14. Cognitive Neuropsychology and Language

Cognitive Neuropsychology: What is it?

  • The study of the relationship between brain regions and behaviour.
  • Historically linked to evidence from damaged brains.
  • Now includes other methods e.g. Imaging, Lesion Studies.

Causes of Brain Damage:

  • Missile wounds (e.g., bullets).
  • Tumours (e.g., cancer).
  • Impact (e.g., road accidents).
  • Injury (e.g., traumatic).
  • Surgery (e.g., intractable epilepsy).
  • Disease (e.g., encephalitis, hydrocephalus, HIV).
  • Strokes (e.g., blocks, bleeds).

Assumption of Cognitive Neuropsychology:

  • Brain function is “localised” or “modular”, with different structures performing different roles.
  • Many functions rely on distributed brain systems.
  • Brain regions are specialized to perform roles, but these may not map neatly onto ideas of “brain functions”.
  • Aims to assign specific psychological functions to particular brain structures (assuming we accept modularity of brain function…).

Cognitive Neuropsychology: History

  • Franz Joseph Gall (1758-1828).
  • Johan Spurzheim (1776-1832).
  • Developed a theory of brain function: Localisation of function.
  • Different parts of the brain are responsible for variations in individual differences.
  • Launched phrenology – the study of skull structure as indications for mental faculties.

Cognitive Neuropsychology: History

  • Pierre Flourens (1794-1867)
  • Lesioned parts of the cortex of different animals: Observed how it behaved.
  • Pattern of loss and recovery seemed inconsistent with the assumption of localisation.
  • More akin to specialization?
  • However: Lesions to: Parts of the brain stem = permanent breathing difficulties; Cerebellum = loss of locomotor co-ordination.

Cognitive Neuropsychology: Localisation

  • Hemispheres, Lobes, Subcortical structures (e.g., Limbic system, Basal ganglia etc.), Brodmann Areas.

Mapping the Brain

  • Brodmann Areas: Appearance of the cortex under microscope (cytoarchitectonics).
  • Labelled zones based on cell organisation (e.g., density), cell type, and number of connections.
  • Korbinian Brodmann (1868-1918) German Neurologist.

Neuropsychology & Language

  • Jean Baptiste Bouilaud (1796-1881) Proposed that certain functions were localised & lateralized.
  • Paul Broca (1824-1880) Received a patient Monsieur “Tan” Leborgne Could only say “Tan” and utter an oath.
  • Tan died a few years later (1861), Autopsy revealed a lesion to the left frontal lobe: Thus demonstrating: Lateralization, Localization, Anterior speech region = Broca’s area.
  • Syndrome that results = Broca’s Aphasia: damage to Broca's area.

Neuropsychology & Language

  • Carl Wernicke (1848-1904) Investigated region of the cortex that receives information from the ear.
  • Behind Broca’s area. Broadmann area 22.
  • This region of temporal lobe = Wernicke’s’s area.
  • Wenicke’s patients spoke fluently, but with no sense and could hear, but could not understand what was said to them.
  • Syndrome that results = Wernicke’s Aphasia: damage to Wernicke's area.

Neuropsychology & Language. Wernicke’s Model of Language processing:

  • Auditory information sent to:
    • (1) Wernicke’s area (Sounds → sound images)
    • (2) Sound images transmitted along Arcuate Fasciculus to
    • (3) Broca’s area (representation of speech movements).
  • From here instructions sent to control mouth muscles….

Neuropsychology & Language. Wernicke’s Model of Language processing:

  • Conduction Aphasia: impairment in the ability to repeat words or phrases despite intact comprehension and fluent speech production.