conditions are compared by the researchers.
What methods can be employed to deliver a stimulus while inhibiting conscious
awareness? Scholars have devised ingenious methodologies grounded on the concept of
interference. Assuming that a yellow dot is clearly visible to you. Subsequently, despite
the persistence of the dot on the display, adjacent dots intermittently illuminate and dim.
The stationary dot is not visible while the flashing occurs. The aforementioned technique
is commonly referred to as flash suppression.
Individuals who are in a state of sleep, coma, or profound anesthesia? Two
research studies tracked individuals as they experienced loss of consciousness due to
anesthesia and subsequently regained consciousness as the pharmacological effects
dissipated. The state of unconsciousness was characterized by a reduction in general
activity and a notable decrease in connectivity between the cerebral cortex and
subcortical regions, including the thalamus, hypothalamus, and basal ganglia. The
recovery of consciousness in the early stages was contingent upon enhanced connectivity
between subcortical and cortical regions, while subsequent enhancements in alertness
were predicated on amplified cortical activity. This was demonstrated in studies
conducted by Långsjö et al. (2012) and Schröter (2012). According to Ishizawa et al.
(2016), a study conducted on monkeys revealed that a decline in synchrony and
connectivity among cortical regions occurred prior to a loss of consciousness. As
previously discussed, the awareness of a stimulus necessitates a widespread distribution
of neural activity throughout a significant portion of the brain. In the absence of
connectivity, any form of stimulus fails to propagate its activity, resulting in a state of
unconsciousness for the individual.
Attention and consciousness are not interchangeable terms, although they exhibit
a strong correlation. According to Huang, Treisman, and Pashler (2007), individuals are
only aware of a limited amount of information that they actively focus their attention on,
despite the vast amount of sensory input they receive through various receptors. An
illustrative case in point is the phenomenon of inattentional blindness or change
blindness. In a complex scene, gradual changes or changes occurring during eye blinks
are likely to go unnoticed unless one directs their attention to the specific item
undergoing alteration.
The differentiation between bottom-up and top-down attention is a recognized
concept within the field of psychology. A stimulus-dependent approach characterizes a
bottom-up process. Whilst sitting on a park bench and engaging in contemplation, one's
attention may be abruptly seized by the sudden appearance of a deer dashing past. The
top-down process is a deliberate and purposeful approach. When attempting to locate a
specific individual within a group, one may engage in a process of visually scanning each
face in succession until the desired person is identified. At times, a hierarchical approach
supersedes the influence of processes that originate from lower levels. Assuming the task
of locating a friend amidst a carnival crowd. While a significant number of individuals
opt for flamboyant costumes such as clown outfits, your acquaintance has chosen to don
a simple shirt and blue denim pants. According to Mevorach, Hodsoll, Allen, Shalev, and
Humphreys (2010), it is necessary to inhibit the attention and activity that would typically
be drawn to atypical objects. The intentional and controlled allocation of attention is
reliant on specific regions of the prefrontal cortex and parietal cortex, as per Buschman
and Miller's (2007) and Rossi et al.'s (2007) research. By enabling responsiveness in
specific regions of the thalamus, they effectively guide attention and subsequently
enhance the activation of relevant sensory cortex areas.
Cerebral injury has the potential to result in distinct forms of attentional deficits.
Individuals who have incurred damage to the right hemisphere frequently exhibit spatial
neglect, which is characterized by a proclivity to disregard the left side of their body, the
left side of objects, a significant portion of auditory input received through the left ear,
and a substantial amount of tactile input received through the left hand. This tendency is
particularly pronounced when there is any concurrent sensory stimulation originating
from the right side. There have been instances where individuals exhibit a tendency to
exclusively don garments on the right side of their physique. The aforementioned impacts
are particularly evident in the initial stages following a stroke or other form of
impairment, and a majority of individuals exhibit some degree of recuperation within the
subsequent 10 to 20 weeks. Neglect of the right side is rarely observed as a significant
consequence of damage to the left hemisphere.
C. Making Decisions and Social Neuroscience
A rudimentary conceptualization of the cognitive process by which the brain
executes decision-making involves the accumulation of evidence by distinct sets of cells
in support of opposing choices, followed by a comparative analysis of said evidence by a
separate set of cells. There is a considerable amount of evidence that supports this notion,
although it is not yet definitive. In a particular research investigation, a rodent was
required to insert its nasal appendage into a central aperture, perceive auditory stimuli in
the form of clicks, and subsequently orient itself towards the direction with a greater
frequency of clicks.
In the posterior parietal cortex, there are two distinct sets of cells that exhibit
proportional responsiveness to the number of clicks on either the left or right side. In a
specific region of the prefrontal cortex known as the frontal orienting fields, which is
located proximal to the motor cortex, a distinct population of neurons exhibited activation
in response to the anterior positioning of the left side, while a separate population of
neurons displayed activation in response to the anterior positioning of the right side.
According to Hanks et al. (2015), the responses observed in the posterior parietal cortex
exhibit a graded nature, whereas the responses in the frontal cortex result in an all-or-
none outcome, similar to that of a scorekeeper who declares the winning team of a game.
Following injury to the frontal orienting fields, a rat exhibits impaired ability to maintain
a score record, leading to a reliance on the most recent auditory stimuli rather than a
cumulative account over a short temporal window when making decisions.
Numerous choices are contingent upon personal preferences. The decision-making
process involves an initial estimation of the potential outcomes associated with each
available choice, followed by a selection of the option that appears to offer the most
favorable outcome. In the context of laboratory research, the complexity of decision-
making is often reduced to a binary choice, whereas in daily life, individuals are typically
presented with a multitude of options to consider. Rats or mice are presented with a
decision-making task where they must choose between turning left or right to receive
varying types or probabilities of reward. Individuals may have the option to place their
wager on one outcome or an alternative. Assuming a pragmatic stance, it can be inferred
that the benefit derived from opting for one alternative is typically superior to the other,
albeit not invariably. The cells located in the basal ganglia undergo a gradual learning
process to determine the optimal choice. The ventromedial prefrontal cortex cells are
involved in modifying the responses of the basal ganglia.
