Biological Foundations of Development3
Terms
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- Penfield
- mapped brain fuction by electrically stimulating brain areas in patients with epilepsy
- Aphasia
- general term for any inability to comprehend or produce language
- Broca's Aphasia
- inability to speak fluently despite normal comprehension and intact vocal mechanisms
- Wernicke's Aphasia
- inability to understand or produce meaningful language although production of works is still intact
- Paul Broca
-
notion that lefot and right hemispheres have different functions
proximity of Brocas Area to the mouth area of the motor cortex - region to production of speech - Broca's Area
-
By mouth area of primary motor cortex, explains relation to speech production
Damage results in broken speech and difficulty speaking - Karl Wernicke
- described patients that had trouble comprehending language after injury to the posterior brain region
- Wernicke's Area
-
Comprehension of language
Damage results in speech like bad mad libs, makes no sense but no trouble saying the words - Anomia
-
Patient H.W.
unable to recall the names of objects - Pathway of Auditory Information
- thought - Wernicke's Area - Broca's Area - Motor cortex
- Noam Chomsky
-
among first to assert that most languages share common core features therefore suggesting that we may posses genetic constraints on language
Innate abilities - Universal Aspects of Language
-
All societies have language
Language is learned early in life, and effortlessly
All languages have structural elements in common (ie verbs) - Representational Constraints
-
type of innateness
mental representations are innately specified in the brain, detailed knowledge, independent of experience - Architectural Constraints
-
type of innateness
the anatomical elements and/or connections necessary for language are innately specified - Chronotopic Constraints
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type of innateness
critical/sensitive period
Timing of developmental events is innately constrained
A combination or architectural and chronotopic constraints that can limit the types of information that a system can learn without requiring that knowledge to be innately specified - L1/L2 Hypothesis A
-
Brain areas recruited for learning and processing L1 are different from those recruited for L2.
Brain lesions in polyglots tend to result in aphasia in only one language
Most studies fail to pinpoint a cosistent neuronal substrate for L2 - L1/L2 Hypothesis B
-
Age of language acquisition affects the cortical representation of the language.
Evidence of a sensitive period for language acquistion that late learning of a language may rely on spearate neural systems.
Languages learned within the same sensitive period would be expected to recruit similar brain systems for production and comprehension - L1/L2 Hypothesis C
-
Proficiency Level affects the cortical representation of the language
Languages that are learned to the same high level of proficiency as native language may tap the same neural system, whilethose languages that are less proficient may rely on a separable set of neural systems
Related to the more general idea that automatic and effortful cognitive processing may be handled by separate systems in the brain - Bilingual Aphasia
-
If both languages were learned early, to a high degree of proficiency, then both languages are affected
If L2 was learned after age 7, late damage may affect only one of the languages (l1 or L2) -
Bilingual Aphasia
L1 vs L2 -
L1 - damage to primitive brain, basal ganglia, automatic cognitive function
L2 - damage to regions like hippocampus and frontal cortex result in loss of L2, effortful cognitive function - Bowlby's Attachment Theory
-
Infant rapidly forms an attachment to the caregiver
Infant seeks caregiver proximity
Caregiver profides a safe haven
Infant will continue to seek contact with the caregiver even if abused - Cupboard Love
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Freud
Infant wants to be near mother becuase mother provides food - Harlow Rhesus Monkeys
- Disproved cupboard love, prefer to go to cuddley mother when threatened
- Prolactin
-
Caretaking hormone
Increases when feeding, and defending young
High prolactin levesl increase caretaking, and caretaking increases prolactin levels - Oxytocin
-
found in mammals
receptors for these hormones throughout the limbic region and brainstem
formation of attachment
