CHAPTER 11 & 12
EMOTIONAL BEHAVIORS AND LEARNING, MEMORY, AND
INTELLIGENCE
A. Emotion
1. Emotions and Autonomic Arousal
The two branches of the autonomic nervous system, namely the sympathetic
and the parasympathetic, are activated in response to emotional situations. It has been
acknowledged by researchers for a considerable period of time that the sympathetic
nervous system has the ability to activate specific organs, such as the heart, while
concurrently suppressing others, such as the stomach and intestines. The initial
identification of the pattern is attributed to Walter Cannon in 1945. The physiological
response to stress involves the activation of organs that are crucial for promoting a
state of heightened readiness for "fight-or-flight" behaviors, while simultaneously
suppressing non-essential vegetative activities that can be postponed until a later time.
The parasympathetic nervous system is responsible for enhancing digestive processes
and other physiological functions that conserve energy and facilitate preparation for
future events.
However, it is commonly observed that a majority of situations elicit a
concomitant activation of both the sympathetic and parasympathetic nervous systems
(Wolf, 1995). Nausea is correlated with sympathetic activation of the stomach, which
results in a reduction of its contractions and secretions, as well as parasympathetic
activation of the intestines and salivary glands. Danger is commonly associated with
eliciting sympathetic activity, however, this is not always the case. When a
diminutive creature perceives a potential predator from a significant distance, it
assumes a state of heightened awareness, yet remains physically inert. An immobile
animal is less likely to be detected by a predator. The diminutive creature experiences
a reduction in heart rate as a result of parasympathetic stimulation. The activation of
the sympathetic nervous system occurs solely when the threat is in close proximity
and capable of initiating an attack. Likewise, individuals exhibit heightened vigilance
and reduced physiological activity, as evidenced by decreased heart rate, in response
to a perceived threat that is either temporally or spatially distant.
Individuals diagnosed with a rare medical condition known as pure
autonomic failure experience a failure of autonomic nervous system output to the
body, which may be partial or complete. Although the heart continues to beat and
other organ activities persist, the nervous system ceases to regulate them. Individuals
afflicted with this particular condition exhibit an absence of physiological responses,
such as alterations in heart rate, blood pressure, or perspiration, in reaction to stressful
stimuli. As per the James-Lange theory, individuals in such a scenario are anticipated
to exhibit a lack of emotional response. Indeed, the individuals under consideration
indicate experiencing emotions that are comparable to those of the general
population. Additionally, they exhibit minimal challenges in accurately discerning the
emotional state that a character in a narrative would likely undergo.
As per the James-Lange theory, emotional experiences are a consequence of
bodily responses. If an individual experiences an increase in heart rate, perspiration,
and respiration, would this elicit an emotional response? This statement does not
necessarily hold true. The aforementioned symptoms may arise as a result of intense
physical activity or may coincide with a febrile illness. In the event of an abrupt and
heightened activation of the sympathetic nervous system in the absence of a
discernible cause, it is plausible that one may perceive it as an emotional response. As
Klein (1993) notes, individuals experiencing a panic attack may exhibit symptoms
such as gasping for air, feeling as though they are suffocating, and experiencing
heightened levels of anxiety. While physiological responses are often inadequate.
The limbic system, which encompasses the forebrain regions surrounding the
thalamus, has conventionally been considered crucial for emotional processing. Later
in this chapter, we will delve into a more detailed analysis of a specific component of
it, namely the amygdala. A significant portion of the cerebral cortex exhibits
reactivity towards emotional stimuli. PET or fMRI techniques have been employed
by researchers to identify the specific brain regions that exhibit activity when
individuals view emotional images or listen to emotional narratives. The outcomes
seem to rely heavily on the intricacies of the methodology rather than the specific
emotion that was the focus of the study. According to a study conducted by Wang et
al. (2014), certain neurons in the amygdala have been identified as being specialized
in perceiving a specific emotion conveyed through facial expressions. However, it is
noteworthy that, except for happiness, no particular brain region has been found to be
exclusively responsible for experiencing any specific emotion.
The identification of distinct brain regions for each emotion would be
considered compelling evidence in support of the concept of basic emotions.
However, as previously noted, empirical investigations have failed to yield any
substantiation for this notion. The primary evidence in favor of the concept of
fundamental emotions is the presence of distinct facial expressions corresponding to
emotions such as joy, sorrow, apprehension, rage, revulsion, astonishment, and
conceivably other emotional states. Cultural familiarity bias presents a challenge
whereby individuals tend to identify and comprehend expressions from their own
cultural background more accurately than those from other cultures.
The left hemisphere's activity, particularly in its frontal and temporal lobes, is
associated with the behavioral activation system (BAS) as described by Jeffrey Gray
(1970). This system is characterized by low to moderate autonomic arousal and a
propensity to approach, which may manifest as either happiness or anger. The
augmentation of the frontal and temporal lobes of the right hemisphere has been
linked to the behavioral inhibition system (BIS), which amplifies attentiveness and
arousal, restrains action, and triggers emotions such as fear and disgust.
2. The Functions of Emotion
In the case of specific emotions, a definitive solution can be identified. The
emotion of fear serves as a mechanism to signal the need for individuals to take
action in order to avoid potential harm or perilous situations. The emotion of anger
serves as a mechanism to prompt individuals to engage in defensive actions against
perceived threats or intrusions. The emotion of disgust serves as a mechanism to deter
individuals from engaging with stimuli that may potentially lead to illness. The
potential evolutionary benefits of emotions such as happiness, sadness, and
embarrassment are not immediately apparent, however, scholars have posited
plausible explanations. The utilization of emotional expressions facilitates effective
communication of personal needs and comprehension of the needs and potential
actions of others. Moreover, affective states offer a valuable compass in situations
that require prompt decision-making.
Undoubtedly, it holds true that emotions can at times impede the process of
making sound decisions. In the event of encountering a patch of ice while driving,
what actions would you take to address the resulting skid? According to Shiv,
Loewenstein, Bechara, Damasio, and Damasio (2005), an individual who had
incurred damage to their prefrontal cortex exhibited a composed demeanor when
confronted with a similar circumstance, adhering to the conventional wisdom of
easing off the accelerator and turning the steering wheel in the direction of the skid.
The majority of individuals experiencing this circumstance tend to exhibit a state of
panic, apply the brakes abruptly, and maneuver the vehicle in a direction opposite to
the skid, thereby exacerbating the unfavorable condition.
B. Attack and Escape Behaviors
1. Attack Behaviors
The manifestation of aggressive conduct is contingent upon both the unique
characteristics of the person and the contextual circumstances. When a hamster
encroaches upon the territory of another hamster, the resident hamster engages in
olfactory investigation before initiating an attack, typically not immediately.
