Chapter 4: Visual Cortex + Beyond

Question 1

Define Cortical Magnification

Answer 1

While the fovea only covers 0.01% of the retina, signals from fovea account for 8-10% of the cortical map’s area

Question 2

Explain Position Emission Tomography (PET) scans

Answer 2

Brain activity is monitored via blood flow via radioactivity caused by an injected radioactive tracer

Question 3

Explain Functional Magnetic Resonance Imagaing (fMRI)

Answer 3

Brain activity is monitored via magnetic response of hemoglobin
( Brain activity takes up oxygen, making hemoglobin more magnetic)

Question 4

What is the Subtraction Technique?

Answer 4

(test condition) - (initial condition) = (activity due to stimulation)

Question 5

What are the 4 types of columns in the visual cortex?

Answer 5

1. Location columns
2. Orientation columns: adjacent columns change orientation preference in order (90 degrees, 85 degrees, 80 degrees, etc.)
3. Ocular dominance columns: columns alternate between L and R eyes at 0.25-0.5mm apart)
   - Eye preference has degrees (1=L, 4=equal, 7=R)
4. Hypercolumns (ice-cube model): contains a location column, L-R dominance columns, and a complete set of orientation columns (0-180 degrees)

Question 6

Define Lesioning

Answer 6

Destruction or removal of tissue in the nervous system

Question 7

According to U+M, what are the pathways in the visual cortex that transmit info regarding what is seen and where it is located?

Answer 7

What pathway: ventral pathway (lower) aka temporal lobe

Where pathway: dorsal pathway (upper) aka parietal lobe

Question 8

What tasks did U+M use during their research to prove the what and where pathways in the visual cortex?

Answer 8

Object discrimination: researchers had monkeys identify a target object when given 2 options
(task was difficult once the temporal lobe was partially removed)

Landmark discrimination: researchers had monkeys remove the food cover closest to a cylinder
(task was difficult once the parietal lobe was partially removed)

Question 9

Where are the ventral and dorsal pathways located?

Answer 9

The pathways originate in the retina, and continue through 2 types of ganglion cells to the cortex

Question 10

According to G+M, what is the dorsal pathway responsible for?

Answer 10

1. Location

2. Action (how)

Question 11

What evidence supports G+M’s proposal of the dorsal pathway being responsible for 2 types of info?

Answer 11

Patient D.F.: isolated damage to ventral pathway and exhibited agnosia (could not name familiar objects)

• She couldn’t draw objects in front of her but could draw from memory
• She couldn’t copy orientation but could put mail through a slot
• G+M proposed damage to ventral pathway did not cause deficit in “how”

Question 12

Define Dissociation (single and double)

Answer 12

One function is absent while another is present

• Single: 1 person
• Double: 2+ people

Question 13

How did Ganel demonstrate separation of perception and action in non-brain-damage subjects?

Answer 13

Researchers used an illusion that distorts perceived line length and asked subjects to (1) estimate length (what) and (2) grasp the line (how)

• When doing task 1, inaccurate
• When doing task 2, accurate

Question 14

Define Modules

Answer 14

Brain structures that are specialized to process information about particular types of stimuli

Question 15

What are 4 examples of Modules?

Answer 15

1. Inferotemporal (IT) cortex in monkeys: respond best to faces in
2. Fusiform Face Area (FFA): responds best to faces
3. Parahippocampal Place Area (PPA): responds best to indoor and outdoor spaces
4. Extrastriate Body Area (EBA): responds best to bodies and body parts

Question 16

Define Prospagnosia

Answer 16

Difficulty recognizing faces of familiar people

Question 17

The Medial Temporal lobe is important for memory. What brain structures does it contain?

Answer 17

• Hippocampus
• Amygdala
  (Also directly receives input from IT cortex)

Question 18

What evidence supports the proposal that the medial temporal lobe is important for memory?

Answer 18

Patient H.M.: lost ability to form new memories when hippocampus was removed during an operation for epileptic seizures