In one line: Every thought, feeling and action depends on tiny chemical signals passing between brain cells.
Neurotransmission is the basic language of the brain. It is how the biological approach explains behaviour at the level of cells.
A signal travels within a neuron as electricity and between neurons as chemicals. This links to the concept of causality: these signals are the physical cause of behaviour — change the signalling, and you can change what a person feels or does.
Memory hook: Electric inside, chemical across. Neurotransmission carries the brain's messages.
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Key idea: A message crosses the gap between neurons in a clear sequence: fire, release, bind, clear.
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How a signal crosses the synapse
Impulse fires
An electrical impulse travels down the sending neuron to its end (the terminal).
Release
The impulse triggers the release of neurotransmitters into the synapse (the tiny gap).
Bind to receptors
The neurotransmitters cross the gap and bind to matching receptors on the receiving neuron, passing on the message.
Clear the gap
Leftover neurotransmitter is broken down or taken back (reuptake), resetting the synapse.
Fire · Release · Bind · Clear
Take feeling calm after exercise. Exercise raises signalling of neurotransmitters linked to mood; they release, bind to receptors, and shift how you feel — then are cleared. Many drugs work by changing one of these steps, showing how neurotransmission causes changes in behaviour.
Go further — higher-level insight: Reuptake is where many medicines act. Some antidepressants block reuptake so a neurotransmitter stays active in the synapse longer. Knowing which step a drug targets — release, receptor, or reuptake — is a high-level way to link biology to treatment.
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Key idea: Neurotransmission is a precise, evidence-based explanation, but behaviour is rarely 'just chemistry'.
Strengths and limitations
| Strengths and limitations | Strengths | Limitations |
|---|---|---|
| Evidence | Backed by drug and lab studies; precise mechanism | Hard to measure exact synaptic activity in living people |
| Use | Explains how many medicines work | Risk of reductionism — 'behaviour is just chemicals' |
| Scope | Underlies mood, memory, movement, arousal | Ignores thoughts, environment and social context |
So neurotransmission is a rigorous, well-supported explanation that underpins much of modern treatment, but a good evaluation notes it can be reductionist — reducing complex behaviour to chemistry — and that thoughts, environment and culture also shape behaviour.
Watch out: Correlation again. Finding that a neurotransmitter level differs in a condition does not prove it caused the condition — the difference could be a result, or a third factor may be involved.