Cognitive Neuropsychology
• Interface between cognitive psychology and
neuroscience at the systems level.
– Systems level:
• brain “regions”
– anatomical (sulci/gyri) to functional (Broca’s area)
– areas with consistent neural architecture
» Brodmann’s Areas
– areas with a “unified” cognitive function
» e.g., Dorsolateral prefrontal cortex
(BA 9/46, superior parts of 45 and 10 )
Brodmann’s areas
Functional Regions vs. Brodmann’s Areas
Major Sulci and Gyri
Orientation and Navigation
Cognitive Neuropsychology
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Goals (for the field and the course):
1) Test cognitive theories of information processing
Primary goal of all cognitive neuropsychologists
2) Map cognitive functions to neural regions
Ascribe functions to individual regions
• Localization
Determine how multiple regions work together as a system
• Connectionism
Not a primary goal of ultra/radical cognitive neuropsychologists
3) Understand the consequences of brain damage and
potential for rehabilitation
Primary goal of clinical neuropsychology
Cognitive Neuropsychology
• Focus: behavior of patients with brain injury
• Explain patterns of impaired/intact cognitive
performance in brain-injured patients in terms of damage
to one or more components of a theory or model of
normal cognitive functioning
• Draw conclusions about normal, intact cognitive
processes from the patterns of impaired/intact
capabilities seen in brain-injured patients.
Case ‘AC’
• Case AC: 67-year old man, formerly employed as a
clerical worker in New South Wales, Australia
– Neurological profile:
• Recent stroke in territory of left middle cerebral artery
– What regions affected?
• CT revealed older small lesions in both hemispheres
– History of cardiovascular disease
Case ‘AC’
– Behavioral profile:
• Severe Reading deficit:
– Could not match upper to lowercase letters (A: a or e?)
– How do we know it is not a vision problem?
» Could correctly match uppercase letters (A: A or E)
– How do we know it is an acquired and not a developmental reading
disability?
» Formerly employed as a clerk!
• Severe Writing deficit:
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Could not write anything to dictation except name & address
Could not draw to dictation well (pictures)
Could not write the lowercase letter to match an upper case example
How do we know he doesn’t have a motor problem?
» Could correctly copy exactly what was shown visually (when
didn’t have to translate auditory to visual)
Case ‘AC’
• Very poor knowledge about properties of animals
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“The Oyster with Four Legs” (Sartori & Job, 1988)
MC: How many legs does an oyster have?
AC: A few
MC: I see. What about an ant?
AC: Some
MC: A caterpillar?
AC: No legs
MC: What about a snake?
AC: None
MC: And a seagull?
AC: Four legs?
– Performance was at chance on further testing…
– Suggests loss of information…perceptual or semantic?
Case ‘AC’
– Problems with “animal” information?
• Compared performance on animals with legs (e.g., bird, dog) to inanimate
objects with legs (e.g., chair, sofa)
• Performance is at chance; deficit is not animal specific
– Problems with “leg-specific” information?
• Question about “tails” yielded chance performance too
• Deficit is not leg-specific
– Problems with “parts” of an object?
• No; Unable to make judgments about overall shapes of objects (round or
not) or color (black or white)
– Damage to information about “perceptual properties”?
• Most likely: semantic knowledge of objects looks intact
• Correctly classified animals as dangerous or not, where found, whether
used as food, etc.
– Damage to information about “visual perceptual properties”?
• Yes! Could successfully retrieve information about auditory and olfactory
features of objects
Case ‘AC’: Case Closed!
– AC has selectively damaged ability to use visual perceptual
information about objects (storage)
– Other abilities are mostly intact
– What does this tell us about the normal object processing
system?
– Complex systems reveal their inner workings more clearly
when they are malfunctioning
– Relies upon assumption of modularity
• When one part of cognitive system is damaged, others stay intact
• Building box models…
Methods: Considerations
• What are the component processes required to
perform a given cognitive test?
• Issues in choosing patients
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Single case vs. Group Studies
Selection on the basis of lesion site or functional deficit
Time of test: acute vs. chronic stages
Site of injury: focal vs. diffuse
Distance effects: disconnection and diaschisis
• What is the appropriate control group?
• How do you define “normal” performance?
Cognitive Neuropsychology and Other Techniques
• Strong theories of brain-behavior relationships require
converging evidence from complementary techniques:
• ERP, EEG, MEG (neuromonitoring)
• fMRI (neuroimaging)
• Virtual lesions (TMS)
• How does this method complement functional neuroimaging?
– Best at determining whether region is critical for process
• With fMRI, regions other than those critical for process may
become activated (e.g., due to feedback connections, strategies)
– Can do extensive testing without time limit or
methodological constraints
• With TMS, “lesion” effects are brief, although “patients” can serve
as their own controls
Functional Neuroimaging of Patients
• Detect regions of residual responsiveness in perilesional area
• Detect abnormal responses in distant regions that result from
diaschesis (clues about systems…)
– Less activation than in normals: region has lost inputs
– More activation than in normals: disinhibition (unmasking), compensation
• Reveals alternative neuronal mechanisms that can support the
same task (degeneracy)
– Words can be read either by “whole word route” or by “letter to phoneme
conversion”
– Objects can be recognized by wholes or by parts
• Reveals structural and functional plasticity/recovery