Localization of brain function is the theory that particular brain regions are specialized for particular behaviours or cognitive processes. For example, the hippocampus is strongly involved in forming new explicit memories, while Broca’s area contributes to speech production.
Localization does not mean that every behaviour is controlled by only one isolated region. Most complex behaviours involve distributed neural networks, although particular regions may make specialized contributions.
How Localization Works
Researchers infer localization when damage to, stimulation of, or activity within a brain region is consistently associated with changes in behaviour. Evidence comes from case studies, experiments, and brain-imaging techniques such as functional magnetic resonance imaging (fMRI).
| Brain region | Localized function or contribution | Important qualification |
|---|---|---|
| Hippocampus | Formation of new explicit memories | Memory also depends on wider cortical networks |
| Broca’s area | Speech production | Language involves several interacting regions |
| Amygdala | Processing emotional significance, especially threat | It does not independently create every emotion |
| Prefrontal cortex | Planning, decision-making, and impulse control | These processes involve connections with other regions |
A key study is Scoville and Milner’s case study of HM. After surgeons removed tissue from HM’s medial temporal lobes, including much of his hippocampal region, he could no longer form new long-term explicit memories, although some procedural learning remained possible. This supports localization because different memory processes were affected differently.
However, the evidence does not support strict one-region-one-function localization. HM’s surgery damaged multiple structures, making precise causal conclusions difficult. Neuroplasticity also shows that the brain can reorganize functions after experience or injury, so localization is specialized but not completely fixed.
Exam Technique
For an IB Psychology response, define localization, explain the proposed brain-behaviour link, and use one relevant study with its aim, method, findings, and explicit link to the concept. Avoid the misconception that one brain region acts alone; stronger answers recognize both specialization and interacting neural networks.