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Behavioral neuro exam 3
secretory hypothalamus
releases hormones into the bloodstream that can act all over the body and in the brain part of the diencephalon that sits below the thalamus - collection of many nuclei (sub- regions) thermostat of the body, regulates homeostasis
autonomic nervous system regulated by the hypothalamus and controls thefunction of internal organs, blood vessels, etc.
homeostasis
keeping the body in a narrow, optimal, physiological range maintains temperature, blood pressure, salinity, glucose, stress responses, social behavior, feeding, sleep, etc.
zones of the hypothalamus
lateral, medial, and periventricular zones periventricular mostly release factors to the blood stream composed of many interconnected nuclei (branches of neurons) connected to the pituitary gland
pituitary gland
extends below the brain where it is held in a delicate bone cradle anterior and posterior lobes “mouthpiece” by which the brain speaks to the body and release to the bloodstream has 2 modes of communication
posterior pituitary magnocellular (big) neurosecretory cells in the hypothalamus project to here release oxytocin and vasopressin in the bloodstream directly
cells reside in the hypothalamus, by is secreted by this
oxytocin
important for social behavior, labor (parturition), and lactation, projected by hypothalamus
vasopressin
anti-duretic hormone (ADH) (prevents water loss), regulates water balance (important in kidney), and also social behavior
anterior pituitary
parvocellular (small) neurosecretory cells in the hypothalamus project here an actual gland itself, secretes hormones in response to hypothalamic inputs
anterior pituitary pathway
- parvocellular neurosecretory cells - transport hormones in axons
- hypophysiotropic hormones released (from hypothalamus to anterior), hormone transport in blood
- stimulation or inhibition of anterior pituitary hormone release - hormone transport in blood
- action on organs of the body
hypophysiotropic hormones
from the hypothalamus, released into hypothalamic-pituitary portal circulation and stimulate or inhibit anterior pituitary hormone secreting cells
follicle-stimulating hormone (FSH)
Gonads ovulation, spermatogenesis
luteinizing hormone (LH)
gonads ovarian and sperm maturation
thyroid-stimulating hormone (TSH), thyrotropin
thyroid thyroxin secretion (increases metabolic rate)
adrenocorticotropic hormone (ACTH), corticotropin
adrenal cortex cortisol secretion, mobilizes energy stores, inhibits immune system, etc
growth hormone (GH) prolactin all cells
mammary glands
- adrenal cortex releases glucocorticoid hormones (GCs) in the systemic blood circulation
- systemic GCs stimulate metabolism and suppress immune function
- GCs circulate back into the brain and stimulate GC receptors, providing negative feedback at multiple levels
prednisone
synthetic steroid/form of cortisol - anti- inflammatory (inhibits immune function) the body thinks that cortisol levels are very high, so it shuts off its secretion if this is stopped too quickly, the body can’t turn on cortisol again fast enough → adrenal insufficiency
adrenal insufficiency
caused by the quick removal of prednisone, low blood pressure, abdominal pain, mood/emotional changes
addison’s disease
degeneration of the adrenal gland leads to fatigue, skin discoloration, stomach pain, weight loss, mood changes
cushing’s disease
anterior pituitary releases too much ACTH (too much cortisol) rapid weight gain, sleeplessness, memory impairment, immunosuppression, irritability
eustress optimal amount of stress, focused attention,emotional regulation, rational thinking
distress (too much with low behavioral performance)
impaired memory, burn out, impaired executive functions
too little stress impaired attention, boredom, confusion, apathy
psychological chronic stressors
personal conflict acute frustration financial grief and loss care-giving school and career
causes of chronic stress
cause the negative feedback loop to break down, chronically high levels of cortisol cause atrophy of the dendrites in places like hippocampus that express glucocorticoid receptors, less responsive to feedback.
low-ranking individuals; high
In primates and animals with social hierarchy, ______ experience chronically ____ levels of stress, leading to ulcers, colitis, memory impairments, immunosuppression, atherosclerosis (hardening of blood vessels), etc.