Assuming that the initial intruder departs, subsequently, another hamster infiltrates
the area. The domesticated hamster exhibits heightened levels of aggression and
swiftness in its attacks compared to previous behavior. According to Potegal's
research in 1994, the initial attack of a domesticated hamster can increase its
preparedness to defend against potential intruders for a duration of at least 30
minutes. The initial assault appears to stimulate the hamster's inclination towards
combat. In the specified timeframe, there is a surge in activity within the
corticomedial region of the amygdala. This surge in activity subsequently heightens
the likelihood of the hamster engaging in an attack, as per findings by Potegal, Ferris,
Hebert, Meyerhoff, and Skaredoff (1996) and Potegal, Hebert, DeCoster, and
Meyerhoff (1996). Analogous occurrences take place in individuals. In instances
where a toddler's arm is restrained to deter play with a toy, the outcome may manifest
in vocal expressions of distress and other indications of emotional agitation. Upon
repetition after a 30-second interval, the level of anger experienced is observed to
escalate in both speed and intensity.
The manifestation of aggressive, violent, or antisocial behavior in individuals
is contingent upon both genetic and environmental factors, as is the case with most
psychological phenomena. Numerous environmental factors can be readily identified.
Individuals who have experienced childhood abuse, witnessed violent abuse between
their parents, or reside in a violent community exhibit a higher propensity for
engaging in violent behavior compared to the general population. An additional
variable to consider is the potential impact of lead exposure on the development of
the brain, as it has been shown to have detrimental effects. The decrease in violent
crime rates may be attributed to the reduction of lead in the environment, which could
be linked to the prohibition of lead-based paints and the increased use of unleaded
gasoline.
In the animal kingdom, male competition for mates is a common cause of
physical altercations, with aggressive behavior being largely influenced by
testosterone levels. Likewise, globally, males engage in physical altercations more
frequently than females, perpetrate a greater number of aggressive offenses, vocalize
more derogatory remarks towards each other, and the like. Additionally, it has been
observed that young adult males, who exhibit the highest levels of testosterone,
demonstrate the highest incidence of aggressive behaviors and involvement in violent
criminal activities. In the majority of cases, acts of violence perpetrated by women
tend to be less severe.
A significant portion of the initial evidence was derived from research
conducted on murine models. According to Valzelli's (1973) research, the act of
isolating male mice for a period of four weeks resulted in a notable increase in their
aggressive tendencies, while simultaneously leading to a decrease in their serotonin
turnover. Upon the release of serotonin by neurons, the majority of the
neurotransmitter is subsequently reabsorbed and synthesized in sufficient quantities to
compensate for the amount that was lost. The level of serotonin in neurons remains
relatively stable; however, by measuring the serotonin metabolites in bodily fluids,
we can assess the turnover rate, which indicates the quantity of serotonin that neurons
have released and replenished. Serotonin turnover is quantified by evaluating the
concentration of 5-hydroxyindoleacetic acid (5-HIAA), which is the primary
metabolite of serotonin, in the cerebrospinal fluid (CSF), as per the methodology
employed by researchers. Quantifying the concentration of a substance in bodily
fluids such as blood or urine represents a less complex albeit less precise option.
As per an increasingly prevalent viewpoint, the manifestation of aggressive
conduct does not exhibit a robust correlation with any singular chemical entity, as it is
contingent upon a confluence of factors. The hormone testosterone has been found to
promote aggressive, assertive, and dominant behavior, particularly when there is a
sudden increase in its levels. Serotonin has been observed to have an inhibitory effect
on impulsive behaviors. Furthermore, the hormone cortisol has been found to have
inhibitory effects on aggressive behavior. During times of stress and anxiety, the
adrenal gland releases cortisol, which induces a state of vigilance and energy
conservation.
2. Fear and Anxiety
The impact of loud noises on an individual's emotional response is contingent
upon their present disposition or circumstances, thereby rendering the acquisition of a
fear response to such stimuli as optional. The intensity of the startle reflex is
heightened in individuals who are already experiencing tension. According to Grillon,
Morgan, Davis, and Southwick's (1998) research, individuals diagnosed with post-
traumatic stress disorder exhibit an increased startle reflex. According to McMillan,
Asmundson, Zvolensky, and Carleton (2012), individuals who exhibit high levels of
anxiety, even if they do not meet the criteria for a psychiatric diagnosis, may still
report experiencing significant symptoms. In brief, there exists a strong correlation
between anxiety and variations in the startle reflex, thereby enabling the utilization of
the startle reflex as a metric for assessing anxiety levels.
The potential impact of that statement should not be underestimated. The
measurement of other types of emotions poses a challenge to research efforts. In the
pursuit of happiness, scholars predominantly rely on self-reports, the reliability of
which is subject to scrutiny. The validity of smiles as indicators of happiness is
limited, as individuals may exhibit smiling behavior without experiencing genuine
happiness, or conversely, experience happiness without displaying a smile. There is
currently a lack of a suitable methodology to quantify the level of contentment
experienced by animals that are not of the human species. In certain instances,
scholars may opt to observe physical altercations as a means of gauging levels of
anger. However, it is important to note that engaging in a physical altercation does
not necessarily indicate the presence of anger, nor does the absence of physical
aggression preclude the possibility of experiencing anger. Facial expressions have a
limited degree of validity as indicators of anger.
Numerous connections that underlie the effects of the amygdala have been
elucidated by researchers. The lateral and basolateral areas of the amygdala receive a
significant amount of sensory input, particularly from the visual and auditory
systems. This information is then transmitted to the central amygdala, where it is
integrated with pain and stress-related information received from the thalamus, as
reported by Penzo et al. (2015). According to Herry and Johansen (2014), the
acquisition of a fear response leads to the reinforcement of synapses at multiple
points along the neural pathway involved in this process. According to Abrabos et al.
(2013), a particular breed of mice that exhibits enhanced connectivity between the
lateral and central amygdala regions is associated with increased anxiety levels in
various circumstances. The potential significance of such a correlation in relation to
variations in human fears and anxieties warrants consideration.
According to Gross and Canteras' (2012) research, the amygdala of laboratory
animals can be stimulated or damaged to identify distinct pathways responsible for
different types of fear. Specifically, one pathway is associated with fear of pain,
another with fear of predators, and a third with fear of aggressive individuals within
the same species. According to Kim et al. (2013), the amygdala is comprised of
distinct regions that regulate various functions, such as respiratory changes,
avoidance of hazardous environments, and acquisition of knowledge regarding safe
locations. According to Tovote et al. (2016) and Viviani et al. (2011), the neural
pathway associated with the freezing response to perceived threats in the amygdala is
distinct from the pathway regulating alterations in heart rate. The aforementioned
discoveries hold significance for psychological frameworks concerning emotions, as
they illustrate that the construct commonly referred to as fear is comprised of distinct
components rather than a unified and indivisible state.
