Psyco

INTRODUCTION TO

PSYCHOLOGY

CLASS #9

Dr. Charles-Etienne Benoit

Today’s Lecture

 Consciousness

 Sleep

 Circadian rhythm

 Genetic of sleep

The mind-brain problem

 How can a purely physical system (the body and brain)

construct conscious intelligence (the mind)?

 Dualism, famously expounded by Descartes, states that mind and

brain are two distinct and separate phenomena, and conscious

experience is nonphysical and beyond the scope of the physical

sciences.

 Materialism asserts that both mind and body are physical mediums

and that by understanding the physical workings of the body and

brain well enough, an understanding of the mind will follow.

 These philosophies ignores an inconvenient problem.

Dualism tends to ignore biological findings, and materialism

overlooks the reality of subjective experience.

Some definitions

 In common parlance the term “cognition” means thinking and reasoning, a usage

closer to its Latin root cognoscere (getting to know or perceiving).

 Thus the Oxford English Dictionary defines it as “the action or faculty of knowing.”

 In 1997, Harvard psychologist Steve Pinker proposed of breaking the problem of

consciousness into three issues: self-knowledge, access to information, and sentience.

 Self-knowledge : Accurate information about being itself.

 Access to information : Access awareness is the ability to report on the content of

mental experience without the capacity to report on how the content was built up in

the nervous system. The nervous system has two modes of information processing:

conscious processing and unconscious processing.

 Sentience : It refers to subjective experience, phenomenal awareness , raw feelings,

and the first person viewpoint (what it is like to be or do something).

 Through the lens of cognitive neuroscience, much can be said about access to

information and self-knowledge, but the topic of sentience remains elusive.

Access vs sentience

 Blindsight refers to the phenomenon that patients suffering a lesion in their visual

cortex can respond to visual stimuli present in the blind part of their visual field.

 Most interestingly, these activities happen outside the realm of consciousness.

Patients will deny that they can do a task, yet their performance is clearly above

that of chance. Such patients have access to information but do not experience it.

Coma

 A coma is when a person shows no signs of being awake and no

signs of being aware.

 A person in a coma lies with their eyes closed and doesn't respond

to their environment, voices or pain.

 A coma usually lasts for less than 2 to 4 weeks, during which time

a person may wake up or progress into a vegetative state or

minimally conscious state.

Vegetative state

 A vegetative state is when a person is awake but is showing no signs of

awareness.

 A person in a vegetative state may:

 They open their eyes.

 They wake up and fall asleep at regular intervals.

 They have basic reflexes.

 They're also able to regulate their heartbeat and breathing without assistance.

 A person in a vegetative state doesn't show any meaningful responses, also show

no signs of experiencing emotions.

 If a person is in a vegetative state for a long time, it may be considered to be:

 a continuing vegetative state when it's been longer than 4 weeks

 a permanent vegetative state when it's been more than 6 months if caused by a non-

traumatic brain injury, or more than 12 months if caused by a traumatic brain injury

 If a person is diagnosed as being in a permanent vegetative state, recovery is

extremely unlikely but not impossible.

Minimally conscious state

 A person who shows clear but minimal or inconsistent awareness is classified as

being in a minimally conscious state.

 They may have periods where they can communicate or respond to commands,

such as moving a finger when asked.

 In some cases a minimally conscious state is a stage on the route to recovery, but

in others it's permanent.

 But it's more difficult to diagnose a permanent minimally conscious state because

it depends on things like:

 The type of brain injury

 How severe the injury is

 How responsive the person is

 In most cases, a minimally conscious state isn't usually considered to be permanent until it's

lasted several years.

Causes of these disorders

 Traumatic brain injury

 Occurs when an object or outside force causes severe trauma to

the brain.

 Non-traumatic brain injury

 Non-traumatic brain damage is usually caused by a health

condition (deprives the brain of oxygen) or a condition that

directly attacks brain tissue.

 Progressive brain damage

 In some cases, brain damage can gradually occur over time.