factors that moderate how stressors impact physiology long term
when they occur in the lifespan how severe they are whether you have social support genetic how much control you have over the situation susceptibility vs. resilience to stress is a balance of all these
control over stressor
can lessen the negative consequences of a stress exposure activates the pre-frontal cortex and blocks some of the negative outcomes
learned helplessness uncontrollable stress can lead to ______phenotype
autonomic nervous system
controlled by periventricular hypothalamus, automatically carried out without conscious control sympathetic and parasympathetic cell bodies outside the CNS in autonomic ganglion before - preganglionic fibers after - postganglionic fibers
sympathetic nervous system
part of autonomic nervous system, increases heart rate and blood pressure, mobilizes glucose reserves, suppresses digestion, fight or flight releases norepinephrine
parasympathetic nervous system part of autonomic nervous system, decreases heart rate and blood pressure, promotes
- hypothalamus-pituitary axis → the hypothalamus causes the release of hormones from the pituitary that affect target organs throughout the body
- autonomic nervous system → the autonomic NS changes the activity of organs throughout the body
set point
the physiological process where the body maintains internal conditions (like temperature, pH, or glucose levels) within a narrow, optimal range around a specific target value
prandial state, postabsorpative state 2 states of energy balance in the body
prandial state
state of energy balance in the body, right after we eat a meal, the blood is filled with nutrients. energy is stored in glycogen and triglycerides anabolism
glycogen
actively using after eating, prandial state, short term and finite liver and skeletal muscle
triglycerides
in prandial state, long term in adipose (fat) tissue virtually unlimited
anabolism
prandial state, the assembly of these macromolecules (glycogen + triglycerides) from simple precursors (storing for later use) intestines (full) → absorbed nutrients → (immediate) glucose → neurons & all cells, fatty acids→ all cells, ketones → all cells, glycogen → liver and skeletal muscle, triglycerides → fat tissue
postabsorptive state state of energy balance in the body with energy for cellular metabolism
catabolism the breakdown of these macromolecules for use
in postabsorptive state intestines (empty)
Adipose fat tissue & liver and glycogen → triglycerides → fatty acids, glucose (neurons), ketones → all cells
- the size of energy reserves
- their rate of replenishment
energy balance requires mechanisms to regulate feeding behavior depending on:
lipostatic hypothesis
gordon kennedy (1953), that the brain monitors the amount of body fat and works to protect this energy store
leptin
released from adipocytes and regulates feeding by acting on the neurons in the hypothalamus to decrease feeding and increase energy expenditure gene that must encode for something that tells the brain that fat reserves are normal/adequate, if not, they just store more fat ob gene effective for weight loos only in __ deficient individuals
anorexia lesions of lateral hypothalamus
overeating lesions of ventromedial hypothalamus
ventromedial hypothalamus, lateral hypothalamus
hunger and satiety centers in the hypothalamus too simplistic, more about the precise where and when and what of hormone signaling
- arcuate nucleus
- paraventricular nucleus
- lateral hypothalamic area
3 important nuclei for the control of feeding
- high circulating leptin activates leptin receptors on neurons in the arcuate nucleus. (these neurons make alphaMSH/CART)
- few things happen:
process when leptin levels are too high (after eating a lot)
into the bloodstream when the stomach is empty activates NPY/AgRP neurons in the arcuate nucleus
Gastric distension
short term regulation, fullness signal, mechanoreceptors sends signals to the nucleus of the solitary tract (ANS control) via the vagus nerve
cholecystokinin
short term regulation, fullness signal, released by the intestine when fatty foods are consumed via the vagus nerve
insulin
short term regulation, a critical regulator of blood sugar, can also act directly on the hypothalamus to regulate feeding released by beta cells in the pancreas, required for the transport of glucose from the blood to other cells of the body blood glucose is tightly regulated by it highest after we have eaten and glucose reaches our blood stream serves as satiety signal by directly interacting with arcuate neurons
high blood glucose low insulin
low blood glucose high insulin
type 1 diabetes
genetic autoimmune disease where the immune system kills beta cells in the pancreas leads to high blood glucose/inability to use glucose treated with insulin injections
can cause blood sugar to plummet, causing insulin shock, delirium, dizziness, tremors, loss of consciousness since the brain uses so much sugar
too much insulin in type 1 diabetes
type 2 diabetes
acquired insulin resistance, cells stop responding efficiently to insulin, also leading to high blood sugar
- because it tastes good, pleasurable, hedonic experience (liking)
- because we are hungry, drive reduction, satisfies a craving (wanting)
*research suggests separate circuits in the brain for each one
2 reasons we eat
affective neuroscience the investigation of the neural basis of emotionand mood
emotional expression facial or bodily responses/behavior that weassociate with a particular feeling (emotions)
emotional experiences feelings themselves
6 basic universal emotions
Paul Ekman anger, sadness, fear, disgust, surprise, happiness studied across cultures to show that these emotions are cross-cultural, not dependent on language
Lisa Feldman Barrett
argues that the 6 basic universal emotions is inaccurate reflects western ideas not necessarily true across all cultures or even all individuals/within a given individual context is hugely important for both understanding and feeling emotions
emotions are based in distributed networks/circuits of brain activity
most up-to-date theory on neural circuits for emotions
james-lange theory of emotion
we experience emotion in response to physiological changes in our body external stimulus →
- perception
- autonomic/physiological response
- emotional reaction the feeling component of emotion derives from the perceived pattern of bodily sensations following encounters with external events
most of these regions do other things too
Damage to the frontal lobe
tamping explosive to build railroad in Vermont explosion sent his tamping rod through his eye socket and out the top of his head Healed, but was no longer himself his personality entirely changed
Phineas Gage case
anterior cingulate cortex
important for understanding and cognitively appraising interoceptive information important for assigning conceptual meaning to sensations inputs from orbitofrontal cortex, the amygdala and hippocampus help it assess the inherent value of interoceptive information about bodily physiology. it then assigns a conceptual meaning to those sensations
orbitofrontal cortex
important for using memories and imagined futures to determine emotional responses inputs from cingulate cortex and hippocampus help it use memories and if/then imagined scenarios to determine an emotional response inputs from hypothalamus, amygdala, and hippocampus help it assign conceptual meaning to sensory signals helps to assign valence (good or bad, etc) to stimuli in the environment
insular cortex receives lots of interoceptive info (from inside the body) primary gustatory cortex stimulation of it leads to sensations of disgust but also social emotions, like empathy, trust, intuition etc.
