Transcript Integrative Brain Function

Integrative Higher Brain Function:
Learning/memory, language, and
interaction of CNS with endocrine and
autonomic nervous systems
Metro AP Psychology
Fall 2016
Stan Misler
<[email protected]>
1. Plasticity: Learning and Memory
•Learning (or learned behavior) is the acquisition of info as a consequence of
environmental experience -> enhanced performance. It is distinct from innate
behavior which is strictly controlled by genes and natural selection (e.g., infant
ducks imprinting on and following first moving object it sees or wiggle behavior of
bees to transmit to hive mates direction, location and quantity of nectar)
•Memory: encoding, storage and retrieval of a memory trace (or engram) in
different ways and places, based on release of glutamate in regions of
hippocampus and cortex to suit different needs. Short-term working memory,
where a small amount of data is stored for at most 100s of sec, is based on
ongoing electrical activity in preformed synapses and it ceases with lapse into
unconsciousness. Later consolidation to long term memory survives
unconsciousness and cessation of electrical activity but requires synthesis of new
protein, sprouting of nerve terminal boutons or elaboration of dendritic spines.
Consolidation, by synaptic remodeling and pruning, occurs during rapid-eye
movement interval of sleep cycles (brain picks out most salient info from day’s
activities = “sleeping on it”).
•Declarative memory: recall of conscious experience and surrounding events that
can be put into words vs. procedural memory: unconscious recall of how to do
Where is memory trace or engram stored?
Seminal case: surgical removal of amygdala and hippocampus as
treatment of intractable epilepsy -> normal working memory and
intelligence, normal procedural memory but not long term declarative
memory
Accessing stored memory
Recognition = association of physical object or event with
something already experienced. Comparing present
information with memory
e.g., an “ace” test taker doing a multiple choice exam or
identifying familiar face in a crowd
Recall = remembering fact, object or event not currently
present. Reconstruction of memory requires activation of
all neurons involved in memory and its transfer into shortterm working memory
(e.g., taking an essay test which requires recalling much info
often not used for a long time and need for thorough
review )
2. Language in thought, speech or writing
Association of arbitrary symbols with specific meanings for
communication. Localized and lateralized in brain. Depends on integrity
of specialized associative areas in temporal and frontal lobes of left
hemisphere, which house verbal memories.
Language involves listening or reading, conceptualization of what to say
or write, and then executing it using innate rules of grammar. Same
areas used for sign language. However, recognition of emotional
content of speech is function of right hemisphere.
Early damage to left hemisphere -> recruitment of right hemisphere for
complexities of language
Anatomy of speech
Broca’s aphasia
Wernicke’s aphasia
3. CNS Regulation of Whole Body Function
a. Input to and output from hypothalamic paraventricular
nucleus (PVN) -> complex visceromotor response
1. PVN Activated by:
(i) olfactory bulb and the integrating limbic system (including
the amygdala) (by feeding, pheromones and auditory
and visual cues)
(ii) thalamic motor generator: jump started by "intended" as
well as actual muscular effort.
(iii) vestibular afferents, carotid and muscle
chemoreceptors, central respiratory generator (early Ds
with exercise)
(iv) superfornical organ (SFO) area postrema with an open
blood-brain barrier, responding to D circulating pH,
pCO2, [angiotensin II].
2. In turn, PVN activates:
(i) central respiratory drive generator
(ii) hypothalamic-pituitary-adrenal axis (CRF)
(iii) ADH release
(iv) central motor limb of the baroreceptor reflex for control
of vasomotor responses
and deactivates: vegetative functions (digestive)
Closer Anatomical View:
Hypothalamic nuclei and pituitary
b. Function of autonomic nervous system
The autonomic nervous system, with
its parasympathetic (acetylcholine
releasing) branch and its sympathetic
(noradrenaline releasing) branch,
modulates involuntary (or vegetative)
functions of most internal organs. It
does this via (i) altering contraction of
smooth muscle of gut and blood
vessel as well as heart muscle and (ii)
stimulating or inhibiting fluid secretion
by exocrine glands and hormone
secretion by endocrine glands.
