Neurotransmission

Neuron definition

A building block for behavior, that sends electrochemical signals to the brain to allow the person to respond to environmental and internal changes

Neuron structure

An axon terminal, dendritic branches and a soma

Neurotransmission definition

The transfer of information from one neuron to another through chemical signals in the synaptic gaps between each neuron

Excitatory neurotransmitter

• Increases probability of action potential

• Increases the chance of neuron firing during depolarization of an action potential

• This causes more activation in the brain and reinforces performances responsible for that part of the brain

Action potential definition

When an electrical impulse travels across a neuron and is released into the synapse that sends a message

What happens to a neurotransmitter after an action potential

1. Neurotransmitter is pulled back into the axon that released it

2. Neurotransmitter is binded to the receptor of the next neuron

Inhibitory neurotransmitter

• Reduces repolarization in an action potential

• Reduces chance of neuron firing

• Less activation of the brain area and inhibits activity responsible for that part of the brain

Antonova aim

Investigate the role that acetylcholine has on memory formation

Fisher aim

Investigate possible link between brain regions related to dopamine and the early stages of romantic love

Scopolamine

An antagonist to acetylcholine

Acetylcholine

An excitatory neurotransmitter that plays a role in the encoding of memory

Why is Martinez and Kesner (2003) not generalizable

The study gives support to the role of acetylcholine on the encoding of memory, but it was done by injecting scopolamine on animals.

Antonova participants

20 healthy males, mean age of 28 years

Antonova design

Experiment, double-blinded and repeated-measures design

Antonova procedure

1. Injected with scopolamine or placebo 90 minutes before the experimental task

2. Participants learnt the game before doing the task

3. The “Arena task” is a virtual reality game that allows researchers to observe how well participants could create spatial memories

4. Participants had to navigate around the arena to reach a pole. After locating it, the screen would go blank for 30 seconds, to allow participants to rehearse its location

5. Afterwards, they would respawn in a different starting point and have to use their spatial memory to relocate the pole

6. They completed this task while under an fMRI scan which measured their brain activity

7. This was done 6 times

8. After 3-4 weeks, they came back to complete the opposite condition

Antonova result

Participants injected with scopolamine had less activation in the hippocampus compared to when they were injected with placebo. This suggests acetylcholine plays a key role in the encoding of spatial memories in humans, as well as in rats

Antonova strengths

• Double-blinded procedure - No researcher bias

• Repeated measures design - No participant variability

Antonova weakness

• Higher rate of error in the scopolamine group, but it wasn’t a significant difference

• Undue harm and stress - Injection and fMRI scan

• Small sample size, only males - Low generalizability

• Error in measuring hippocampus - Other factors like other neurotransmitters and hormones can affect activity

Fisher participants

Self-selected 17 undergraduate students with mean age of 20 years from NYU, reportedly in love for 7 months

Fisher procedure

1. Participants were interviewed to measure duration and intensity of love

2. Participants completed passionate love scale to measure traits that were commonly associated to early stages of romantic love

3. These steps were done to compare later to brain activity of an fMRI scan

4. They were observed under an fMRI and were shown a photo of their partner for 30 seconds, followed by a filler task before being shown a neutral photo for 30 seconds

5. This was repeated 6 times

Fisher results

• Increased activity in brain reward system when shown photo of partner

• More activation in brain regions related to dopamine when shown photo of partner

• This suggests during early stages of romantic relationships, people could access brain regions associated to dopamine in the presence of their partner

Fisher strengths

• Supports previous research on the role of dopamine in substance addiction, suggesting that romantic love may resemble craving and withdrawal

• Humans may have evolved a brain system that fosters “addiction” to specific individuals, boosting reproductive chances

• Standardized procedure - high reliability

Fisher weaknesses

• Reductionist - Using brain scans to determine how romantic love is experience, other factors can interfere, such as other neurotransmitters and hormones

• Low ecological validity - Artificial environment, use of fMRI

• Small sample size from NY - Cultural bias and low generalizability

Dopamine

Excitatory neurotransmitter and controls the brain’s reward and pleasure centers, giving motivation for one’s action

Testability

Neurotransmission can be tested through various methods including neuroimaging, animal models and pharmalogical studies, allowing for direct observation of how neurotransmitters affect behaviour.

But because there is complexity in the interaction between different neurotransmitters and their effects, it can be dificult to siolate them during testing.

Empirical evidence

There is empirical evidence linking neurotransmitter activity to biological behaviour and mental health conditions. For example, dopamine is associated with reward and pleasure centers while acetylcholine plays a role in encoding memories as suggested above.

However, studies regarding neurotransmitters often only establish correlation and no cause-and-effect relationships, since the role of neurotransmitters varies in individuals, complicating the interpretation of evidence provided.

Application

Understanding neurotransmission has application in clinical settings, particularly in developing treatments for disorders such as antidepressants for depression.

Construct validity

There is low construct validity as the neurotransmitter systems and their interactions with systems are very complex

Universality

The function of neurotransmitters may be universal, but the impact of these functions can vary in every individual and can be affected by genetic and environmental factors.

Predicting

Predicting behaviours based on soley neurotransmitter activity can be difficult due to the nature of human behaviour, as there are many biological and environmental influences.