lecture 10

Question 1

definition of synaptic plasticitiy

Answer 1

change in connection strength between a neuron and its target cell that can lead to changes in behavior

Question 2

sensitization

Answer 2

behavioral term describing increased response to stimulus

not a cellular change

Question 3

frog NMJ

Answer 3

activity dependant plasticity

reptitive stimulation allows for facilitation of transmitter release until you run out of vesicles

Question 4

synaptic facilitation

Answer 4

rapid increase in synaptic strength that occurs when 2 APs invade the presynaptic terminal within a few miliseconds
results from the prolonged elevation of presynaptic calcium levels (slow to return)

Question 5

synaptic depression

Answer 5

causes neurotransmitter release to decline during sustained synaptic activity

Question 6

synaptic potentiation/augmentation

Answer 6

enhance the ability of incoming Ca to trigger fusion of synaptic vesicles with membrane
augmentation- a few seconds
potentiation- minutes

Question 7

paired pulse facilitation

Answer 7

increase in probability of release

characterize how much enhancement at any given interval after an action potential

Question 8

facilitation time constant

Answer 8

F1- fast at first 20-30msec
F2- slow 100-300msec
facilitation decays over time

Question 9

giant squid synapse

Answer 9

normal Ca- shows depression
lowering Ca- reduces transmitter release and mix of depression/augmentation
lowering more- eliminated depression and shows only augmentation
normally release a large amount of vesicles fast but by dropping calcium you release a maintainable amount and facilitation occurs

Question 10

post tetanic potentiation

Answer 10

train of high frequency stimuli followed by enhancement lasting several minutes
- potentiation outlasts stimulus that induces it

Question 11

short term sensitization of aplysia gill

Answer 11

first time siphon is touched, gill contracts vigorously
repeated touches elicit smaller gill contractions due to habituation
subsequently, pairing a siphon touch with an electrical shock to tail restores a large rapid gill contraction

Question 12

synaptic mechanisms of sensitization

Answer 12

touching siphon skin activates sensory neurons that excite gill motor neurons to contract
a shock to tail stimulates modulatory interneurons that alter synaptic transmission b/w siphon sensory neuron and gill motor neurons resulting in sensitization

Question 13

short term facilitation caused by post translational changes

Answer 13

1. serotonin receptor - G protein activates adenylyl cyclase to make cAMP to activate PKA to phosphorylate K channel so K becomes less active and AP is broader
   leaves more time for Ca channels to open and more release
   probability is indirectly affected by increasing Ca

Question 14

long term sensitization

Answer 14

requires changes in gene expression-
PKA phosphorylates CREB which binds to cAMP (CRE) and increases the rate of transcription by stimulating ubitquitin hydrolase which frees up catalytic PKA
C/EBP stimulates growth of synapse

Question 15

summary of short/long term

Answer 15

short- post translational modification of existing proteins

long- changes in gene expression, new protein synthesis and possibly growht of new synapses

Question 16

mutants deficient in learning

Answer 16

dunce- phosphodiesterase degrades cAMP
rutabaga- adenyly cyclase
amnesiac- peptide that stimulates adenylyl

Question 17

coincidence detection

Answer 17

two events that occur close together in time causing persistent changes in behavioral responses at later times

Question 18

classical conditioning of aplyasia

Answer 18

paired touch of siphon (CS) to tail shock (UCS)
delay- touch siphon then shock tail
trace- touch and wait awhile

Question 19

how is pairing different from sensitization

Answer 19

1. required fewer repititions to produce a big withdrwal
2. shows specificity for siphon touch
   same machinery that produces sensitization but amplifies for pathway that is touched

Question 20

classical conditioning mechanism

Answer 20

touching siphon sends AP into terminal which opens CaV allowing Ca to come in and bind to calmodulin
calmodulin mediated potentiation of adenylate cyclase which is now in ready form
shocking tail releases 5Ht activating G protein which activates adenylyl cyclase
summary: need to touch first to put AC in ready state then shock to allow G protein to activate AC

Question 21

classical conditioning specificity

Answer 21

if siphon is touched before shock and mantle touched after then siphon is the only stimulus enhanced or vice versa
why? need calcium before serotonin (need touch before shock)

Question 22

is classical conditioning hebbian?

Answer 22

no because the post synaptic neuron does not need to fire an AP