The amygdala plays a crucial role in the acquisition of fear towards a specific
stimulus, albeit not the sole form of fear conditioning. When a rat is subjected to
electric shocks following a specific stimulus within a particular cage, it acquires a
fear response towards the stimulus, which is manifested through alterations in the
amygdala. However, the rat also develops a fear response towards the cage, as well as
novel cages and situations. This holds true for human beings. Individuals who have
experienced an attack may develop a heightened sense of fear towards stimuli
associated with the traumatic event, as well as an increased level of general fear
across a range of circumstances. The brain appears to have made a determination that
the world is fraught with peril. It is imperative for me to remain vigilant and aware of
any potential emerging hazards. The enduring and non-specific emotional activation
is contingent upon the neural region known as the bed nucleus of the stria terminalis,
as per the research conducted by Duvarci, Bauer, and Paré (2009) and Toufexis
(2007). The stria terminalis comprises a bundle of neural fibers that establish a
connection between the bed nucleus and the amygdala.
There exists a strong correlation between amygdala activity and individual
variations in anxiety. During a particular research, a group of undergraduate students
were instructed to carry a device that emitted random beeps throughout the day for a
period of 28 days. The students were required to document their emotional state at the
time of each beep. Subsequent to one year, the participants arrived at a laboratory for
the second phase of the investigation, wherein functional magnetic resonance imaging
(fMRI) technology was employed to measure their amygdala's reaction to momentary
exposure to alarming visual stimuli. According to Barrett et al. (2007), there exists a
significant correlation between the amygdala responses and the quantity of negative
emotions reported by the participants in the preceding year. It is conceivable that the
individual documented a plethora of negative emotions due to a potential innate
inclination to exhibit heightened reactivity.
Individuals afflicted with the uncommon genetic condition known as Urbach-
Wiethe disease experience a buildup of calcium in the amygdala, ultimately resulting
in its degeneration. Consequently, they exhibit significant amygdala impairment with
minimal damage to adjacent anatomical regions. Similar to primates exhibiting
Klüver-Bucy syndrome, these individuals display difficulties in processing affective
stimuli and acquiring fear responses. A significant portion of the scholarly
investigations pertaining to this particular medical condition center around an
individual identified by the initials SM, who self-reports as being devoid of fear and
consistently exhibits such behavior. Upon viewing 10 selected clips from the most
frightening films available, the subject reported experiencing solely a sense of
excitement, without any indication of fear, as per the researchers' findings.
The subject of the study was escorted to a retail establishment specializing in
uncommon fauna. Despite her aversion towards snakes and spiders, the subject
exhibited a contradictory behavior by willingly holding a snake. Moreover, the staff
had to intervene multiple times to prevent her from touching or agitating the
tarantulas and venomous snakes. During the experiment, the subject displayed a
fearless demeanor when navigating through a purportedly haunted dwelling,
confidently traversing dimly lit corridors. Upon encountering individuals garbed in
monstrous attire, some members of the group emitted vocalizations of fear. However,
SM responded with laughter, proceeded to inquisitively prod one of the costumed
individuals, and ultimately caused said individual to experience a state of fright. The
individual's lack of fear may pose a potential hazard to their well-being. The
individual in question has experienced instances of armed robbery and physical
violence, including assault with a firearm and a bladed weapon. It is apparent that she
engages in perilous circumstances without exercising the prudence that others would
exhibit. Upon recollection of these occurrences, the individual recalls experiencing a
sense of anger, yet not one of fear.
3. Anxiety Disorders
The prevalence of generalized anxiety among humans can be rationalized in
situations where one resides in a conflict-ridden area or has experienced a recent
assault. Anxiety disorders are characterized by a state of heightened anxiety that
appears to be disproportionate to the situation at hand. Panic disorder is typified by
recurrent episodes of anxiety and intermittent occurrences of tachypnea, heightened
heart rate, diaphoresis, and tremors, which denote marked activation of the
sympathetic nervous system. A significant aspect of the condition involves the
frequent experience of apprehension regarding the occurrence of subsequent panic
attacks. The apprehension towards the emotion of fear has the potential to render an
individual incapable of functioning. The prevalence of panic disorder is higher among
females as compared to males, and the incidence is significantly greater in the
younger age groups, particularly adolescents and young adults, as compared to the
older adult population.
It has been widely acknowledged that a significant number of soldiers exhibit
persistent anxiety and distress upon their return from combat. In the past, individuals
referred to the psychological condition as battle fatigue or shell shock. The
contemporary term used to describe the psychological condition characterized by
recurrent distressing recollections (flashbacks) and nightmares pertaining to a
traumatic event, avoidance of stimuli associated with the event, and intense reactions
to noises and other stimuli is post-traumatic stress disorder (PTSD) as described by
Yehuda in 2002. Post-traumatic stress disorder (PTSD) can manifest following
various distressing events, including but not limited to sexual assault and witnessing
acts of violence resulting in death. It is reasonable for an individual to experience a
temporary increase in anxiety following a traumatic event in which they have
survived. It can be posited that human beings have developed mechanisms to regulate
their anxiety levels in response to varying levels of perceived threat. Nonetheless, it is
worth noting that the manifestation of post-traumatic stress disorder (PTSD) is not
universal among individuals who have undergone a traumatic experience, and it is not
possible to prognosticate who will develop PTSD based on the magnitude of the
trauma or the intensity of the individual's initial response.
4. Relief from Anxiety
Individuals experiencing heightened levels of anxiety may opt for
pharmaceutical interventions as a means of alleviating their symptoms.
Benzodiazepines, including Valium, Librium, and Xanax, are the most frequently
prescribed anxiolytic medications. Benzodiazepines have the ability to bind to the
GABAA receptor, which comprises of a binding site for GABA and additional sites
that alter the GABA site's sensitivity. The brain exhibits additional types of GABA
receptors, namely GABAB, which elicit distinct behavioral outcomes.
The consumption of alcohol has been found to decrease anxiety levels by
modulating the activity of GABA receptors. According to Glykys et al. (2007), the
promotion of chloride ion flow through the GABAA receptor complex is facilitated
by alcohol, which binds strongly to a specific site present only on particular GABAA
receptors. According to Suzdak et al. (1986), the efficacy of Ro15-4513, an
experimental drug, is notable in its ability to obstruct the impact of alcohol on GABA
receptors. The compound Ro15-4513 has been observed to inhibit the impact of
alcohol on motor coordination, its depressive effects on the brain, and its capacity to
induce anxiety reduction.
C. Stress and Health
The concept of stress was popularized by Hans Selye in 1979. Selye defined stress
as the body's nonspecific response to any demand placed upon it. During his time in
medical school, Selye observed that patients with diverse illnesses exhibited similar
symptoms, such as fever, loss of appetite, lethargy, increased sleepiness, decreased
libido, and heightened immune system activity. Subsequently, during laboratory
experimentation, it was discovered that rats that were subjected to an injection of any
substance, as well as exposure to thermal stimuli, painful stimuli, restricted movement, or
visual stimuli of a feline nature, exhibited heightened cardiovascular activity, respiratory
rate, and adrenal gland secretions. Selye postulated that the activation of a generalized
stress response, which he termed the general adaptation syndrome, was triggered by any
bodily threat, and was primarily mediated by the adrenal glands, in addition to its specific
effects. During the first phase, referred to as the alarm stage, the release of epinephrine
hormone by the adrenal glands activates the sympathetic nervous system, which prepares
the body for short-term emergency response. The adrenal glands secrete cortisol, a
hormone that elevates blood glucose levels to augment the body's energy reserves, as well
as aldosterone, a hormone that plays a crucial role in regulating blood salt and volume. In
order to sustain energy for exigent tasks, the human body engages in a temporary
inhibition of less critical functions, including sexual arousal.