The ventromedial prefrontal cortex, along with other adjacent regions, transmits
information to the orbitofrontal cortex in close proximity. The orbitofrontal cortex, in
turn, reacts in accordance with the relative value of an anticipated reward in comparison
to alternative options. According to Frank and Claus (2006), the level of satisfaction or
dissatisfaction resulting from obtaining a B1 on a term paper is contingent upon the
anticipated grade. Individuals may exhibit a preference for pizza on certain occasions,
while displaying a preference for cake on other occasions. The orbitofrontal cortex is
responsible for the computation of the anticipated value of a given action, contingent
upon the prevailing environmental conditions.
Social neuroscience is an emerging field of research that investigates the role of
genes, chemicals, and brain regions in shaping social behavior. Despite its novelty, this
area of study has garnered increasing interest and excitement. The present discussion will
encompass two distinct themes, namely the concepts of love and altruism. Assuming a
scenario where an individual experiences intense romantic affection towards another
person. Research utilizing functional magnetic resonance imaging (fMRI) has revealed
that observing images of one's romantic partner elicits robust activation of brain regions
linked to reward, akin to the neurochemical effects of addictive substances. According to
Ortigue et al. (2010), the observation of images depicting a person who is held dear also
triggers the activation of the hippocampus and other regions that are significant for
cognitive and memory processes. Recalling past shared experiences is a common
response to contemplating affection for another individual. The concept of love
encompasses a confluence of factors, including but not limited to, motivational,
emotional, mnemonic, and cognitive components.
The function of oxytocin and its closely associated hormone vasopressin has
garnered significant interest within academic circles. The hormone oxytocin has been
observed to induce uterine contractions during labor, facilitate lactation in the mammary
glands, and generally encourage maternal behavior, social interaction, and bonding
between mates across various mammalian taxa. Both genders secrete it during sexual
intercourse. The hormone in question has been commonly referred to as the "love
hormone," although a more appropriate terminology would be a hormone that enhances
or magnifies the experience of love.
The sustenance of civilized society is contingent upon individuals providing
mutual aid and support. Assisting a peer who is vying for a favorable grade in a shared
course could be a viable option. One potential action that individuals could take in
response to a natural disaster occurring in a distant location is to provide financial
contributions to support the affected victims. The degree of helpfulness exhibited by an
individual is contingent upon their level of empathy, which refers to their capacity to
relate to others and experience their suffering as if it were their own. While empathy is
not exclusive to the human species, it is comparatively more pronounced in humans than
in other organisms.
Individuals vary in their capacity to exhibit empathy. A significant proportion of
the observed diversity can be attributed to cultural and familial socialization, however,
biological determinants also play a role. Frontotemporal dementia, also known as
frontotemporal lobe degeneration, is characterized by the gradual degeneration of specific
regions of the cerebral cortex, namely the frontal and temporal lobes. This condition is
associated with the most profound effects. The consequences are contingent upon the
precise site of injury, however, frequently the impairment encompasses the ventromedial
prefrontal cortex and orbitofrontal cortex. The evaluation of potential rewards is crucial
in the interpretation and assessment of emotional expressions exhibited by others, as
highlighted by previous studies. Individuals who have incurred such damage frequently
exhibit a lack of recognition or response to the reactions of others, including those
indicative of distress, resulting in a dearth of empathy or concern. Individuals who have
incurred injury to their ventromedial prefrontal cortex exhibit a greater tendency to
calmly support a utilitarian ethical stance, which posits that sacrificing one individual to
save five would be morally acceptable, across a range of situations.
D. Substance Abuse
Pharmaceutical substances have the capacity to either enhance or impede the
transmission of signals across synaptic gaps. In pharmacology, a substance that inhibits
the activity of a neurotransmitter is classified as an antagonist, whereas a substance that
imitates or enhances the effects of a neurotransmitter is categorized as an agonist. The
etymology of the term agonist can be traced back to its Greek origin, where it is derived
from a word that signifies a participant in a competition. The term "agony" has its
etymological origins in the same root. The term "antagonist" refers to an individual who
is considered as an "anti-agonist" or a member of the opposing team. A mixed agonist-
antagonist is a substance that exhibits agonistic properties for certain effects while
simultaneously displaying antagonistic properties for others. Additionally, it may act as
an agonist at specific dosages and as an antagonist at others. As per the investigators'
statement, a drug exhibits an affinity towards a receptor when it effectively binds to it,
akin to the mechanism of a key fitting into a lock. The degree of affinity can range from
robust to feeble. The efficacy of a drug refers to its capacity to stimulate the receptor. A
pharmacological agent that exhibits binding to a specific receptor without eliciting a
biological response is characterized by a high affinity but low efficacy.
The majority of individuals consume alcohol in a moderate manner, leading to
feelings of relaxation and reduced anxiety. However, there are those who develop a
pattern of alcohol abuse. Individuals may experiment with various substances, and while
some may discontinue use after a few instances, others may develop a dependency. It is
apparent that individuals exhibit varying inclinations towards alcohol or substance
misuse. The likelihood of substance abuse is contingent upon a combination of genetic
and environmental factors. The quantity of alcohol consumption by parents exhibits a
correlation with the amount of alcohol consumed by both biological and adopted
children. However, the correlation is comparatively stronger with the biological children.
The likelihood of substance use or abuse is increased in children who are raised in an
unstable environment, particularly if they possess a specific gene that impacts serotonin
synapses, as indicated by Windle et al. (2016). The likelihood of substance use is
influenced by a number of additional genes, however, the impact of these genes is
contingent upon the specific environmental context.