Resting state

 Resting state is a method of functional magnetic resonance imaging that is

used in brain mapping to evaluate regional interactions that occur in a resting

or task-negative state, when an explicit task is not being performed.

 Five modules were identified in a functional network of the human brain,

represented by five different colors.

 Surface representation of modular architecture of a functional brain network.

Brain correlates

 Scientists still don't understand exactly how

human consciousness works.

 Magnetic resonance imaging brain scans of

coma patients (some recovered, more than half

died) and compared them with healthy

volunteers.

 The team tracked 417 different brain regions

for changes in blood flow a marker of brain

activity. They then correlated synchronized

increases or decreases in activity between

different regions.

 In healthy patients, about 40 regions lit up in

concert with many other parts of the brain.

Brain correlates

Important consciousness brain correlates

 The reticular formation is a collection of nuclei in the brainstem that project up to

the thalamus and cortex and are important for attention and arousal.

Anesthesia: artificial unconsciousness

 Anesthetics inhibit neuronal activity.

 As anesthetic dose is increased, metabolic activity in the brain decreases.

 At some point, consciousness is abruptly lost.

 Activity in high order association areas is reduced.

 Significant decrease in thalamic activity.

Consciousness altering drugs

 Psychoactive drugs

 A chemical that alters perceptions, thoughts, moods, or behavior.

 Physical dependence

 An addiction in which a drug is needed to prevent withdrawal.

 Psychological dependence

 An addiction in which a drug is needed to maintain a sense of

well-being.

Consciousness altering drugs

 Sedatives

 Depressants; slow down central nervous system activity.

 Alcohol is a sedative.

 Stimulants

 Excite the central nervous system; energize behavior.

 Hallucinogens

 Psychedelic drugs that distort perception and cause

hallucinations.

 Opiates

 Highly addictive drugs that depress neural activity and

provide temporary relief from pain and anxiety.

Consciousness altering drugs

Hypnosis

 Hypnosis: A social interaction during which a person,

responding to suggestions, experiences changes in memory,

perception, and/or voluntary action.

 Induction: Hypnotist makes a series of suggestions.

 “You are becoming sleepy. Your eyelids are drooping”.

 If all goes well, the subject(s) behave in ways consistent with suggestions.

 Hypnosis works primarily for people who are highly suggestible (1 in 5 persons).

Theory explaining hypnosis

Social Influence Theory Hypnotic subjects may simply be imaginative people who go along with the “subject” role

they have agreed to play.

Divided Consciousness Theory

Hypnosis is a special state of dissociated (divided)

consciousness of our dual-track mind.

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Known benefits of hyponosis

 Hypnotic analgesia: Clinical evidence shows hypnosis can be

used to treat immediate (e.g., surgery, burns) and chronic (e.g.,

arthritis, cancer) pain (Patterson & Jensen, 2003)

 Self-hypnosis: Also be shown to be effective in improving recovery from surgery

 Clinical evidence: Hypnosis doesn’t reduce the sensation of pain, but rather alters our interpretation (i.e., perception) of it

 Reducing obesity, anxiety, and hypertension.

 Improving concentration and performance.

Meditation

 A mental procedure that focuses attention on an external object or on a sense of awareness

Known effects:

 One study found greater stress reduction and attention among participants who meditated compared to a group that underwent relaxation training (Tang et al., 2007)

 Another study showed that when participants were made to feel sad, those who received meditation training were less sad than those who had not (Farb et al., 2010)

Sleep

 The purpose of sleep is unclear.

 Restorative Hypothesis: busier we are, more sleep we need

◼ Species with higher metabolic rates typically spend more time in sleep

◼ CSF circulates during sleep to remove toxins

 Adaptive Hypothesis

 The amount of sleep depends on the availability of food and on safety

considerations.

 Vulnerable animals without shelter (cattle) and those that need to spend hours

feeding (elephants) sleep very little.

Sleep

Brainwaves

20 – 60 Hz

14 – 20 Hz

8 – 13 Hz

4 – 7 Hz

> 4 Hz

Brainwave speed is measured in Hertz (cycles per second) and they are

divided into bands delineating slow, moderate, and fast waves.

