31 Stress and Fear

Question 1

Define stress from a neuroendocrine perspective.

Answer 1

a state of homeostatic dysregulation produced by aversive stimulus causing activation of the HPA axis

Question 2

What is allostasis?

Answer 2

process by which systems deal with changes in set point due to severe or prolonged stress (adverse result)

Question 3

Name 3 factors that will determine the effect that stress will have on an individual.

Answer 3

chronicity, percieved controllability, physical v. psychological stressors

Question 4

Acute stressors activate which brain system(s) (neuro-endocrine system) ?

Answer 4

HPA (hyothalamic-pituitary-adrenal) axisis the main neuroendocrine system mediating stress response, specifically mediated by the paraventricular nucleus

Question 5

Why is PVN’s anatomical position optimal for its function?

Answer 5

PVN receives lots of converging information from both cognitive and visceral sources and then sends output to primarily the HPA axis but also the locus coeruleus and its parallel stress response system

Question 6

What effect does the PFC have on stress?

Answer 6

PFC “dampens” recruitment of PVN but specifically for psycological stress (dampening is not as prominent with physical stress)

Question 7

Describe the pathway of HPA which is transiently activated in response to stress.

Answer 7

PVN is stimulated and produces CRH which stimulates the anterior pituitary to create ACTH and the adrenal to produce glcocoritcoids

Question 8

How is the stress response usually transient?

Answer 8

negative feedback of glucocorticoids on the hypothalamus

Question 9

In what sense does PVN generate “good” stress?

Answer 9

stress response by HPA promotes a survival response in the transient sense

Question 10

What are the effects of moderate and excessive levels of glucocorticoids in learning and memories.

Answer 10

moderate levels aid learning and memory, excessive levels are neurotoxic (hippocapus); chronic or unpredictable stress can cause increased cortisol which can lead to depression

Question 11

How is fear related to stress?

Answer 11

fear is considered a subset reaction within stress, an extreme stress response

Question 12

How is the amygdala important in stress and fear?

Answer 12

amygdala is the main neural site mediateing fear responses (is part of the limbic system anterior to the hippocapus)

Question 13

Is the amygdala a unifed structure or an arbitrary grouping of heterogenous nuclei?

Answer 13

it is a collection of heterogeneous nuclei that function together, these nuclei include basolateral complex (cortical-like), central neuclei (autonomic system) and cortical and medial nueclei (part of olfactory sytem- direct connection)

Question 14

What is the CRF system?

Answer 14

a collection of extrahypothalamic sites that make CFR but work independently; CFR works independently from but parallel to ((complements) the HPA axis

Question 15

Contrast lesion and stimulation of the amygdala.

Answer 15

lesions lead to Kluver-Bucy syndrome or Urbach Wiethe (loss of fear), stimulation of the amygdala potentiates fear

Question 16

What are the 3 F’s and what is ther significance?

Answer 16

fight, flight and freeze which are survival responses to stress

Question 17

What can happen if your glucocorticoid levels are chronically elevated?

Answer 17

excessive fear or stress can contribute to etiology of depression and other psychiatric illnesses by allostatically altering the systems that regulate normal adaptive stress/fear responses (baseline levels of cortisol are elevated)

Question 18

Name 5 characteristics of stress that may lead to likely hood of developing depression.

Answer 18

repeated/chronic, unpredictable, uncontrollable, intense and interaction with underlying genetic vulnerability (may be important especially during developmental periods such as childhood)

Question 19

What types of fear may be helpful to understanding depression?

Answer 19

overly intense expression fo fearful behavior, regular expression of fearful behavior in an inappropriate contex (other symptoms include anhedonia, psychomotor retardation and ingestive disruption)

Question 20

Chronic psycological stress causes neuronal atrophy in the ______, as demonstrated by studies with tree shrews.

Answer 20

hippocampus (impovershed dendritic arbors)

Question 21

T/F Psychological stress attenuates normal neurogenesis (# cells) in adult hippocampus.

Answer 21

TRUE

Question 22

What was the notable observation from learned helplessness experiements on rats?

Answer 22

rats that had control over their stress and those without stressor showed similar response while rat with stress showed decreased appetite, loss of body weight, decreawed motor actiivty, sleep disturbances and behavioral dispair *** as well as changes in monoamines like norepi, serotonin and dopamine

Question 23

Patients with depression have chronic overactivity within the ______

Answer 23

amygdala

Question 24

What are 4 paradigms that are used to measure fear/anxiety in animals?

Answer 24

potentiated startle, approach-avoidance, defensive burrying and freezing