The risk for alcoholism is also influenced by the prenatal environment. Research
has shown that maternal consumption of alcohol during pregnancy is associated with an
increased likelihood of alcoholism in offspring, irrespective of the amount of alcohol
consumed by the mother during the child's upbringing. Research conducted on rats has
demonstrated that prenatal exposure to alcohol is associated with an elevated level of
alcohol consumption post-natal.
One approach to identifying individuals who are at risk involves conducting long-
term studies on large cohorts of people. Conduct a comprehensive assessment of multiple
factors pertaining to a cohort of minors or young adults, subsequently identifying those
who manifested alcohol-related issues, and subsequently examining which antecedent
factors were predictive of the emergence of alcoholism. Research indicates that
individuals who exhibit impulsive, risk-taking, easily bored, sensation-seeking, and
outgoing behaviors during their childhood are more prone to developing alcoholism.
The impact of drugs on synapses varies depending on the specific stages of an
individual's experiences. The neurological effects of the drug while it is present in the
brain are distinct from the effects that manifest during the withdrawal phase, as well as
the effects that give rise to cravings. The mitigation of drug abuse necessitates the
consideration of diverse mechanisms. The investigation into the significance of dopamine
in reinforcement originated from a duo of youthful psychologists who were endeavoring
to address an unrelated inquiry. The study conducted by James Olds and Peter Milner in
1954 aimed to investigate the potential impact of stimulating a specific region of the
brain on the directional behavior of rats. During the implantation procedure, the electrode
was inadvertently placed in the septum region, rather than the intended target. Upon
receiving brain stimulation, the rat exhibited unexpected behavior by sitting up,
surveying its surroundings, and engaging in olfactory exploration, suggestive of a
positive response to the stimulus. Subsequently, Olds and Milner provided rats with the
chance to operate a lever that would result in the generation of cerebral self-stimulation
via electricity. According to Olds' study in 1958, rats were observed to press up to 2000
times per hour in response to electrodes placed in the septum and other specific locations.
Subsequent studies have revealed that rodents exhibit a propensity to engage in operant
behavior aimed at activating numerous cerebral regions that possess axonal connections
that either directly or indirectly augment the discharge of dopamine within the nucleus
accumbens.
Addictions are enduring behavioral patterns, and certain indications suggest that
individuals with addictions encounter difficulties in discontinuing any behavioral pattern,
not exclusively limited to drug addiction. A comparative analysis was conducted to
examine the differences between individuals who use cocaine and those who do not.
Initially, all the participants acquired responses that were conducive to earning monetary
rewards or avoiding electric shocks. Subsequently, the available funds experienced a
reduction, leading to the disconnection of the electric shock apparatus. According to
Ersche et al. (2016), following a certain point, individuals who did not use cocaine
exhibited a significant reduction in their level of responding, whereas those who were
cocaine users continued to respond at a rate that was similar to their previous level. The
significance of addiction lies in the fact that a conditioned desire can endure even after
the associated action no longer elicits a pleasurable response.
Individuals with prefrontal cortex impairment exhibit a comparable trend.
Individuals exhibit a tendency to exhibit a slow response in updating their learned
responses or preferences upon being presented with novel information. A characteristic
hallmark of addiction is the presence of intense craving, which manifests as an
unwavering pursuit of the addictive substance. Following a prolonged period of
refraining from substance use, stimuli linked to the substance elicit a resurgent desire to
consume. The phenomenon of cue-induced cravings has been observed in various
contexts. For instance, Hutchison et al. (2002) found that smokers experience a
heightened urge to smoke upon encountering a lit cigarette, while Volkow et al. (2006)
reported that cocaine users experience similar cravings upon viewing videos of cocaine
use. Additionally, Thalemann et al. (2007) found that excessive video game players
experience cravings upon exposure to video games. The neural processes underlying the
experience of craving exhibit distinct characteristics when compared to the neural
response associated with the initial engagement in the activity.
As addiction progresses, a significant reduction in its impact, particularly the
pleasurable effects, is observed. The phenomenon of a reduction in response to a stimulus
over time is commonly referred to as tolerance. Due to the phenomenon of tolerance,
individuals who use heroin may gradually increase both the quantity and frequency of
their usage, ultimately reaching levels that could prove fatal to non-users. The
phenomenon of drug tolerance is a multifaceted process that is predominantly acquired
through learning. Studies have shown that rats which are repeatedly administered drugs
in a specific location exhibit greater tolerance in that particular location as compared to
other locations.
Following repeated administrations of morphine, a rat acquires tolerance to the
drug. Upon receiving successive injections of saline solution devoid of morphine, the
rat's acquired association between injection and morphine is attenuated. According to
Siegel's research in 1977, the subsequent administration of morphine injection results in
reduced tolerance. The phenomenon of heightened physiological response in the absence
of a drug, due to the body's anticipation of its presence under specific circumstances, is
commonly observed. The aforementioned response is commonly referred to as
withdrawal. Withdrawal symptoms that arise after an individual discontinues heroin or
other opiates may include anxiety, sweating, vomiting, and diarrhea. The manifestation of
alcohol withdrawal is characterized by symptoms such as irritability, fatigue, tremors,
diaphoresis, and nausea. In instances of heightened severity, the cessation of alcohol
consumption may lead to the advancement of hallucinatory episodes, convulsive
episodes, elevated body temperature, and complications pertaining to the cardiovascular
system.
Certain individuals who engage in substance abuse have the ability to reduce their
consumption without external assistance. Individuals who encounter difficulties in
resolving their issues independently may seek assistance from Alcoholics Anonymous,
Narcotics Anonymous, or comparable groups, which are particularly prevalent in the
United States. One potential option is to seek the assistance of a therapist, specifically
one who specializes in cognitive behavioral therapy. Contingency management is a
therapeutic approach that involves providing incentives for individuals who maintain
abstinence from drug use, as outlined by Kaminer (2000). A limited number of
individuals resort to pharmacological interventions, albeit a handful of alternatives are
accessible.