Sleep stages

Sleep stages

 Non-REM sleep or Slow-waves sleep

 REM sleep or Rapid-eyes movement

 There are 5 Stages of sleep  (4) Non REM and (1) REM

 During an 8 hour period, people typically progress through all 5 full cycles,

 Each cycle lasts about 90 minutes

Sleep stages

 Stage 1  Light sleep, drift in and out, awaken easily

 Eyes move slowly, muscle activity slows

 May experience a sense of falling followed by

sudden muscle contractions

 Stage 2  Eye movement stops

 Brain waves are slower, occasional bursts of rapid

waves

 Stage 3  Extremely slow waves-Delta waves

 Interspersed with smaller faster waves

 Considered deep sleep

◼ No eye or muscle movement, difficult to awaken

◼ Time when sleepwalking, bedwetting, or terrors occur

 Stage 4  Almost exclusively Delta waves

 Considered deep sleep

K-complex

 It is the largest event in healthy human EEG.

 They are more frequent in the first sleep cycles.

 K-complexes have two proposed functions.

 Suppressing cortical arousal in response to stimuli that the

sleeping brain evaluates not to signal danger.

 Aiding sleep-based memory consolidation

REM sleep

 REM sleep

 Increased cerebral activity, erratic EEG (beta and theta

waves).

 Rapid eye movements.

 Loss of core muscle tone (paralysis).

 Autonomic arousal (elevated heart rate, blood pressure and

respiration).

 Narrative dreams with much visual imagery.

 Initially referred to as “paradoxical sleep”

Functions REM sleep

 Theories that REM sleep is required for normal

 Mental health

 Motivation

 Cognitive processing

 Interesting links between REM sleep and depression

 REM deprivation has antidepressant effects

 Most antidepressant drugs also reduce REM sleep.

 There’s considerable research on links between REM

sleep and learning/memory.

Memory consolidation

REM vs awake state

 Brain waves of an awaken person and of those of a person in rapid

eye movement (REM) sleep are similar in frequency and amplitude.

 However, the muscle activity is very quiet during REM sleep.

Brain waves

Muscle activity

Eye mouvements

Dream

 Products of an altered state of consciousness in which images

and fantasies are confused with reality.

 REM dreams: More likely to be bizarre and include intense

emotions, visual and auditory hallucinations, and uncritical

acceptance of illogical events.

 Brain structures associated with motivation, emotion, reward, vision are

active; pre-frontal cortex is not

 Non-REM dreams: Relatively dull.

 General de-activation of many brain regions

Lucid dream

 Experienced through history

 St. Augustine (5th century)

 Tibetan Buddhists (8th century) ◼ ‘Dream’ Yoga - reaching the ‘light’

 The “Conscious” Dream

 Knowing you are dreaming, when you are dreaming.

 Ability to make free decisions in the dream.

 Memory functions as if in awake state.

Lucid dream

 As demonstrated by LaBerge and

other researchers, lucid dreaming

does indeed exist. It is attainable

by almost everyone but however is

not our default state.

 Brainwave Pattern Analysis proved

conscious thought during REM sleep.

Lucid dream

Sleepwalking

 The cause of sleepwalking is unknown.

 There may be a genetic component to

sleepwalking.

 One study found that sleepwalking occurred

in 45% of children who have one parent

who sleepwalked, and in 60% of children if

both parents sleepwalked.

 A number of hypotheses are suggested:

 Delay in the maturity of the central nervous

system.

 Increased slow wave sleep.

 Sleep deprivation, fever, and excessive tiredness.

Insomnia

 Inability to sleep or obtain quality

sleep

 Can shorten the lifespan and may

contribute to obesity

 Triggers include stress, depression and

using sleeping pills. It is more common in

people with mental health issues.

 Drugs used in treatment can be addictive

 Circadian phase delay or advance

 Desynchrony between body temperature

and sleep period

Sleep deprivation

 Early reports of bizarre or psychotic behavior.

 Wide individual variability (personality and age

factors).

