Localisation of Function: The theory that different areas of the brain are responsible for specific behaviours, processes or activities.

Motor Area: A region at the back of the frontal lobe involved in regulating movement.

Somatosensory Area: An area at the front of both parietal lobes that processes sensory information such as touch. It is separated from the motor area by the central sulcus.

Visual Area: A part of the occipital lobe (at the back of the brain) that receives and processes visual information.

Auditory Area: Located in the temporal lobe and concerned with analysing speech-based information.

Broca’s Area: An area of the frontal lobe in the left hemisphere (in most people), responsible for speech production.

Broca’s Aphasia: Caused by damage to the Broca’s area and characterised by speech that is slow, laborious and lacking in fluency.

Wernicke’s Area: An area of the temporal lobe (encircling the auditory complex) in the left hemisphere (in most people), responsible for language comprehension.

Wernicke’s Aphasia: Caused by damage to the Wernicke’s area characterised by the production of nonsense words as the victims cannot understand language.

Hemisphere’s in the Brain: The brain is split into left and right hemispheres. The left side of the body is controlled by the right hemisphere and the right controlled by the left.

Evidence From Neurosurgery: Dougherty et al reported on 44 people with OCD who had undergone a cingulotomy (removing the cingulate gyrus which had been implicated in OCD). At post-surgical follow-up after 32 weeks, about 30% had met the criteria for a successful response to the surgery and 14% for a partial response. This suggests behaviour associated with serious mental disorders may be localised.

Evidence From Brain Scans: Peterson et all (1988) used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task. Also, Buckner and Peterson revealed that semantic and episodic memories reside in different parts of the prefrontal cortex.

Language Localisation Questioned: Dick and Tremblay (2016) found that only 2% of modern researchers think that language in the brain is controlled by Broca’s and Wernicke’s area. Neural imaging shows language function is distributed more holistically in the brain than first thought. Language streams have been identified in the right hemisphere as well as the subcortical regions.