Theories

Question 1

Domain-specific theory vs. domain-general theory

Answer 1

“Localization” vs. “generalist”. two dominant paradigms concerning cerebral functional organization.

1. Localization theory: aka domain-specific theory. the dominant paradigm that dominates modern neuropsych starting in 60s.
   - 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 (e.g., the left inferior frontal gyrus in the case of expressive speech).
2. Domain-General Theory (generalist): idea is nurture over nature- experience and cuture facultatively shape the mind as a whole, whereas biology plays little role.–
   - the brain has only one or a few fundamental properties, such as general learning and reasoning capacity, a position also favored by behaviorists and anthropologists
   - 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 tissues has equipotentiality: any brain area can do what any other brain area can do for perception; only sensory and motor functions are specialized.
   - the observed variety of organic syndromes is explained by either lesion size, lesion “intensity”, or the combo of the fundamental cognitive deficit (whatever it is) with a specific motor-sensory impairment

Question 2

equipotentiality

Answer 2

any brain area can do what any other brain area can do for perception; only sensory and motor functions are specialized. Karl lashley’s theory that an intact brain region can carry out the functions of damaged brain regions.

Question 3

Franz Gall (1796)

Answer 3

Key Figure in the prominence of localization. proposed that personality traits were localized and predictable by studying variations (“prominences”) in skull contour by palpating the skull. This practice of phrenology was the major tenet of Faculty Psychology, now the subject of derision. But the movement represented two important conceptual breakthroughs:

a. the materialist view of the brain as subject to scientific scrutiny
b. mental modularity/localization (of personality traits or “faculties,” rather than cognitive functions, in this view)

Question 4

Paul Pierre Broca (mid 1800s)

Answer 4

key in prominance of localization. french neurologist. founder of the idea of cerebral dominance, observed that

a. acquired language loss was reliably associated with left-brain strokes in most patients
b. loss of expressive speech and syntactic sentence structure was associated with left frontal strokes. “we speak with the left hemisphere”

later he also discovered that left-handed people apparently had language in the right hemisphere

Question 5

Carl Wernicke (mid to late 1800s)

Answer 5

key in prominance of localization. German neurologist further correlated types of aphasia with cerebral anatomy, observing that

a. auditory comprehension (recepetive language) but not fluency was impaired by left hemisphere posterior lesions
b. disconnection explained why some left subcortical lesions affected language repetition but not comprehension (i.e., conduction aphasia due to damage to the arcuate fasciculus)

Question 6

Joseph Dejerine (late 1800s)

Answer 6

key in prominance of localization. described 2 forms of reading of reading loss of “alexia” associated wtih either

a. direct destruction of left angular and supramarginal gyrus of the left brain or
b. disconnection of visual input to an intact memory center

Question 7

William James (late 1800s)

Answer 7

key in prominance of localization. anticipating evolutionary psychology , he proposed that the brain evolved to contain dozens and perhaps hundreds of “instincts”

Question 8

Hugo Liepmann (late 19th - early 20th century)

Answer 8

key in prominance of localization. showed that left parietal lesions affected skilled movement in both hands, even when language was intact (ideomotor apraxis).

Question 9

Alexander Luria (1930-70s)

Answer 9

key in prominance of localization. systematized the modular geography of the entire brain based on inferences from clinical cases consisting mostly of Russian solders with brain injuries. Unlike his contemporary Vygotsky, Luria suggested prototypical bedside tasks for each module, tasks still used today.

Question 10

Wolfgang Kohler

Answer 10

key in prominance of generalist theory. German Gestalt psychologist- studying visual perception, illustrated how the brain transformed separate parts into a new whole, such that the whole is greater than the mere sum of its parts.

Question 11

Behaviorists such as John B. Watson (early 1900s) and B.F. Skinner (1930-60s)

Answer 11

key in prominance of generalist theory. maintained that the brain had only a general capacity to learn.