interoceptive and exteroceptive info is sent to here from thalamus and somatosensory cortex projections to/from other cortical regions that process memory, language and reasoning help it support appraisal processes that are essential for introducing subjective feelings, personal reflections on the feelings and the cognitive resources to express them.
amygdala
sits in the medial temporal lobe comprised of several subdivisions/nuclei medial central basolateral cortical
Kluver-Bucy Syndrome
animals with lesions/removal of the temporal lobes demonstrated very strange behavior also observed in humans altered visual perception oral fixation hypersexuality absence of fear responses
Patient S.M. and lesions of the amygdala 30 yr old woman studied with rare case of bilateral, isolated, amygdala damage normal intelligence and visual/facial perception indiscriminately trusting friendly showed no fear in typical fear assessments difficulty recognizing particularly fear and anger in others (not look at eyes) said she “hated snakes” but was highly curious and wanted to touch them - had to be stopped from touching poisonous snakes and tarantulas
mental disorders as mental deficiencies (of will power, morality, etc)
psychoanalysis mental illness arises from conscious and unconscious elements of the psyche in conflict
Sigmund freud’s view on mental disorders
Behaviorism mental illness is a result of maladaptive learned behaviors
BF Skinner’s view on mental disorders
mental and physical illness are both physiological and can be understood in terms of biological processes mental illnesses are brain disorders caused by changes in the function of neurons/neural circuits/glial cells understanding the neurobiology of the disorder allows us to develop better biomarkers for intervention and therapeutic targets
biological approaches to mental illness
Diagnostic and Statistical Manual of Mental Disorders 5th Edition
diagnoses are based on symptoms and severity of impairment
DSM-
diagnosed based on symptoms, not on etiology or biomarkers symptoms can vary between people same diagnoses can have many different causes no clear genetic basis and/or many genes implicated modeling complex neuropsychiatric disorders in animals is basically impossible
what makes it difficult to understand and treat mental illnesses?
anxiety disorders inappropriate expression of fear
obsessive-compulsive disorder post-traumatic stress disorder
types of anxiety disorders
panic disorder agoraphobia generalized anxiety disorder specific phobias social phobia
panic disorder
frequent panic attacks consisting of discrete periods with the sudden onset of intense apprehension, fearfulness, or terror, often associated with feelings of impending doom
agoraphobia
anxiety about, or the avoidance of, places or situations from which escape might be difficult or embarrassing, or in which help may not be available in the event of a panic attack
generalized anxiety disorder at least 6 months of persistent and excessive anxiety and worry
specific phobias
clinically significant anxiety provoked by exposure to a specific feared object or situation, often leading to avoidance behavior
social phobia
clinically significant anxiety provoked by exposure to certain types of social or performance situations, often leading to avoidance behavior
obsessive-compulsive disorder
obsessions- intrusive thoughts, significant anxiety or distress compulsions- ritualized attempts
PTSD symptoms
nightmares flashbacks avoiding reminders of event forgetting important aspects of the traumatic event unable to experience positive emotions irritability and angry outbursts negative thoughts about yourself and others
stressors threatening stimuli
serotonin system
diffuse neuromodulatory system 14 (at least) different GCPR receptors regulates mood, emotion, sleep, and more
selective serotonin re-uptake inhibitors (SSRIs)
block serotonin from being re-uptaken (cleared) from the synaptic cleft → more serotonin in the synapse not an acute acting drug, takes approx. a month for it to change overall serotonin tone and behavior not useful for treating panic attacks acutely serotonin may increase glucocorticoid receptors in the hippocampus → more inhibitory feedback for HPA axis
affective disorders
Major Depressive Disorder Bipolar Disorder
Major Depressive Disorder most common mood disorder, 6% of populationgets diagnosed every year
Bipolar disorder (manic-depressive disorder) periods of mania intermixed with periods of depression
depressed mood changes in appetite changes in sleep fatigue feelings of worthlessness and guilt inability to concentrate recurrent thoughts of death
depressive symptoms
inflated self-esteem and grandiosity increased talkativeness decreased need for sleep racing thoughts distractibility increased goal directed activity
manic symptoms
monoamine hypothesis of affective disorder suggested that monoamines like serotonin might regulate mood
reserpine
