Term
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Definition
| visual areas in temporal/parietal and occipital cortices |
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Definition
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Definition
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Definition
| superior frontal and motor cortex |
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Definition
| parietal/somatosensory and temporal/auditory |
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Term
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Definition
| CC and anterior commissures are surgically removed (for relief of intractable epilepsy) |
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Term
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Definition
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Term
| What is cut in split-brain surgery? |
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Definition
Always: CC (target structure)
Sometimes: anterior commissure (connects temporal and limbic structures) and hippocampal commisure (inadvertantly)
Never: collicular connissure (connects superior colliculli- very deep) |
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Term
| Heterotopic callosal connection |
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Definition
connects different regions
(Left V2-Right V3) |
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Term
| Homotopic callosal connection |
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Definition
connects same regions
(Left V2-Right V2) |
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Term
| Information transmission in the CC |
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Definition
Access to specialized processors
Unifies the sensory world - advantage to redundancy
Unifies the psychological world - the left brain interpreter |
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Term
| Resource allocation of CC |
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Definition
| as task difficulty increases, both hems are engaged to meet task demands |
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Term
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Definition
| "fear episodes" (2 min long partial seizures), memory problems, problems learning new skills, loss of energy |
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Term
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Definition
| complex partial seizures with secondary generalization |
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Term
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Definition
medication for generalized seizures
temporal lobectomy (epileptic focus in temporal lobe) |
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Term
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Definition
Immediately: severe headaches
2 days: flurry of seizures
Several weeks: persistent seizures despite meds
3 months: seizures stop with meds
1 year: weaned off meds and no seizures return |
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Term
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Definition
Idiopathic: no obvious cause (possible lowered seizure threshold or lesion)
Symptomatic: known cause of brain damage (stroke, head injury, tumor, etc.) |
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Term
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Definition
specific area of one hem (1-2 min)
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Term
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Definition
| no general change in consciousness, motor movements or sensory sensations |
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Term
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Definition
| interference of higher-level cerebral functioning, disturbance of consciousness, possible aura (fear, smell, or vision) |
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Term
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Definition
| loss of consciousness, bilateral electrical activity |
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Term
| Tonic-clonic Generalized Seizures |
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Definition
| muscle contraction, shallow or no breathing, loss of bladder or bowel control, 2-3 min seizure with no memory of it |
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Term
| Simple Absence Generalized Seizure |
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Definition
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Term
| Complex Absence Generalized Seizure |
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Definition
| includes subtle movements |
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Term
| Akinetic Generalized Seizure |
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Definition
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Term
| Myoclonic Generalized Seizure |
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Definition
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Term
| Monkey commissurotomies (1930s) |
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Definition
severed CC in monkeys
few obvious behavioral effects
stopped spread of epileptic seizure activity, reduced response of mirror focus (scar tissue reflected to opposite hem)
not as successful as predicted
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Term
| Von Wagenen first human commissurotomy (1940s) |
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Definition
| local focus removal to help relieve epileptic seizures |
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Term
| Akelaitis' conclusions about effects of surgery |
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Definition
only minor motor disturbances in behavior
concluded the CC is hardly connected with any psychological function at all |
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Term
| Myers and Sperry experiment in cats/monkeys (1952) |
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Definition
Commissurotomy on animals: severed CC and optic chiasm so that each eye only projects to single hem and input to each hem could be controlled
Findings: the intact animals showed increased performance when the other hem viewed the object (already learned) while the severed animals had to re-learn when the other hem viewed
Conclusion: hems learn separately and CC is source of shared experience between them |
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Term
| Vogel and Bogen surgeries |
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Definition
suspected von Wagenen's poor results were due to incomplete cutting of the CC
used hem separation to relieve intractable epilepsy in 24 pts |
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Term
| Sperry, Gazzaniga, and Bogen's findings regarding the "dual-brain" |
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Definition
| 2 minds within a single cranium --> independent functioning (differences in preferences, decision-making, personality, etc.) |
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Term
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Definition
| have pt fixate centrally and provide brief exposure of image to each hem (one on each side) |
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Term
| Visual-verbal disconnection |
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Definition
| only the RVF objects can be named because language is controlled by the LH |
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Term
| Tactile-verbal disconnection |
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Definition
| can only name object in right hand because projects to LH, but each hand will select objects according to info presented to the contralateral hem |
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Term
| Visual-visual disconnection |
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Definition
| cannot match stimuli between the two visual fields (performance at chance) |
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Term
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Definition
contralateral hem controls hand
left hand apraxia (deficient gestures)
alien hand sign (left hand perceived as belonging to someone else) |
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Term
| Tactile-tactile disconnection |
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Definition
| cannot match stimuli in opposite hands (performance at chance) |
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Term
| Holtzman and Gazzaniga study (1985) |
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Definition
| superior performance in split brain pts on mixed displays because the hems do not share info so there is no confusion (as there is in control pts) |
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Term
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Definition
pt attempts to make info accessible to both hems (passes clues from one hem to the other)
making sound with object
subvocal signaling (gestures, taps) |
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Term
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Definition
| seizures that increased in severity, complete commissurotomy at age 13, seizures reduced, at age 16 experienced left sided focal motor seizures (right side abnormality) |
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Term
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Definition
normal IQ, could draw and write with both hands (good ipsilateral control), normal language, 50% verbal naming but good LVF identification
both hems readily and equally recognized objects that can be verbalized |
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Term
| Acute disconnection syndrome |
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Definition
| occurs immediately after surgery - pt is mute and shows left-sided apraxia |
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Term
| Late disconnection syndrome |
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Definition
| displays cross-cuing - using subtle cues to help other hem recognize) |
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Term
| Relationship between language and consciousness |
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Definition
| The interpreter: LH is language dominant so it promotes theories to account for dissociations (tries to make sense of things and find causal relations, may be incorrect) |
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Term
| Reuter-Lorenz and Miller study (1998) |
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Definition
Task: present target images (letters or location) followed by a probe - does probe match target image?