As previously stated, the liver undergoes the process of alcohol metabolism,
which involves the conversion of alcohol into acetaldehyde, a toxic substance, and
subsequently into acetic acid, a harmless compound. Disulfiram, commercially known as
Antabuse, acts as an antagonist to the enzyme responsible for acetaldehyde metabolism.
As a result, individuals who consume Antabuse experience nausea upon alcohol
consumption. The discovery of the effects of Antabuse was serendipitous in nature.
According to Schwartz and Tulipan's (1933) findings, the employees at a particular
rubber-manufacturing facility experienced a rash upon exposure to disulfiram on their
skin. If an individual has inhaled it, they may experience adverse effects upon consuming
alcohol. Subsequently, disulfiram was explored as a pharmacological intervention by
therapists, with the aim of inducing an aversion to alcohol in individuals suffering from
alcoholism, thereby leading to abstinence.
Methadone, akin to heroin and morphine, triggers identical brain receptors and
elicits corresponding effects. Nonetheless, it possesses the benefit of being administrable
through oral ingestion. When orally ingested, the majority of heroin or morphine is
metabolized by stomach acids. Oral administration of methadone results in a gradual
increase in its concentration in the bloodstream and subsequently in the brain, thereby
mitigating the occurrence of a sudden and intense euphoric sensation that may interfere
with normal functioning. Due to its slow metabolism and prolonged presence in the brain,
the manifestation of withdrawal symptoms is gradual. Moreover, individuals circumvent
the potential hazard of needle-borne infections by refraining from injection.
Buprenorphine and levomethadyl acetate (LAAM) are pharmacological agents utilized in
the treatment of opiate addiction, akin to methadone. LAAM offers the benefit of
sustained efficacy, thereby reducing the frequency of clinic visits to thrice a week as
opposed to daily visits. According to Vocci, Acri, and Elkashef (2005), individuals who
utilize any of the aforementioned drugs tend to have a longer and healthier lifespan
compared to those who use heroin or morphine. Additionally, they are more inclined to
maintain employment. Nonetheless, these pharmaceutical substances do not terminate the
state of addiction. They provide a relatively safer alternative to fulfill the desire.
E. Mood Disorders
Individuals may experience periods of discouragement. Major depression is
characterized by heightened severity and longer duration. Individuals diagnosed with
major depression experience persistent feelings of sadness and helplessness throughout
the majority of each day for a duration of several weeks. They possess limited capacity to
envision deriving pleasure from any activity. According to Russo and Nestler's (2013)
findings, the responsiveness of the nucleus accumbens to reward diminishes. Individuals
experience feelings of low self-worth, engage in suicidal ideation, and exhibit sleep
disturbances. Individuals with this condition exhibit cognitive impairments such as
reduced motivation, attention deficits, compromised memory, and diminished olfactory
function.
The cognitive impairments frequently endure despite the efficacious management
of affective disorders. The manifestation of happiness can be considered a more
dependable indicator than heightened feelings of sadness. In a particular research
investigation, participants were equipped with a beeper that emitted an unanticipated
signal prompting them to report their current emotional responses. According to Peters et
al. (2003), individuals experiencing depression reported an average number of unpleasant
experiences, but a significantly lower number of pleasant experiences compared to the
general population. In previous research endeavors, individuals were presented with
visual stimuli in the form of photographs or films, while their responses were
documented by the researchers. Individuals experiencing depression exhibited typical
responses to negative or threatening portrayals, yet demonstrated infrequent displays of
positive affect, such as smiling, in response to comedic or pleasant imagery.
Research on twins and adopted individuals suggests that depression has a
moderate level of heritability. The etiology of depression cannot be solely attributed to
genetic factors. Multiple research studies have reported heightened immune system
activity, which may be triggered by factors such as physical trauma, high levels of stress,
inadequate dietary intake, or other related factors.
Antidepressant medications are classified into distinct categories, namely
tricyclics, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and
atypical antidepressants. Tricyclic antidepressants, such as imipramine (marketed as
Tofranil), function by inhibiting the transporter proteins responsible for the reuptake of
serotonin, dopamine, and norepinephrine into the presynaptic neuron subsequent to their
release. The process by which the serotonin transporter protein retrieves a serotonin
molecule from outside the membrane and subsequently transports it to the interior of the
neuron. According to Penmatsa, Wang, and Gouaux (2013) and H. Wang et al. (2013), a
particular tricyclic medication has the ability to immobilize the transporter in its original
position, as depicted on the left side of the illustration. The outcome is to extend the
duration of the neurotransmitters' existence within the synaptic cleft, thereby sustaining
their stimulation of the postsynaptic cell. According to Horst and Preskorn (1998),
tricyclics have the ability to inhibit histamine receptors, acetylcholine receptors, and
specific sodium channels. The inhibition of histamine results in somnolence. The
inhibition of acetylcholine results in xerostomia and urinary retention. The inhibition of
sodium channels results in cardiac arrhythmias and other associated complications.
It is recommended that individuals restrict their utilization of tricyclic drugs in
order to mitigate the associated adverse effects. Selective serotonin reuptake inhibitors
(SSRIs) are a class of drugs that share similarities with tricyclic antidepressants, but are
specifically designed to target the neurotransmitter serotonin. According to Coleman,
Green, and Gouaux (2016), the serotonin transporter protein is inhibited by the
attachment of certain molecules to its center, which results in a conformational change
that hinders the binding of serotonin to it. Selective serotonin reuptake inhibitors (SSRIs)
are associated with comparatively less severe adverse effects in comparison to tricyclic
antidepressants. However, their efficacy is similar. Selective serotonin reuptake inhibitors
(SSRIs) are a class of drugs that are commonly prescribed for the treatment of depression
and anxiety disorders.
