class 4

Question 1

1. Major brain areas involved in the stress response
   - What are the main limbic structures, what are they responsible for, and how are they impacted by chronic stress (from class discussion and slides)

Answer 1

1. limbic structures: flight/fight/freeze, regulate emotion and memory
2. limbic system: hippocampus, amygdala (works to determine emotional meaning of events)
   –impacted by trauma: Hyperactive amygdala:
   Sends fear signals even when there is no more danger
   Smaller hippocampus: Decreased volume
   Diminshed capacity to compare new stimuli to stored memories

Question 2

HPA Axis and the stress response, including the role of cortisol

Answer 2

-Hypothalamus, pituitary gland, adrenal gland, HPA Axis (neuroendocrine system)
Adrenal cortex is producing cortisone, circulars body which increases heat rate, dilating pupils etc to get the body to flee or fight to respond

-other system is neurotransmitter process)-neuropenephrine. Chronic exposure to stress makes the stress response system stay on, that level of circulating cortisol is bad for the body—effects brain structure adversely—amygdala is overactive, hippocampus is smaller, brain value could be smaller, fewer neurons, damaged synaptic connections—less dense brain and lower volume. The corpus collosum is decreased in volume.

Question 3

Epigenetics – be able to explain

Answer 3

genetic function can be altered through environmental influences on the expression of genetic material
-Signals from the environment which activate and silence different genes
Diet, differences in physical activity, stress, and exposure to toxins can all affect the epigenome for example

Question 4

Clinical effects of stress in humans

Answer 4

Smaller hippocampus and amygdala in adults
Smaller corpus callosum in children
-Neurons
Decreased synaptic connections / migration / differentiation =
Decreased brain volume/mass
Myelination
Delayed speed and strength in nerve signal conduction
Corpus Callosum
Decreased Volume = poor integration of affect and cognition
Hippocampus +
Neurotoxic effects on learning, concentration, memory
Amygdala; Stress Hormone System
Constantly primed for Fight/Flight = over-responsive
-HPA Axis
Central Nervous System Hypervigilace to danger
Primed to perceive angry faces
Harder to attain emotional self-regulation
Less attention for other information

Question 5

Relevant alleles and genes regarding risk for depression or difficulties following trauma

Answer 5

• People are born with different alleles (versions/forms) of the same gene.
• Different alleles lead to different phenotypes.
• Alleles are affected by the environment in different ways.
• The interaction between the allele and the environment leads to both positive and negative outcomes.-S/s/SS/ss

Question 6

Prefrontal cortex

Answer 6

The limbic system communicates with the prefrontal cortex to assess the potential threat and activate the stress response
The HPA Axis communicates with the rest of the organs through receptors (MR and GR) and the release of cortisol
This causes an immediate stress response (fight or flight) and long term structural and genetic changes

Question 7

how do the brain areas work together

Answer 7

• The amygdala perceives emotions
• The hippocampus stores emotional memory for reference later
• The prefrontal cortex dictates the response to the stressor or emotion
• These areas of the brain work in concert with other organ systems to create the stress response

Question 8

in summary…

Answer 8

The limbic system communicates with the prefrontal cortex to assess the potential threat and activate the stress response
The HPA Axis communicates with the rest of the organs through receptors (MR and GR) and the release of cortisol
This causes an immediate stress response (fight or flight) and long term structural and genetic changes