 Most common effects of sleep deprivation:

 Increased irritability

 Decreased concentration

 Confusion/disorientation

 Performance on brief tasks or tasks involving high

motivation are generally not impaired.

REM sleep deprivation

 Following REM deprivation,

there is a compensatory

increase in REM sleep, which

seems to suggest REM sleep is

a necessary brain function.

 REM deprivation can produce

cognitive/memory deficits.

 REM sleep increases following

new learning.

Recovery of sleep deprivation

 Sleep Recovery (Randy Gardner story)

 11 days (264 hours) sleep deprivation

 1st night, ~ 15 hours; stage 4 increased at expense of stage 2

 2nd night, ~10 hours; greatest REM recovery

 Percentages of sleep recovery not equivalent across all stages:

7% of stages 1 and 2, 68% slow-waves sleep, 53% REM sleep

“made up”.

Slow-waves vs REM sleep

Sleep cycle

Sleep life changes

Variance in animals

What do animals dream about?

Neural mechanism of sleep

From animal lesions sleep studies

Sleep neurotransmitters

Neural mechanism of sleep

Neural mechanism of sleep

Slow-waves sleep REM sleep

Sleep-wake control

Schematic

representation of the

regulatory circuits that

control sleep–wake and

REM–NREM transitions,

as well as their key

inputs and outputs.

Sleep-wake control

Circadian rhythm

 A circadian rhythm is any biological process

that displays an endogenous, entrainable

oscillation of about 24 hours.

 Although circadian rhythms are endogenous

(self-sustained), they are entrained to the

local environment by external cues (ex.

Isolation chambers, jet lag).

24-h Day

25-h Day

24-h Day

Biological clock

 Organisms from algae to people have evolved to keep time with the planet’s

light/dark beat. They do so using the world’s most important timekeepers.

 Daily, or circadian, clocks that allow organisms to schedule their days so as not to

be caught off guard by sunrise and sunset.

Mother of all clock

 A single-celled descendant

of the last universal common

ancestor (LUCA) may have

developed a primitive

circadian clock.

 The ancient timer may have

arisen in an ancestor of

animals, plants and fungi to

meet environmental

challenges, such as oxygen

toxicity.

Circadian rhythm

 Suprachiasmatic nucleus (SCN) is the main “clock”.

 Zeitgebers: environmental light based stimuli that regulate

sleep/wake cycle via the retinohypothalamic pathway.

 Without light, our circadian rhythm tends to increase to 25 hours

Suprachiasmic nucleus

Circadian rhythm

Circadian hormones

Melatonin

 Melatonin is a small sleep inducing hormone released from the

pineal gland of the brain.

 It is synthesized from the essential amino acid tryptophan, which

also serves as the precursor to serotonin.

 Tryptophan may be used as a supplement for people who have

trouble falling asleep.

Melatonin receptors

 Melatonin exerts its effects through MT1 and MT2 melatonin receptors, which are

G-protein coupled receptors, a class of integral proteins that mediate diverse

signaling pathways in the cell.

Cortisol

 Cortisol is a steroid hormone, in the

glucocorticoid class of hormones.

 It is produced in humans by the zona

fasciculata of the adrenal cortex

within the adrenal gland.

 It is released in response to stress and

low blood-glucose concentration. It

functions to increase blood sugar

through gluconeogenesis, to suppress

the immune system, and to aid in the

metabolism of fat, protein, and

carbohydrates.

Genetic of the clock in mammals

 per codes for a protein (PER) that gradually builds up over time.

 tau codes for an enzyme that breaks down PER.

 tim codes for a protein (TIM) that binds with PER to cross the membrane and suppress transcription of PER.

 Photoreceptor not yet known.

 Cycle repeats every 24 h.

Genetic of the clock in mammals

The molecular basis

of the circadian clock

expressed in a single

cell of the

suprachiasmatic

nucleus of the

anterior

hypothalamus.

Consciousness

Next class

Time for revision!

That’s it for today!

We can all make the choices for a change.

Let’s keep on moving forward.