Maternal euphoria after birth
Maternal feeling of contentment and well being while breast feeding
Transmitted to baby while breast feeding, mild sedative, both feel happy
Associated with massage and sexual arousal
associated with orgasm in females
levels decrease with sad feelings - Imprinting
-
Attaching to the first thing a (duckling, kitten, etc) sees
Humans dont imprint, if a critical period exists it is much longer - Vasopressin
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Male attachment hormone
related to paternal behavior and pair attachment
associated with orgasm in males - Seretonin Transportor Gene
-
Long allele codes for more rapid removal of seritonin from synapse
Prone to anxiety and irritability
More common in European children than japanese - DRD-4 Gene
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Long allele related to preference for novelty and high activity
Related to ADHD - Gonadal Hormones
- Androgens and Estrogens
- Sexual Dimorphism
- Testosterone produced by testes, binds with aromatase in the liver, becomes estradiol (a form of estrogen, but can enter neurons because of testosterone base), enters neurons, masculinizes the brain
- Androgen-Insensitivity Syndrome
- Male fetus produces androgens and the body is not responsive to them, problem with the receptors, default is female
- Congenital Adrenal Hyperplasia
-
A female fetus is exposed to androgens and takes a male appearence
Extreme cases: partial development of male external genitalia - Sex Differences in Cognitive Organization
-
Females better at short term memory and verbal fluency tasks
Males better on spatial realations type tasks and mental rotation type tasks -
Neural Basis Sex Differences
Medial Prefrontal Cortex - Larger dendritic fields (presumably more synapses)in male rats than female rats
-
Neural Basis Sex Differences
Orbitofrontal Cortex - larger dendritic fields (and presumably more synapses)in female rats than male rats
- Sex differences in human hypothalamus
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In heterosexual males
Preoptic area contains twice as many neurons
Bed nucleus of the stria terminalis is 2.5 times larger
NAH3 region is 2 times larger
Suprachiasmic nucleus contains twice as many neurons - Hypothalamus and sex behavior
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Ventromedial Hypothalamus
Controles female mating posture in rats
Preoptic Area of Medial Hypothalamus
Controls copulatory behavior in males, but not sexual motivation - Amygdala and sex behavior
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Controls sexual motivation in males (possibly in females, outside of their estrous cycle).
In females, larger ratio size of orbitocortex to size of amygdala - Odor learning in rat pups
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Sensitive period to learn mother's scent (icreased ability to prefer odors, decreased ability to odor aversions)
Attach to odor milk scent and odor shock scent -
Attachment behaviors
Prairie Voles vs Mountain voles -
PV - monogamous, long-term care taking of young, proximity seeking, distressed by mother separation
MV-polygamous, mom abandon 8-14 days after birth, avoid proximity, no distress - Oxytocin in rats
-
receptors only present with onset of maternal behavior
soothes infant because is administered in milk
infant associates environmental cues with mother face, smell, feel - Oxytocin in Prairie Voles
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Have receptors in limbic system
adding increases maternal behavior, and increases pair bond (reduces need to mate)
supressing reduces maternal behavior and pair bond (but mate normally) - Oxytocin in Mountain Voles
- Have no receptors, therefore adding or supressing oxytocin has no effect
- Milk Letdown response
-
Infant-related stimuli - hypothalamus - oxytocin - mammory glands - milk letdown
Anxiety - hypothalamus - oxytocin - mammory glands - milk letdown - Androgens
-
male hormones
body detects like on/off switch, if present is on, if absent is off and by default female - Testosterone
- stimulates development of male reproductive organs and affects brain development
- TDF
-
Testes Determining Factor
coded by y chromosomes
stimulates the development of the testes - Timing of Menses
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early menstruation - girls are better at verbal than girls who begin later
late menstruation - better at spatial tasks than girls who begin earlier - Gonadal Hormones and experience
