Learning and Memory

Question 1

What are the two elementary mechanisms of cortical synaptic plasticity?

Answer 1

LTP: neurons that fire together, wire together

LTD: Neurons that fire out of sync lose their link

Question 2

What NT is particularly important for long term potentiation?

Answer 2

glutamate

Question 3

What receptors are important for LTP? Why?

Answer 3

NMDA receptors

because they are normally blocked the a Mg2+ ion, so it requires depolarization of the postynaptic neuron before it will become active and allow Ca2+ through

Question 4

What is the mechanism for LTP?

Answer 4

Glutamate is released

NMDA receptors are activated

Ca2+ enters the cells

new AMPA receptors are incoporated into the synaptic membrane

this means the neuron becomes more sensitive to glutamate - it will fire with a lower concentration of glutamate because ther eare more receptors there

Question 5

What happens in long term depression?

Answer 5

1. weak NMDA receptor activation
2. AMPA receptors are removed from the membrane
3. neurons become less sensitive to glutamate

Question 6

What is a broad definition of memory and learning?

Answer 6

adaptive change on the part of an organism in response to an environmental input

Question 7

What is the difference between learning nad memory?

Answer 7

learning is the acquisition of new knowledge

memory is the retention of learned knowledge

Question 8

What does memory consolidation require?

Answer 8

protein synthesis

Question 9

What were Hebb’s theories on memory?

Answer 9

that th ephysical representation or location of a memory is an engram

that engrams are CELL ASSEMBLIES - groups of simultaneously active neurons

Question 10

WHat region ofthe brain is particularly important for memory consoidaiton>

Answer 10

hippocampus

Question 11

What are the models for moecular mechanisms of memory?

Answer 11

1. aplysia calfornia - sea slug that retracts its gills with water spray, but not after habituation
2. Drosophila - used to determine the genetics of memory (train them to fly away from areas with bad odor bc they learn they’ll get shocked)

Question 12

What were the 4 genes identified for memory in drosophila?

Answer 12

1. dunce: encodes a phosphodiesterase that converts cAMP to AMP
2. Rutabaga encodes a protein that uses ATP to make cAMP
3. Amnesiac for making a NT - cPACAP
4. Ddc for making serotonin and dopamine

Question 13

In higher organisms, what is the biochemical correlate for short term memory?

Answer 13

1. serotonin released
2. binds a GPCR
3. activation of adenylyl cyclase
4. cAMP produced
5. activates protein kinase A
6. PKA phosphorylates a K+ channel in such a way that the flow of K+ is slowed
7. This allows more Ca2+ to enter the cell instead of K+
8. the Ca2+ then stimulates the pathway —- short term memory

Question 14

How is PKA also involved with higher organisms’ long term memory?

Answer 14

It can also go to the nucleus to activate transcription factors like CREB

this will bind to the cAMP response elements on the DNA and upregulate the expression of cAMP, AMP receptors, etc.

this essentially makes the synapse bigger and more active - LTP

Question 15

What is the role of CaM Kinase 2 and CASK in long term memory?

Answer 15

CaM Kinase 2 is a protein kinase that will phosphorylate proteins and improve memory

CASK is an enzyme that stimulates CaM Kinase 2

Question 16

What role does neuroplastin play in memory?

Answer 16

It is a protein-coding gene that is likely a cell adhesion molecule involved in LTP and synaptic plasticity —- specifically, it somehow increases cortical gray matter thickness.

Question 17

How does the size of dendrites correlate with memory?

Answer 17

bigger dendrites = better memory