Chapter 4 Hemispheric Specialisation Flashcards
What does homotropic mean?
A neural pathway from an area in one hemisphere to a corresponding area in the other via the corpus callosum
What does heterotopic mean?
A connection from one hemisphere via the corpus callosum to a different location in the other hemisphere.
What does ipsilateral mean?
A connection that starts and finishes in the same hemisphere of the neocortex. It does not travel via the corpus callosum.
Describe the wada test
It is often administered before split brain surgery; it involves injecting amobarbital into the carotid artery to put the ipsilateral (same side) hemisphere to sleep to mimic a split brain
What is the effect a right hemisphere lesion in regard to facial expressions?
A voluntary smile will only be produced on the left side of the face whereas a spontaneous smile will be produced on both sides of the face
What is the effect of damage to the midbrain in regard to facial expressions?
A voluntary smile is able to be produced but a spontaneous smile isn’t (usually seen in Parkinson’s patients)
What evidence is there that the left hemisphere is the interpreter?
Results of the simultaneous concept task - split brain patient is shown an image in each visual field and asked to choose them from a selection, when asked why he chose those specific items he would know that the item on the right is what he saw but the item in his left hand is not recognisable even though that is also what he saw, therefore the left brain ‘interprets’ why that item was chosen by making an association with the item from the right
What evidence is there that the right hemisphere is the interpreter?
Illusionary contours - fat and skinny shapes shown from partial circles, the right hemisphere is good at causal perception whereas the left hemisphere is good at causal inferences
List 5 asymmetrical differences in the two hemispheres
RH protrudes at the front
LH protrudes at the back
RH has more volume in the frontal region
LH is larger posteriorly in the occipital region
RH’s sylvian fissure has a more prominent upward curl
List the 3 parts of the corpus callosum
Genu (anterior portion)
Body (middle portion)
Splenium (posterior portion)
What differences are there with regards to facial recognition in each hemisphere?
LH is better at recognising self, the RH is better at recognising other familiar faces
Where does the neural pathway for voluntary facial expressions start?
Motor cortex
Where does the neural pathway for spontaneous facial expressions begin?
Basal ganglia (caudate nucleus)
In the probability guessing paradigm by Wolford and colleagues, which side if the brain was more inclined to use the maximising strategy?
Right hemisphere
What is the matching strategy in the probability guessing paradigm?
When given a choice between which of 2 colours will flash on a screen, one that will appear 75% of the time and one that will appear 25% of the time, the matching strategy is to guess one colour 75% of the time and the other colour 25% of the time
