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73 Cards in this Set

  • Front
  • Back
region of corpus callosum connects visual areas in occipital and temporal/parietal brain regions
splenium
superior frontal and motor cortical areas are connected by this region of the corpus callosum
rostral body
two hemispheres of the prefrontal cortex are connected by this region of the corpus callosum
the genu
somatosensory (parietal) and auditory (temporal) sensory modalities send connecting fibers through this region of the corpus callosum
caudal body
rostrum
connects orbital frontal cortex
aphasia
loss of previously held ability to speak or understand spoken or written language, due to disease or injury of the brain
agnosia
partial or total inability to recognize objects by use of the senses
hemisphere that is dominant for comprehension of grammar
left
angular gyrus (area 39)
graphine to phoneme conversion- translates things from written form into form can be used by wernicke's area that can be sent along the arculate fasciulous area to Broca's area which can then be read out loud, read for meaning have to go from wernicke's area up to the rest of the brain where meaning is going to be accessed
Broca's area (45/44)
controls motor programs/sequences for producing phonemes (language output)
-important for syntax/grammar (for generating and comprehending).
wernicke's are (22)
stores memories of sound sequences that constitute words.
-uses phonemic codes to access meaning
interhemispheric transfer time
right hand responds faster to RVF lights than to LVF lights
Interhemispheric connections
heterotopic connects different rgions Left V2 -Right V3
homotopic- connects same regions Left V2- Right V2
commissures
projection fibers that connect structures on the left and right sides of brain
Akelaitis
revealed only minor motor disturbances resulting from commissurotomy
commisure that is never cut in split brain surgery
collicular commisure connects superior colliculi
commisures that sometimes get cut in split brain surgery
-anterior commisure- connects temporal and limbic structures
-hippocampal c.- part of the fornix
commisurotomy
corpus callosum and anterior commissures are surgically severed
callosotomy
only the corpus callosum is severed
staged section
first stage: only anterior or posterior portion is cut; second surgery completes the callosotomy
anterior c
connects temporal and limbic structures
alexithymia
difficulty exprssing emotions
ex: patient L.B.
techistoscopic
exposure brief, fixation central, unimanual nature of response- only want one hand to respond
z-lense
provides for longer viewing can restrict vf so only one hemiretina of the seeing eye is stimulated , patches one eye
emotional tone may be transferred through these structures ex: patient P.S.
subcortical limbic
visual verbal disconnect
item presented to right visual field can be properly named, lvf stimuli can not be named verbally
-visual disconnect from language
-can be probed in diff. ways point to correct word or can select object
the role of a split-brain patient's left hemisphere in explaining what the left hand is doing
interpreter
tactile-verbal disconnection
1) cannot name object held in the left hand
2) each hand will select objects according to the info. presented to the contralateral hemisphere
ex: right hand can select what it can't say, opportunity to assess the capactity of the right hemisphere for language
visual-visual disconnection
1) cannot match stimuli between the two visual fields
-stimulus projected to the right visual field and another in the left visual field, patient cannot tell you whether those two objects are the same or different
the interhemispheric transfer task involves this function of the corpus callosum
information transmission
VF differences reflect
1) interhemispheric transfer time and
2) info degradation
visual input gets transferred to
specialized hemisphere- info. is processed by the hemisphere specialized for the material or task
monaural listening
input to only one ear
both ears project
bilaterally so both hemispheres receive the stimulus
dichotic listening
input to both ears- introduces competition
-ipsilateral ear's input is suppressed
-asymmetries based on ear of input are more evident
patient V.J.
left handed split brain patien- speech in left hemisphere, writing in right
is the left hemisphere better at reporting auditory stimuli from the right ear than the left ear
yes but only through dichotic listening through suppression
info. is delivered predominantly to one hemisphere
1) by tachistoscopic lateralized visual input
2) Dichotic listening
left-hand apraxia, a symptom of motor diconnection, is an impairment of this ability
nonverbal gestures
left handers require constant communication btw. the two hemispheres (70%) b/c
speech is localized in the left hemisphere and the writinggrapho-motor module in the right
cross cuing
patient attempts to make info. accessible to both hemispheres
ex: making a sound w/the object- left hand makes noise w/ob then left hemisphere can guess what that object is
-subvocal (inaudible) signalling- left hemisphere could whisper to right hemisphere so right could choose the answer through whichever method is availble to it
-tongue movements- could tap out a certain number of taps to cue some info. available in the environment
-tap the opposite side of body
because of the info. transmission function of the corpus callosum, a simple 3-item visual match is faster for this kind of display
within-field
because of the allocation of resources function of the corpus callosum, a complex 5 item name match is faster for this kind of display
across- field
tactile-tactile disconnection
patient given object for each hand and asked if object is the same or different, can't do that
motor disconnection
contralateral hemisphere controls fine hand movements of the contralateral hand
-more gross movements such as moving the arm is proximal movements available to both hemispheres, finger movements and positioning of the hand are contralaterally controlled more distal movements
alien hand sign
left hand is perceived as belonging to someone else
for normal subjects in the Holtzman & Gazzaniga experiment, redundant displays are helpful but mixed displays are difficult because of this function of the corpus callosum
unification of sensory world
left hand apraxia
deficient nonverbal gestures e.g. salute, comb hair etc.
