Lecture 15 - Cognitive Neuropsychology and Language

Question 1

What is cognitive neuropsychology?

Answer 1

• The study of the relationship between brain regions and behaviour (mapping cognitive functions to brain regions)
• Historically linked to evidence from damaged brains – see how damage affects behaviour
• Generally, now includes other methods e.g. imaging, lesion studies (and case studies where humans have suffered brain injuries – not ethical to lesion humans)

Question 2

What kind of damaged brains were used for study?

Answer 2

• Missile wounds (e.g. bullets) – survive but long recovery
• Tumours (e.g. cancer) – grow/invade and damage surrounding regions
• Impact (e.g. road accidents)
• Injury (e.g. traumatic) – Phineas Gage
• Surgery (e.g. intractable epilepsy)
• Disease (e.g. encephalitis, hydrocephalus, HIV) – cause shrinking/damaging
• Strokes (e.g. blocks, bleeds) – cause localised death

Question 3

What are the main aims and assumptions of cognitive neuropsychology?

Answer 3

• Aims to assign specific psychological functions to particular brain structures (assuming we accept modularity of brain function)
• Assumption: brain function is ‘localised’/’modular’ with different structures performing different roles
• Modularity is a relatively new idea – for many years, we assumed that the brain is ‘one’ thing that enabled us to be
• Just because someone loses the ability to do something with brain damage (e.g., short term memory), it does not necessarily mean that the brain area was the sole functioning area used in it. It may have just played a (perhaps critical) part
• Many functions rely on distributed brain systems
• Language, memory etc. use much of the brain
• Brain regions are specialised to perform roles, but these may not map neatly onto ideas of ‘brain functions’

Question 4

Who are the key figures in the history of cognitive neuropsychology?

Answer 4

• Franz Joseph Gall (1758-1828)
• Johan Spurzheim (1776-1832)
• Pioneers of the field, but ‘neuropsychology’ as a term didn’t exist in their time
• As a youth, Gall was annoyed by students with a good memory but poor original thinking
• Recalled these students had large protruding eyes (thought brain pushing eyes out of skull)
• Developed a theory of brain function: localisation of function
• Here, different parts of the brain responsible for variations in individual differences
• They began collecting data

Question 5

What is phrenology and localisation?

Answer 5

• Studied individuals with skills in maths, music, sense of colour, combativeness, - discovered “bumps” in some areas
• Depressions in skull indicate underdevelopment
• Launched phrenology – the study of skull structure as indications for mental faculties
• E.g. amativeness (sex drive) behind lower part of ears
• They collected lots of data, from vegaterians vs. meat eaters, different genders and backgrounds and even Gall’s own dog (they didn’t stop at just humans)
• They didn’t pay much attention to those with actual brain damage
• Samuel George Morton – Crania Americana (1839) – racist

Question 6

Describe the rise and fall of phrenology

Answer 6

• Cranioscopy = used as a method of ‘personality’ assessment (good way for quacks to make money)
• Soon invited quackery and ridicule by association. Most assessments entirely subjective
• Outside of the skull does not mirror even the inside of the skull, let alone the underlying brain
• Pierre Flourens showed Spurzheim an imbecile’s brain but told him it was a clever mathematician, and he examined the brain to be genius (disproved)

Question 7

What is localisation?

Answer 7

• 2024
• Hemispheres, lobes, subcortical structures (e.g. limbic system, basal ganglia etc.), Brodmann Areas
• TL; DR = we localise the brain in lots of ways now

Question 8

Describe recovery within the brain

Answer 8

• Flourens conducted experiments – lesioned parts of the cortex of different animals and observed how it behaved:
• At first = moved very little, refused to eat and drink
• Later = recovery of function (to the point of appearing ‘normal’) e.g. after a stroke
• In essence, created animal models of humans
• Patten of loss and recovery seemed inconsistent with the assumption of localisation. More akin to specialisation?
• However, lesions to:
• Parts of the brainstem = permanent breathing difficulties
• Cerebellum = loss of locomotor coordination

Question 9

What are Brodmann’s areas?

Answer 9

• Korbinian Brodmann (1868-1918)
• German neurologist
• Died of septic infection after pneumonia
• Appearance of the cortex under microscope (cytoarchitectonics)
• Labelled zones based on cell organisation (e.g. density), cell type, and number of connections
• Despite some of the problems linked with localisation of function, it is still the case that many researchers still associate specific parts of the brain with specific aspects of behaviour/cognition
• Used natural “creases” (fissures/gyrus) in the brain to inform initial decisions. These typically follow a standard pattern from person to person
• Broadmann’s (1909) cytoarchitectic map

Question 10

Describe the relationship between neuropsychology and language

Answer 10

• Jean Baptiste Bouilaud (1796-1881)
• Proposed that certain functions were localised and lateralized
• Physicians noted that damage to left hemisphere resulted in impaired movement on an individual’s right
• Writing also disrupted…Language on the left?
• Right side = drawing, writing, painting etc.
  Therefore, the area that controls these may be on the left hemisphere
• Bouilaud’s son in law reported a case of a patient who lost the ability to speak when pressure was applied to the exposed frontal lobes

Question 11

Who was Paul Broca?

Answer 11

• 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 temporal lobe, demonstrating lateralization and localisation

Question 12

What is Broca’s area?

Answer 12

• Anterior speech region - enables you to talk
• Made up of Brodmann areas 44 (pars opercularis) and 45 (pars triangularis)

Question 13

What is Broca’s aphasia?

Answer 13

• Syndrome that results from damage to this area = Broca’s aphasia – inability to talk (effortful speech)

Question 14

Who was Carl Wernicke?

Answer 14

• Carl Wernicke (1848-1904)
• Investigated region of the cortex that receives information from the ear. Behind Broca’s area. Brodmann area 22
• Wernicke’s patients spoke fluently, but with no sense, and could hear but not understand what was said to them

Question 15

What is Wernicke’s area?

Answer 15

Region of temporal lobe

Question 16

What is Wernicke’s aphasia?

Answer 16

• Syndrome that results from damage to this area = Wernicke’s aphasia (fluent speech but meaning is impaired)

Question 17

What is Wernicke’s model of language processing?

Answer 17

• 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
• So if the temporal lobes are damaged, individuals can still produce speech but are unable to be fluent (i.e., make sense)
• Conduction aphasia = impairment in the ability to repeat words or phrases despite intact comprehension and fluent speech production