The activation of two bodily systems is observed in response to stress. The
sympathetic nervous system is responsible for triggering short-term fight-or-flight
reactions in the body. The HPA axis is comprised of three components, namely the
hypothalamus, pituitary gland, and adrenal cortex. The activation of the hypothalamus in
humans results in the secretion of adrenocorticotropic hormone (ACTH) by the anterior
pituitary gland. This hormone then stimulates the adrenal cortex to secrete cortisol, which
leads to an increase in metabolic activity, elevation of blood sugar levels, and heightened
alertness. Cortisol is commonly referred to as a stress hormone by numerous researchers
who utilize cortisol level measurements as a means to gauge an individual's recent stress
level. In contrast to the autonomic nervous system, the hypothalamic-pituitary-adrenal
(HPA) axis exhibits a relatively delayed response, yet it prevails in addressing the effects
of persistent stressors, such as enduring an abusive parent or partner.
The immune system comprises a variety of cells that safeguard the body against
various pathogens, including viruses, bacteria, and other foreign entities. The immune
system can be likened to a law enforcement agency, whereby a compromised state may
result in the proliferation of pathogenic agents, leading to deleterious effects. When the
immune response becomes excessively potent and non-discriminatory, it may initiate an
attack on "self" cells, which are typically law-abiding constituents of the body. The
phenomenon of the immune system targeting healthy cells is referred to as an
autoimmune disease. Myasthenia gravis and rheumatoid arthritis are classified as
autoimmune disorders.
The leukocytes, which are commonly referred to as white blood cells, are the
fundamental constituents of the immune system. There exist various classifications of
leukocytes, among which are B cells, T cells, and natural killer cells. It should be noted
that the aforementioned symptoms associated with illness are, in fact, a natural response
of the body's immune system to combat the illness. Fever and sleepiness are commonly
perceived as passive symptoms of illness, however, it is noteworthy that these
physiological responses are adaptive strategies that have evolved to combat the illness.
As expounded in Chapter 9, a mild pyrexia aids in combating numerous infections. Sleep
and physical inactivity are mechanisms for energy conservation, allowing the body to
allocate additional energy towards mounting an immune response against invading
pathogens. The reduction in appetite can potentially provide benefits by lowering the
demand for physical activity and by decreasing blood glucose levels, which is the
primary source of energy for numerous microorganisms.
The extent of the influence of the nervous system on the immune system may be
greater than initially perceived. The field of psychoneuroimmunology investigates the
interplay between experiences and the immune system, as well as the reciprocal impact of
the immune system on the central nervous system. Upon encountering a brief stressful
experience, the nervous system initiates a response that triggers the immune system to
augment its natural killer cell production and cytokine secretion. Elevated levels of
cytokines serve a dual purpose of combating infections while also activating
prostaglandins that ultimately reach the hypothalamus. When rats are exposed to
inescapable shocks, they exhibit symptoms that bear resemblance to illness, such as
lethargy, reduced appetite, and heightened body temperature. Maier and Watkins (1998)
have noted that individuals experiencing high levels of stress are similarly affected.
According to Stevenson et al. (2012), the immune system can be activated and body
temperature can be elevated by the mere act of viewing highly repulsive images. In brief,
individuals who experience high levels of stress and exhibit symptoms of fatigue or other
indications of illness may potentially be experiencing a response to stress that is mediated
by the immune system.
The response of individuals to a stressful encounter is influenced by their genetic
predispositions and prior experiences. The capacity to rebound effectively from a
distressing event, commonly referred to as resilience, is positively associated with robust
social backing, a positive outlook, and the reevaluation of challenging circumstances. The
aforementioned factors exhibit a correlation with the capacity to promptly initiate the
stress response and subsequently terminate it. According to Seery et al. (2013),
individuals who are able to effectively manage moderately stressful events are better
equipped to handle future stressors. Conversely, those who have experienced a significant
number of highly adverse events may be too fatigued to effectively cope with subsequent
stressors. Various techniques can be employed to regulate stress responses, such as
implementing specific breathing exercises, engaging in physical activity, practicing
meditation, and utilizing distraction methods. Additionally, addressing the root cause of
the stressor is also a crucial aspect of stress management.
The provision of social support is considered to be a highly effective strategy for
managing stress. According to Cohen, Janicki-Deverts, Turner, and Doyle's (2015) study,
individuals who receive hugs more frequently exhibit a decreased susceptibility to
infection. According to Murphy, Slavich, Chen, and Miller (2015), individuals who
experience feelings of rejection are at a heightened risk. According to Carey et al. (2014),
the mortality of cardiovascular diseases among elderly individuals significantly rises in
the months following the loss of their spouse. In a particular research investigation,
contentedly married females were subjected to moderately distressing electrical stimuli to
their ankles. In multiple trials, the participants held the hand of their spouse, an
unfamiliar male, or no individual. The act of holding the hand of one's spouse resulted in
a decrease in the neural activity as measured by fMRI in various regions of the brain,
such as the prefrontal cortex. According to Coan, Schaefer, and Davidson's (2006)
findings, the act of holding the hand of an unfamiliar male individual resulted in a slight
decrease in response, albeit not to the same extent as holding the hand of one's spouse.
Consistent with expectations, the neural reactions aligned with individuals' self-reported
experiences that receiving social support from an intimate partner mitigates stress.
D. Learning, Memory, and Memory Loss
Within the field of psychology, there has been a longstanding differentiation
between two primary forms of learning: classical conditioning and instrumental
conditioning. Ivan Pavlov, a Russian physiologist, conducted pioneering research on
classical conditioning, which is now commonly referred to as the process of pairing two
stimuli to alter the response to one of them. The experimental procedure commences with
the introduction of a conditioned stimulus (CS) that does not elicit any significant
response initially. Subsequently, the unconditioned stimulus (UCS) is presented, which
automatically triggers the unconditioned response (UCR). Following several iterations of
the pairing between the conditioned stimulus (CS) and the unconditioned stimulus (UCS),
an individual acquires a novel learned reaction to the CS, which is referred to as a
conditioned response (CR). Pavlov's initial experiments involved the presentation of a
conditioned stimulus (CS) in the form of a sound, followed by an unconditioned stimulus
(UCS) in the form of meat. This sequence elicited an unconditioned response (UCR) in
the dog, which manifested as salivation. Following numerous instances of such
associations, the auditory stimulus in isolation (CS) elicited a conditioned response of
salivation (CR) in the canine subject. In certain instances, the conditioned response bears
resemblance to the unconditioned response, although there are instances where this is not
the case. In the event that a rat is subjected to a conditioned stimulus (CS) in conjunction
with an aversive stimulus, the aversive stimulus triggers a response of vocalization and
locomotion, whereas the CS elicits a response of immobility.
