CPSY 450 Exam 1 Semi Final

Describe the language models of the diagram makers exemplified by the “House of Lichtheim.”

linked centers for motor patterns, auditory images, and concepts

What was novel about the approach of the diagram makers to understanding the cognitive function of brain-damaged patients? In the context of this model, how did the diagram makers explain a variety of language syndromes exhibited by different types of patients (e.g., Broca’s aphasia)?

localism became much more popular than holism + aphasias are based on which areas are damaged or disconnected

What were the weaknesses of the diagram makers, and why did this approach fall out of favor?

Weaknesses included:

• inadequate psychological foundation (didn’t develop concept of centers + didn’t use computational information processing vocabulary)

• lack of empirical constraints (based on case studies) + support (theory driven, not data driven)

• strictly tied to anatomy ( neural areas = proposed cognitive modules)

What are the aims of cognitive neuropsychology?

- can a particular function be spared/impaired relative to other cognitive functions?

- address questions about cognitive components

- single-case studies

- FIND COGNITIVE MODELS which will eventually help neural models

Compare the advantages and disadvantages to studying brain-damaged patients versus healthy subjects for understanding cognitive processes.

Brain Damage Advantages: You can see the actual effect on behavior from brain damage, organic lesions allow subcortical regions to be studied, changes in behavior are more apparent

Brain Damage Disadvantages: hard to localize lesions, danger in concluding a function is localized

Healthy normal subjects advantages: temporary effects, reversible nature, can investigate functional integration

Healthy normal subjects disadvantages: only affects close to the surface brain areas

What distinguishes the field of cognitive neuropsychology from that of classical neuropsychology?

classical neuropsychology:

- what functions are disrupted by damage to area X?

- address questions about functional specialization

- link cognitive and neural models

- tends to use group study methods

cognitive neuropsychology:

- can a particular function be spared/impaired relative to other cognitive functions?

- address questions about cognitive components

- single-case studies

What are the different ways of grouping patients in classical neuropsychology?

Syndrome: multiple cognitive impairments grouped together. Useful for investigating neural correlates of disease pathology

Behavior symptom: identify multiple regions implicated in a behavior

Lesion Location: useful for testing causal predictions derived from functional imaging

Define each of the underlying assumptions of cognitive neuropsychology.

Assumptions are:

Fractionation (damage to the brain can produce selective cognitive lesions + Modularity of cognitive system + Neurological specificity of cognitive modules)

Universality (All individuals share the same cognitive system + Effects of lesions are stronger than individual variation)

Transparency (Performance reflects the total cognitive system minus those subcomponents (or connections) which have been affected by the lesion)

What are the consequences if any of these assumptions are false?

Fractionation: Cognitive disorders wouldn't be selective to one region or another

Universality: findings from a group of patients can't be generalized to anyone else

Transparency: patient data can't be used to learn about cognitive functions and structures in cognitive psychology.

In neuropsychological studies, describe the different methods (i.e., associations, dissociations) that scientists use to determine whether two or more tasks utilize different cognitive/neural resources

Associations or Similarities: Patients impaired on Task 1 also impaired on Tasks 2 & 3

 Common cognitive process or illusory association?

Single Dissociations or Differences: Patient A impaired on Task 1 but intact on Task 2 (could be due to task difficulty)

Double Dissociation: Patient A impaired on Task 1 but intact on Task 2 + Patient B impaired on Task 2 but intact on Task 1

What factors contribute to the behavioral performance of a patient? How do these factors influence our conclusions about the underlying cognitive processes?

• Factor most interested in

• normal individual variation

• effects of compensatory operations

• effects from disruptions of other processes

What are the benefits and challenges associated with using single-case studies?

benefits:

- no confounds between different subjects

- each case is a separate, replicated experiment over time

- good for establishing cognitive models

disadvantages:

- individual ability can change overtime (deficit heals, ability fades)

- cognitive impairments aren't stable

- not as good for linking to specific brain structures

What is the fundamental issue with simply taking group-averages of performance measures across brain-damaged subjects with similar lesions?

- tough to localize lesions for some forms of brain damage due to tumors and swelling

- danger in concluding a function is localized to a region or purpose of a region to to support that function

- need to consider if region has multiple functions

How is it possible to infer anything about human cognition from single-case studies?