Examples of SSRIs include fluoxetine, which is marketed under the trade name
Prozac, sertraline (Zoloft), fluvoxamine (Luvox), citalopram (Celexa), and paroxetine
(Paxil or Seroxat). Serotonin norepinephrine reuptake inhibitors (SNRIs) are a class of
drugs that inhibit the reuptake of both serotonin and norepinephrine. Examples of SNRIs
include duloxetine (Cymbalta) and venlafaxine (Effexor). In contrast to alternative
antidepressant medications, SNRIs have been shown to enhance specific facets of
memory. It has been observed that a considerable number of patients are currently
administered with multiple medications that exhibit distinct modes of action. However,
the efficacy of this therapeutic strategy remains ambiguous, as per Millan's (2014)
findings. Monoamine oxidase inhibitors (MAOIs) such as phenelzine, commercially
known as Nardil, function by obstructing the activity of monoamine oxidase (MAO), a
presynaptic enzyme that breaks down catecholamines and serotonin into inactive forms.
The inhibition of the enzyme by MAOIs results in an increased availability of transmitter
for release at the presynaptic terminal.
The category of atypical antidepressants encompasses all antidepressant
medications that are not included in the aforementioned types, as stated by Horst and
Preskorn in 1998. An instance of such a pharmacological agent is bupropion
(Wellbutrin), which functions by impeding the reuptake of dopamine and to a certain
degree, norepinephrine, while not affecting serotonin. Despite variations in the targeted
neurotransmitter(s) such as serotonin, dopamine, norepinephrine, or a combination
thereof, all antidepressants seem to exhibit comparable efficacy.
One of the primary theoretical challenges pertains to the temporal aspect of
antidepressant medication. While these drugs typically affect neurotransmitters within
synapses in a matter of minutes to hours, the manifestation of significant mood
improvement in individuals generally requires a minimum of two weeks of drug
administration. The present state of neurotransmitter levels does not provide a sufficient
explanation for the occurrence of depression or the therapeutic effects of medications.
The generation of fresh neurons in the hippocampus, which is linked to novel
learning, seems to hold significance for the therapeutic effects of antidepressants.
According to Airan et al. (2007), the inhibitory effects on neuron production have a
corresponding impact on the behavioral advantages of antidepressant medications. The
significance of novel learning could potentially elucidate the reason why individuals who
are not experiencing depression do not experience an elevation in mood upon taking
antidepressants. This is due to the absence of negative thoughts that require unlearning,
as posited by Castrén and Rantamäki (2010). The genesis of fresh neurons does not
provide a comprehensive rationale for the efficacy of antidepressant medications, given
that these medications also elicit crucial impacts on fully developed hippocampal
neurons.
Empirical research indicates that antidepressants exhibit a moderate level of
efficacy in comparison to placebos, as per the majority of controlled studies. However, it
is noteworthy that the potency of placebos is robust and seemingly escalating in
contemporary times. Despite statistical significance, the clinical advantage of
antidepressants over placebos may be minimal, and studies suggest that these medications
have limited impact on reducing suicide rates. The Hamilton Depression Rating Scale is
represented on the horizontal axis, with higher scores indicating greater severity of
depression. The y-axis denotes the magnitude of enhancement. In the study, patients who
were administered the drug were represented by triangles, while patients who received a
placebo were represented by circles. The magnitude of the triangle or circle is directly
proportional to the quantity of patients within a given cohort. Placebos have been
observed to elicit positive responses in individuals, which may be attributed to either
natural recovery over time or the psychological expectation that arises from the act of
ingesting a pill. In the case of patients exhibiting mild to moderate depression, the
outcomes observed in placebo cohorts exhibit a degree of overlap with those of drug
cohorts, and the distinctions between these groups appear to be of insufficient magnitude
to be deemed significant. The drugs exhibited a significant advantage solely for
individuals with severe depression.
Cognitive behavioral therapy and various other modalities of psychotherapy have
demonstrated efficacy in promoting positive outcomes. According to Bortolotti et al.
(2008), evaluations of the research literature indicate that both antidepressant medication
and psychotherapy are similarly efficacious in addressing depression across all degrees of
severity, ranging from mild to severe. It is worth noting that a significant portion of the
observed response to antidepressant medication can be attributed to the placebo effect.
By extension, it stands to reason that a similar phenomenon may be at play in the context
of psychotherapeutic interventions. The overlapping effects of antidepressants and
psychotherapy are more significant than anticipated. According to studies conducted by
Brody et al. (2001) and S. D. Martin et al. (2001), it has been observed that both
antidepressants and psychotherapy have a similar effect of increasing metabolism in
specific areas of the brain as revealed by brain scans. If we adhere to the concept of
mind-body monism, it is not particularly unexpected that such a resemblance exists. If
mental activity is equivalent to brain activity, then altering an individual's thoughts
should result in a corresponding modification in brain chemistry. Psychotherapy
possesses an advantage over other forms of treatment due to its potential for enduring
effects. Research suggests that the probability of experiencing a relapse into depression is
higher following antidepressant medication treatment compared to psychotherapeutic
interventions.
An alternative therapeutic approach, albeit with a tumultuous past, is
electroconvulsive therapy (ECT), which involves the induction of seizures through
electrical stimulation. The genesis of Electroconvulsive Therapy (ECT) can be traced
back to the observation that individuals suffering from both epilepsy and schizophrenia
exhibit a negative correlation between the exacerbation of symptoms of one disorder and
the amelioration of symptoms of the other. During the 1930s, Ladislas Meduna and other
medical professionals endeavored to alleviate symptoms of schizophrenia through the
administration of a substantial insulin dosage, which would induce convulsions. The
experience of insulin shock is distressing and challenging to manage. Ugo Cerletti, an
Italian medical practitioner, devised a technique for triggering seizures by means of an
electric shock administered through the cranium, following extensive experimentation
with animals. Electroconvulsive therapy is a rapid medical procedure, wherein the
majority of patients regain consciousness in a tranquil state without any recollection of
the event.
