Functional localisation and split brain

Question 1

What is the corpus collosum?

Answer 1

A massive white matter tract that connects the 2 cerebral hemispheres

Question 2

What is the function of the corpus collosum?

Answer 2

To connect the left and right hemispheres

Question 3

What is the function of the anterior Commissure?

Answer 3

Connect the right and left temporal lobe of the cerebral cortex and right and left amygdala

Question 4

What is the role of the hippocampal commissure?

Answer 4

Connect the right and left hippocampus

Question 5

What is the role of the adhesio interthalamica?

Answer 5

connects the right and left thalamus

Question 6

What are seizures caused by?

Answer 6

abnormal electrical activity in the brain

Question 7

What doe seizures cause?

Answer 7

Sudden disturbances in movement, sensation or behaviour

Question 8

What % of the world’s population have epilepsy?

Answer 8

1%

Question 9

Who can experience provoked seizures?

Answer 9

anyone

Question 10

What do primary generalised seizures involved?

Answer 10

cerebral hemisphere at onset and consciousness is usually lost at the beginning of the seizure

Question 11

Where do partial (focal) seizures originate from?

Answer 11

the primary motor cortex

Question 12

What do partial (focal) seizures cause?

Answer 12

convulsions in the opposite half of the body

Question 13

What do partial (focal) seizures begin with?

Answer 13

involuntary movements in one part of the body

Question 14

What causes the jerky movements to spread to consecutive body parts during a partial (focal) seizure?

Answer 14

As the wave of abnormal electrical activity spreads across the motor strip

Question 15

When does a secondary generalise seizure occur?

Answer 15

When a partial seizure spreads to involve both cerebral hemispheres can be proceeded by focal symptoms (twitching of a body part)

Question 16

What is a clue that there is a discrete cortical origin of the epilepsy?

Answer 16

The presence of localising neurological signs after the seizure (such as weakness)

Question 17

What does surgery for epilepsy involve?

Answer 17

partial or complete removal of a lobe (lobectomy)

Question 18

What is the commonest procedure to treat drug-resistant temporal lobe epilepsy?

Answer 18

temporal lobectomy

Question 19

What can be divided to prevent interhemispheric spread of seizures (stop the seizure from turning from partial into global)?

Answer 19

Corpus collosum

Question 20

What is a more severe type of surgery to treat epilepsy?

Answer 20

resection of an entire cerebral hemisphere (hemispherectomy) or surgical ‘disconnect’ of the cerebral cortex (functional hemispherectomy)

Question 21

What is suggested to prevent callosal propagation of epileptic seizure taking over whole brain?

Answer 21

cutting the collosum (last resort)

Question 22

What is interocular transfer?

Answer 22

if one eye is close and a discrimination task is learnt, the same discrimination can be recalled in the untrained eye

Question 23

What is the optic chiasm?

Answer 23

where info from an eye crosses to the opposite hemisphere

Question 24

What happens to interocular transfer if the corpus collosum is removed?

Answer 24

it becomes absent

Question 25

What occurs in a normal brain if information is learnt through one trained eye?

Answer 25

the information can be transferred between hemispheres and the untrained eye can use the information to complete the task

Question 26

What happens to information if the corpus collosum and chiasm is cut?

Answer 26

information cannot cross the midline and the learned state is stuck in the hemisphere it was learnt in

Question 27

How do the hemispheres work in a split brain patient?

Answer 27

separately

Question 28

What is mutism dyspraxia?

Answer 28

a lack of coordination

Question 29

What is Contradictory 'anarchic' actions?

Answer 29

when one hand is picking one thing and the other is changing it

Question 30

What are the symptoms of acute disconnection syndrome?

Answer 30

mutism dyspraxia contradictory anarchic actions

Question 31

What happens to vision as a result of a cut corpus collosum?

Answer 31

report stimuli in the RVF but deny seeing it in the LVF yet they can still correctly point to where the stimulus was presented

Question 32

What happens to touch (stereognosis) as a result of a cut corpus collosum?

Answer 32

objects held in one hand could not be matched with the other hand -object in right hand = could name and describe the object -object in left hand = could not name it but could identify it non-verbally

Question 33

What happens to information processing abilities in patients with split brain?

Answer 33

Image in RVF = processed in LH + can describe what they saw Image in LVF = processed in the RH + would say they didn't see anything but could point the object out

Question 34

What else could cause damage to the corpus collosum?

Answer 34

Stroke

Question 35

What are the roles of each hemisphere when controlling hand movement?

Answer 35

LH= analysis of RVF, left hand stereognosis, language RH= analysis of LVF, Left hand stereognosis, Spatial abilities

Question 36

What is a hemispherectomy done for?

Answer 36

To stop epilepsy

Question 37

What is a hemispherectomy?

Answer 37

Removal of an entire hemisphere