Lecture 8

Question 1

Who was Wilder Penfield?

Answer 1

A neurosurgeon world-renowned for treating epilepsy via surgery

Question 2

What is the primary motor cortex surrounded by?

Answer 2

• Supplementary Motor Area (SMA)
• Premotor Area (PM)
• Primary Somatosensory Cortex (S1)

Question 3

What is the precentral gyrus?

Answer 3

The precentral gyrus is the location of the primary motor cortex (M1)

Question 4

The precentral gyrus contains —–% of neurons that project into —–

Answer 4

Contains 50-60% of neurons that project into spinal cord

Question 5

What does probing M1 cause?

Answer 5

Causes certain body parts to twitch

Question 6

Define:

Homuncular representation

Answer 6

The representation is not even for each part (e.x. the systematic mapping of M1 is not even for each body part)

Question 7

Describe:

Historical view of organization in M1

Answer 7

• M1 contains topographic map of the body
• Each point in the map specifies tension in a single muscle
• M1 is a final common pathway to action
• Organization is invariant

Question 8

What does it mean that “each point in the map specifies tension in a single muscle”?

Answer 8

Each point specifies the ability to contract a specific muscle

Question 9

True or False:

M1 produces movement

Answer 9

False, M1 serves as a relay station (not a contemporary view)

Question 10

What does it mean to be “invariant”?

Answer 10

Not plastic, not able to change

Question 11

Define:

Dysmelia

Answer 11

Incomplete development due to drug interference in development

Question 12

What does dysmelia show about M1? Why was this different from Penfield’s observations?

Answer 12

M1 is indeed a plastic structure that changes with its needs
Penfield’s conclusions could have been resulted by doing testing on epileptic people instead of normal people

Question 13

Why might Penfield’s results be different from a normal human’s results?

Answer 13

Individuals with epilepsy may have different motor map than normal people

Question 14

What does overlapping representations evidence show about M1?

Answer 14

No strict, discrete representation of neurons in the M1 (intermingled + overlapped)

Question 15

True or False:

M1 has more than one final pathway to action

Answer 15

True

Question 16

With evidence, what is M1 responsible for?

Answer 16

Directional tuning, neurons responsible for coding the direction of a final movement

Question 17

True or False:

M1 can coordinate sophisticated movement

Answer 17

True

Question 18

Explain a raster plot

Answer 18

• Small ticks represents an activity in the trial
• Depicts how briskly or robustly the activity is
• Really dense tick marks = around 0 milliseconds

Question 19

Define:

Neuroplasticity

Answer 19

Cellular through structural changes to the brain resulting from environmental interactions

Question 20

True or False:

Neuroplasticity is a dynamic process allowing adaptation and learning from experiences and allowing the brain to recover function following injury

Answer 20

True

Question 21

Where else does neuroplasticity occur?

Answer 21

In spinal cord

Question 22

Do inductive reasoning, numerical ability, and verbal ability peak at the same time?

Answer 22

No, the all peak at different/later times, different from brain volume peak

Question 23

True or False:

Neurogenesis rate will decrease as one gets older

Answer 23

True