Sensorimotor System 2

Question 1

Dorsolateral Prefrontal Association Cortex (DLPFC)

Answer 1

Input: Posterior parietal cortex
Output: Secondary motor cortex, primary motor cortex, frontal eye field
Function: Integrates object and location info; plans and initiates voluntary movements
Neuronal responses:

• Some neurons respond to object features
• Some to object location
• Some to both

Some to the motor response itself (fire before & during action)
Key point: Neurons fire earlier than other motor areas → voluntary movement decisions occur here, in coordination with posterior parietal and frontal areas

Question 2

What inputs and outputs define the secondary motor cortex?

Answer 2

Receives input from association cortex (posterior parietal & dorsolateral prefrontal cortex) and sends output to primary motor cortex.

Question 3

Name the two historically recognized areas of secondary motor cortex.

Answer 3

Supplementary motor area (SMA) and premotor cortex.

Question 4

Where are the supplementary motor area and premotor cortex located?

Answer 4

SMA: wraps over the top of the frontal lobe and extends medially. Premotor cortex: strip from SMA to lateral fissure.

Question 5

How many areas of secondary motor cortex are suggested in each hemisphere?

Answer 5

At least eight areas, each with subdivisions.

Question 6

What is the main function of secondary motor cortex?

Answer 6

Programming specific movement patterns from general instructions from the dorsolateral prefrontal cortex.

Question 7

What happens when secondary motor cortex is electrically stimulated?

Answer 7

It typically elicits complex movements, often involving both sides of the body.

Question 8

How do secondary motor cortex neurons behave during voluntary movement?

Answer 8

They initiate activity before movement begins and continue firing throughout the movement.

Question 9

What evidence supports the role of secondary motor cortex in planning?

Answer 9

Brain-imaging studies show activity when a person imagines or plans a series of movements.

Question 10

What are mirror neurons?

Answer 10

Mirror neurons are special brain cells that “mirror” what we see other people do.
They fire both when you do something and when you watch someone else do it.

Question 11

Where and when were mirror neurons discovered?

Answer 11

In the early 1990s in macaque ventral premotor cortex by Giacomo Rizzolatti’s lab.

Question 12

Why are mirror neurons important for social cognition?

Answer 12

They help understand others’ actions and intentions, and facilitate imitation and cooperation.

Question 13

Do mirror neurons respond only to seeing actions?

Answer 13

No, they respond to the purpose of an action and can fire even when mentally representing the action.

Question 14

Where is the primary motor cortex located?

Answer 14

In the precentral gyrus of the frontal lobe.

Question 15

What is the primary role of the PMC?

Answer 15

All movement-related signals from different brain areas come together (converge)

Then those signals leave (depart) from there to control your muscles.

Question 16

How did Penfield and Boldrey map the PMC?

Answer 16

By applying low-intensity electrical stimulation to cortical sites in conscious patients and noting which contralateral muscle moved.

Question 17

How is the PMC organized?

Answer 17

Somatotopically, meaning it is mapped according to body regions—the “motor homunculus.”

Question 18

Which body parts have the largest representation in the PMC?

Answer 18

Parts capable of intricate movements, like the hands and mouth.

Question 19

Does each PMC site receive sensory feedback?

Answer 19

Yes, from receptors in muscles and joints influenced by that site, with some exceptions for stereognosis-related hand areas receiving input from skin.

Question 20

What is the conventional view of PMC neuron function?

Answer 20

Each neuron encodes the direction of movement, with different neurons having different preferred movement directions.