1. Core concept

Neurotransmission is how neurons communicate. An electrical impulse reaches the end of one neuron and triggers the release of neurotransmitter molecules into the synapse; these cross the gap and bind to receptors on the next neuron, making it more or less likely to fire (excitatory vs inhibitory); leftover transmitter is then broken down or reabsorbed (reuptake). Agonists amplify a transmitter's effect and antagonists reduce it. Because mood and behaviour ride on this signalling, changing it changes behaviour — but, because neurons act in combination, any cause-and-effect claim should be treated with caution.

2. Key studies

IB Psychology answers must be supported by named studies. Learn these to cite as evidence:

3. Evaluation (AO3)

Strength — mechanistic and drug-testable — The process gives testable targets — SSRIs act on reuptake — allowing causal manipulation.

Limitation — correlational and interacting — Linking a transmitter to a behaviour is largely correlational, and each transmitter interacts with many systems, so 'more X → behaviour Y' oversimplifies.

4. Scope