Localisation

• What is Localisation of Function?

  The principle that specific functions such as language, memory and hearing have specific locations within the brain
• What is the Motor Cortex?

  - Responsible for voluntary motor movements

  - Located in frontal lobe in precentral gyrus

  - Both hemispheres have motor cortex, with each one controlling the muscles on the opposite side of the body
• What is the Somatosensory Cortex?

  - Detects sensory events from different regions of body

  - Located in parietal lobe in postcentral gyrus

  - Dedicated to processing sensory info related to touch producing sensations of touch, pressure, pain and temp

  - Within both hemispheres, each sides control opposite side of the body
• What is the Visual Cortex?

  - Primary visual centre, located in occipital lobe

  - Visual processing begins in retina, nerve impulses transmitted via optic nerve with majority terminating in thalamus

  - Spans both hemispheres

  - Each area processes a type of visual info e.g. colour, shape, movement etc
• What is the Auditory Cortex?


  - Processes hearing, mainly lies within temporal lobes

  - Pathway begins in cochlea, nerve impulses pass via auditory nerve to cortex

  - Stops at brain stem for basic decoding, through to relay station thalamus, then to cortex where sound is recognised and results in response
• What is Broca's area?

  - Named after neurosurgeon Broca, who treated 'Tan' patient

  ○ Patient was unable to say anything but 'Tan', despite being able to understand spoken language, he was unable to speak or write

  ○ Broca then studied 8 patients with language deficits and lesions in their left frontal hemisphere

  ○ Patients w/these injuries in the right didn't have lang diff

  - Led to identification of language cents in posterior left frontal lobe, believed to be critical for speech production

  - Fedorenko discovered two regions of Broca's area, one for language and one for responding to demanding cognitive tasks
• What is Wernicke's area?

  - Area of brain involved in understanding language

  - Posterior left temporal lobe

  - Patients with lesions in this area could speak but unable to understand language

  - Wernicke proposed that language involved separate motor and sensory regions located in diff cortical regions

  ○ Motor region in Broca's area close to area that controls mouth, tongue and vocal cords

  ○ Sensory region in Wernicke's area, recognised as language and associated with meaning

  ○ Neural loop between them allows communication
• Evaluate the Localisation of Function

  ✗ Communication maybe more imp. than localisation . Though diff region so brain have spec. func., they are interdependent

  ✓ Evid. for Broca and Wenicke's area

  ○ Expressive aphasia (Broca's) impaired ability to produce language

  ○ Receptive aphasia (Wernicke's) impaired ability to understand language

  ✗ Dronkers re-examined preserved brains of 2 Broca's patients to identify extent of any lesions using modern MRI → Revealed that other areas may contribute to reduced speech abilities