According to Leppämäki, Partonen, and Lönnqvist (2002), a program of regular,
moderate-intensity exercise is the most cost-effective and uncomplicated form of
treatment for depression. Empirical investigations have substantiated limited but
discernible therapeutic advantages of antidepressants, particularly among individuals
aged 60 years and above. According to Miller and Krizan's (2016) research, engaging in
the activity of walking has the potential to enhance one's positive affect. The utilization
of exercise is most effective when employed as a complementary measure to other forms
of treatment, as opposed to being utilized as a standalone therapeutic intervention.
The majority of individuals who experience depression exhibit disturbances in
their sleep patterns, with these disruptions typically occurring prior to the onset of mood
alterations. Numerous studies have indicated that individuals who experience difficulties
with sleep are at an elevated risk for developing depression at a later stage. Individuals
with depression typically exhibit a sleep pattern akin to that of healthy individuals who
have traversed a few time zones to the west. Individuals exhibit a tendency to initiate
sleep at the prescribed time, yet experience an accelerated onset of rapid eye movement
(REM) sleep and premature awakening. What is the impact of staying awake throughout
the night on one's physical and mental state the following morning? The majority of
individuals experience feelings of lethargy and irritability. According to Benedetti and
Colombo (2011), a significant number of individuals diagnosed with depression
experience a notable improvement in their symptoms. It is conceivable that this therapy
was fortuitously stumbled upon. It is difficult to conceive of any rational justification for
attempting it.
Notwithstanding the prompt amelioration, the advantages of sleep deprivation are
transient, given that depressive symptoms typically resurface following the subsequent
night's sleep. An alternative method involves modifying the sleep pattern by advancing
the bedtime by several hours in comparison to the customary routine. If an individual's
circadian rhythm is altered, it may be beneficial to adjust their sleep schedule to align
with their rhythm by sleeping earlier. The individual subsequently obtains a standard
duration of sleep with regular occurrence of rapid eye movement (REM) sleep.
According to Riemann et al. (1999), this particular method typically provides prompt
relief from depression, and its advantages persist for a duration of one week or beyond.
Subsequently, the circadian rhythm undergoes a shift, akin to the individual having
traversed a few more time zones towards the west without making any corresponding
adjustments. To date, the practice of phase-advancing the sleep schedule has not gained
widespread acceptance as a therapeutic intervention, potentially due to individuals' social
motivations for remaining awake beyond the early evening hours. The efficacy of sleep
deprivation or alteration in sleep patterns suggests a correlation between depression and a
misalignment of the circadian rhythm with the external environment. Empirical support is
derived from the occurrence of seasonal affective disorder (SAD), a form of depression
that reoccurs during a specific season, namely winter.
Depression can manifest as either unipolar or bipolar in nature. Individuals
diagnosed with unipolar depression exhibit fluctuations between periods of normal mood
and depressive episodes. Individuals diagnosed with bipolar disorder, previously referred
to as manic-depressive disorder, experience alternating episodes of depression and mania.
Mania is a state of being marked by heightened levels of activity, excitement, laughter,
excessive self-assurance, incoherent speech, and reduced restraint. Individuals with
bipolar disorder may experience either severe manic episodes, referred to as bipolar I
disorder, or milder hypomanic episodes, known as bipolar II disorder. Bipolar disorder
typically manifests during adolescence or early adulthood. Gender does not appear to be a
significant factor in the prevalence of bipolar disorder, however, research suggests that
men may be more susceptible to severe bipolar I cases while women may be more likely
to seek treatment.
Lithium salts remain the primary and efficacious treatment for bipolar disorder,
having been the first to demonstrate success in its management. The therapeutic
properties of lithium were serendipitously uncovered by J. F. Cade, an Australian
researcher, who hypothesized that uric acid could potentially alleviate symptoms of
manic and depressive episodes. Cade administered a solution to patients by combining
uric acid, a constituent of urine, with a lithium salt to facilitate its dissolution. The
information provided proved to be beneficial; however, subsequent investigations
revealed that the efficacious agent was lithium, rather than uric acid.
Additional pharmaceuticals utilized for this purpose include anticonvulsants such
as valproate (known commercially as Depakene, Depakote, among others) and
carbamazepine. In cases where the efficacy of these drugs is not optimal, medical
practitioners may opt to complement them with antidepressants or antipsychotics, which
are also commonly prescribed for schizophrenia. Antidepressant medications carry a
certain degree of risk, as they may elicit a transition from a depressive state to a manic
state. Although antipsychotic medications can be beneficial in treating certain conditions,
they can also elicit adverse effects that are undesirable.
F. Schizophrenia
The term "dementia praecox," which translates to "premature mental
deterioration" in Latin, was the initial designation for the mental disorder now known as
schizophrenia. The term schizophrenia was introduced by Eugen Bleuler in 1911. Despite
the Greek origin of the term "split mind," it is not associated with dissociative identity
disorder, a condition characterized by the presence of multiple personalities that an
individual alternates between. Bleuler's conception of schizophrenia referred to a division
between affective and cognitive dimensions of human experience. The individual's affect
appears to be dissociated from present circumstances. Instances of inexplicable laughter
or tears, or a lack of response to positive or negative information, may be observed in
some individuals. The concept of emotional detachment from cognitive processes is no
longer regarded as a primary characteristic of schizophrenia, however, the terminology
persists. As per the DSM-5 guidelines established by the American Psychiatric
Association in 2013, an individual must exhibit a decline in their daily functioning
(including but not limited to work, interpersonal relationships, and self-care) for a
minimum of six months, without any underlying cause attributable to other disorders, in
order to receive a diagnosis of schizophrenia.
The individual is required to exhibit a minimum of two symptoms from the
enumerated list, with at least one symptom being present from the initial three. Delusions,
which refer to beliefs that lack justification, can manifest in various forms such as the
conviction that extraterrestrial entities are manipulating one's actions. Hallucinations, on
the other hand, are false sensory experiences that can occur in the absence of external
stimuli, such as the perception of auditory stimuli like voices when an individual is alone.
