Localisation of Function

• What was Franz Gall’s theory of phrenology?

  The study of someone’s character based on the structure of the skull.
• The Motor Cortex is located…

  In the frontal lobe along precentral gyrus.
• What does the Motor Cortex do?

  It is responsible for voluntary motor movements.
• The Somatosensory Cortex is located…

  In the parietal lobe along the postcentral gyrus ink both hemispheres.
• The Visual Cortex is located….

  At the back of the occipital lobe in both hemispheres.
• What does the Somatosensory Cortex do?

  Process sensory information related to touch.
• What does the Visual Cortex do?

  It takes nerve impulses transmitted from the the retina to the brain via the optic nerve and . The majority of these signals terminate in the thalamus and the rest get sent to and translated in the visual cortex.
• The Auditory Centre is located…

  In the temporal lobe on both sides of the brain.
• How does auditory information travel?

  The pathway starts at the cochlea where the waves travel via the auditory nerve. The brain stem does basic decoding and the thalamus carries out further processing. The last stop is the auditory cortex.
• What are the two language centres?

  - Broca’s area

  - Wernicke’s area
• What was Paul Broca’s research?

  Most famously he studied the patient ‘Tan’ who could only produce one syllable. In Tan and various other patients he found damage in the left frontal hemisphere causing an inability to produce language. He named this language centre Broca’s area.
• What was Carl Wernicke’s research?

  Wernicke realised his patients could produce but not understand it. He found damage in the left temporal lobe and named this Wernicke’s area. He also suggested a neural loop between Wernicke’s and Broca’s area.
• Challenges to localisation:

  - Equipotentiality

  - Communication may be more important than localisation

  - Language may not be confined to Broca’s area alone

  - Individual differences
• What is Equipotentiality?

  Lashley (1930) believed that only basic motor and sensory functions were localised while higher mental functions were not. Argues that the extent of the damage is more important than location. Supported by brain damaged patients being able to regain cognitive abilities.
• Is communication more important than localisation?

  Wernicke’s claimed that while areas of the brain were specialised to specific tasks, they had to interact with one another to work effectively. Joseph Dejerine describes a case where damage between the connection of the visual cortex and Wernicke’s area meant the patient lost the ability to read.
• Aphasia supports language centres because…

  Expressive aphasia is an impaired ability to produce language ( linked to damage in Broca’s area) and receptive aphasia is an impaired ability to understand language (linked to damage in Wernicke’s area).
• Individual differences for localisation of function:

  Harasty et al (1997) found that women have proportionally larger Broca’s and Wernicke’s areas, resulting in women’s greater use of language.
• Is language confined to Broca’s area?

  Dronkers et al (2007)preserved the brains of two of Broca’s patients. The MRI found damage in other areas that could have contributed to their reduced speech abilities.