2.1.9—Neurotransmission
- Syllabus
- First assessment 2027
- Objective
- 2.1.9
- Level
- HL
Neurotransmission links a signal to a circuit, not a diagnosis
Neurotransmission is communication between neurons: an electrical signal triggers chemical release, receptors respond, and the signal is terminated by reuptake or breakdown.
A neurochemical explanation of a disorder proposes that altered signalling contributes to symptoms. Evidence from medication response, receptor studies or imaging can support a pathway, but treatment effects are not a direct measurement of the original cause.
If a reuptake inhibitor improves mood for some patients, it is consistent with serotonin involvement; it does not show that low serotonin alone caused every case or that the drug works through one mechanism only.
Do not turn a group-level association into an individual diagnosis. Separate synaptic mechanism, clinical outcome and alternative explanations.