The individual exhibits a pattern of speech that lacks organization, characterized by
rambling or incoherent expression. The individual exhibits behavior that is severely
disorganized. Individuals may exhibit deficiencies in emotional expression, speech, and
socialization.
The initial four elements enumerated, namely delusions, hallucinations,
disorganized speech, and disorganized behavior, are categorized as positive symptoms,
denoting the presence of behaviors that ought to be absent. Negative symptoms in
schizophrenia refer to the absence of behaviors that are typically present in healthy
individuals, such as weak emotional expression, speech, and socialization. Typically,
negative symptoms exhibit a stable pattern over time and present a challenge for effective
treatment.
Huntington's disease is classified as a genetic disorder. Analysis of a specific
segment of chromosome 4 enables a highly accurate prediction of an individual's
likelihood of developing the disease. Previously, numerous scholars held the belief that
schizophrenia could potentially be classified as a genetic disorder in a similar manner.
Nevertheless, the growing body of evidence suggests that it is not contingent upon any
individual gene. The likelihood of an individual developing schizophrenia is positively
correlated with their degree of biological relatedness to an individual with schizophrenia.
In addition, Kendler (1983) found that monozygotic twin pairs who were initially
unaware of their monozygotic status exhibited greater concordance than twin pairs who
were aware of their monozygotic status but were actually dizygotic. The significance of
monozygotic status outweighs the significance of being perceived or managed as
monozygotic.
The prevalence of schizophrenia in biological relatives is higher than that in
adopting relatives for adopted children who develop the disorder. According to Kety et
al. (1994), a study conducted in Denmark revealed that 12.5 percent of the immediate
biological relatives were diagnosed with schizophrenia, whereas none of the adopting
relatives were found to have the disorder.
The neurodevelopmental hypothesis posits that during the prenatal or neonatal
period, genetic, environmental, or combined factors can result in anomalies in the
developing brain. Although these anomalies may not be the direct cause of schizophrenia,
they render the brain susceptible to other disruptions during crucial developmental stages
in childhood or adolescence. The aforementioned disruptions may encompass traumatic
occurrences, viral contagions, inadequacies in dietary intake or allergic reactions,
exposure to hazardous chemicals, and other potential sources of harm. According to
Fatemi and Folsom (2009) and Weinberger (1996), the accumulation of an effect has the
potential to alter brain function, and subsequently, behavior.
According to Torrey et al. (2012), the etiology of schizophrenia is multifactorial,
involving both genetic and environmental factors. The researchers differentiated between
environmental factors that pose intermediate risk and those that pose low risk. No factor
was deemed significant enough to qualify as a high-risk factor. An additional proposition
regarding prenatal influences is presented through the season-of-birth effect, which
denotes a proclivity for individuals born during winter to exhibit a marginally higher
likelihood of developing schizophrenia in comparison to those born during other seasons.
The aforementioned inclination is particularly accentuated in regions located at
significant distances from the Earth's equatorial line.
The research conducted by van Erp et al. (2016) has identified certain anomalies
in the anatomy of the brain, particularly in the hippocampus, amygdala, and thalamus,
which are characterized by below-average levels of gray matter. The studies conducted
by Kochunov and Hong (2014), Meyer-Lindenberg (2010), Wolkin et al. (1998), and
Wright et al. (2000) have reported a reduction in white matter and enlargement of
ventricles in the brain. According to Spoletini et al. (2011), there is a prevalence of minor
abnormalities in subcortical areas. According to Meier et al. (2013), the presence of
irregularities in the retinal blood vessels indicates suboptimal cerebral blood flow.
However, the deviations observed are relatively moderate in comparison to those evident
in individuals with Alzheimer's disease or numerous other ailments. The average
reduction in brain volume is approximately 5%, and a significant proportion of
individuals exhibit negligible or no anatomical irregularities.
Prior to the advent of antipsychotic medications in the mid-1950s, individuals
diagnosed with schizophrenia were typically institutionalized in mental health facilities
with limited prospects for remission. Presently, the utilization of medications and
outpatient treatment has resulted in a significant reduction in the occupancy rates of
mental hospitals. During the 1950s, psychiatrists made a significant discovery that
chlorpromazine, also known as Thorazine, has the ability to alleviate the positive
symptoms of schizophrenia in a majority of patients, albeit not all. Subsequent to the
initial discovery, scientists identified additional antipsychotic medications, also known as
neuroleptic drugs, which exhibit a tendency to alleviate symptoms associated with
schizophrenia and related disorders. These medications belong to two distinct chemical
families: the phenothiazines, such as chlorpromazine, and the butyrophenones, such as
haloperidol (commercially known as Haldol).
The gradual development of behavioral benefits resulting from the use of any of
these drugs occurs over a period of several weeks. The recurrence of symptoms following
the discontinuation of treatment is variable and unpredictable. The study conducted by
the researchers involved the determination of the average dose administered to patients
diagnosed with schizophrenia for each drug. This information was presented on the
horizontal axis. Additionally, the amount of the drug required to obstruct dopamine
receptors was also determined and displayed on the vertical axis. Medications exhibiting
the highest efficacy in treating schizophrenia, and thus administered in minimal dosages,
are those that demonstrate the greatest potency in inhibiting dopamine receptors.
The aforementioned discovery served as the impetus for the development of the
dopamine hypothesis of schizophrenia, which posits that the condition arises from an
overabundance of activity at dopamine synapses located in specific regions of the brain.
While the overall concentration of dopamine in the brain remains normal, there is an
elevation in dopamine release in the basal ganglia, particularly in reaction to stressful
occurrences. Additional evidence in favor of the dopamine hypothesis is derived from the
observation that prolonged misuse of amphetamine, methamphetamine, or cocaine, all of
which elicit an elevation of dopamine levels at the synapses, can result in the
development of substance-induced psychotic disorder, which is typified by the presence
of hallucinations and delusions. LSD, a substance that induces psychotic symptoms, is
primarily recognized for its impact on serotonin synapses, although it also elicits
stimulation of dopamine synapses.
