The Mind Detective
Introduction
• Neuropsychology
• Understanding and assessing the consequences of damage to the brain
• Cognitive Neuropsychology
• Understanding how the mind works functionally (not biologically) by understanding
how it works differently when it breaks down
• Reasoning backward
• How must have it worked before in order for these symptoms to be possible?
Are capacities localised in the mind or globally distributed?
History:
• Franz Joseph Gall – founder of phrenology
• Talented in dissection of the brain
• Fundamental faculties were localised in the brain
• Pressure from the brain determined the shape of the skull
• More developed/stronger capacities were larger so would form bumps on skull
• Therefore, abilities could be determined by examining the sizes of bumps on the skull
(1790s)
Phrenology
Ideas behind phrenology:
The Brain is the organ of the mind
The brain is not a homogenous unity, but an aggregate of mental organs with specific
functions
The cerebral organs are topographically localized
Other things being equal, the relative size of any particular mental organ is indicative of the
power or strength of that organ
Since the skull ossifies over the brain during infant development, external craniological
means could be used to diagnose the internal states of the mental characters
Criticisms
The main feature was completely wrong
Bumps on the skull are not related to the size of brain areas or to mental abilities
Aspects of phrenology developed into ideas that have an unhappy history – observations
made in prisons and asylums
Dividing people into inferior and superior categories by aspects of their appearance
Used to justify inequalities in gender and race
Overall
, Phrenology was influential, however, because it introduced the idea that the mind could have
local areas devoted to specific capacities
It was the concept that was influential, not the specifics of Gall’s system
Note how his principles, if not associated with bumps on the head, would not be out of place
today:
The Brain is the organ of the mind
The brain is not a homogenous unity, but an aggregate of mental organs with specific
functions
The cerebral organs are topographically localized
The equipotential brain: no localisation of function
One of the reasons the concept localisation of function fell into doubt was due to the
experiments of
Jean Pierre Flourens
He developed a method of damaging the brain and then observing the effects of the lesion
(rabbits and pigeons – 1825) note relationship to neuropsychology
Jean Pierre Flourens
Removed cerebral hemispheres
Blocked perception, movement, judgement
Concluded: Higher cognitive functions
Removed cerebellum
Disturbed coordination and balance
Concluded: Regulates movements
Removed brainstem
Caused death
Concluded: Regulation of vital functions (e.g. circulation/respiration)
Failed to isolate memory and cognition
Concluded: These are distributed throughout the brain
Did not find fine-grained localization as predicted by the phrenologists
Making relatively large lesions – could not find specifics
Broca – localisation of language
Paul Broca
Surgeon
Early supporter of evolution
Interested in localisation of language
Broca’s patient ‘Tan’
Broca heard of a patient with long-term progressive loss of speech (1861)
At the time he could only say the syllable “tan” (hence his pseudonym)
Today “Tan” would be classified as a global aphasic
After death, Broca dissected his brain and found a lesion in the left frontal lobe
Lesion was due to untreated syphilis
Left hemisphere – the seat of language
, Broca identified 12 other patients with speech disturbances and lesions to the left inferior
frontal lobe.
Here is Broca’s area on an idealised brain
NOTE -- Marc Dax discovered the same thing 25 years earlier (1836), but died shortly after
and his discovery remained almost unknown
Carl Wernicke
Carl Wernicke -- physician, anatomist, psychiatrist, neuropathologist
Studied a patient who had very poor language comprehension, along with an intact ability to
speak and good hearing
Dissected the patient’s brain after death
Wernicke found that the patient had a lesion in the left superior temporal lobe (1873)
Wernicke’s theory development
Based on Broca’s area and his own discoveries, Wernicke predicted the existence of patients
where the connection between areas was disrupted, but both areas were intact
This would cause a disruption to the ability to repeat words
Conduction aphasia was later confirmed by Wernicke
Problems in repetition tasks
Intact comprehension
Fluent speech (even if errors are present—contrast with dysfluent patients or patients with
anomia, failure to come up with words) – when deciding what they want to say, not repeating
what others say
Ludwig Lichtheim
Lichtheim extended Wernicke’s predictions
Produced “Lichtheim’s house” diagram
Predict types of aphasia by making diagrams and assessing the consequences of damage to
either:
- brain centres
- connections between centres
- Links to modern neuropsychology
Lichtheim’s ‘house’:
‘sensory speech images’ = input lexicon
‘motor speech images’ = output lexicon
‘motor output’ = movements required to speak
• Lesion at A – Wernicke’s aphasia
• Poor comprehension
• Poor repetition
• Lesion at M – Broca’s aphasia
• Poor speech
• Good comprehension
• Poor repetition
Introduction
• Neuropsychology
• Understanding and assessing the consequences of damage to the brain
• Cognitive Neuropsychology
• Understanding how the mind works functionally (not biologically) by understanding
how it works differently when it breaks down
• Reasoning backward
• How must have it worked before in order for these symptoms to be possible?
