Neurotransmitters and behaviour - SAQ

Question 1

What is the nervous system?

Answer 1

A system of neurones

Question 2

What are the 3 parts of a neuron?

Answer 2

Body (soma)
Dendrites
Axon

Question 3

Dendrites

Answer 3

To receive signals from other neurons

Question 4

Axon

Answer 4

To transmit signals further

Question 5

How is a synapse formed?

Answer 5

The axon of one neuron approaches a dendrite or soma of another neuron

Question 6

What type of transmission is used?

Answer 6

Electrical and chemical

Question 7

How does a neuron fire an action potential?

Answer 7

Every neuron has a certain threshold of excitation received from the other enrols, and if the sum excitation exceeds this threshold, the neuron ‘fires’ and generates a brief pulse called action potential that travels along the axon to other enrols, passing the excitation further.

Question 8

How does the mechanism of transmission become chemical?

Answer 8

When the action potential reaches the end of the axon, a neurotransmitter is released for the axon terminal into the synaptic gap.

Neurotransmitters are chemical messengers.

They are constantly synthesised in the neurone and moved to the axon terminal to be stored there.

A related neurotransmitter is available in the synaptic gap for a short period during which it may be destroyed, pulled back in to the pre-synaptic axon terminal through reuptake, or real the post-synaptic membrane and bind to one of the receptors on its surface.

Question 9

What are the different neurotransmitters?

Answer 9

Excitatory and inhibitory

Question 10

Excitatory

Answer 10

Allows the impulse to cross the synapse and produce a stimulating effect on the brain.

Question 11

Inhibitory

Answer 11

Stops the impulse, preventing it from crossing the synapse.

They produce calming effects on the brain. These neurotransmitters are also always in a state of dynamic balance.

Question 12

Agonists

Answer 12

Agonists are chemicals that enhance the action of a neurotransmitter.

Any chemical that binds to a receptor site on a post-synaptic neuron, causing the neuron to fire.

Neurotransmitters are endogenous agonists - the brain’s natural chemicals that bind to receptor sites, leading to an action potential.

Drugs can play the same role and are called exogenous agonists.

Question 13

Antagonists

Answer 13

An antagonist is any substance that fits into a receptor site on the post-synaptic neuron, inhibiting the neuron.

This means that the neuron will not fire and therefore a behaviour will not happen.

Acetylcholine is a neurotransmitter that plays a role in the formation of memories.

It is not possible for researchers to directly observe the role of neurotransmitters, so one of the ways that they attempt to understand the role of different neurotransmitters is by giving animals or human participants an antagonist.

They want to see what happens when acetylcholine receptors are blocked and the neurons are “not allowed” to fire.

Question 14

Neurotransmitters are what?

Answer 14

Natural agonists that are endogenous (produced by the body and act inside the body).

They bind to synaptic receptor neurons to generate either an excitatory or inhibitory

Question 15

Agonists

Answer 15

Chemical agonists are substances that bind to synaptic receptors and increase the effect of the neurotransmitter. They do this by imitating the neurotransmitter. If you think of the ‘lock and key’ mechanism, agonists oil the lock and make it easier for the neurotransmitter to have an increased effect.

Question 16

Example of an agonist

Answer 16

Alcohol

Binds with dopamine receptor sites, causing dopamine neurons to fire.

The firing of these neurons results in the activation of the brain’s reward system - the nucleus accumbens, and a feeling of pleasure.

Question 17

Antagonist

Answer 17

Antagonists are chemical substances, both naturally found in food, and medicines, and artificially manufactured.

They also bind to synaptic receptors but they decrease the effect of the neurotransmitter.

Therefore, if a neurotransmitter is excitatory, an antagonist will decrease its excitatory characteristics.

Question 18

Aim of Antonova (2011)

Answer 18

Wanted to see if scopolamine affected hippocampal activity in the creation of spatial memory.

Question 19

Aim of Antonova (2011)

Answer 19

Wanted to see if scopolamine affected hippocampal activity in the creation of spatial memory.