The human brain is known to possess multiple dopamine pathways that serve
distinct physiological roles. The therapeutic effects of dopamine synapse inhibitors are
mediated through their interaction with neurons in the mesolimbocortical system, which
are responsible for transmitting signals from the midbrain to the prefrontal cortex and
limbic system. Nonetheless, it should be noted that these pharmaceutical substances also
impede the activity of dopamine neurons located in the mesostriatal system, which
subsequently transmits signals to the basal ganglia. According to Kiriakakis, Bhatia,
Quinn, and Marsden (1998), tardive dyskinesia (TARD-eev dis-kih-NEE-zhee-uh) is a
condition that results from the impact on the basal ganglia, and it is characterized by
gradual development of tremors and other involuntary movements that vary in severity
among patients. According to Kiriakakis et al. (1998), the manifestation of tardive
dyskinesia may persist even following discontinuation of the medication. Thus, the
optimal approach is to proactively avoid its initiation.
According to Carbon, Hsieh, Kane, and Correll's (2017) research, a specific
category of medications known as second-generation antipsychotics, or atypical
antipsychotics, have been found to decrease the likelihood of experiencing movement-
related issues from 30 percent to 20 percent. Clozapine, amisulpride, risperidone,
olanzapine, and aripiprazole are among the most frequently used drugs in this category.
The dopamine hypothesis, although widely accepted, presents an incomplete
understanding of the pathophysiology of schizophrenia, as a significant proportion of
patients exhibit resistance to dopamine-blocking medications. The glutamate hypothesis
of schizophrenia posits that a deficiency in glutamate synaptic activity in the prefrontal
cortex is partly responsible for the condition. Dopamine has been observed to exert
inhibitory effects on glutamate release in various regions of the brain, while in other
areas, glutamate has been found to activate neurons that subsequently inhibit dopamine
release. Thus, an elevation in dopamine levels may elicit comparable outcomes to a
reduction in glutamate levels. Research has consistently demonstrated a reduction in
glutamate release within the prefrontal cortex among individuals diagnosed with
schizophrenia. Additional evidence in favor of the glutamate hypothesis is provided by
the impact of phencyclidine (PCP), a substance that suppresses the NMDA glutamate
receptors. When administered in small quantities, it induces a state of inebriation and
impairs the ability to articulate clearly. At higher dosages, the substance elicits both
favorable and unfavorable manifestations of schizophrenia, such as perceptual
distortions, cognitive impairment, affective flattening, and amnesia.
G. Autism Spectrum Disorders
Previously, mental health professionals employed the terminology Asperger's
syndrome to describe individuals with a mild form of impairment akin to autism.
However, given that the distinction between Asperger's syndrome and autism is primarily
one of severity, the updated nomenclature of autism spectrum disorder amalgamates the
two conditions. Within this module, the term autism is utilized for the sake of brevity.
However, it is important to acknowledge that this term encompasses a broad spectrum of
disorders. The prevalence of autism in males is approximately four times higher than in
females. According to Turner et al. (2015), the severity of the condition tends to be
higher in females when it does occur. According to Elsabbagh et al. (2012), Autism
Spectrum Disorder (ASD) is a global phenomenon, and there is currently no compelling
evidence to suggest that its incidence differs based on geographical location, ethnicity, or
socioeconomic status. According to the American Psychiatric Association (2013), autism
spectrum disorder is characterized by the following important features: The observed
characteristics include deficiencies in social and emotional reciprocity, deficits in
nonverbal communication such as gestures and facial expressions, stereotyped behaviors
such as repetitive movements, resistance to changes in routine, and atypical responses to
stimuli, such as either indifference to pain or an exaggerated reaction to a sound.
According to de la Torre-Ubieta, Won, Stein, and Geschwind (2016), autism can
be caused by numerous uncommon genes, but the cumulative effect of these genes is
responsible for only approximately 5% of cases. Aoki and Cortese (2016) have identified
a mutation in a mitochondrial gene. According to Harris (2016), Sanders et al. (2015),
and Tian et al. (2015), it has been observed that newly occurring mutations are
accountable for at least 10 percent of the cases. Krishnan et al. (2016) have reported that
despite the vast number of potential mutations associated with autism, their impact is
concentrated on a limited number of biochemical pathways that influence the initial
stages of brain development. Investigating these pathways may shed light on the
underlying mechanisms of autism. Through the analysis of the genetic material flanking a
novel mutation and subsequent comparison with the parental chromosomes, scholars can
deduce the parental origin of the mutation or ascertain its de novo occurrence.
The majority of autism cases are observed on paternal chromosomes, and
advanced paternal age is associated with a slightly higher likelihood of autism in
offspring. Similarly, this holds true in the context of schizophrenia. According to Lee and
McGrath (2015), the reason behind the older-father effect can be attributed to the fact that
women produce all their egg cells at an early stage in life, while men continue to generate
new sperm throughout their lifetime, leading to the accumulation of mutations. The
prenatal environment has been identified as a potential contributing factor to the
development of autism. It is worth noting the parallel to schizophrenia.
None of the available medical interventions effectively address the core issues of
diminished social interaction and communication. The administration of Risperidone, a
second-generation antipsychotic medication, has been observed to potentially decrease
stereotyped behaviors, albeit with the possibility of significant adverse reactions.
According to Han et al. (2012) and Novarino et al. (2012), there are instances where
autism can be attributed to a genetic mutation that may potentially be remedied through
chemical intervention. Theoretically speaking, that statement holds true. There have been
no reported instances of implementing this approach. Behavioral interventions aim to
target the deficiencies in social interaction and communication. The attention of the child
is often elicited and favorable behaviors are reinforced by parents, teachers, and
therapists. This methodology has demonstrated efficacy with a considerable number of
juveniles, although it may not yield positive outcomes for every individual. The
management of stereotyped behaviors involves the implementation of interventions such
as reinforcement of alternative or competing behaviors.
