Motor Systems II

Question 1

What does the monkey wrist flexion/extension experiment say about the integration of movement in the brain?

Answer 1

-Neurons can encode force & direction. The brain uses these codes to integrate all aspects of movement. These codes can be monitored and animals and humans can use brain control (think about movement) on computers.

Question 2

What is the premotor cortex especially important in? How does it differ from the the primary motor cortex?

Answer 2

• Planning and learning movements, more synergistic movements
• The premotor cortex is involved in higher processing of movements than what the primary motor cortex is (primary motor cortex is single joint simple movement). Also the premotor cortex DOES NOT HAVE A HOMUNCULUS.

Question 3

What is the Supplementary Motor Area important in?

Answer 3

• Internal generation of movements & sequences of learned movements (when one becomes highly proficient at a task, SMA has less activity)
• Has a homunculus (falls in between primary motor cortex and premotor cortex in how complicated of movements it ‘controls’)

Question 4

What do lesions of SMA produce?

Answer 4

Deficitis in internally guided and sequences of movements

• Patients become stimulus bound, show utilization behaviors (no inhibition, see glasses put them on)
• Alien hand syndrome
• Patient [monkey] makes semi-purposeful movements apparently outside of their control

Question 5

What is the ventral premotor cortex involved in?

Answer 5

• Control of grasping, encodes higher level properties of grasping
• contains mirror neurons

Question 6

What is seen in lesions of the premotor cortex?

Answer 6

• Can’t execute complex motor plans requiring visuomotor transformation i.e. plan execution
• Can’t learn new sensory-motor associations

Question 7

What is seen in lesions of the pyramidal tract?

Answer 7

Deficits in control of hand (loss of opposition of thumb and index finger..use hand like cup. Loss of independent extension of one digit. Reaching, locomotion and other movements are intact.

Question 8

What is seen in lesions of the primary motor cortex?

Answer 8

• Upper motor neuron syndrome (paresis, increased extensor tone, increased stretch reflexes)
• Deficits in fine motor control of hand, foot, mouth, and tongue
• Corticobulbar signs
  a. Lower facial muscles: loss of smiling, baring of teeth symmetrically, or puff out cheek on contralateral side
  b. Accessory nucleus: weakness of ipsilateral trapezius/sternocleidomastoid mastoid
  c. Hypoglossal nucleus: weakness of the contralateral tongue

-Sense of mental effort (from Alf Brodal)