Plasticity

Question 1

What is plasticity?

Answer 1

The ability of the brain to chaneg

Question 2

How are connections fine-tuned?

Answer 2

As we interact with our environment, synaptic connections start to change, with new ones being made, useful connections becoming stronger and connections that are infrequently used becoming weaker or even lost for good

Question 3

What is a normal electrical response to neurotransmitter release a measure of?

Answer 3

Synaptic strength

Question 4

What process has long-lasting enhancement in synaptic strength that can be produced by brief periods of neuronal activity?

Answer 4

Long-term potentiation (LTP)

Question 5

Which process has long-lasting depression in synaptic strength that can be produced by brief periods of neuronal activity?

Answer 5

Long-term depression (LTD)

Question 6

What is a common amino acid used to build proteins?

Answer 6

Glutamate

Question 7

Where do glutamate function?

Answer 7

Most plastic synapses, those that exhibit LTP and LTD

Question 8

Where are Glutamate receptors found?

Answer 8

At the receiving side of the synapse

Question 9

What are the 4 variates of Glutamate receptors?

Answer 9

Ionotropic receptors: AMPA, NMDA and kainate

Metabotropic receptors: mGluR

Question 10

Do all types of glutamate receptors respond to the same type of neurotransmitter?

Answer 10

Yes

Question 11

What are the functions of ionotropic glutamate receptors?

Answer 11

They use their ion channels to generate an excitatory post-synaptic potential (epsp)

Question 12

What is the function of metabotropic glutamate receptors?

Answer 12

Modulate the size and nature of the response

Question 13

What receptors are most commonly thought of as memory molecules?

Answer 13

AMPA and NMDA

Question 14

What receptors are the fastest to act?

Answer 14

AMPA receptord

Question 15

What happens when glutamate is bound to AMPA receptors?

Answer 15

The receptors rapidly open their ion channels to produce a transient (not permanent) excitatory postsynaptic potential, the glutamate is only bound to the AMPA receptor for a fraction of a second and once it leaves and it removed from the synapse, ion channels close and electrical potential reverts to its resting state

Question 16

What is the critical molecule that trigger synaptic plasticity?

Answer 16

NMDA receptors

Question 17

How does glutamate bind to NMDA receptor?

Answer 17

It binds to NMDA receptors on the postsynaptic neuron

Question 18

What happens to the NMDA receptor when the synapse is activated slowly?

Answer 18

The NMDA receptors play little to no role

Question 19

Why do NMDA receptors play little to no role when NMDA receptors are activated slowly?

Answer 19

As soon as NMDA receptors open their ion channels, it becomes plugged by Mg2+ ions that are present in the synapse

Question 20

What happens when synapse are activated by several pulses very quickly to a set of inputs on to a neuron?

Answer 20

The greater synaptic activity causes a large depolarisation in the postsynaptic neuron and this dispels Mg2+ from the NMDA ion channels by a process of electrical repulsion, NMDA receptors can then partake in synaptic communication

Question 21

What are the ways NMDA receptors undergo synaptic communication?

Answer 21

1. They conduct Na+ and K+, which adds to the depolarisation
2. They allow Ca2+ to enter the neuron

Question 22

What happens when Ca2+ enters the neuron?

Answer 22

Ca2+ binds to proteins located extremely close to the synapses where the NMDA receptors were activated, many of these proteins are physically connected to the NMDA receptors in a molecular machine, some are enzymes that are activated by Ca2+ which leads to chemical modifications of other proteins within or close to the synapse, these chemical modifications are the first stages of formation of the memories

Question 23

What are the ways to express change in strength?

Answer 23

1. Enable AMPA receptors to work more efficiently, such as pass more current into the neuron upon activation
2. Enable more AMPA receptors to be inserted into the synapse

Question 24

How does the two ways lead to change in strength?

Answer 24

They both lead to a larger epsp, LTD

Question 25

What does the reduction in efficiency and number of AMPA receptors result in?

Answer 25

LTD

Question 26

What is the beauty of the mechanism of inducing LTP or LTD?

Answer 26

It’s relative simplicity that all can occur within a single dendritic spine and therefore alter synaptic strength in a highly localised manner

Question 27

What are the structural alterations that occur in the brain when memories become more permanent?

Answer 27

Synapses with more AMPA receptors inserted following the induction of LTP change their shape and may grow bigger or new synapses may sprout out of the dendrite so the job of one synapse can be done by two

Question 28

What happens to synapses that lose AMPA receptors following the induction of LTD?

Answer 28

They may wither and die

Question 29

What is how well we learn influenced by?

Answer 29

Our emotional state and when we pay attention

Question 30

What neuromodulator is released during heightened attention?

Answer 30

Acetylcholine

Question 31

What neuromodulator is released during novelty, stress and anxiety?

Answer 31

Cortisol

Question 32

What other neuromodulators are released during emotional states?

Answer 32

Dopamine, noradrenaline and steroid hormones

Question 33

What do modulators do to neurons?

Answer 33

They change the functioning of NMDA receptors, activate special genes specifically associated with learning, make proteins to stabilise LTP and make it last longer

Question 34

What happens when neurons are damaged?

Answer 34

Neurons do not grow back but other neurons adapt and can take on similar functioning roles to lost neurons, forming another network that is similar