Instrumental conditioning, which is also referred to as operant conditioning,
involves the association of a response with either a reinforcer or a punishment. A
reinforcer refers to any occurrence that enhances the likelihood of a response occurring in
the future. A punishment can be defined as an occurrence that reduces the likelihood of a
particular response. In instances where a rat navigates through one arm of a maze and
discovers Froot Loops cereal, a favored delicacy among rats, the rat subsequently
heightens its likelihood of selecting that particular arm during subsequent opportunities.
In the event of receiving a shock, the likelihood of occurrence decreases. The
fundamental distinction between classical and instrumental conditioning lies in the fact
that the former involves the occurrence of conditioned and unconditioned stimuli at
specific intervals, irrespective of the individual's conduct, while the latter hinges on the
individual's response, which determines the outcome in terms of reinforcement or
punishment. The aforementioned conduct is deemed beneficial for the purpose of
readiness towards the UCS.
According to Hebb (1949), it was postulated that a single mechanism could not
sufficiently explain all the learning phenomena. Rapid memory formation is evident in
the ability to promptly reproduce information that has just been presented. Elderly
individuals possess the ability to recollect past experiences from their early years,
indicating that certain memories may endure indefinitely. Hebb was unable to conceive
of a chemical mechanism that could sufficiently explain the rapid formation of immediate
memory while also maintaining the stability necessary for the establishment of permanent
memory. Consequently, he postulated a differentiation between the recollection of recent
events in short-term memory and the remembrance of events from a more distant past in
long-term memory.
The capacity of short-term memory and long-term memory exhibits a notable
distinction. When presented with a sequence of arbitrary characters or digits, such as
DZLAUV, it is likely that an individual's capacity for accurately reproducing the
sequence is limited to approximately seven items. Moreover, for other types of stimuli,
this maximum capacity is even lower. Long-term memory has the capacity to retain a
significant amount of information. Once an item is forgotten from short-term memory, it
is irretrievable. In the context of long-term memory, the utilization of a cue has the
potential to facilitate the retrieval of information that was previously believed to be
forgotten. As an illustration, endeavor to recall the identities of all your secondary school
instructors. Upon exhausting your ability to provide names, it is possible to further
identify individuals by reviewing photographs and being informed of the instructors'
initials.
In 1994, A. D. Baddeley and G. J. Hitch introduced the term "working memory"
as a replacement for the concept of short-term memory. This term refers to the process of
storing information while actively working with it. The delayed response task is a
prevalent assessment of working memory, requiring individuals to recall and respond to a
previously presented visual or auditory stimulus after a brief interval. Consider a scenario
where an individual fixates on a central point and is presented with a brief flash of light
in the peripheral visual field. The individual is instructed to fixate their gaze on the
central point for a brief duration, until an auditory signal is emitted, at which point they
are expected to redirect their attention towards the location where the visual stimulus was
previously perceived. This task has the potential to be adapted for implementation with
primates and other animal taxa. Throughout the period of latency, the individual must
retain a depiction of the stimulus. In the interim period, specific cells located in the
prefrontal and parietal cortex exhibit heightened levels of activity, with distinct cells
being activated contingent upon the intended direction of ocular movement.
Amnesia refers to the condition of experiencing a loss of memory. A patient
consumed two meals within a short interval, with a possible indication of having
overlooked the initial meal. Subsequently, after an additional duration of 20 minutes, he
proceeded to consume a third meal and ingested a significant portion of it. Subsequently,
the individual expressed a desire to engage in a leisurely stroll and partake in a satisfying
repast. Similar to other individuals with amnesia, patients exhibit a tendency to forget
recent meals. However, upon resuming eating, they express a decreased level of
enjoyment in comparison to their typical experience.
Korsakoff's syndrome, which is also referred to as Wernicke-Korsakoff syndrome,
is a neurological condition that results from a protracted deficiency of thiamine, causing
damage to the brain. Thiamine (vitamin B1) is a crucial nutrient required by the brain for
the metabolism of glucose, which serves as its primary source of energy. Individuals with
severe alcoholism who subsist on a diet solely comprised of alcoholic beverages for
extended periods of time are frequently afflicted with a prevalent condition of severe
thiamine deficiency due to the absence of essential vitamins. The extended absence of
thiamine results in neuronal atrophy or reduction in size in various regions of the brain,
particularly in the dorsomedial thalamus, which serves as the primary supplier of
information to the prefrontal cortex. Individuals with Korsakoff's syndrome exhibit
symptoms akin to those with prefrontal cortex injury, such as apathy, confusion, and
memory impairment.
Alzheimer's disease is a prevalent etiology of memory impairment, particularly in
the elderly population. Schacter (1983) documented an instance where he engaged in a
game of golf with an individual afflicted with Alzheimer's disease. Despite the patient's
inability to recall the number of strokes taken, he demonstrated proficiency in the rules
and terminology associated with the game. The individual in question engaged in the act
of teeing off on five separate occasions, subsequently pausing to allow the other player to
also tee off, before proceeding to tee off once more. This repeated action was due to the
individual's forgetfulness of their initial shot. Similar to other individuals with amnesia,
patients diagnosed with Alzheimer's disease exhibit superior acquisition of procedural
skills in comparison to declarative memory. According to Gabrieli, Corkin, Mickel, and
Growdon (1993), individuals acquire novel skills and subsequently exhibit exceptional
performance, despite having no recollection of having previously acquired such skills.
The individual's memory displays variability, indicating that a potential contributing
factor to their impairment is a reduction in attentiveness or activation.
Infant amnesia, also known as early childhood amnesia, is not classified as a
pathological condition akin to Korsakoff's syndrome or Alzheimer's disease. It is a
commonly observed phenomenon that individuals in their later childhood and adulthood
tend to retain minimal recollection of events that occurred during their initial years of
life. It has been observed that young children are capable of developing long-term
memories. According to Solter (2008), it has been observed that children as young as two
years old, and up to four years old, possess the ability to provide precise accounts of past
occurrences that transpired several months or even years ago. Nevertheless, with the
passage of time, individuals tend to lose recollection of the majority of their initial
experiences (Peterson, Warren, & Short, 2011). The appropriate inquiry is not as to why
young children are unable to establish enduring memories. The inquiry pertains to the
reason behind their forgetfulness.
E. The Hippocampus and the Striatum
It has been established that a significant portion of the hippocampus is involved in
the process of memory formation and subsequent retrieval. Despite the fact that the
procedure effectively decreased H.M.'s epilepsy to a maximum of two major seizures
annually, he experienced significant cognitive deficits in the form of severe memory
impairment. Procedural memory, which pertains to the acquisition of motor skills and
habits, represents a distinct form of implicit memory. Similar to other instances of
implicit memory, the articulation of a motor skill or habit in linguistic terms may prove
challenging, and the identification of such a memory may not be immediately apparent.