this test anesthetizes one hemiphere of the brain at a time to determine which one is responsible for speech control
WADA- used prior to surgery for treatment of disorders such as epilepsy to determine which hemisphere possesses language
why are functions lateralized?
-may foster more efficient recruitment or untilization of these resources, keeping them separate allows them to work more efficinetly
disconnection in split brain patients
indication information transmission, inability to access the specialized processor
-magnifies asymetries
accessing specialized processors the evidence
-disconnection syndromes
-disconnection amplifies asymmetries
-crossed-uncrossed Reaction Time (interhemispheric transfer time)
-asymmetries in the intact brain- information needs to be transmitted across the cc and is a means by which to access specialized processors
Case V.J. highlights
inability for graphomotor module to access speech and vice versa.
one of the ways that we know broca's aphasia is not just a motor problem, not jsut how they express themselves verbally when speaking
written output would have broca's aphasic output also
L.B.
important for understanding the different roles of each hemisphere of the brain.
-underwent a complete commissurotomy
-neurological scans were normal
-only unable to write with his left hand and copy with his right hand for a few weeks before he regained these abilities
-was not good at copying Rey complex figure with his right handand demonstrated considerable visuospatial impairment
-drawing was more proportionally with his left hand than his right better at Taylor complex figure with his left hand than his right but was still way below average
-left hemisphere showed normal comprehension, right hemisphere able to comprehend nounds, adjectives, and verbs but not carry out written commands lateralized to his right hemisphere
-mathematical abilities confined to left hemisphere
-showed strong left visual field advantage over right visual field advantage and orientation tasks
-alexithymia
Wechsler Adult Intelligence scale and digital symbol test used to assess
neuropsychological abilities
after WADA
administer memory test
WAIS-R, Wechschler Memory scale, recognition memory test, rey complex figures test, digit symbol test
generalized intelligence tests- make sure cognitive impairments are consistent with focal point of seizures
EEG
used to find focal pt. of seizures
MRI
determine if there are subtle changes in brain tissue
fmri
directly visualize origins of seizures, very specific
deep brain stimulation
surgical procedure that implants a pacemaker into the brain
avoidance therapy
avoiding possible stimuli that will induce a seizure
Broca's comprehension versus Wernicke's area comprehension
- wernicke's comprehension is severely impaired
-Broca's area- comprehension is relatively spared
Holtzman and Gazzaniga (1985) study
superiorr performance in split brain patients on mixed displays
L.B.
images presented techistochopically
-makes up story to explain left hands action-interpreter, difficulty expressing emotions- Alexithymia, showed that self awareness is present in both hemisphees
V.J.
left-handed split brain patient
-right handed agraphia
Acute disconnection syndrome
occurs in most patients immediately after commisurotomy, patient is mute and can communicate by body language and unable to move left side of body purposefully, symptoms resolve within days or weeks. poor or absent writing with the left hand, normal writing with the right, good drawing of cubes and other spatial nonverbal pics with the left hand but not w/the right
-right hand is better at the block design subtest of WAIS (L.B.)
-sometiems leading to left side apraxia- inability to perform purposeful movements with the left side of the body
Late disconnection syndrome
-long-term disconnection of right and left visual fields
-visual disconnection is assessed by a series of tests involving flash stimulus in visual fields
boston diagnostic aphasia exam
request to tell a story
psychoeducation
about epilepsy and antiepileptics is a first step in assisting an individual who wishes to cope better with his seizures and usually improves compliance with medication regimens
broca's area
more on the production side of language not motor output
behavioral modification and cognitive-behavioral programs and epilepsy
require a careful assessment of the context in which the seizures occur to determine whether any patterns emerge regarding the antecedents of seizures and the events (consequences) that follow seizures.