Question 12

John Hughlings Jackson (1870-1890s)

Answer 12

key in prominance of generalist theory. a British neurologist who argued that mental functions are hierarchical, not localized. He proposed that only two types of deficits were caused by cerebral damage:

• positive symptoms that represent disinhibited expression of lower centers (like the brainstem) when removed from higher cortical control and
• negative symptoms that represent the loss of function when the superordinate functions are impaired. Essentially, this was a regression theory of brain damage.

Question 13

Lev Vygotsky (1920-30s)

Answer 13

key in prominance of generalist theory. The regression theory of Vygotsky also asserted (like John Hughlings Jackson’s theory) that brain damage causes a regression to earlier developmental stages. Consistent with Marxist orthodoxy, he argued that

a. mental function evolves steadily through the internal representation of social experience only, and
b. inner speech is the domain-general processor that directs all goal-directed behaviors.

Question 14

Karl Lashley (1920-50)

Answer 14

key in prominance of generalist theory. psysiological psychologist who revealed a group effect for lesion size, not localization in rat brain lesion studies. for example, he reported in 1948 that primate frontal lesions caused no greater deficit in conditional learning (now termed “flexibility”) than did nonfrontal lesions

Question 15

Kurt Goldstein (1930-50s)

Answer 15

key in prominance of generalist theory. Neurologist who argued that “loss of abstract attitude” (reasoning) was the fundamental defect in any type of brain damage. He used his famous patient Schneider to prove that a small occipital lesion resulted in many deficits that were thought to have localization elsewhere. Later findings that Schneider was malingering his diffuse impairments.

Question 16

Key developments dooming the Generalist View

Answer 16

• -famous 1950 essay by Karl Lashley implied that domain-general theory was an intellectual dead-end b/c his methods forced him to the absurd conclusion that memory could not be located in the brain
• -evidence that Goldstein and Gelb’s patient Schneider was likely malingering
• Geshwind pointed out that Goldstein’s insights were indistinguishable from those of the classical localizationists
• “Regression theories” were illogical b/c they implied that children must act like adults with brain-damage. to the contrary, children are capable of extraordinary feats of memory and learning, with rapid language acquisition being the best example.

Question 17

Landmark studies in support of domain-specificity

Answer 17

• famous case of HM, who suffered dense amnesia due to bilateral hippocampal damage (1953), clearly linking function (anterograde memory) to specific anatomy
• split-brain studies of Sperry and Gazzaniga (1960s), who proved that qualitatively different forms of information (verbal, visual) were specifically encoded with either the right or left hemispheres (i.e., the lateralization of material-specific memory)
• Ralph Reitan’s 1964 demonstration that single tests of “organicity” were poor at classifying persons with brain damage. Instead, patterns of performance, pathognomonic signs, and interrelationships of different test scores, as well as a composite score that represented the battery average (Impairment Index), improved prediction and understanding.
• Geschwind’s catalogue of disconnection syndromes
• Brenda Milner’s team (1980-90s) who found that large excisions of prefrontal tissue cause impairment in executive functions such as shifting of strategy, without any generalized intellectual decline (essentially dissociating general intellect, g, from executive function)
• the finding that right-brain strokes were more likely to cause hemifield inattention than were left-brain strokes, proving a role for what was referred to as “reality monitoring” in the right hemisphere
• the finding that inferior temporal lobe lesions in the fusiform gyrus cause prospagnosia, the inability to recognize familiar faces, with retained ability to detect faces.
• the results of frontal lobotomies and leukotomies, popular in the 40s and 50s, which resulted primarily in affective and personality changes.
• Hans Lukas Teuber (1955) coined the concept “double dissociation” as an important standard of proof in neuropsychology. An example of DD occurs when a lesion in brain zone A impairs verbal memory bu not visual memory, but a lesion in zone b weakens or impairs visual memory but not verbal learning. Used in conjunction with neuropsychological, neuropathological, and neuroimaging results, the observation of DD has allowed neuroscience to draw inferences regarding the localization of certain cognitive functions.