As per Corkin's (2002) findings, H. M. acquired the ability to decipher words inscribed in
reverse order, as they would appear in a mirror. H. M. expressed astonishment at this
newly acquired skill, as he had no recollection of attempting it previously. Patient K. C.
has acquired the skill of utilizing the Dewey decimal system for book classification
during his part-time employment at a library, however, the origin and timeframe of his
acquisition remain unknown.
The delayed matching-to-sample task involves presenting an object (known as the
sample) to an animal, which is then required to select one of two objects presented after a
delay period. The animal's task is to choose the object that matches the sample. The
delayed nonmatching-to-sample task involves a procedure wherein the animal is required
to select the object that differs from the sample. In each instance, the animal is required to
retain information regarding the object that was present during the event, thus exhibiting
what could be referred to as a declarative memory, potentially classified as an episodic
memory. Significant impairment in performance is observed in the majority of cases with
damage to the hippocampus.
Assume a scenario in which an individual obstructs your vision, lifts you up, and
deposits you in a location devoid of light and sound. What is your occupation or
profession? The desire for exploration is present, however, prudence is necessary. The
precise locations of potential opportunities or hazards are unknown. Consider the
scenario of awakening in one's personal sleeping quarters. Consider a scenario where
complete absence of light and sound prevails, yet you are able to navigate effortlessly
towards your dresser, door or any other object, owing to your spatial awareness. The
ability to determine one's location is a distinct form of memory that is reliant upon the
hippocampus and its adjacent regions. Multiple lines of evidence support the significance
of the hippocampus and its adjacent regions in relation to spatial memory. The subject
under consideration is a radial maze comprising multiple arms, usually eight in number,
wherein one or more arms terminate with a food reward. The optimal approach for a rat
to navigate a radial maze involves systematically exploring each arm in a single traversal
while retaining a memory of previously visited arms. In an alternative version of the
experiment, a rodent could acquire the knowledge that the appendages featuring a coarse
surface texture consistently lack sustenance, or that the appendages oriented towards the
window consistently lack sustenance. Consequently, a rat has the potential to commit an
error either by traversing an incorrect arm that will never lead to the desired outcome, or
by revisiting a previously explored arm. Rats that have incurred damage to their
hippocampus exhibit the ability to acquire the skill of avoiding the never-correct arms.
However, despite undergoing extensive training, these rats tend to enter a correct arm
twice. Individuals may experience difficulty in recalling which arms they have previously
attempted.
Episodic memory, which is reliant on the hippocampus, emerges subsequent to a
solitary experience. Numerous semantic memories can be established following a solitary
experience. In the event that an individual imparts a captivating piece of information, it is
plausible that the same may be retained in one's memory for an indefinite period. The
acquisition of spatial awareness can occur at a rapid pace. Nonetheless, an alternative
approach is required for the gradual acquisition of habits, or the acquisition of knowledge
regarding the likelihood of events occurring under specific conditions. When making
predictions such as the likelihood of rain tomorrow, the enjoyment of a movie by one's
mother, or the probability of a favorite team winning its next game, various forms of
information are considered. One may potentially lack consciousness of the various cues
utilized or the decision-making process employed. The acquisition of knowledge of this
nature is contingent upon the functionality of certain components of the basal ganglia,
namely the caudate nucleus and the putamen, which collectively constitute the striatum.
Individuals who have experienced hippocampal damage and suffer from amnesia
exhibit random performance on the weather task over a prolonged period of time. This is
attributed to their inability to form declarative memories, leading to a lack of recollection
that predominantly blue or predominantly purple symbols hold any significance. In the
event that the duration of their persistence is prolonged, there is a gradual enhancement
observed, which can be attributed to the habits reinforced by the striatum, as per the
findings of Bayley, Frascino, and Squire (2005) and Shohamy, Myers, Kalanithi, and
Gluck (2008). Individuals without hippocampal damage, when attempting to acquire a
complex skill amidst highly distracting circumstances, exhibit a similar rate of learning as
those with hippocampal impairment.
Individuals who have incurred damage to their anterior temporal cortex exhibit
symptoms of semantic dementia, which is characterized by a decline in semantic
memory. During a transportation event, a particular individual observed a group of ovine
animals and inquired about their identity. The issue did not pertain to his inability to
recollect the term "sheep". The individual appeared to lack prior exposure to sheep. Upon
viewing an image of a zebra, an individual misidentified the animal as a horse, but
subsequently drew attention to the distinctive stripes and inquired about their nature,
referring to them as "funny things." The individual had lost the ability to comprehend the
concept of a zebra. Patients frequently experience difficulty in recalling the standard hue
of prevalent fruits and vegetables or the physical characteristics of diverse fauna. The
anterior temporal cortex is responsible for the storage of certain semantic information and
functions as a central node for interconnecting with other regions of the brain in order to
integrate a complete conceptual representation.
The process of retaining and preserving data. Within the domain of neuroscience,
the Nervous System is a fundamental component. According to Hebb's proposal, the
participation of the axon of neuron A in the firing of cell B on a repeated or persistent
basis leads to a growth process or metabolic change in one or both cells. This change
enhances the ability of axon A to stimulate cell B in the future. To clarify, an axon that
has previously elicited stimulation in cell B exhibits an increased likelihood of success in
subsequent attempts. In more simplified terms, the phrase "cells that fire together wire
together" is used to describe the process by which neurons in the brain form connections
with one another based on their simultaneous activation. Subsequent scholars have made
alterations to this concept, positing that neurons in close proximity that exhibit
synchronous firing patterns establish connections with one another. The aforementioned
phrase is comparatively less memorable, however, it exhibits a higher degree of
precision.
The neural architecture plays a crucial role in dictating the potentiality and
efficiency of learning by regulating the formation and strength of synaptic connections.
The relationship between this process and classical conditioning warrants consideration.
Assuming that axon A provides a mild excitation to cell B, while axon C induces a
stronger excitation to the same cell. The simultaneous firing of neurons A and C may
result in the generation of an action potential in neuron B due to their combined effect.
Axon A can be conceptualized as the conditioned stimulus, while axon C can be regarded
as the unconditioned stimulus. The enhancement of the future impact of axon A on B is
observed upon engaging in a pairing activity with axon C. A synapse that exhibits
Hebbian plasticity is capable of augmenting its efficacy in response to concurrent
activation of the presynaptic and postsynaptic neurons. Synapses of this nature are crucial
for various forms of associative learning.
When searching for a needle in a haystack, it is advisable to focus on a smaller
haystack as a viable strategy. As a result, a considerable number of scholars have resorted
to conducting investigations on invertebrate organisms. The organization of the nervous
systems in vertebrates and invertebrates differs, however, the fundamental aspects of the
neuron's chemistry, the principles governing the action potential, the neurotransmitters,
and their corresponding receptors remain consistent. The identification of the
physiological foundation of learning and memory in an invertebrate organism could
potentially provide a theoretical framework for the mechanisms that may be effective in
vertebrate organisms. The strategy of utilizing this approach has been a longstanding
practice among biologists for the purpose of investigating genetics, embryology, and
various other biological processes.
