lecture 6 - cerebral asymmetry

Question 1

left brain - folk psychology

Answer 1

analytical
logical
detail
reading, writing, arithmetic, language
intelligence
dominant?

Question 2

right brain - folk psychology

Answer 2

holistic
intuitive
whole picture
artistic
music
emotional intelligence
spare tire?

Question 3

anatomical asymmetries
- weight and size?
temporal lobe asymmetry

Answer 3

• right larger and heavier than left
• planum temporale: larger in left
• Heschl’e gyrus: larger in right

Question 4

slope of sylvian fissure

asymmetry

Answer 4

• gentler on left

Question 5

hemisphere differences.

Answer 5

right = further anterior
left = further posterior

Question 6

split brain procedure

- commussurotomy

Answer 6

• surgical procedure of severing ther corpus callosum

- two hemispheres can’t communicate. - motor crossover at brainstem, not affected. sensory info to just one hemisphere.

Question 7

neurologically intact vision

Answer 7

left visual field of each eye goes to right visual cortex.
both right visual field project to left visual vortex.
- left = language. seeing visual on right hemisphere - cross info over to left to name.

Question 8

split brain patient vision

Answer 8

left visual field of each eye goes to right hemisphere.

info cant cross to left hemisphere to name.

Question 9

2 conclusions from split brain patients

test on 2nd conclusion

Answer 9

1. language processing is (usually) lateralized on left
2. after tactile tests - maybe right hemisphere cant ID?
   test #2 = ask about function of object. both functionally ID, right cant semantically name.

Question 10

chimeric face

Answer 10

verbal description compared to left hand ID.

• strong left langugae usually = strong right face *
• name the face = rvf to LH. cant name in lvh.
• point w left hand = Lvf, RH - fusiform face area. LH, Right hand makes more errors.

Question 11

WADA technique

• use?
• substance?
• process?

Answer 11

• surgery planning
• sodium amobarbital
  inject thru carotid, ipsilateral brain anesthesia = contralateral paralysis.
• speech output test. if language is on only on L -> wont speak when L is anesthetized.

Question 12

bilateral presentation
unilateral presentation
perceptual asymmetries

Answer 12

• both sides = stimuli on both sides.
  : face on LVF = more accurate than on RVF. language better on RVF(LH) than LVF(RH)
• one side

perceptual asymmetry - different accuracy in perception at different places.

Question 13

lateralized auditory

Answer 13

• stimuli from each ear goesto both sides of brain.

cochlear nucleus multiplies auditory. one copy to L olive, other copy to R olive. for both ears

Question 14

dichotic listening presentation.
ipsilateral suppression,
contralateral dominance

Answer 14

two ears, different auditory info.
Ba in L ear, to RH.
Ga in R ear to LH.
Ga in LH so say Ga. then maybe say Ba bc ipsilateral works (less suppressed)

Question 15

3 theories to perceptual asymmetriers?

Answer 15

1. direct access theory
2. callosal relay model
3. activating-rienting model

Question 16

direct access theory

Answer 16

perceptual asymmetry theory.

- input hemiphere processes info. performance varies

Question 17

callosal relay model

Answer 17

perceptual asymmetry theory
- info transferred to best side, which degrades performance.
(left not processing face, has to send to RH via corpus callosum)

Question 18

activating-orienting model

Answer 18

perceptual asymmetry

• attentional bias leads to information aliency
• priming /tuning to LVF for face. and RVF for words.

Question 19

spatial frequency hypothesis

• spatial frequency =alternating btw light and dark. - distinguish btw things
• hemispheric laterality

Answer 19

in order to distinguish things that are very easy = low spatial frequency. right hemisphere advantage.
distinguish objects that look v similar = high spatial frequency. left hemisphere advantage.
=> right big picture
=> left more details

Question 20

hemispheric differences in auditory processing of pitch

* ipsilateral suppression.

Answer 20

same pattern as vision.
lower tones = right hemisphere
higher tones = left hemisphere.

Question 21

Is hemispheric difference in auditory/sensory absolute or relative phenomenon?

Answer 21

relative phenomenon.
same pattern in 2 different sound ranges = not consisten (above XHz, the dominance is not only one side) sensory system silters frequency information in rangein which they are experiencing.

Question 22

split brain patients - modes of processing rely on different hemispheres

• • chimeric stimuli
• hemispheric advantage

Answer 22

test set + match set. designed to be matched on appearance and function.
- match by appearance: see LVF (in RH), by function: see RVF (in LH)

• hemispheric advantage - work different ways in terms of context. LH - pick by function. RH - pick by appearance.

Question 23

global vs local processing

-lesion patients - dunno where they are, but use this test to determine.

Answer 23

in both linguistic and non-linguistic tests.

RH lesion = see local processing (seeing detail) - LH in tact (bigpic)

LH lesion = big pic. RH working.

Question 24

transfer of sensory information between hemispheres

• average adult.
• LVF vs RVF. ERP response in O1 vs O2.

Answer 24

flickering checkboard in LVF or RVF - push button, sometimes Lhand, other Rhand. collect ERP in response to visual stimulus.
O1- left, O2 = right.
- LVF -> RVF, peak in O2 before O1. time btw 2 peaks = time to cross CC.
-RVF -> LH. O1 first, O2 second.

Question 25

inter-hemispheric interaction
-neurologically intact patients.

easy test - better or worse performance for contralateral same number?

difficult - better or worse performance for contralateral same number?
*why?

Answer 25

fixate on spot. 2 numbers above, 1 number below. say if number on bottom matches either of top ones.
both numbers on same side of visual field = better. when opposite sides of visual field - need to cross hemispheres = worse performance

-difficult: add numbers to get !0 or more.
-same visual field= worse performance
contralateral visual field- hemispheres’stalk = better performance
*maybe ned both hemispheres to calculate, so having VF on either sides facilitates the process.