3. Cerebral Asymmetry

Question 1

8 major anatomical differences between hemispheres

Answer 1

1. RH is larger and heavier than the LH. LH has more grey matter
2. There is structural asymmetry of the temporal lobes
3. Asymmetry of the temporal lobes is correlated with symmetry of medical structures like the thalamus
4. Slope of the lateral fissure is more gentle in the LH, therefore the temporoparietal area is smaller
5. Frontal operculum (brocas) appears larger on the RH as it is more hidden in sulcus in the LH (EVIDENCE AGAINST LH MORE DEVELOPED FOR LANGUAGE??)
6. RH extends further anteriorly, whilst LH extends further posteriorly
7. Asymmetrical distribution of neurotransmitters
8. Symmetry is affected by sex and handedness (left handed and women are more symmetrical/ integrated than men)

Question 2

Jun Wada

Answer 2

Discovered the sodium amobarbital carotid injection

WADA test

Causes a transient anaesthesia of the ipsilateral hemisphere

Used in epileptics to determine language dominant side prior to surgery

Question 3

Milner

Answer 3

Handedness and language dominance

98% R handed = LH language

70% L handed = LH

2% R handed = RH

15% L handed = RH

15% L handed = bilateral

Question 4

Gazzangia

Answer 4

1967/1998 split brain studies

Anything processed in the right hemisphere has no verbal representation but semantics are there because they are able to identify or match objects

Right hemisphere is better at illusions and can still perceive the rectangles even when the lines are drawn (more creative and less logical than the left)

Hemispheres cannot integrate information to be drawn if presenter to the two hemispheres separately

Question 5

Hughlings-Jackson

Answer 5

1860s-

Discovered that the cortical convolutions mature faster in the LH