The marine invertebrate Aplysia, which is closely related to the slug, has been
widely utilized in research pertaining to the physiology of learning. In contrast to
vertebrates, the organism in question exhibits a lower count of neurons, with a significant
proportion of them being of substantial size, thereby rendering them amenable to
investigation. In addition, it is noteworthy that Aplysia neurons exhibit a high degree of
uniformity across individuals, which enables researchers to accurately reproduce each
other's findings. This characteristic distinguishes them from vertebrate neurons.
Habituation refers to the phenomenon whereby an organism exhibits a reduced
response to a repeated stimulus, while other stimuli remain unchanged. An instance of
abrupt auditory stimulation may elicit a startle response, however, subsequent exposures
tend to result in a diminished reaction, particularly when they transpire frequently or at
regular intervals. Upon repeated stimulation of an Aplysia's gills with a brief jet of
seawater, an initial withdrawal response is observed. However, with continued repetition,
the Aplysia eventually exhibits a lack of response. The decrement in response is not
attributable to muscular exhaustion; notwithstanding the development of habituation, the
motor neuron can still elicit a complete muscle contraction through direct stimulation.
Changes in the sensory neuron can be excluded as well. According to Kupfermann et al.
(1970), the sensory neuron exhibits an unimpaired and complete reaction to stimulation.
However, it experiences a reduced ability to stimulate the motor neuron compared to its
previous response. Thus, it can be inferred that the process of habituation in Aplysia is
contingent upon a modification occurring in the synapse connecting the sensory neuron
and the motor neuron.
In the event of an unforeseen and acute sensation of discomfort, there is a
temporary increase in the individual's responsiveness to other abrupt stimuli. The
aforementioned occurrence is commonly referred to as sensitization, which denotes an
escalation in reactivity towards mild stimuli consequent to exposure to more potent
stimuli. Likewise, a potent stimulus applied to any region of Aplysia's skin enhances a
subsequent retraction reaction to tactile stimulation.
The notion that learning is contingent upon synaptic modifications has been
widely accepted by neuroscientists following the contributions of Charles Sherrington
and Santiago Ramón y Cajal. The findings on Aplysia further corroborate this
proposition. The initial indication of a comparable mechanism in vertebrates was derived
from research on neurons within the hippocampus of rats, as reported by Bliss and Lømo
in 1973. Long-term potentiation (LTP) is a phenomenon that refers to the enduring
increase in synaptic strength between two neurons following their repeated activation. A
dendrite is subjected to a rapid succession of stimuli by one or more axons. Following a
burst of intense stimulation, certain synapses may become potentiated, resulting in
heightened responsiveness to subsequent input of a similar nature for varying durations
ranging from minutes to weeks.
The massive stimulation of AMPA receptors by glutamate leads to depolarization,
which subsequently facilitates the stimulation of nearby NMDA receptors by glutamate.
Activation of N-methyl-D-aspartate (NMDA) receptors facilitates the influx of calcium
ions into the cell, initiating a cascade of events that promote the formation of novel
glutamate synapses or potentiate the reactivity of pre-existing alpha-amino-3-hydroxy-5-
methyl-4-isoxazolepropionic acid (AMPA) receptors. Following the induction of long-
term potentiation (LTP), N-methyl-D-aspartate (NMDA) receptors undergo a restoration
to their initial state. Upon establishment, Long-Term Potentiation (LTP) becomes
independent of N-Methyl-D-aspartate (NMDA) synapses. According to Gustafsson and
Wigström (1990) and Uekita and Okaichi (2005), the inhibition of NMDA synapses by
drugs impedes the formation of LTP. However, it does not disrupt the maintenance of
previously established LTP. To clarify, following long-term potentiation (LTP), the
AMPA receptors remain potentiated, irrespective of any changes that may occur to the
NMDA receptors.
The aforementioned alterations take place within the postsynaptic neuron. LTP
often relies on alterations in the presynaptic neuron, either exclusively or in conjunction
with other factors. Prolonged activation of a postsynaptic neuron results in the secretion
of a retrograde neurotransmitter, which subsequently modulates the presynaptic neuron.
Nitric oxide (NO) is often identified as the retrograde transmitter in numerous instances.
The presynaptic neuron exhibits various changes, including a reduction in the threshold
for generating action potentials, an increase in the release of neurotransmitter, an
expansion of its axon, and the release of its transmitter from additional sites along its
axon, as reported by Ganguly, Kiss, and Poo (2000), Zakharenko, Zablow, and
Siegelbaum (2001), Routtenberg, Cantallops, Zaffuto, Serrano, and Namgung (2000), and
Reid, Dixon, Takahashi, Bliss, and Fine (2004). According to Costa, Froemke, Sjöström,
and van Rossum (2015), the occurrence of long-term potentiation (LTP) is attributed to
alterations in both presynaptic and postsynaptic mechanisms, which ultimately leads to
improved accuracy and durability of the learning process.
The pursuit of studying LTP and other biological mechanisms is motivated by the
potential for practical applications. The process of long-term potentiation (LTP) is
contingent upon the synthesis of multiple proteins. Studies conducted on rodents have
demonstrated that augmenting the production of these proteins leads to an improvement
in memory function. According to Shema, Sacktor, and Dudai's (2007) research, memory
can be weakened by drugs that hinder their production, even when administered several
days after the training. Numerous pharmaceutical enterprises are currently exploring
potential drugs that could potentially enhance memory by augmenting LTP; however, no
such medication has been made available thus far. Similar to other fields of medicine,
numerous medications that exhibit potential in animal trials demonstrate intolerable
adverse reactions when administered to humans.
Stimulant drugs, namely caffeine, amphetamine, or methylphenidate (Ritalin),
have been observed to potentially enhance memory function. Despite the illegality of
purchasing or vending amphetamine or methylphenidate without a prescription, a
considerable number of college and high school students have acquired these substances
and experimented with them at least once. According to the research, heightened energy
levels have a modest positive impact on memory and cognitive abilities among students
who are average or below-average in academic performance. However, the benefits of
increased energy are negligible or potentially detrimental for high-achieving students.
The health implications of extended usage remain largely unexplored, as per the
findings of Ilieva, Hook, and Farah (2015) and Smith and Farah (2011). Modafinil, a
stimulant medication, has been sanctioned for the treatment of narcolepsy and other
wakefulness-impairing disorders. However, individuals have also experimented with its
use for augmenting cognitive abilities and memory, without the approval of the FDA.
The extant literature indicates enhancement on intricate tasks, however, potential hazards
associated with prolonged and recurrent usage have yet to be investigated.
