NEUROTRANSMITTERSWhat are they?

neurotransmitters

Nerve cells called neurons are one of the building blocks of behaviour.

There are around 10-100 billion neurons in the nervous system and neurons make 13 trillion connections with one another.

How do they affect behaviour? The neurons send electrochemical

signals to the brain so that people can respond to stimuli. Stimuli can be from the environment or from internal changes within the body.

The method the messages are sent is called neurotransmission.

Neurotransmission

Imagine…….

Imagine you have a ball thrown at you. You see the ball coming towards you, this sends an electrical impulse down the body of neurons that are all connected.

When it reaches the end of one neuron, it needs to cross the gap (synapse) in order to travel up the next neuron and so on…..

How does it do this?

How?

Neurotransmitters are the body’s natural chemical messengers which transmit information from one neuron to the next. Neurotransmitters are different depending on the impulse. They are found at the end of the neuron.

They are released from the end of the neuron, cross the synapse, and fit into SPECIFIC receptor sites on the next neuron- like a lock and key.

Then….

Once the message reaches the next neuron, the left over neurotransmitters are broken down or reabsorbed to be used again in the future.

Behaviour

N.T have a wide range of effects on human behaviour. They underlie the behaviour of mood, memory, sexual arousal, and mental illness.

Neurotransmitters and behaviour Acetylcholine- role of developing

memories in the hippocampus of the brain and muscle contraction.

Dopamine- learning, feelings of pleasure. Dopamine is closely associated with reward-seeking behaviors, such as approach, consumption, and addiction

Dopamine

Recent researches suggest that the firing of dopaminergic neurons is a motivational substance as a consequence of reward-anticipation. This hypothesis is based on the evidence that, when a reward is greater than expected, the firing of certain dopaminergic neurons increases, which consequently increases desire or motivation towards the reward

We will look at dopamine in detail when we look at depression.

Noradrenaline

Involved in arousal, alertness, stimulation of the symapthetic nervous system (fight or flight).

We will also look at the role of noradrenaline when we look at depression.

Serotonin

Involved in sleep, arousal levels and emotion.

Also used as an explanation of OCD- low levels linked to feelings of depression.

Knowledge check

1. Explain how N.T work. Give me one example of a N.T and

which area of behaviour it affects.

Kasmatsu and Hirai, 1999

Key study on how serotonin affects behaviour.

Read the study and produce an APFCC hand.

Martinez and Kesner, 1991

Looked at the role of acetylcholine on memory.

Read through the study and again, produce an apfcc hand. I will go through the study with you to clarify any points once you have read it.

Next lesson

We will look at the role of serotonin and OCD (known as the serotonin hypothesis).

We will also look at the role of serotonin, dopamine and noradrenaline on depression (known as the monoamine hypothesis)

If you wish to clue up a little on these before the lesson, please feel free to look up on the internet.

Any questions?

Recap