- accounting for all reported cases

- accounting for all data from cognitive neuropsychology

Characterize the distinctions between apperceptive vs. associative agnosia made by both Lissauer and Warrington.

Apperceptive (Object Perception)

Can’t differentiate between similar objects

Can’t copy or make 3d Model

Associative (Object Meaning)

Can differentiate between similar objects but can’t give them meaning/significance

Able to make 3d Model

Can copy but can’t identify

Describe Warrington & Taylor’s model of object recognition. What neuropsychological evidence is there for hemispheric specialization of different aspects of visual process?

Visual Anlaysis → Post-Sensory: ( Perceptual Categorization → Semantic Categorization)

Visual Analysis (sensory visual analysis,visual cortex in occipital lobe, "pseudo-agnosia": can't perceive object)

Perceptual Categorization (3d object recognition, posterior right

"apperceptive agnosia": inability to perceive integrated object)

Semantic Categorization (what object is recognition, posterior left hemisphere, "associative agnosia": inability to name/recognize object )

What neuropsychological evidence is there for hemispheric specialization of different aspects of visual process?

- perceptive vs perceptive + conceptual study

- object/picture matching study vs ghent matching study

deficits on different sides of hemisphere respond differently

Briefly describe the different stages of Marr's computational model of visual object recognition?

Primal Sketch → 2 ½ D Model (only know depth for viewer's angle) → 3D Model (know depth of object at any angle) → Semantic System

How does Marr's model different from Warrington's model?

visual analysis = primal sketch/2.5

perceptual categorization = 3d model representation

semantic = semantic

What neuropsychological evidence did Marr use to support the necessary "principal axis extraction" computation in the model?

In Humphrey & Riddoch's foreshortened principal axis vs minimized distinctive features test, agnosics preformed poorly on foreshortened axis and well on minimized distinctive features

To what degree do the perceptual deficits of patients with agnosia support or refute Marr's model or Warrington's distinctive-features model?

more so support warrington and refute marr

Challenges:

- overlapping figures test

- Gollin figures

- changes in lighting

- warrington's shadow rotating test

Above tests minimize distinctive features but keep principal axis intact, but agnosics still perform poorly

Also difficult to know how much distinctive features are minimized

Briefly describe Riddoch and Humphrey’s hierarchical model of object recognition. How does this model relate to Marr’s and Warrington’s conceptualization of object recognition?

Warrington: matching stage between stored

• matching feature to feature

• unusual views rely on detection and integration of elements

• in the posterior right hemisphere

Marr: brain stores canonical view

• recognition requires view normalization to this canonical view

• in parietal cortex

What are the characteristic features of integrative agnosia (Patient HJA)?

CAN'T GROUP VISUAL ELEMENTS

Functional abilities
- able to copy drawings of objects that he can't recognize
- able to draw objects from memory
- able to recognize objects from modalities other than vision
Impaired abilities
- unable to recognize features as an integrated percept
- unable to determine if combined objects (candle doorknob) are real or not

Unique skill
- did better on silhouettes of combined objects than line drawings

What is the significance of the face inversion effects and the Thatcher illusion? What does it tell us about how faces are processed by our visual system?

there is something "special" about how we process faces

Describe Bruce & Young’s model of face perception along with the neuropsychological evidence in support of the model

- patient who doesn't see faces as faces
- patient who can see faces but not recognize them
- precise paring test did not show improvement in true pairings

What is the difference between covert vs. overt face recognition in prosopagnosia, and how is covert recognition demonstrated?

How is the difference between covert and overt face recognition accommodated by Bruce & Young’s model?

study with skin conductance response showed that prosopagnosic had covert facial recognition even without overt facial recognition
- skin conductance/covert response is at face recognition unit, but NOT person identity node

What are the various arguments described in class for why faces are or are not special?

Yes special:
- are patients who are object agnosic but not prosopagnosic
- controls are worse on glasses than faces. prosopagnosic is normal on glasses but impaired on faces, so it can't just be that faces are difficult
- faces are so special and dedicated that system mandatorily grabs faces, even in it is damaged
Not special:
- faces are just difficult
- faces are very similar to each other and its difficult to discriminate between them
- simply expertise specific

Describe cortical pathway of visual information from retina to primary visual cortex (V1).

What are the distinct patterns of visual field deficits that would result from damage at different points along this pathway?

Describe how dissociations have been demonstrated between conscious awareness and visual discrimination performance in blindsight patients