Lecture 15

Question 1

What is the spinal cord involved in?

Answer 1

• processing commands from the brain
• reflexes
• rhythmic motor patterns

Question 2

What organs generate basic patterns of rhythmic muscle activity?

Answer 2

Spinal cord and brainstem circuits

Question 3

What are rhythmic muscle patterns used for?

Answer 3

• locomotion
• breathing
• chewing
• swallowing

Question 4

What kind of commands does the brain give the spinal cord and brainstem circuits?

Answer 4

• stop/start
• speed
• force
• direction

Question 5

What is in the primary motor cortex?

Answer 5

An ordered map of the body (somatotopy)

Question 6

What is the corticospinal (pyramidal) tract?

Answer 6

A pathway used for For regulation of spinal cord motor systems by the primary motor cortex.
output from motor cortex controls spinal neurons for fine movements (crosses over to opposite side).

Question 7

What is the secondary motor cortex involved in?

Answer 7

Planning of movements

Question 8

What is somatotopy?

Answer 8

Body parts are represented roughly sequentially across the cortex. The area devoted to each part is dependent on level of fine control and extent of use.

Question 9

What happens if damage occurs to the primary motor cortex?

Answer 9

Problems with movement, particularly with fine voluntary control in specific parts of the body

Question 10

What is the role of brainstem pathway?

Answer 10

In charge of coordinated activity in large muscle groups for posture, locomotion, and routine activities (can be crossed or uncrossed).

Question 11

What are the roles of the primary motor cortex?

Answer 11

• controlling force of muscle contraction

- controlling direction of movements (steering occurs around the joints)

Question 12

Where do most motor cortex axons synapse

Answer 12

interneurons

Question 13

What is the role of motor cortex neurons which synapse onto alpha-motor neurons?

Answer 13

• mostly for control of distal limbs

- direct, fast and powerful effect

Question 14

What are motor programs?

Answer 14

sequences about what muscle contracts which are put in place prior to the action. actions are worked out in detail before they are put forwards

Question 15

What is the planning loop?

Answer 15

sensorimotor cortex –> basal nuclei –> thalamus

Question 16

What happens during the planning stage?

Answer 16

Dopamine is released to confirm a plan is going to be successful, and central motor neurons send down the input in order to generate movement

Question 17

What are the roles of basal ganglia?

Answer 17

• monitors and helps plan cortical activity involved in movement
• helps cortex select combinations/sequences of muscle activation
• cycle through loop occurs during preparation for movement
• positive feedback to cortex for selected motor output pathways
• needed for initiation of movements
• dopamine input vital to allow proper functioning

Question 18

What occurs due to death of dopamine neurons?

Answer 18

Parkinson’s disease

Question 19

What are symptons of Parkinson’s disease?

Answer 19

• difficulty beginning movements
• slowed movements
• tremor

Question 20

What are possible treatments for Parkinson’s?

Answer 20

• dopamine replacing drugs
• deep brain stimulation
• transplantation of dopamine cells

Question 21

What is the role of the cerebellum and brainstem feedback loop?

Answer 21

It incorporates sensory information from planning as well as sensory feedback from the environment to decide how to best execute the motion.

Question 22

What are the roles of the cerebellum?

Answer 22

• helps plan ,execute, and learn motor programs
• integrates sensory information with planned motor programs
• organises timing of individual muscle contractions around joins
• compares the intended results of a planned movement with the actual result, and modifies ongoing activity

Question 23

What happens if the cerebellum is injured?

Answer 23

Movements become slow and uncoordinated. Tend to have a drunken gait.

Question 24

How does alcohol affect the cerebellum?

Answer 24

The cerebellum has a lot of GABA receptors. Alcohol inhibits those receptors, so individuals tend to sway and stagger when walking.