L6

Question 1

describe Atkinson and Shiffrin’s model of memory

Answer 1

the first 300ms is sensory information

if that sensory information is attended then it goes into your short term memory (20 sec)

if this is reherced then it will go into long term memory

Question 2

what is distributor processing

Answer 2

Distributor processing is storing information across multiple neurons

Question 3

what is a cell assembly

Answer 3

particular pattern of activity in a group of interconnected

neurons

Question 4

Each psychologically significant event, sensation, percept, expectation, memory or thought is the result of what

Answer 4

a cell assembly

Question 5

what happens during the perception of an event

Answer 5

When you are perceiving an event, it corresponds to particular neurons cell assemblies that are becoming active

Question 6

when something is in your short term memory, what is happening

Answer 6

Reverberating neural activity in closed-loop circuitry

Question 7

why do we not store out memories in the way that we store short term memories

Answer 7

because the circuit needs to be active all the time you would run out of neurons and it would also be metabolically expensive

Question 8

what is long term memory

Answer 8

Long term is when you strengthen the connections between neurons responsible for that particular experience

stronger synapse happen after consolidation meaning that those neurons have an increased potential for activation

Question 9

how you you recall a memory

Answer 9

you activate the network from when you perceived the event that was that memory

the reactivation of this assembly occurs because of differential synaptic strength

Question 10

what are Hebbs rules for whether a synaptic connection would strengthened or not

Answer 10

1. when neurons fire you strengthen the connection which tends to induce lasting cellular changes that add to its stability (what happens)
2. When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased. (how it happens)

Question 11

what is Hebbian learning

Answer 11

When the postsynaptic and the presynaptic cell fire together then the connection between
them is strengthened

(cells that fire together, wire together).

Importantly, this allows for the association of inputs

Question 12

what is the function of the amygdala

Answer 12

to produce an emotional response

Question 13

explain how Hebbian learning allows for association of inputs

Answer 13

eg pain has a strong synapse to a neuron that causes you to feel fear.

when you are walking down the beach you see a crab. the neuron activated when you see a carb has a weak synapse to the neuron that causes fear therefore the action potential is not propagated.

however if the crab pinches you both the carb and the pain neuron are going to be activated at the same time and the weak synapse will become stronger

this means that the next time you walk down the beach and you see a crab, the synapse has become stronger so now you the AP will be propogated and you will feel fear

Question 14

what is long term potentiation (LTP)

Answer 14

the strength of connections which last a long period of time

the bigger the strength of the EPSP the stronger the connection

Question 15

why does long term potentiation suggest how memory works

Answer 15

you have a phenomenon which can strengthen synapses for a year (or possibly more)

Question 16

does LTP have Hebbian properties

Answer 16

yes

specific to the pathways that are activated

This allows the nervous system to be very selective and gives you trillions of synapses which can be changed

Question 17

what receptors are on the postsynaptic neuron that allow for LTP

Answer 17

AMPA subtype of glutamate receptor and NMDA subtype of glutamate receptor

Question 18

describe the LTP induction mechanism

Answer 18

when glutamate binds to the AMPA receptor it lets Na+ into the cell causing depolerisation of the membrane

Sufficient depolarisation of membrane leads to unblocking of the NMDA channel

Calcium influx leads to LTP induction via downstream changes which increases receptors and then changes protein synthesis that
can induce long-term alterations in the strength of the synapse

Question 19

describe the AMPA receptor

Answer 19

when glutamate binds it lets Na into the cell

Question 20

describe the NMDA receptor

Answer 20

the NMDA receptor has a Mg2+ gate

Sufficient depolarisation of membrane leads to unblocking of channel because the inside becomes more positive pushing the +ive charge of the Mg gate out of the way

when this happens and glutamate is bound Ca can enter the cell

Question 21

what is the critical aspect of the LTP mechanism

Answer 21

it requires a conjunction of presynaptic and postsynaptic activity (Hebbian synapse)

You need a significant depolerisation to get the Mg out of the pore so Ca can get in

This can happen from one big input or lots of small ones

Question 22

how could you test to see whether LTP has anything to do with memory

Answer 22

Show that blocking LTP prevents memory formation

Show that reversal of LTP produces forgetting

Show that learning leads to LTP-like changes

Show that producing LTP creates false memories or masks existing memories

Question 23

what is an antagonist of the NMDA receptor

Answer 23

AP5

Question 24

how does AP5 effect LTP

Answer 24

you need the NMDA receptor for LTPs to occur therefore if the receptor is not working than LTPs cant happen

This is a dose dependent response

Question 25

what is the Morris water maze

Answer 25

it is a test for memory

it consists of a pool of water with a platform placed in a specific location just under the water so the rats cant see it

a rat is then placed in the water and they swim around until they find the platform. they learn very quickly where the platform is

you would then take the platform out of the water and if the rat spends more time swimming around where the platform was then it shows that they are looking for the platform and they have formed a memory of where the platform was

Question 26

how could you test to see if AP5 had an effect on memory using the morris water maze

Answer 26

you have a control group and then groups where the dose increases

you find that as the dose increases the time spent in each 1/4 of the pool balances out showing that with very high doses of AP5 that the animal never learns where the platform is

Question 27

LTP maintenance is dependent on….

Answer 27

protein kinase M zeta (PKMz)

Question 28

what dose ZIP (Zeta-Inhibitory Peptide) do

Answer 28

it inhibbits PKMz

this reverses the maintenance of late-phase LTP in vivo (it turns off LTP)

this means that when zip is injected the animal forgets what it has learnt

Question 29

what does zip show

Answer 29

it shows that when a normal action potential is fired there is no change but when zip is injected it dramatically decreases the baseline for EPSP

Question 30

what does protein kinase M zeta (PKMz) inhibition cause

Answer 30

PKM ζ inhibition abolishes long-term retention of spatial information

Question 31

what does 2 photon microscopy allow for

Answer 31

the imaging of tissue within a band 1 micron thick and at depths of up to 1 mm inside the brain

Question 32

when you are looking at a 2 photon microscopy image of a dendrite what are the fuzzy things

Answer 32

dendritic spines

this is where the axon terminals connect to the dendrite

Question 33

dendritic spine formation can be blocked by which NMDA antagonist

Answer 33

MK-801

Question 34

why is it important that the number of dendritic spines (connections) are regulated

Answer 34

As you learn more and more information you get more and more strong synapses

This could be dangerous as this is what happens in epilepsie

Also if this is the case what happens if the brain becomes full

Question 35

what is synaptic scaling

Answer 35

it is a form of homeostasis

This means that there is a continuous process in cell where when you strengthen some synapses you weaken others