PSYD33H3 Lecture Notes - Lecture 3: Sympathetic Nervous System, Allostatic Load, Anterograde Amnesia
•Watch video online: brain neuroanatomy; involves the limbic system
•Stress is not always a bad thing - acutely, mild-moderate stress motivates us
•However, chronic stress becomes physiologically devastating
Bruce McEwen
•Prenatal and early childhood - biological embedding
•Critical periods of neurodevelopment; brain development
•There is an enzyme that breaks down cortisol in the blood during; however, when the cortisol
amount is HIGH, it’s problematic
•When there is insufficient protective nurturing buffering and caregiving by parents, the brain can
change
•Epigenetics - this area above the genome, methyl groups are added to the genome; has
mechanisms such as histo-modification
•Gives us a biological threshold for adulthood
•Adulthood
•Polymorphisms and our genes interact with our environment
•Cumulative effect on our physiology
•Allostasis: achieving balance through adaptation
•Allostatic load
•In acute stress, immediately, adrenaline, noredrenaline, epinephrine and norepinephrine are released
as neurotransmitters
•Second is an endocrine response - about 30 different hormones are released
•Some of these are in effect 2 weeks later
•Sympathetic nervous system
•Parasympathetic system shuts down unnecessary functions
•We are most interested in cortisol
•HPA-Axis, the neuro-endocrine system of the response of Beta-endorphins being released to numb out
pain in the case of an injury
•The amygdala, prefrontal cortex, hypothalamus, etc., instantly
•Acutely, these responses HELP; chronically, these responses cause wear and tear
Systems Involved
•Immune system - in acute stress, the immune system is enhanced
•Blister study: created wounds (blisters), and observed that people more stressed out required a
longer amount of time for healing
•Same happened for stressed students during exam times
•Metabolic system
•CNS; especially sympathetic nervous system
•Reproductive
•Cardiovascular - arteries stretch, and inflammation occurs there, lesions develop; cholesterol
•Cognitive system
•Prefrontal cortex (has glucortical (sp?) receptors) , hippocampus (long term memory, spatial
memory, memory consolidation), and amygdala are the three brain areas most affected
•Chronic stress and trauma can cause neuronal death - whereas acute/somewhat acute stress
usually leads to regeneration of neurons
•There is plasticity in the brain
•Studies show that there is smaller hippocampal volume in people with chronic stress or depression
•Larger amygdala in people with chronic stress or trauma
•HPA-Axis (hypothalamic-pituitary-adrenal axis)
•If there are repeated hits; or perhaps HPA dysfunction, or a dis-regulated system in which there are
too low cortisol levels (as seen in PTSD)
Lecture 3!Tuesday, May 29th, 2018
