Brain Damage and the Mind

Four periods of neuropsych

• classical antiquity period

  • localization of the soul

• Medieval Period

  • ventricular localization theory (three-part model of cognition)

• Transitional or Renaissance Period

  • really truly located in the brain, not in the cerebrospinal fluid CSL

• Emergence of Modern Cognitive Neuropsychology

  • Localists won

  • 1st Golden Age (1860s)

Classical Antiquity Period

• localization of the soul

• Heart/diaphragm (aristotle) vs the Brain (plato)

  • e.g. learning something by heart is an ex of the aristotle way of thinking

• brain was vessel that held the real substance of thought (Galen) - cerebrospinal fluid

  • Brain is the place to hold the soul through the fluid because the soul had unity  and you could subdivide the soul and the fluid seemed more like a homogeneous substance — soul in the cerebrospinal fluid

Medieval Period

Ventricular localization theory (three-part model of cognition) The Cell Doctrine

• cell doctrine: subdivide the mind into three domains which classifies the ventricular system

• localize cognitive function in the three chambers

  • 1. perception

  • 2. reasoning

  • 3. memory

Transition or Renaissance Period

• really truly located in the brain, not in the cerebrospinal fluid

• mind caused by the fluid and the brain interacting with creates the mind

Gall vs Flourens

• debate became unity vs separability thing (localism/holism) — is the mind unitary or fractionated? Are there different components of the mind that are different from other components? Is it modular? Can it be localized in diff parts of the brain, or does it not matter which part of the brain you’re talking about and the loss of cognitive function relies on how much of the brain you take away, not which part you take away?

Gall (phrenology + localization)

discovered the distinction between white matter and gray matter, first one to discuss that the frontal lobe was for thinking

Gall (Good)

Pushing for th idea that different cognitive functions assigned to different regions of the cortex, brain is not just homogenous, different components of the mind has different functions, could be damaged independently from others (localization)

Gall (Bad)

Also pushed that differences in cognitive and personaltiy traits manifest in differences in cortical size and bumps on skull

• the size of each part could dictate the function of that particular part of the brain

Analysis of the shape of the skull would reveal personality and intellect

• because he came up with so much stuff that he lost reliability, but the localization part was right

Flourens (Holism)

believed in unity of the seoul and didn’t believe in fractioning of the mind, clearly winning the debate

• not enough evidence to argue against Gall but more people believed him bc Gall was creepy

Phineas Gage

put a stick through skull and the person was still able to reason and be normal, gave evidence to the holism theory

• there were still effects but they were more subtle than let’s say the visual cortex, therefore they thought holism was fire

Emergence of Modern Cognitive Neuropsychology

• localists won

• 1st Golden Age (1860s)

  • terminology came from the 1st golden age

  • got completely beaten down and suppressed

Paul Broca (1861) Patient “Tan” (Louis Victor Leborgne)

• Tan was all he could say, he could hear you and understand you but couldn’t produce words

• “could no longer produce but a single syllable, which he usually repeated twice in succession”

  • circumscribed lesion in the lateral inferior frontal lobe leads to = good comprehension, non fluent speech, poor repetition

Paul Broca Patient “Tan” Conclusions

• language is a function that can be damaged separately, there are different functions, there are many modules and damage different functions separately

• just because the mind is modular doesn’t mean that the brain is

• function is anatomically localizable, can be isolated from other cognitive functions

Wernicke (1874)

poor comprehension, fluent speech, poor repetition

Wernicke conclusions

there are at least 2 language areas in the brain that can be independently affected by brain damage

• one controls comprehension, one controls speech

• found out the arcuate fasciculus is a “language circuit” which connects comprehension and speech areas

• created the language model

  • Based on the model, he predicted a third form of aphasia: conduction aphasia

arcuate fasciculus

they found out the ______ is a “language circuit” which connects comprehension and speech areas

• broca: motor center

• Wernicke: sensory center

• when the circuit between motor and sensory center is impaired, they will have good comprehension, fluent speech, but poor repetition

diagram makers

• make models for the connections of the brain

• not only isolating different syndromes but also producing a theoretical framework to explain them

House of Lichtheim (1885)

still used to diagnose patients right now

2nd Golden Age (1960s)

• the idea resurfaced in a different way

• foundation created in the 1860s, then modern psychological methods were developed which allowed for more research on this topic

The age of the diagram (1860s-1890s)

• despite modern appearance, these models came under intense attack

  • fierce battle between diagram makers and their critics (Freud, Bergson, Marie, Head)

  • even resulted in formal challenge to a duel

    • Holists won, beat down the whole localization enterprise around the 1900s

Weaknesses of the diagram makers

• inadequate psychological formulation

• lack of empirical constraints

• lack of empirical support

• strictly tied to anatomy

weaknesses of the diagram makers: inadequate psychological formulation

• didn’t develop concepts of centers (center for the meaning of words, center for speaking)

• didn’t connect with psychological models of the day

• Don’t have the tools to think about what the reason is behind these centers, how they work, etc.

• Kinda like phrenology — not very deep, not much explanation, hence isolation and mad psychologist

weaknesses of the diagram makers: lack of empirical constraints

• based entirely on case studies

• didn’t make sure they were consistent with other cognitive models in the field of psychology

• didn’t have a lot of constraints when they were developing the model, didn’t look at other models from other fields

• Confirmation bias, sselection of case studies, wasn’t believed to be generalized

weaknesses of diagram makers: lack of empirical support

• theory driven, not data drive

• why did you choose that specific patient? They chose the subjects that would confirm their hypothesis

• didn’t have enough trials and experiments

• experiments were not controlled, the evidence taking was very unspecific, evidence was weak

weaknesses of diagram makers: strictly tied to anatomy

• neural areas = proposed cognitive modules

• didn’t make a conceptual distinction between the cognitive modules (flow of information) and neural models (where these things were located in the brain)

• because models were tied to anatomy, they could fall with anatomy

• if something didn’t match the model, they couldn’t tell if the cognitive model was wrong or the neural model was wrong, they couldn’t make the connection between the two

The aftermath and reemergence

• rejection of single-case study

• Developments in the 1960s brought neuropsychology back to life

Rejection of single-case study

• e.g. Halstead-Reitan school (just give patients a lot of tests to test a whole lot of different functions, use the data to see if based on the overall pattern, you can try to find their lesion were)

• more psychometric approach

The aftermath and reemergence: Developments in the 1960s brought neuropsychology back to life

• rise of information processing models

  • able to understand the difference between software and hardware, computation models that allowed you to understand the information processing underlying these things

  • methods to test the specific cognitive psychology models

  • in 1965, Norman Geschwind began to resurrect diagram-makers from neglect

    • did the experiments again, used more sophisticated experimental techniques

      • solid empirical experiments

      • connected with the psychological models of the time

      • no more just “clinical anecdotes”

  • new models were not necessarily localizable

    • distinguish between neural structure and cognitive structure, realized that they were not just the same thing

3 stage model of memory

• viewed the brain as completely irrelevant, saw the study of brain damage with disdain

  • took the computer metaphor too hard

  • took the distinction between software and hardware too far, thought the hardware wasn’t relevant