Sympathetic branch acts as
accelerator to mobilize body for action
and output of energy while
parasympathetic branch acts as
brake that slows body down after
acceleration and keeps it running
smoother
Relaxing after fright;
rest and digest
Fright, flight or fight
c. Central role of amygdala in "fright, fight or
flight response" = “visceromotor " +
"behavioral” responses
a) Amygdala -> locus coeruleus: CNS arousal (EEG activation),
startle reaction and increased vigilance
b) Amygdala -> brain stem nuclei : pupillary dilation, facial
expressions of rage or fear
c) Amygdala -> thalamocortical pathways: motor behavioral
responses (crouching, stalking)
Rage (fight) vs. fear (flight) response depends on amygdala’s
assessment of prospective outcome based on life experience
d. CNS Regulation of activity of endocrine
system & endocrine feedback on CNS function
1. Body’s blood borne chemical messenger (or endocrine) system
releases hormones (modified amino acids, peptides, and steroids)
into the bloodstream from where they are filtered into interstitial
fluid and then bind to and affect peripheral tissue.
2. Endocrine “messages” tend to work slowly (over minutes) using
cell membrane G-protein coupled receptors to set off a cascade of
cytoplasmic second messengers and/or cytoplasmic and nuclear
receptors to increase synthesis of specific proteins; they outlast
the effects of neural messages (working over sec at longest).
3. Under normal (unaroused) conditions, the endocrine system
works in parallel with the parasympathetic nervous system to
sustain our baseline body processes. In crisis, the endocrine
system shifts into a new mode to support the sympathetic nervous
system….it releases epinephrine (adrenalin) which triggers the
“fight or flight” response
4. Hormones also feedback on CNS where they modulate
interest in sex and food, help control aggression and regulate
adult neurogenesis, the life and death of neurons.
Glucocorticoid excess reduces synaptic plasticity by
promoting withdrawal of dendritic processes of neurons,
while estrogen does the opposite. Hence moderately high
levels of estrogen in blood help reduce the severity of a
neurological insult caused by low oxygen or glucose levels of
blood, while high concentration of corticosteroids worsens
outcome of insult
5. Hormones do not cause behavior but play on pre-existing
tendencies (lower pain threshold)
e. Secretory Organs of the Endocrine system
Pineal (1) secretes melatonin for circadian rhythm
Hypothalamus controls anterior pituitary gland and secretes from its nerve
endings in posterior pituitary both vasopressin (antidiuretic hormone) and
oxytocin (for uterine contraction during childbirth, ejection of milk while
nursing and promotion of attachment)
Anterior Pituitary (2) secretes thyroid stimulating hormone that regulates
thyroid secretion of thyroxine and ACTH regulating steroid production in
adrenal cortex. At puberty it secretes LH and FSH to promote (a) testosterone
secretion by testes (-> growth of testes and penis and secondary sex
characteristics = deepening voice, body hair) or (b) estrogen and
progesterone secretion by the ovary -> development of breasts and menarche
(menstrual cycles) but only after acquisition of stores of body fat. Also
secretes growth hormone that stimulates bone and muscle growth
Thyroid (3) effects cell metabolism
Parathyroids (3), embedded in thyroid, regulate serum Ca levels
Adrenal medulla (5) secretes catecholamines as back up for sympathetic
nervous system
Adrenal cortex (5) secretes corticosteroids as part of a long lasting stress
response
Pancreas (Islets of Langerhans) (6) secrete insulin and glucagon for push-pull
response in regulation of serum glucose
Testes/ovaries (7,8) secrete male/female sex hormones
4. Emotions & Emotional Motor System
Emotional processing is part of complex brain function. It involves:
(i) physiological changes in facial expression and brain and body functions,
(ii) cognitive processing for interpretation of events and (iii) cultural influence
that shape display rules (or body language) for response
To review, for example, a treat which evokes fear
invokes fast physiological and behavioral
responses by the following series of events :
(i) stimulation of reticular activating system in
brainstem or cortical neurons -> (ii) activation of
limbic system (amygdala) -> (iii) activation of
hypothalamus (paraventricular nucleus, PVN).