Question 20

Sample of Antonova (2011)

Answer 20

Twenty healthy male adults, with a mean age of 28 years old.

Question 21

Type of study Antonova (2011)

Answer 21

Double-blind procedure

Question 22

What did the researcher first do with the participants? Antonova (2011)

Answer 22

Participants were randomly allocated to one of two conditions. They were injected with either Scopolamine or a placebo 70 - 90 minutes before taking part in the experimental task.

Question 23

What is the Arena task?

Answer 23

Complex virtual reality game in which the researchers are observing how well the participants are able to create spatial memories.

The goal is for the participants to navigate around an “arena” with the goal of reaching a pole. After they have learned where the pole is located, the screen would go blank for 30 seconds.

Question 24

What is the Arena task? Antonova (2011)

Answer 24

Complex virtual reality game in which the researchers are observing how well the participants are able to create spatial memories.

The goal is for the participants to navigate around an “arena” with the goal of reaching a pole. After they have learned where the pole is located, the screen would go blank for 30 seconds.

Question 25

What were the participants asked to do during the ‘Arena Task? Antonova (2011)

Answer 25

During this time, the participants were told to actively rehearse how to get to the pole in the arena.

When the arena reappeared, the participant was now at a new starting point in the arena. The participants would have to use their spatial memory to determine how to get to the location of the pole.

Question 26

What did the participants do before the experiment? Antonova (2011)

Answer 26

The participants were first trained in the game to make sure that they were comfortable with the use of the joystick and that they understood the rules of the game. After they were trained, they then took part in the experiment. The participants’ brain activity was measured for six trials.

Question 27

What did the participants do 3-4 weeks later? Antonova (2011)

Answer 27

The participants returned between 3 - 4 weeks later and redid the test - receiving the opposite treatment to the original study.

In other words, the study was a repeated measures design.

Question 28

Results of Antonova (2011)

Answer 28

The researchers found that when participants were injected with scopolamine, they demonstrated a significant reduction in the activation of the hippocampus compared to when they received a placebo.

It appears that acetylcholine could play a key role in the encoding of spatial memories in humans, as well as in rats.

Question 29

Draganski (2004) aim

Answer 29

To see whether learning a new skill - in this case, juggling - would have an effect on the brains of participants.

Question 30

Sample of Draganski (2004)

Answer 30

24 volunteers between the ages of 20 and 24.

There were 21 females and 3 males.

All participants were non-jugglers at the start of the study. Each participant had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure.

Question 31

The two conditions of Draganski (2004)

Answer 31

Participants were allocated to one of two conditions - the jugglers and the non-jugglers. Those that were in the juggling condition were taught a three-ball cascade juggling routine. They were asked to practice this routine and to notify the researchers when they had mastered it.

Question 32

What happened afterwards to the participants. Draganski (2004)

Answer 32

At that point the jugglers had a second MRI scan.

After the scan, they were told not to juggle anymore and then a third and final scan was carried out three months later.

The non-juggling group served as a control group for the duration of the study.

Question 33

How did the researchers analyse the MRI scans? Draganski (2004)

Answer 33

The researchers used voxel-based morphometry [VBM] to determine if there was significant differences in neural density (grey matter) in the brains of jugglers vs. non-jugglers.

Question 34

Results of Draganski (2004)

Answer 34

From the baseline scans - taken before the study began - they found no significant regional differences in grey matter between the two conditions.

However, at the end of the first part of the study, the jugglers showed a significantly larger amount of grey matter in the mid-temporal area in both hemispheres - an area associated with visual memory.

Three months after the participants stopped juggling - when many were no longer able to carry out the routine - the amount of grey matter in these parts of the brain had decreased.

There was no change over the duration of the study in the non-juggling sample.

Question 35

What to know for Neurotransmitters

Answer 35

Nervous system
The 3 parts of a neuron
How is a synapse formed
How does a neuron fire an action potential
Excitatory and inhibitory
Agonist and antagonist
Antonova (2011)
Draganski (2004)
Maguire (2000)