Learning and Memory

Question 1

what are examples of declarative memory?

Answer 1

facts, events

Question 2

what are examples of nondeclarative memory?

Answer 2

procedural memory, classical conditioning

Question 3

what is LTP?

Answer 3

long-term potentiation - strengthening of synapses that produce a long lasting increase in signal transmission between 2 neurons

Question 4

what is HFS?

Answer 4

high frequency stimulation (1 HTP lasts hours, multiple HFS lasts days/months)

Question 5

what experiment shows that LTP is important in learning?

Answer 5

morris water maze - put rat in water that can only escape by stepping on a platform. every time the rat goes in it finds that platform quicker.
rats with hippocampal lesions act the same every time and do not improve

Question 6

what impairs learning and blocks LTP?

Answer 6

NMDA antagonist AP5

Question 7

what happens when glutamate binds to an NMDA channel?

Answer 7

calcium is released into the neuron

Question 8

what ion goes through AMPA channels?

Answer 8

sodium

Question 9

what does calcium do inside the post-synaptic neuron?

Answer 9

activates CAMKII

Question 10

what is CAMKII?

Answer 10

an enzyme which phosphorylates the AMPA receptor and introduces new AMPA receptors in the membrane - this causes larger EPSPs - causes LTP

Question 11

what happens when an AMPA receptor is phosphorylated?

Answer 11

it becomes more effective - stays open for longer and so lets in more sodium

Question 12

how long can the effects of CAMKII last, and how?

Answer 12

minutes to hours, because it is autocatalytic which means it phosphorylates itself

Question 13

how can LTP strengthen the pre-synaptic neuron?

Answer 13

• calcium activates nitric oxide synthase in the postsynaptic neuron
• this diffuses to the presynaptic neuron and activates guanylyl cyclase
• guanylyl cylase produces 2nd messenger cGMP
• cGMP increases glutamate release into the synapse

Question 14

what is CREB and what is its role in LTP?

Answer 14

a transcription factor activated by phosphorylation. switches on genes which make structural proteins which are necessary in synapses. these proteins are transported to the post synaptic terminal and build up and change the structure of the synapse.

Question 15

what is the evidence that protein synthesis is important in learning?

Answer 15

when protein synthesis inhibitors are injected right after acquisition, recall is affected. therefore, protein synthesis is necessary for consolidation

Question 16

descrbe the 3 phases of LTP

Answer 16

• early phase post synaptic (CAMKII)
• early phase pre synaptic (nitric oxide, guanylyl cyclase & cGMP)
• late phase (changing the structure of the synapse - CREB & protein synthesis)

Question 17

what is LTD?

Answer 17

the opposite of LTP: long term depression

this is where synapses get weakened.

Question 18

how can LTP be tested in humans?

Answer 18

during surgery inferotemporal cortex can be removed

Question 19

what are theta rythms?

Answer 19

waves of activity in the hippocampus. are used as physiological evidence of LTP. they play a role in synchronising activity in different brain areas. you can do a stimulation at the troughs and you will see LTD occurring, and a stimulation at the peaks where you will see LTP occurring. if you block theta waves you will se deficits in learning.

Question 20

can you enhance LTP?

Answer 20

yes, genetically - by increasing the amount of a particular NMDA receptor (NR2B) - this increases LTP because they are better at fluxing calcium, so more LTP pathways are triggered

Question 21

what can affect LTP?

Answer 21

1. age/memory - young rats learnt morris water maze task quicker than older rats. decreased acquisition = decreased LTP = decreased expression of NMDA receptors (NR1 & NR2B)
2. learning - rats reared in an enriched environment learn a lot quicker compared to control mice.

Question 22

how can effects of aging be reversed?

Answer 22

by having an enriched environment - spatial maze task: aged mice in impoverished environment show greater deficits in learning and memory than those in a normal or enriched environment.