Lecture 17 - Stress and Motivation Flashcards Preview

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Flashcards in Lecture 17 - Stress and Motivation Deck (12):
1

Depression

Abnormal stress and fear substrates
very undertreated
-reduced input from PFC to subcorticol structures
-less dampening on HPA axis (PVN)
-hyperactive HPA = stress response
-chronic elevated cortisol damaging to body

2

Stress

Anything that shifts homeostasis --> daily occurence
-state of homeostatic dysregulation produced by aversive stimulus
-release epinephrine and activate HPA axis

3

Fear

Perception of threat
-considered at one end of arousal-stress continuum

4

Homeostasis

process by which stable internal milieu maintained in face of challenges
-set point, sensor to detect deviations, mechanism for returning to set point
-important for acute changes

5

Allostasis

process by which system deals with changes in SET PT
-positive feed back loops due to compensatory changes
-opponent process causing change in set point
-chronic, repeated, extreme changes to set point

6

Factors determining stress effect

Chronicity
Perceived controllability
Stressor physical vs. psychological

7

HPA axis

hypothalamus-pituitary-adrenal axis
-fight or flight from cortisol and epinephrine
-neuroendocrine system mediating stress response
-transiently activated in response to stress
-cortisol preps body for stress, helps produce glucose
-neg feedback direct to PVN and hippocampus
-moderate glucocorticoids aid in learning/memory
-high glucocorticoids are neurotoxic to hippocampus

8

Paraventricular nucleus

PVN of hypothalamus initiates response to acute stress
-multimodal sensory inputs to PVN
-releases corticotropin releasing hormone
-affects Locus coeruleus (arousal, awareness activation)
-affects Ant. Pit via portal system --> ACTH --> Cortisol
-affects dorsal motor X (decrease parasympathetic tone)
-possibly affects lateral T1-L2 (increase sympathetics)

PFC dampens PVN activity from psych stress

9

CRF system

Corticotropin-releasing factor (separate from HPA)
-unique and independent population of neurons in central nuclei of amygdala that also produces CRF
-amygdala transiently activated when afraid or stressed
-psych stress recruits CRF production in amygdala
-enhance learning/memory associated with acute stress

10

Excessive stress

contributes to depression and other psychiatric illness by allostatically altering systems that regulate normal adaptive stress/fear responses
-chronic stress causes hippocampal atrophy (decreases normal neurogenesis)

11

Learned helplessness model

3 mice
1. control
2. able to stop stressful stimuli (stops both 2. and 3's)
3. feels stimuli but dependent on 2 to stop
#3 mouse has depression

12

CRF

Corticotropin-releasing factor
-widespread localization of CRF and receptors in forebrain for coordinated stress response
-CRF elevated in depressed patients
-major regulator of stress/fear
-activates HPA axis
-activates LC-NE (autonomic response)
-elicits anxiety and fear resposne from amygdala