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Female rats exposed to enriched environments had increased dendritic branching in the cortex
Male rats exposed to enriched environment had increased dendritic spine densities in the cortex - Sex difference between damage to left frontal and left posterior cortex
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Females more likely to be aphasic and apraxic after lesions to left frontal cortex
Males likely to be aphasic and apraxic after lesions to left posterior cortex
**Sex difference in organization within left hemisphere - Sexual Dimorphism throughout life
-
Sex differences strong from 15-30 months of age
Disappear at 32-55 months
Reappear around puberty
Removal of ovaries (historectomy/menopause) masculinizes Medial Prefrontal Cortex, and Orbitofrontal cortex - Temperament
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Constitutionally based infividual differences in emotional, motor, and attentional reactivity and self regulation
Temperamental characteristics are seen to demonstrate consistency across situations as wellas relative stability over time -
Kagan's Approach
Temperament - Divides groups into inhibited and uninhibited temperaments
- Uninhibited Temperament
- Bold, usually approach unfamiliar people and situations
- Inhibited Temperament
- Shy or timid with unfamiliar people or objects
- Kagan's Temperaments 2
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10-15% fal in each of these highly reactive groups
Twin studies with toddlers show about .5 hertiability of these extreme temperament groups - Inhibition and the Amygdala
- Amygdala is activated by unfamiliar events and projects to brain regions related to physiological arousal, motor activity and emotional distress
- Amygdala response to novelty
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Amygdala is highly reactive to novelty, child is more likely to be inhibited
Amygdala has low reactivity to novelty, child is more likely to be uninhibited - Heart rate and Inhibited Temperament
- Behaviorally inhibited children tend to have heart rates that are higher and less variable
- Heart Rate and Uninhibited Temperament
- Behaviorally uninhibited tend to have lower and more variable heart rates
- EEG and Inhibited Temperament
- Behaviorally inhibited children tend to have more activity of the right frontal cortex
- EEG and Uninhibited Temperament
- Behaviorally uninhibited children tend to have more activity in the left frontal cortex
- Stability of behaviorally inhibited group
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Behavioral inhibition at 4 months of age predicts to shyness, social withdrawel, and lower positive affect at ages 4 and 7 years
*also predicts to symptoms of anxiety and depression in preschool and even adolescence - Stability of behaviorally uninhibited group
- Behaviorally uninhibited at 4 months are likely to show hyperactivity and acting out in preschool
- Health Paradox of Adolescence
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Developmental period of strength and resilience
vs
Period of vulerability - Developmental Period of strength and resilience
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Stronger, bigger, faster
Maturational improvements in reaction time, reasoning abilities, immune system, ability to withstand cold, heat, injury, and physical stress - Period of Vulnerability
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200% increase in mortality rates and morbidity
Difficulties in control of behavior and emotion
High rates of accidents, suicide, homicide, depression, alcohol and substance abuse, violence, reckless behavior, eating disorder, and risky sexual behaviors - Biological changes in puberty
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Dramatic changes in body size and composition (ratio of fat vs muscle)
Sexual maturation - breast and phallic development, secondary characteristics (pubic hair)
Looking like an adult
-social experiences/expectations - Adrenarche
- The increase in outpout of adrenal hormones that begins to occur prior to other signs of impending adolescence (6-8 years of age)
- Gonadarche
- the pubertal increase in gonadal hormones associated with the process of sexual maturation
- Menarche
- onset of menstruation
- Hormonal Changes
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Adrenarche/peak of sex hormones
Gonadarche, Menarche - GnRH