The latter has two effects (a) recruitment of
sympathetic autonomic nervous system to evoke
the complex visceromotor response and (b)
recruitment of endocrine system for release of
epinephrine and corticosteroids by adrenals. This
fast initial response (i) can be modified or
overridden by slower but more complete appraisal
by prefrontal cortex (executive function) and (ii)
can be consolidation as memory by hippocampus
to be used for comparison with later “emotional”
stimuli
a. Complexities
1. Role of facial expression: (a) communicates emotion to observers
that could be contagious (infant reads mother’s face to decide
whether fall should be alarming or passed over) (b) identifies own
emotion by feedback to limbic system (put on angry face and heart
rate speeds up).
2. Stressors that most commonly effect body are social stressors =
problems at work, bereavement, constant noise, poverty and
powerlessness. Shaping response to such a stressor depends on:
previous medical and social history; genetic predisposition to
chronic disease; optimism (belief that difficulty can be overcome) vs.
pessimism; feeling of control over circumstances
b. Emotional style and coping
Resilience = rate of recovery from setback or loss (a function of
connectivity between prefrontal cortex and amygdala) depends on:
• Outlook: capacity to sustain positive emotion over time
• Social intuition: sensitivity to emotional states of others
• Self-awareness: awareness of our own physiological and emotional
cues
• Sensitivity to context: awareness of social environment and
sensitivity to rules of social engagement
• Attention: the ability to focus attention and screen out emotional
distractions
Aids to coping: benefits of confession (communicating worrying
thoughts; forgiveness of aggressor (“letting go”, “He who pursues
revenge should dig two graves”) and rethinking problem; relaxation
training; exercise; massage
5. Stress
1. Physical, emotional and behavioral response to situations that are
threatening or require changes in pattern of life: acute and brief
stress disorder (with hassles) vs. ongoing PTSD.
2. Hans Selye, stress, and psychosomatic medicine:
3. New field of Health psychology:
(i) investigation of how physical activities, psychological traits, social
relationships, food and drug consumption, poverty, ethnicity and
religious beliefs affect health and rate of recurrence of illness.
(ii) Promoting health through food, exercise, socialization,
regularization of sleep pattern, management of time, management
of anxiety/panic
(iii) Use of social readjustment rating scale as predictor of getting ill or
having an accident due to distraction
a. Adaptive and Maladaptive Stress Responses
(a) Features of acute adaptational stress : “turn on” of sympathetic autonomic
nervous system by hypothalamic paraventicular nucleus + rhythmic ventilatory
controller. Eustress =optimal amount of stress to promote high level function
(b) Features of chronic maladaptational stress
(1) Behavioral deactivation e.g., disordered gonadotropin response (young
female athletes’ triad = underweight and short stature, delayed menarche or
amenorrhea, decreased bone mineralization)
(2) Slow disorganization of visceromotor program (e.g. disordered vascular
regulation, decrease in blood flow to gut mucosa -> susceptibility to bacterial
and endotoxin invasion -> increased susceptibility to multi-organ system failure
(3) Persistent ACTH and cortisol release -> Catabolism, immunosuppression
(4) Depression = “fog over the mind” “dulled personality”. Accompanied by
atrophy of hippocampus = area of plasticity in learning and highest density of
corticosteroid receptors -> (?) premature dementia
(c ) General adaptive syndrome in response to continuous stress
(catastrophes): alarm, resistance (analgesia to lessen alarm), exhaustion
(decreased body reserve of glucose, decreased immune response, muscle
fatigue, increased risk for heart attack & stroke)
Home Study
1. Localizing origin of language components
using PET scanning
2. Brain-Heart Connection: poor heart contraction
under extreme stress
No angiographic evidence of
fixed vascular lesion or spasm –
induced blockade; akinetic apex
Like panic-induced asthma attack
of the heart
3.
Inhibitory
influences