Biology of Behavioral Disorders

Question 1

ACh receptors at the NMJ

• have what structure?
• are what kind of channels?

Answer 1

• 5 subunits: 2 alpha, beta, gamma, delta
• are ligand-gated ion channels

Question 2

what are the major molecules are involved in synaptogenesis (synapse synthesis) are the NMJ?

list their roles.

Answer 2

both act at post-synapse (NMJ)

• neuregulin (growth hormone): induces generation of AChR
• agrin (a proteoglycan): triggers clustering of AChR

Question 3

agrin

• has what role?
• works how?

Answer 3

• NMJ synaptogenesis: induces clustering of AChRs
• process:
  
  • binds MuSK receptor on post-synaptic membrane
  • this induces kinase production
  • kinases activate rapsyn, an adjacent cytoskeltal protein
  • receptors cluster

Question 4

which membrane receptors are key for AChR clustering?

Answer 4

• MuSK - muscle specific tyrosine kinase
• rapsyn - cytoskeletal protein adjacent to MuSK

Question 5

neuregulin

• has what role?
• works how?

Answer 5

• role: NMJ synaptogenesis - induces synthesis of AChR
• process:
  
  • activates ErbB tyrosine kinases
  • transciption modified
  • more AChR synthesized

Question 6

other than neurogelin, what can increase production of ACh receptors at the post synapse?

Answer 6

increased activity

Question 7

discuss the ideal regulation of AChR synthesis

Answer 7

• up regulation of AChR near NMJ
• down regulation of AChR distant from the NMJ
  
  • done by electrical activity

Question 8

what is the 1st line treatment of myasthenia gravis?

review its MOA & AEs

Answer 8

pyridostigmine

• MOA: AChE inhibitor
• AEs: excess ACh - diarrhea / N&V / cramps, sweating, salivation

Question 9

summarize the overall roles of the limbic system

Answer 9

• emotional behavior
• memory
• sexual behavior
• motivation
• integration of species preservation instincts - flight or fight, securing food

Question 10

indentify the specific role of each limbic system region

• hippocampus
• cingulate gyrus
• amygdala
• nucleus accumbens
• pre-frontal cortex

Answer 10

• hippocampus: memory and learning formation
• cingulate gyrus: emotions, behavior and pain
• amygdala: emotions - especially fear**
• nucleus accumbens: addiction and feelings of pleasure
• pre-frontal cortex: social interaction

Question 11

the hippocampus

• has what role (s) in the limbic system?
• damage results in?

Answer 11

• roles: memory-related
  
  • formation of anterograde memory
  • storage of explicit (declaritive) memory
  • memory of stressful events - w/ amygdala
• damage:
  
  • anterograde amnesia
  • loss of declarative memory
  • Altzheimers

Question 12

the amygdala

• has what role in the limbic system?
• works how?
• damage results in?

Answer 12

• role: emotional response - especially fear - in multiple ways:
  
  • fear conditioning
  • enhanced memory of fearful situation - w/ hippocampus
  • information modulation - w/ septum
• does this by: inducing release of fear hormones
  
  • hypothalamus -> CRF
  • adrenals -> cortisol
• damage: blockage of fear conditioning

Question 13

what is fear conditioning?

what mediates fear conditioning?

Answer 13

a learned fear response mediated by the amgydala

• amygdala receives several afferents
  
  • visual, auditory, olfactory, somatosensory
• links conditioned stimulus (CS) to unconditioned stimulus (US)
• encounter with stimulus: adrenal HPA → cortisol release

Question 14

what is information modulation?

what mediates information modulation?

Answer 14

mediated by the amygdala & septum

a state dependent recall - “things learned in a happy state are recalled better during a happy state then a sad state”

Question 15

what mediates enhanced memory of a stressful event?

Answer 15

the amygdala & hippocampus

Question 16

the nucleus accumbens is important for _?

Answer 16

addiction and feelings of pleasuren

Question 17

the pre-frontal cortex is important for _?

Answer 17

social interaction

Question 18

expain the pathogenesis of anxiety

Answer 18

chronic activation of the adrenal HPA (hypothalmic pituitary axis)

= release of cortisol even in the absence of a threatening stimulus

Question 19

explicit memory

• another name?
• includes which types of memory
• depends on what process?
• may be disrupted by damage ot?

Answer 19

• aka declaritive memory: conscious recall
• includes: episodic & semantic
  
  • episodic - events & experiences
  • semantic - facts
• depends on: long term potentiation (LTP) in the hippocampus
• disrupted d/t damage of: median temporal lobes, hippocampus

Question 20

episodic memory

is memory of…?

is what type of memory?

Answer 20

memory of events & experiences

type of explicit (declarative) mmeory

Question 21

semantic memory

is memory of…?

is what type of memory?

Answer 21

memory of facts

type of explicit (declarative) memory

Question 22

implicit memory

• another name?
• includes which types of memory?
• depends on which process?

Answer 22

• aka non-declarative memory: unconscious recall
• includes: perception, motor skills
• depends on: habituation

Question 23

damage to the bilateral medial temporal lobe leads leads to_?

Answer 23

• impaired explicit (declarative) memory
• anterograde amnesia

Question 24

damage to the enterohinal cortex leads to_?

Answer 24

alzheimers

Question 25

damage to the mamillary bodies can lead to_?

what can cause this?

Answer 25

amnesia - both anterograde & retrograde

caused by wernicke-kosakoff’s: a thiamine deficiency syndrome

Question 26

how does herpes simplex encephatlitis present?

Answer 26

• focal seizures
• focal neurological signs
• progressive deterioation of consciousness
• necrotizing process of temporal lobe - esp limbic system

Question 27

how does damage to the amygdala vs the hippocampus affect

• conditioned fear response
• declarative memory

Answer 27

Patients with amygdala damage

• Lack conditioned response to fearful stimul
• Declarative memory of stimuli is intact

Patients with hippocampus damage

• Retain conditioned response to fearful stimuli
• Lack declarative memory of stimuli (lack conscious recall)