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GnRH (hypothalamus) - pulses -LH/FSH (pituitary) - Gonadarche - estrogen/testosterone - secondary sexual character
or
GnRH - LH/FSH - Adrenarche - adrenal androgens - secondary sexual character - GRH
- GRH(hypothalamuys)-GH (pituitary)- growth spurt
- LH, FSH
-
Luteinizing Hormone
Follicle Stimulating Hormone -
Puberty and Brain development
Upstream -
neural changes leading directly to the pubertal hormonal cascades
Brain - puberty -
Puberty and Brain development
Downstream -
Brain changes that are consequence of pubertal processes
Puberty - brain -
Puberty and Brain development
Independent - aspects of adolescent brain maturation and cognitive development that are not affected by puberty and continue long after puberty is over
- Interval between puberty and adult roles
-
Traditional societys 2yrs for females, 4yrs for males
Contemporary
about 14 years -
Implications bewteen adult and puberty
Positive - More time to learn and develop skills, formal educations, explore different relationships, career choices
-
Implications bewteen adult and puberty
Risks - gap between emotional and motivational changes adn the completion of cognitive development
- Puberty specific maturational changes
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romantic motivation
sexual interest
emotional intensity, mood lability
changes in sleep/arousal regulation
risk for affective disorders in females
increase in risk taking, novelty sensation, and reward seeking - Engine with Unskilled driver
- Cognitive development (logic, reasoning, planning, problem solving, understanding consequences and capacities for self regulation of emotions and rives, and inhibitory control) are still developing, dependent on age and experience, and continue long after puberty is over
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Brain Changes in adolescence
Myelination -
Active myelination is still occuring, prefrontal cortex last to undergo process
Increased speed of neural processing may facilitate cognitive complexity and ablility to combine information from multiple sources -
Brain Changes in Adolescence
Pruning -
Massive loss of synapses in neocortical brain regions during adolescence
-as many as 30,000 synapses may be lost per second over the entire cortex druing the pubertal period in primate brain
-leading to an ulrimate loss of almost half the average number of synapses per cortical neuron
Most are in excitory in nature, leading to lower brain activity - Developmental Hypermetabolism
- brain activity (rates of glucose metabolism, oxygen utilization and blood flow)show developmental declines during adolescence - decrease in brain metabolism
-
Brain Changes in Adolescence
Focal Activation -
Increase in focal activation in the brain
-less widespread activation of brain fuction during task performance -
Brain Changes in Adolescence
Independant Processing - Marked increase in the degree to which the two cerebral hemispheres can process information independently
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Brain Changes in Adolescence
Hemispheric Asymmatry - Increase in amount of hemishpereic asymmetry evident in the EEG
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Brain Changes in Adolescence
Dopamine fiber -
Prefrontal Cortex - Dopamine concentrations and fiber density increases during adolescence
-may be at least partially compensated later in adolescence by a developmental decline in DA synthesis
Nucleus Accumbens - net DA hypofunctioning in NA. Reward systems decrease in dopamine, adolescents more susceptible to addiction - Social Scaffolding
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Earlya ctivation of intense motivations and passions can be channeled into a wide range of goal directed behaviors (hobbies, sports, music, art, etc) and passionate commitments to idealistic causes
Shaped by experience
Importance of appropriate social scaffolding - Risk Taking
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Promoted by developmental events occuring in brain during adolescence
Evolved to promote attainment of the necessary skills for independence
May predispose adolescents to initiate use of alcohol and other drugs - Mesolimbic Dopamine Reward system
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pathways connect structures in brainstem with the midbrain, limbic system, and frontal cortex
Electrical stimulation of lateral hypothalamus activates one aspect of dopamine system and induces a rewarding sensation
