Ch 3 Flashcards
What theory does aphasia represent?
Modular organization and cerebral localization theory
Domain specificity theory is also known as
Cerebral Localization Theory
Domain-specificity theory states that
- the brain has a modular organization
- each module is a specialized processor devoted to one task or function
- each specialized processor is reliably associated with specific zones in the brain
Domain General theory is also associated with terms like
organismic
organic brain syndrome
Domain General theory states that
- the brain has only one of a few fundamental properties
- any mental act of function requires the entire brain working in concert
- long term memory is distributed around the brain
- symptoms are in part the expression of the undamaged part of the brain
- only motor and sensory functions are localized, not higher cognitive functions
- brain tissue has equipotentiality
- organic syndrome is explained by lesion size, lesion intensity or combination of cognitive deficit with specific motor sensory impairment
Meaning of equipotentiality
- any brain area can do what any other brain area can do for perception; only sensory and motor function are specialized
- intact brain region can carry out functions of damaged brain regions
Phrenology is an example of which theory
Localization
Broca’s theory is an example of which theory
Cerebral dominance/Localization
Wernicke proposed that auditory comprehension (receptive language) but NOT fluency (expressive language) was impaired by…
Left hemisphere posterior lesions
Gestalt theory is an example of which theory
Generalist theory - whole brain working in concert, plays a central role in human experience
John Hughlings Jackson argued that mental functions are
Hierarchical NOT localized
Which other theorists purported that brain functions are generalized and NOT localized?
- Lev Vygotsky - brain damage causes regression to earlier developmental stages
- Karl Lashley - group effect for lesion size, not localization in rat brain lesion studies
- Kurt Goldstein - loss of abstract attitude was the fundamental defect in brain damage
- Watson and Skinner - brain had only a general capacity to learn
Modern evidence supporting domain specificity
- HM - bilateral hippocampal damage
- Sperry and Gazzaniga - split brain studies
- Norman Geschwind - disconnection syndromes
- Milner - excisions of prefrontal tissue causes impairment in EF such as shifting, but no IQ decline
- Right ear advantage for verbal stimuli - right auditory nerve has strongest connection with L brain and vice versa
Cerebral laterality
hybrid of domain specificity and domain generality
Split brain studies show that RIGHT hemisphere is better than the LEFT at
- translating 3D object into unfolded equivalent
- discriminating nonsense shapes from each other
- remembering designs (object recognition) and location (spatial recognition)
- making similarity judgment among designs
- recognizing and processing faces
R hemisphere
regulate arousal and attention
Focal R parietal lesion
-causes L hemispatial inattention (neglect) but L brain lesions typically do not cause contralateral neglect
R hemisphere
- places emphasis on negative valence on stimuli
- R-sided lesions -> euphoria
- L-sided lesions -> dysphoria
- R brain lesions -> speech prosody affected
What is the Two-streams hypothesis
Dorsal and Ventral system
Dorsal (top) brain refers to which structures
- Structures above the horizontal plane formed by the Sylvian fissure
- Includes the parietal lobes and dorsolateral prefrontal cortex (DLPFC)
What are the functions of the dorsal system
- processing and storage of spatial features of information (e.g. where something is located or event sequence)
- spatial relations
- dorsal frontal lobe - determines how action is carried out
- known as the WHERE system
the “Where” system
Dorsal brain
Ventral (bottom) brain refers to which structures
below the Sylvian plane, e.g. inferotemporal cortex
What are the functions of the ventral system
- ventral posterior cortex - extracts object information (e.g. shape, color, identity)
- movement detection
- ventral frontal lobe - makes decision about causal relations between objects and actions, does NOT carry
out actions - WHAT system - NATURE of the object
the “What” system
Ventral system
Balint syndrome
- difficulty reaching for objects directly but can recognize them
- bilareral superior occipital-parietal lesions
Automaticity
- behavioral routines that are carried out quickly, effortlessly, accurately
- overlearned
Effortful processing
- mental operations carried out with effort, planning, careful attention
- more sensitive to brain injury or dysfunction than automatic response systems
Brain Reserve hypothesis and Cognitive Reserve Hypothesis
increased reserve can be protective against the onset of dementia or long term impact of acquired brain injury
Brain Reserve Hypothesis
- brain’s ability to absorb insult and potentially recover
- passive threshold model
- hinges primarily on brain’s physical health prior to insult or disease onset
- a critical threshold of brain cell loss must be crossed before a deficit achieves clinical expression in symptoms or test score abnormalities
- those with more brain matter to spare (more brain cells, or denser synaptic networks) are less likely to show observed deficits
Cognitive Reserve Hypothesis
- education and enriched experience can increase cerebral reserve and are relatively protective against the expression of symptoms following brain disease or injury
- higher cognitive reserve may modify the functional and clinical expression of dementia or impairments 2/2 TBI
- efficiency model –> refers to the mind’s resistance to brain damage due to presence of more efficient synaptic networks or preexisting cognitive abilities
- Notre Dame Nun study
Brain Reserve Hypothesis would predict
people with remote TBI should experience earlier or more frequent age-related declines in function than those without hx of TBI
Central Executive
- system responsible for the control and regulation of cognitive process, helps to regulate attention, working memory and memory
- related to prefrontal regions