Findings: showed verbal/spatial processing asymmetries both in control and split brain pts, but more pronounced in split brain |
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Term
| Hemispheric differences in verbal and spatial processing |
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Definition
LH is verbal (language)
RH is spatial |
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Term
| Guessing game study by Wolford et. al (2000) |
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Definition
The interpreter: LH integrates what it knows about the world to the situation
Maximizing strategy: give most frequent item (simpler solution) -->RH
Matching strategy: guessing based on a perceived "hidden pattern" -->LH |
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Term
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Definition
Lab ensured lateralized output (controlled for cross-cuing)
Pts had complete callosal section (accurate surgery)
Success inspired study of laterality of the normal brain (consequences of severing CC) |
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Term
| Dichotic listening method |
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Definition
| input to both ears, suppress ipsilateral ear's input --> asymmetries based on ear of input are more evident (more often report sound in right ear because it goes to the verbal LH |
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Term
| Interhemispheric transfer time (IHTT) effect (crossed vs. uncrossed) |
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Definition
causes performance asymmetries in people with intact CC
crossed: CC must be involved, slower RT
uncrossed: no CC involvement, faster RT |
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Term
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Definition
info is processed by the hem specialized for the material or task
interhemispheric transfer time
info degradation |
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Term
| Banich and Belger (1989) experiment |
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Definition
Study: unilateral processing vs. bihemispheric processing across 3 levels of task difficulty
Results: as task difficulty increased, RT of within field comparison increase > RT of across field comparison
Conclusion: for easier tasks within field matches are faster but for harder tasks across field matches are faster |
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Term
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Definition
after CC surgery left hand writing intact, right hand agraphic
RH: writing ok, speech wrong (both wrong in right handers)
LH: speech ok, writing wrong (both intact in right handers)
unique because writing dissociates from other language abilities |
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Term
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Definition
| Used to determine which hemisphere is responsible for speech output in pts about to undergo tissue removal to control epileptic seizures - anesthetize only one hem and determine if pt can still speak (done once for each hem) |
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Term
| Difference in laterality of speech control between left and right handers |
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Definition
Right handers: 95% LH 5% RH
Left handers: 70% LH, 15% RH, 15% both |
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Term
| Why are functions lateralized? |
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Definition
One fundamental lateralized function drives other asymmetries - requires difference in circuitry (left vs. right) separate from other abilities
Advantages to having varied representations (don't become confused)
Advantage to insulate different processors (improves efficiency) |
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Term
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Definition
| units of sound that make up language |
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Term
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Definition
| smallest units of written language combined to make words |
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Term
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Definition
| representations of words stored in memory |
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Term
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Definition
| auditory (what words look like) |
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Term
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Definition
| visual (what words look like) |
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Term
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Definition
| meanings that correspond to lexical items |
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Term
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Definition
| grammar (rules for combining words) |
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Term
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Definition
| linking sentences into coherent narrative |
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Term
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Definition
| disabled motor functions associated with speech |
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Term
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Definition
| severe nonfluency of speech (awkward articulation, phonemes), responses make sense but are ungrammatical (simple and telegraphic), comprehension is relatively spared, word finding is impaired, repetition shows same impairments as spontaneous speech |
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Term
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Definition
| phonetically and grammatically normal but nonsensical speech, generally fluent and well articulated, normal intonation, nonsense words (neologisms), meaning expressed in a roundabout way, severely impaired comprehension |
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Term
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Definition
| normal speech comprehension and production, impaired naming ability, deficits in repetition of non-meaningful words and word sequences |
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Term
| Transcortical Motor Aphasia |
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Definition
| similar to Broca's but with repetition intact |
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Term
| Transcortical Sensory Aphasia |
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Definition
| similar to Wernicke's but with repetition intact |
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Term
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Definition
| damage to Broca's area and Wernicke's area (extensive), loss of ability to comprehend language as well as to produce it |
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Term
| Where/how is meaning stored? |
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Definition
| knowledge of world is distributed in different ways (categories) that can be dissociated (evidence from category specific deficits and category specific brain activation) |
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