Amount determines how rewarding something is
Increase with sex, eating, etc - Adolescent Brain Changes in Reward sensitivity
- Dopamine concentrations and fiber density in PFC increases
- Increase in risk taking in adolescence
- Adolescents appear to show some signs of attaining less reward from a variety of stimuli relative to individuals at other ages leading them to seek additional reinforcers via persuit of new social interactions and engagement in risk taking or novelty seeking behaviors
- Shift in dopamine balance
- Shift in DA balance toward PFC predominence, resulting in net DA hypofunctioning in ACC
- Hot Cognitions
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Process of thinking under new conditions of high-arousal and/or strong emotion
Adolescents often appear to be relatively good at making decisions under conditions of low arousal and cool emotions, but under intense emotional arousal, can have much more difficult time making a responsible choice - Methodological problems
-
Questionnaires: very similar to adults
-1 adolescent at a time, yet most risk taking is a group phenomenon while peer conformity to antisocial behaviors peaks in early to mid adolescence
Hypothetical dilemmas
Undercontiditons that minimize emotional influences on decision making, yet most risk taking occurs under conditions of emotional arousal
anxiety vs eurphoria - Mesolimbic Dopamine Pathway
-
Located in Ventral Tegmental Area (VTA)
Projects to many areas including the nucleus accumbens (part of the basal ganglia) - Drug Cravings
-
drug related cues produce dopamine release in VTA
Dopamine release was associated with drug seeking behavior - Drug action at synapses
-
Drugs can alter chemical processes at any of seven major stages of synaptic transmission
Most psychoactive drugs exert their effects by influencing chemical reactions of synapses - Agonist
-
Substance that enhances the function of a synapse
abusive substances - Antagonist
- substances that block the function ofa synapse
- Dopamine and Drug abuse
-
abusive drugs are dopamine agonists
cause the release of dopamine or prolong its availability in the synapse
eventually block vaccuum cleaners and dopamine is no longer effective at normal levels (cocaine) - Psychopharmacology
- study of how drugs affect the nervous system and behavior
- Psychoactive drugs
- substance that acts to alter mood, thought, or behavior and is used to manage neuropsychological illness
- Drug Routes into nervous system
- Oral administration, Inhalation, injection
- Oral administration of drugs
-
Absorbed through stomach or lining of small intestine
Enters bloos stream (diluted 6 pints)
Extracellular fluid
deiluted by 35 liters
modified/destroyed by cell metabolic process
Each step reduces the effect by 10
Fastest and easiest but most barriers - Blood Brain Barrier
-
helps prevent most substances including drugs from entering the brain via the bloodstream
Endothelial cells in capillaries located throughout the body are not tightly joined, so it is easy for substances to move into and out of the blookstream
Endothelial cells in the brain are tightly joined and the presence of astrocytes (glial cells) help keep most substances out - Elimination of Drugs
-
Drugs are broken down in the kidneys, liver, and intestines
Drigs are then excreted in urine, feces, sweat, breast milk, and exhaled air
Some substances that cannot be removed may build up in the body and become more toxic ie mercury -
Drug routes
In order to enter -
Small uncharged molecules (ie oxygen, carbon dioxide) are fat soluable and can cross freely the BBB
Larger charged molecules (eg glucose, amino acids, fats) must be actively transported across the BBB - Difficulty developing drugs for the brain
- Must be small and uncharged or they must be structurally similar to a substance that already has an active transporter that allows it to pass the BBB
- Individual differences in drug response
-
Age - older individuals are more sensitive to drugs. Less effective barriers and less effective of eliminating drugs
Body Size - smaller individuals are more sensitive to drugs. Fewer body fluids to dilute drugs
Sex - females are more sensitive to drugs, smaller than men on average - Metabolic Tolerance
- number of enzymes needed to break down alcohol may increase
- Cellular Tolerance
- Activities of brain cells may adjust to minimize the effect of alcohol
- Learned Tolerance