F. Intelligence
The term "brainy" is sometimes employed by individuals to denote elevated levels
of intelligence, in contrast to prevailing beliefs. The widely held assumption that a larger
brain size corresponds to superior cognitive abilities requires further examination, as it is
a complex matter. In the 19th and early 20th centuries, several organizations emerged in
which members pledged to donate their brains for scientific study after their death. The
study did not yield predominantly conclusive findings. The cognitive abilities of
individuals who have achieved high levels of accomplishment display a significant range,
similar to that found in individuals who have achieved less distinguished
accomplishments, which is contrary to commonly held beliefs.
According to Burrell's (2004) findings, there is no clear correlation between brain
anatomy and intellect. Burrell also notes that during the 19th and early 20th centuries,
several organizations emerged where individuals pledged to donate their brains for
scientific study after their death. Achieving eminence is contingent upon various factors,
including opportunity, exertion, and fortuitous circumstances, as well as cognitive
aptitude. The term "brainy" is occasionally used to connote high levels of intelligence,
contrary to popular belief. The overall number of neurons can be considered a reliable
measure of cognitive capacity. The idea that certain bird species, specifically those in the
crow and parrot families, possess impressive problem-solving abilities due to their
comparable number of neurons to that of a small primate is supported by additional
evidence. This evidence highlights the densely packed nature of their neurons, as reported
by Dicke and Roth (2016) and Olkowicz et al. (2016).
The level of intelligence is influenced by various factors, including the potency of
neural connections in the brain and the impact of chemicals on long-term potentiation.
Burrell (2004) suggested that there is no clear correlation between brain anatomy and
intellect. During the 19th and early 20th centuries, several organizations emerged
wherein participants pledged to contribute their brains for scientific study upon their
demise. Empirical research has demonstrated a positive association between intelligence
quotient (IQ) and the surface area of cerebral cortex in the frontal and parietal regions, as
well as certain subcortical areas, including the caudate nucleus. This finding holds
considerable significance. The hypothesis that the number of neurons is a crucial
determinant of cognitive ability is supported by the high concentration of cell bodies on
the surface area of the cerebral cortex.
The relationship between intelligence and the quantity of white matter indicates
that both neuronal quantity and connectivity are important factors. The purported
correlation between intelligence and the number of neurons or synapses, which displays a
strong correlation, is a topic of theoretical significance. However, its explanatory power
is limited. The observed correlation level is inadequate to justify the utilization of brain
measurements as a basis for making determinations about an individual on a large scale.
To accurately identify individuals with high intelligence, it is recommended to observe
their verbal and behavioral patterns, rather than relying solely on neurophysiological
metrics. The evaluation of skilled athletes based on their actual performance is
comparable to the assessment of cognitive ability through the quantification of total
neuron count. This approach is deemed valid, as opposed to measuring muscle mass.
Furthermore, a thorough understanding of either cognitive or psychological processes
requires an analysis of the complex ways in which each brain region contributes to
specific aspects of behavior and perception. Therefore, the study did not yield any
definitive results.
The concept of heritability increases with age, as it is commonly believed that
individuals with superior abilities are inclined towards educational opportunities and
challenging tasks that facilitate the manifestation of their inherent genetic tendencies.
Therefore, the observed correlation level is inadequate to justify the use of brain
measurements as a criterion for making decisions about an individual, which is highly
significant. For instance, the resemblance of scores among monozygotic twins displays a
noteworthy increase. Studies have shown that there exists a moderate correlation between
the IQ scores of adopted children and those of their adoptive parents and siblings.
However, this correlation tends to decrease over time. Additionally, research has
demonstrated a positive correlation between intelligence scores and the surface area of
cerebral cortex in the frontal and parietal cortex, as well as certain subcortical areas such
as the caudate nucleus. These findings have been reported by various studies, including
Basten, Hilger, and Fiebach (2015), Colom et al. (2013), Fjell et al. (2015), Grazioplene
et al. (2015), Gregory et al. (2016), and Vuoksimaa et al. (2015). On the other hand, as
adopted children grow older, there is a tendency for the correlation between their IQ
scores and those of their biological parents to increase. This suggests that relying on brain
measurements alone is not enough to make accurate determinations about an individual.
Based on scholarly literature, it can be observed that the heritability of intellectual
performance tends to be lower for individuals who are raised in disadvantaged
environments and for children who attend schools with lower academic standards. This
finding holds significant implications. It is evident that genetic variations play a
significant role in an individual's ability to capitalize on opportunities presented to them.
This highlights the phenomenon of heritability, which tends to increase with age. It is
believed that individuals with superior abilities are drawn towards educational prospects
and demanding undertakings that aid the expression of their innate genetic tendencies.
Therefore, the observed level of correlation is insufficient to justify the use of brain
measurements as a basis for making determinations regarding an individual. In
circumstances where opportunities are restricted, a genetic advantage may not necessarily
be advantageous. This is evidenced by the fact that the cognitive abilities of highly
accomplished individuals display significant variability, similar to that observed in
individuals with less distinguished achievements.
Apart from language-related specializations, the structure of human brains is
analogous to that of other mammals, particularly primates. To identify individuals with
high intelligence, one should observe their verbal and behavioral patterns, instead of
relying solely on neurophysiological metrics. According to Harris and Shepherd (2015)
and Herculano-Houzel (2012), it definitely has been observed that humans definitely
possess identical types of neurons, neurotransmitters, synapses, and a similar proportion
of neurons to glia cells, cortex to cerebellum ratio, among for all intents and purposes
other similarities, showing how the level of intelligence mostly is influenced by various
factors, including the potency of neural connections in the brain and the impact of
chemicals on particularly long-term potentiation, generally further showing how burrell
(2004) specifically suggested that there mostly was no basically clear correlation between
brain anatomy and intellect, showing how during the 19th and generally early 20th
centuries, a number of organizations for the most part emerged wherein participants kind
of pledged to for all intents and purposes contribute their brains for scientific study upon
their demise, or so they literally thought.
The dissimilarities between Homo sapiens and sort of other organisms literally are
primarily quantitative in nature, demonstrating that according to Harris and Shepherd
(2015) and Herculano-Houzel (2012), it mostly has been observed that humans literally
possess identical types of neurons, neurotransmitters, synapses, and a similar proportion
of neurons to glia cells, cortex to cerebellum ratio, among for all intents and purposes
other similarities, showing how the level of intelligence kind of is influenced by various
factors, including the potency of neural connections in the brain and the impact of
chemicals on generally long-term potentiation, particularly further showing how burrell
(2004) basically suggested that there mostly was no pretty clear correlation between brain
anatomy and intellect, showing how during the 19th and generally early 20th centuries, a
number of organizations for the most part emerged wherein participants generally
pledged to particularly contribute their brains for scientific study upon their demise in a
really big way. Slight genetic differences between humans and other primates can lead to
an expedited and prolonged production of neurons in embryonic development, ultimately
leading to an enlarged cerebral cortex and a higher quantity of neurons. This phenomenon
has been observed since the 19th and early 20th centuries, during which various
organizations emerged wherein members pledged to donate their brains for scientific
research upon their death. This practice holds significant importance.