Are capacities localised in the mind or globally distributed?
History:
• Franz Joseph Gall – founder of phrenology
• Talented in dissection of the brain
• Fundamental faculties were localised in the brain
• Pressure from the brain determined the shape of the skull
• More developed/stronger capacities were larger so would form bumps on skull
• Therefore, abilities could be determined by examining the sizes of bumps on the skull
(1790s)
Phrenology
Ideas behind phrenology:
The Brain is the organ of the mind
The brain is not a homogenous unity, but an aggregate of mental organs with specific
functions
The cerebral organs are topographically localized
Other things being equal, the relative size of any particular mental organ is indicative of the
power or strength of that organ
Since the skull ossifies over the brain during infant development, external craniological
means could be used to diagnose the internal states of the mental characters
Criticisms
The main feature was completely wrong
Bumps on the skull are not related to the size of brain areas or to mental abilities
Aspects of phrenology developed into ideas that have an unhappy history – observations
made in prisons and asylums
Dividing people into inferior and superior categories by aspects of their appearance
Used to justify inequalities in gender and race
Overall
, Phrenology was influential, however, because it introduced the idea that the mind could have
local areas devoted to specific capacities
It was the concept that was influential, not the specifics of Gall’s system
Note how his principles, if not associated with bumps on the head, would not be out of place
today:
The Brain is the organ of the mind
The brain is not a homogenous unity, but an aggregate of mental organs with specific
functions
The cerebral organs are topographically localized
The equipotential brain: no localisation of function
One of the reasons the concept localisation of function fell into doubt was due to the
experiments of
Jean Pierre Flourens
He developed a method of damaging the brain and then observing the effects of the lesion
(rabbits and pigeons – 1825) note relationship to neuropsychology
Jean Pierre Flourens
Removed cerebral hemispheres
Blocked perception, movement, judgement
Concluded: Higher cognitive functions
Removed cerebellum
Disturbed coordination and balance
Concluded: Regulates movements
Removed brainstem
Caused death
Concluded: Regulation of vital functions (e.g. circulation/respiration)
Failed to isolate memory and cognition
Concluded: These are distributed throughout the brain
Did not find fine-grained localization as predicted by the phrenologists
Making relatively large lesions – could not find specifics
Broca – localisation of language
Paul Broca
Surgeon
Early supporter of evolution
Interested in localisation of language
Broca’s patient ‘Tan’
Broca heard of a patient with long-term progressive loss of speech (1861)
At the time he could only say the syllable “tan” (hence his pseudonym)
Today “Tan” would be classified as a global aphasic
After death, Broca dissected his brain and found a lesion in the left frontal lobe
Lesion was due to untreated syphilis
Left hemisphere – the seat of language
, Broca identified 12 other patients with speech disturbances and lesions to the left inferior
frontal lobe.
Here is Broca’s area on an idealised brain
NOTE -- Marc Dax discovered the same thing 25 years earlier (1836), but died shortly after
and his discovery remained almost unknown
Carl Wernicke
Carl Wernicke -- physician, anatomist, psychiatrist, neuropathologist
Studied a patient who had very poor language comprehension, along with an intact ability to
speak and good hearing
Dissected the patient’s brain after death
Wernicke found that the patient had a lesion in the left superior temporal lobe (1873)
Wernicke’s theory development
Based on Broca’s area and his own discoveries, Wernicke predicted the existence of patients
where the connection between areas was disrupted, but both areas were intact
This would cause a disruption to the ability to repeat words
Conduction aphasia was later confirmed by Wernicke
Problems in repetition tasks
Intact comprehension
Fluent speech (even if errors are present—contrast with dysfluent patients or patients with
anomia, failure to come up with words) – when deciding what they want to say, not repeating
what others say
Ludwig Lichtheim
Lichtheim extended Wernicke’s predictions
Produced “Lichtheim’s house” diagram
Predict types of aphasia by making diagrams and assessing the consequences of damage to
either:
- brain centres
- connections between centres
- Links to modern neuropsychology
Lichtheim’s ‘house’:
‘sensory speech images’ = input lexicon
‘motor speech images’ = output lexicon
‘motor output’ = movements required to speak
• Lesion at A – Wernicke’s aphasia
• Poor comprehension
• Poor repetition
• Lesion at M – Broca’s aphasia
• Poor speech
• Good comprehension
• Poor repetition