- People can learn to cope with effects of alcohol and therefore may not appear to be drunk
- Sensitization
-
Increased responsiveness to successive equal doses of a drug
Opposite of tolerance
More likely to occur with occasional use (sensitization to amphetamine may be because this drug causes more dopamine release) - Adolescent Tolerance
-
Reduced sensitivity to varous drugs of abuse
promotes greater use per occasion relative to more mature individuals
Greater propensity for developing acute and chronic tolerance to adverse drug effects -
Adolescent drug abuse
and dependence -
Most adolescent smokers try to quit after a year, but 97% are still smoking and are dependent 2 yrs later
Early alcohol exposure strong predictor of subsequent alcohol abuse - Adolescent Addiction
-
Adolescent rate of relapse approximate those of alcoholic adults despite the much shorter chronicity of the adolescent alcohol users
Escalation of cocane use appears more rapid among adolescents than adult users, grater addiction potential of cocaine - Withdrawel symptoms
-
physical and psychological behaviors displayed by an addict when drug use ends
Withdrawel symptoms from alcohol and morphine start within several hours of last dose and intensity over several days before subsiding - Psychomotor Activation
-
Increased behavioral and cognitive activity
At certain levels of consumption, the drug user feels energetic and in control
Occurs with many drugs (narcotics, stimulants, anti-anxiety etc) - Stages of Addiction
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Pleasure Activation
Associative Learning
Incentive Salience -
Stages of Addiction
Pleasure Activation - User likes the experience
-
Stages of Addiction
Associative Learning - Plesure becomes linked to cues associated with the drug experience (eg people, places, objects)
-
Stages of Addiction
Incentive Salience - The drug cues become highly desired and sought-after incentives in their own right
- Incentive Sensitization Theory
-
WHen a drig is associated with certain cues, thecues themselves elicit desire for the drug: also called the wanting/liking theory
Wanting (craving) and liking (pleasure) may be produced by different parts of the brain
Wanting-mesolimbic dopamine system
Liking-opioid neruons - Disinhibition Theory
-
Alcohol has a selective depressant effect on the cortex (controls judgement) while sparing subcortical structures (more primitive instincts)
Limitation - Behavior under the influence of alcohol often differs depending upon the context - Alcohol Myopia
-
nearsightedness
People respond to restriced set of immediate and prominent cues and ignore more remote cues and potential consequences.
Immediate and prominent cues will differ according to the context - Individual Differences in Drug Use
-
Genetics?
Personality traits?
unusual risk taking may be trait common to drug abusers -
Drugs and Brain Damage
Drugs that cause brain damage -
Amphetamines
-MDMA (ecstasy) Seratonin Neurons
-Meth Dopamine Neurons
Cocaine
Blocks cerebral blood flow
Phencyclidine (PCP)
Blocks NMDA receptors -
Drugs and Brain Damage
Drugs that don't cause brain dammage -
LSD
Opiates
Marijuana
-400 different chemicals and impurities - Biological Rythm
- Inherent rythm that controls or initiates various biological processes. Linked to cycle of days and rotation around sun, polar animals more effected, human behavior is governed more by daily than seasonal cycles
- Biological Clocks
-
Neural system that times behavior
Allows animals to anticipate events before they happen (migration) -
Entrainment
Part of biological clock - Determination or modification of the period of a biorythm
- Free Running Rythms
-
Rythm of the body's absence of the body's own devising in the absence of all external cues
Without input from external cues, our bodies have their own rythms with periods of 25-27 hours. (dialy hour shift)
Animals extend their sleep periods as the sleep related lighting period expands or contracts - Suprachiasmatic Nucleus
-
SCN
Main pathway of circadian rythms located just aboce the optic chiasm - Retinohypothalamic Pathway
- Neural route from a subset of cone receptors in the retina to the SCN of the hypothalamus; allows light to entrain the rythmic activity of the SCN
- Period
- Time required to complete a cycle of activity
- Circadian Rythm
- Daily rythm ie human sleep/wake cycle
- Suprachiasmatic Rythms
-
Metabolic activity of the SCN is higher than the light period of the day-night cycle than it is during the dark period of the cycle