Question 18

Double Dissociation

Answer 18

-Hans Lukas Teuber (1955) coined the concept “double dissociation” as an important standard of proof in neuropsychology. An example of DD occurs when a lesion in brain zone A impairs verbal memory bu not visual memory, but a lesion in zone b weakens or impairs visual memory but not verbal learning. Used in conjunction with neuropsychological, neuropathological, and neuroimaging results, the observation of DD has allowed neuroscience to draw inferences regarding the localization of certain cognitive functions.

Question 19

Cerebral laterality Theory

Answer 19

A middle theory- a hybrid of domain-specificity and domain-generality. proposes two domain-general processors rather than one, in which the two halves of our brain are organized differently and control qualitatively different (but still broad) classes of behavior. AKA cerebral asymmetry and “hemispheric locentr”

Support: dichotic listening tasks showing better identification of sounds coming into the right ear, which has a strong connection with left hemisphere (but some research diicsputing this)

Question 20

Split-brain studies show the right hemisphere is better than the left at:

Answer 20

(under cerebral laterality theory)

• translating a 3-dimensional object into its unfolded equivalent.
• discriminating nonsense shapes from each other
• remembering designs (object recognition) and locations (spatial recognition)
• making similarity judgments among designs
• recognizing and processing faces

Question 21

Landmark studies of the Two-Streams Hypothesis

Answer 21

(dorsal and ventral streams hypothesis).

• Pohl (1973) integrated decades of primate research to prove distinct functions can be organized into a ventral-dorsal scheme, such as egocentric and allocentric perception.
• Ungerledier and Mishkin (1982) lesioned primate inferotemporal cortex and found not only object discrimination deficits but also the inability to relearn spatial location tasks following parietal lobe lesions
• Goldman-Rakic and co (80-90s) showed dorsal-ventral organization in monkey frontal lobes: dorsolateral areas serve spatial working memory and ventrolateral areas serve working memory
• Those with Balint syndrome (identified in 1909; bilateral superior occipital-parietal lesions) have difficulty reaching for objects directly, but can recognize them (optic ataxia)
• Borst, Thomson, and Kosslyn’s (2011) recent meta-analysis showed a strong association between dorsal activation/damage and grouped data for
• spatial relations and
  b. movement detection. ventral activation /damage was associated with parallel processing performance.

Question 22

Automatic vs. Controlled processing

Answer 22

separate from task content, neuropsychology requires awareness of task demands as informative of diagnostic questions. Task demands correlate roughly with task difficulty. The two key concepts are automatic and controlled processing and most tests have both components to varying degrees.

• Automaticity: Refers to behavioral routines that are carried out quickly, effortlessly, accurately, and with little forethought. a popular synonym from clinical jargon is “overlearned.” Examples include basic mental addition or reciting math facts, digits forward, speaking and formulating sentences, recognizing written words, greetings and helping responses in social settings, and motor skills such as riding a bike. Individuals wtih normal reading skills (those without a reading disorder for example, are said to read automatically, effortlessly. Poor readers typically do not read effortlessly.
• Effortful processing: Refers to mental operations carried out with effort, planning, and careful attention to proximate conditions. Synonyms are “effortful” and “online.” Examples include striking out all the letter A’s preceded by the letter X in a novel cancellation task, reciting digits backward, driving to an unfamiliar location, remembering what you did last Tuesday, and learning a new work skill.

