Lecture 16

Question 1

Optic ataxia

Answer 1

Patient with parietal damage

Cannot reach to an object despite being able to see it

Question 2

Patient DF

Answer 2

Damage to occipital lobe
Cannot verbally discriminate sizes of different objects
When she tries to pick up objects, she does so with the correct grip/hand size (somehow seems to know the size now)
The “how” pathway is intact, but not the “what” pathway

Question 3

Size illusion with small/large objects

Answer 3

Small and large objects with identical weights
The smaller one will be judged to be heavier, this will continue even after you pick both up several times
However, the motor system lifts with the same force - seems to know the true weight of the objects is equal

Question 4

Importance of proprioception

Answer 4

Proprioception = sensory feedback

Reaching movements need proprioception in order to be made more accurate

Question 5

AMPS

Answer 5

Anterior-Motor
Posterior-Sensory
Anterior (forward) part of spinal cord is involved in motor control, posterior (back) part of spinal cord is involved in sensation

Question 6

Pyramidal tract

Answer 6

10% of fibers are monosynaptic to alpha motor neurons from Betz cells in M1
From M1 through midbrain, pons, medulla, crosses over to anterior side, eventually reaches skeletal muscles

Question 7

Tectospinal tract

Answer 7

Coordinates head and eye turning

Question 8

Vestibulospinal tract

Answer 8

Balance

Question 9

Reticulospinal tract

Answer 9

Posture, muscle tone, antigravity muscles

Question 10

Organization of homunculus in M1

Answer 10

M1 about movements, not muscles
Same muscle encoded in different parts of the M1 homunculus
Many neurons contribute to a single movement, self-correction (unless lesion)

Question 11

Premotor cortex (when do neurons fire?)

Answer 11

Neurons can either fire during movement or to the movement cue

Question 12

Supplementary motor cortex

Answer 12

Proposed to be involved in movements guided by internal stimuli (like memories)
Seems to play a role in sequence of movements

Question 13

“Affordances” with parietal damage

Answer 13

Affordances are the parts of objects that are natural gripping/grasping points
Patients with parietal lobe damage have trouble with grips

Question 14

Mirror neurons

Answer 14

First discovered in monkeys - region F5 of PMC
Fire when an action is performed or perceived
Same portion of F5 will fire based on goals

Question 15

Evidence for mirror neurons in humans

Answer 15

Mu rhythm suppressed when you make a movement, or when you watch another make the same movement
fMRI studies of dancers watching a dance video: mirror neuron activity if they know the dance (and thus know the action)