Neurons in the SCN maintain their rythmic electrical activity even when all the pathways into and out of the SCN are cut
more active at night? - Pacemaking Circadian Rythms
-
Light entrains the SCN pacemaker
SCN pacemaker drives a number of "slave oscillators'" each of which controls the rythmic occurrence of one behavior (eg body temp)
SCN pacemaker may drive the slave oscillators via hormones, proteins, or neurotransmitters - EEG
-
electoencephalogram
Record of brain-wave activity - EMG
-
Electromyogram
Records muscle activity - EOG
-
Electrooculogram
Records eye movement - Beta Rythm
- Fast brain wave activity pattern associated with a waking EEG
- Alpha Rythm
- Large, extremely regular brain waves associated with drowsiness
- Delta Ruthm
- Slow brain wave activity pattern associated with deep sleep
-
REM sleep
EEG -
Fast brain wave patter displayed by the neocortical EEG record during sleep
Resembles wake state - Non REM Sleep
-
Slow wave sleep associated with deep sleep
4 stages 1 Shallow - 4 Deep - NOrmal night
- REM increases after 5 hours, as night goes on less time spent in deep sleep and more in REM, people awaken better from REM sleep than a deep sleep
- Developmental Trends
- Infants spend about half time in REM sleep and decreases from there on to adulthood at 1/4, increases in pregnant women
- Adolescence Phase Delay
-
A preference for going to sleep and wakeing up later
Also show decrease in total time spent sleeping - Behaviors associated with Non REM sleep
-
Decrease in body temp, heart rate, blood flow, increase in growth hormone release
Much less dreaming occurs and less vivid
Tossing, turning, kicking, flailing
Sleeptalking, walking
Night Terrors - Behaviors and REM sleep
-
Atonia - no tone, condition of complete muscle inactivity produced by the inhibition of motor neurons
Mechanisms that regulate body temp stop working - Dreaming
-
Vivid dreams occur in REM sleep
Everyone dreams every night
Dreams occur in real time -
Activation Synthesis
Dream theory -
Dreams are personal but have no meaning
IN response to activation from the brianstem, the cortex generates reandom images from personal memory stores -
Evolutionary Hypothesis
Dream Theory - Dreams are biologically important because they lead to enhanced performance in dealing with threatening life events (adaptive function)
-
Sleep as a
Passive process - Is not a passive process
-
Sleep as a
Biological adaption -
Sleep is an energy conserving strategy
-gather food at optimal tiems and sleep to conserve energy the rest of the time
-Animals sleep when they dont travel best
Predators sleep more than prey -
Sleep as a
Biological adaption
Humans -
Basic rest-activity cycle: recurring cycle of temporal packets
About 90 min in humans in which animals arousal waxes and wanes -
Sleep as a
Restorive Process -
Chemical events that provide energy to cells are reduced during waking and are replenished during sleep
Fatigue and alertness may simply be aspects of the circadian rythms and have nothing to do with wear and tear on the body or depletion of resources - Sleep Deprivation Studies
-
No marked physiological effects
Decreased cognitive perfomance
REM sleep deprivation studies, more likely to return to REM sleep and spend longer periods in REM sleep -
Sleep as a
Process solidifying and organizing events in memory - Cell activity during sleep is similar to that during searching for food when awake
- Reticular Activating System
-
RAS
Large reticulum (misture of cell nuclei and nerve fibers -like a net) that runs through thecenter of the brainstem - Stimulation of the RAS
- produces a waking EEG
- Damage to RAS
- Coma, a prolonged state of unconsiousness resembling sleep
-
Neural Basis of EEG Changes
Basal Forebrain - Contains neurons that secrete acetylcholine onto neocortical neurons that stimulate a waking EEG when animal is STILL AND ALERT
-
Neural Basis of EEG Changes
Median Rapne Nucleus (midbrain) - Contains serotonin neurons that project widely throughout the neocortex; when stimulated, neocortical cells produce a waking EEG when the animal is MOVING
-
Neural Basis of REM Sleep
Peribrachial Area - Cholinergic nucleus in the dorsal brainstem having a role in REM sleep behaviors, projects to the medial pontine reticulum
-
Neural Basis of REM Sleep
Medial Pontline Reticular formation -
Nucleus in the pons participating in REM sleep
Projects to several other brain areas that produce REM-related behaviors