Facts:

• much of human behavior is composed of automatic response patterns that are triggered by common contexts.
• automaticity can be seen in any neurobehavioral domain, including language, motor skills, psychomotor speed, and even some forms of problem solving. many automatic responses are perceptual-motor biases built into the brain by evolution. For example, localizing sound during sensory-perceptual testing is not learned.
• automatic response patterns, termed the “habit system,” likely have a neuroanatomical base. there is compelling evidence that subcortical areas, particularly the basal ganglia, form an integrated habit system with respect to motor skills.
• evidence for a separate neurobiological substrate is a double dissociation: preserved pursuit-rotor learning in patients with Korsakoff amnesia, patients who have no motor impairment (no basal ganglia damage), versus impaired motor learning in patients with subcortical disease (e.g., huntingtons).

Question 23

Brain Reserve Hypothesis vs. Cognitive Reserve Hypothesis

Answer 23

central premise of both theories is that increased reserve can be protective against the onset of dementia or the long-term impact of acquired brain injury.

BRH (aka cerebral reserve) refers to a brain’s ability to absorb insult and potentially recover. often described as a “passive threshold model” because it hinges primarily on the brain’s physical health prior to insult or disease onset. it states that a critical threshold of brain cell loss must be crossed before a deficit achieves clinical expression in symptoms or test score abnormalities. those with “brain matter to spare” (more brain cells or denser synaptic networks) are less likely to show observed deficits, despite documented brain disease.

-CRH: states that 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 does not prevent dementia or impairments followign TBI or neurological conditions, but it can modify the functional and clinical expression of such conditions. Thus, it is an “efficiency model” because it refers to the mind’s resistance to brain damage due to the presence of more efficient synaptic networks or preexisting cognitive abilities. Some research on environmental enrichment and brain development has supported the idea that there are modifiable variables that can enhance synaptic networks and provide a buffer against the impact of brain compromise on mental abilities. Quality of education, healthy lifestyle variables, and learning history are good examples.

Key facts:

• CRH was developed to explain the disagreement between disease (objective brain damage) vs. illness (the felt experience of the patient) in neuropsychology
• theory was stimulated by findings in the dementia field when an imperfect correlation was observed between brain abnormalities at autopsy and scores on cognitive screens such as MMSE when the patient lived
• Landmark studies evoking or testing CRH:
  
  • sisters of notre dame prospective dementia study: nuns with limited literacy showed dementia signs at earlier ages than did more literate (presumably more intelligent) nuns. essays written to the pope (prior to convent admission) were scored as to compexity as a proxy for verbal intelligence (Snowden 1996)
  • Bigio et al (2002) showed lower synaptic count in early as compared to late dementia onset.
  • Stern (2002) showed that level of education, talents/skills, and life achievements were associated with later onset of AD

Question 24

Executive Function Theory

Answer 24

one or more general-purpose processors control domain-specific (specialized) mental operations to guide attention and action. Different sets of control processes have been proposed, with different localizations. Some EFTs propose a single controller, others a family of semi-general-purpose controllers.

examples:
- Alan Baddeley (1970-80s) argued for a single “central executive,” a mental process that regulates (manipulates in his terms) the content of two domain-specific short-term memory stores (phonological loop and visuospatial sketchpad). the combo of this single control mechanism and the two “slave” operations constitutes “working memory,” although some critics point out that this is indistinguishable from other views on short-term memory.

• Akira Mikyake’s (2000) factor analysis proposes 3 general-purpose mechanisms: shifting, inhibiting, and “updating” (monitoring in other terms). These are latent variables that underlie most commonly used neuropsychological measures of “frontal system functioning”
• Donald Norman and Timothy Shallice’s supervisory attentional system (SAS, 1986). These cognitive psychologists relied on the automatic-controlled distinction to identify situations that are novel and require “attentional” control for an optimal adaptive response. Examples are hazards, poorly practiced responses, decision-making, and “troubleshooting.” They proposed only one mechanism: inhibition of a prepotent response, meaning effort to suppress the perceptual-motor patterns (“schema” in their terms) that are typically evoked. Two criticisms include a- no situation is truly novel; a situation is hazardous only because we recognize it as dangerous (implying familiarity) and b- the SAS model only refers to ordinary learning.