Topic 5 (Attention) Lecture 3 (Brain damage and attention)

Question 1

What is hemisphere asymmetry when referring to vision?

Answer 1

• The right hemisphere of our brains processes information related to the left eye and vice versa

Question 2

What is unilateral neglect syndrome?

Answer 2

• A disorder caused by damage to a certain hemisphere of the cerebral cortex e.g a stroke
• This means that individuals wont respond to stimuli presented on the affected side
• e.g if there was damage to the right hemisphere of the brain then the individual wouldnt respond to stimuli in the left field of vision
• So when individuals are asked to copy a drawing of a house or clock say, they only draw half the picture

Question 3

Describe Bisiach and Luzzatti’s study on stroke patients

Answer 3

• Participants were told to imagine they were standing on a piazza in milan which they all knew well
• They were only able to recall things like shops and cafes on the right hand side of their standpoint
• This indicates that unilateral neglect syndrome is not about vision

Question 4

Describe the case study of Alan Burgess

Answer 4

• A stroke left him with hemispatial neglect
• This means he was unable to pay attention to sensory stimuli on his left side
• The stroke damaged the parietal lobe on his right hemisphere- an area which deals with executive attention
• His sketches would have rich and detailed right half, and a poor and unfinished left half
• When walking along the street, he is unable to notice potential dangers coming from the left

Question 5

Describe Behrmann and Tippers study on stroke patients

Answer 5

• They studied participants with right parietal cortex damage from a stroke
• They showed them a barbell, with a stimlulus on one side of the barbell.
• Participants were found to show less patience and make significantly more errors when the static stimulus was on the left hand side of the barbell
• However, when slowly rotating the barbell 180 degrees, the opposite pattern emerged and patients detected the stimulus on the formerly right but moving left side of the bar more succesfully

Question 6

Describe the study by Volpe, Ledoux and Gassaniga on stroke patients

Answer 6

• The patients in the study suffered damage to the parietal cortex in the right hemisphere and they suffered from unilateral neglect syndrome
• He found that patients were in fact able to name an object that appeared on both sides of their visual field, if it was the only object present
• This is because the right hemisphere of these patients was successfully able to communicate with the left hemisphere via the corpus callosum
• if there was two objects presents the patient could only name the one on the right.
• But then, if they were asked if the two objects were the same or different they were able to answer correctly, but without conscious knowledge of what the other was.
• This suggests there is still some unconscious awareness of objects in the left field of vision

Question 7

Describe Marshal and Halligans study on stroke patients

Answer 7

• studied patients with damage to the right parietal cortex
• Showed them two drawings of a house, with one house being on fire and the other house not being on fire
• The patients were not aware of any difference between the images
• However, when asked which house theyd rather live in, the majority chose the house that was not on fire

Question 8

Describe the study by Rees, Wojciulic, Clarke, Hussain, Frith and Driver on stroke patients

Answer 8

• They studied patients who had damage to their right parietal cortex
• They showed them an image of a house and a face next to each other
• This is because faces and houses are processed in specific areas of the brain
• They found that when the face was on the left, the patient was not aware of a face being there
• However fMRI showed that there was nevertheless activation in the fusiform face area
• This suggests there was unconscious processing of the stimulus on the left

Question 9

What do Volpe et al, Marshal and Halligan, and Rees et al’s studies all indicate

Answer 9

• There is a difference between conscious awareness and unconscious processing in patients with damage to their right parietal cortex

Question 10

What can damage to the prefrontal cortex cause damage to?

Answer 10

Difficulties with executive functions. This can be referred to as goal neglect syndrome

Question 11

Describe the Wisconsin card sorting test, used on patients with damage to the prefrontal cortex

Answer 11

• Participants were asked to sort the image on the bottom right of the screen into a pile by colour
• They were then asked to switch and sort by number of shapes instead
• Patients with damage to the prefrontal cortex were unable to switch between tasks and continue to sort by colour

Question 12

What part of the brain is most strongly associated with unilateral neglect sydrome?

Answer 12

The (right) parietal cortex