LTP (McGregor)

Question 1

What is LTP?

Answer 1

Long Term Potentiation – enhancement of the firing of post synaptic cells

Question 2

What are the two key properties of LTP?

Answer 2

It is long term

Only occurs when firing of pre-synaptic neurons = followed by firing of post-synaptic neuron

Question 3

WHat was Hebb’s postulate for memory?

Answer 3

Assumption that co-occurence = a physiological necessity for leanring and memory

Question 4

What did Hebb believe was the basis of memory?

Answer 4

If synapse is active at the same time as post-synaptic neuron fires, physical changes to the synapse will take place taht will strengthen it

Question 5

CAtchprase

Answer 5

NEURONS THAT FIRE TOGETHER WIRE TOGETHER

Question 6

Role of NMDA receptor?

Answer 6

For glutamate. Allow changes to the membrane potential in the post synaptic cell which, if there’s enough glutamate around should lead to firing of hte neuron.

Question 7

When does the NMDA recpetor work properly?

Answer 7

If post-synaptic neuron is partially depolarised, aswell as glutamate binding to it

Question 8

What are the two types of glutamate receptor?

Answer 8

NMDA and AMPA

Question 9

How does AMPA work?

Answer 9

When glutamate binds to it, AMPA receptor opens membrane chanels leading to depolarisation regardless of potential across membrane

Question 10

What kind of detectors are NMDA ones?

Answer 10

Coincidence detectors

Question 11

Why are NMDA receptors sometimes called coincidence detectors?

Answer 11

Coincidence detectors only open in the presence of glutamate and when post-synaptic membrane = depolarised. Coincidence detector that post-synatpic activity and pre-synaptic activity - occurring.

Question 12

Why are NMDA receptors coincidence detectors – explanation in terms of biology?

Answer 12

Ion channel (allows stuff through membrane) associated with NMDA = blocked by postitively charged magnesium ion. When membrane= sufficiently depolarised, the ion is no longer attracted to the cell

Question 13

What do changes in AMPA receptors mediate and who found this?

Answer 13

Muller et al (1988) – change in synaptic effciiency was mediated by changes in AMPA receptors

Question 14

Which receptor did LTP change numbers of and whof ound this?

Answer 14

Tocco et al (1992) – LTP changed AMPA but not NMDA receptor numbers – cell makes new AMPA receptors as a result of LTP.

Question 15

What happens if you block the process that makes new cellls and who found this and what is the process called?

Answer 15

LTP is also blocked. Nugyen et al (1994) – protein synthesis

Question 16

WHat other effect occurs as well as a post-synaptic effect and who has evidence of this?

Answer 16

Pre-synaptic effect – Dolphin et al (1982)

Question 17

What did Dolphin et al find and when?

Answer 17

1982 – more radioactivity in synapse after LTP. You get radioactive glutamate in pre-synaptic cell as result of LTP. When calcium enters cell –> activates messengers in cell –> releases nitrous oxide (increase amount of NO being produced). This acts as retrograde transmitter being detected by postiive inducing changes in pre synaptic cell

Question 18

What is the type of transmitter that goes from post to pre synaptic cell called?

Answer 18

retrograde transmitter