Motor function intro

Question 1

What are the classes of movement?

Answer 1

Reflexes, rhythmic (respiration, swimming, etc.), maintain equilibrium and posture, and free, goal oriented movements

Question 2

What kind of movements require feed-forward control?

Answer 2

Rapid movements, e.g., the vestibuloocular reflex

Question 3

What kind of movements require feed-back control?

Answer 3

Sensing the error between the actual and desired position of e.g., the hand

Question 4

What are the main executive motor areas in the mammalian CNS?

Answer 4

Premotor + primary motor cortex, posterioparietal cortex, BG, cerebellum, brainstem and spinal cord.

Question 5

How are the brainstem involved in movement?

Answer 5

Contains motor nuclei and large complexes of nerve cells involved in motor behaviour

Question 6

Which kinds of movements are the cortical areas involved in?

Answer 6

Goal directed, internal decision to act or sensory triggered acts, grasping and reaching

Question 7

Describe what the different cortical areas are involved in.

Answer 7

• primary motor cortex: execution, different aspects of movement (direction force)
• premotor: planning, preparing, controlling complex sequences of movement, sensory trigger or internal drive

Question 8

Describe how the BG and cerebellum are involved in motor function.

Answer 8

They are subcotical loops projecting to the motor cortex

Question 9

Describe how the brainstem are involved in motor function.

Answer 9

Serotonergic nuclei project widely and modulate motor behavior
- B1-B3: project to the spinal cord and modulate output
B1-B2: nuclei raphe pallidus and obscurus - motor
- Noradrenergic projections from locus ceruleus (pons) project to the spinal cord and cortex

Question 10

Describe the motor area connections of the descending systems.

Answer 10

BG/cerebellum –> motor cortex/brainstem centers –> (local circuit neurons)/ –> motor neuron pools –> skeletal muscles

Question 11

What are some motor diseases?

Answer 11

Parkinsons’, cerebellar ataxia, ALS, spinal muscular atrophy (SMA), spinal cord injury, stroke

Question 12

What are cerebellar ataxia?

Answer 12

Degeneration of cerebellar cells –> poor coordination, change in speech, involunvary back- and forth eye movement

Question 13

What are ALS?

Answer 13

Degeneration of motor neurons –> weakness, paralysis, spasticity

Question 14

What are SMA?

Answer 14

Degeneration of motor neurons (in infants) –> weakness of muscle activity in limb and eventually respiration

Question 15

Describe the overall strategy for investigating motor circuits and function.

Answer 15

• Describe the behavior at a high level
• Which circuits are involved - wherein the NS? –> isolate region and record activity
• How are the circuits connected? –> tracing anatomical and physiological
• Functional assesments of the motor behavior –> activation/inactivation of circuit elements - record cellular activity

Question 16

Describe anatomicall tracing.

Answer 16

Small molecule retrograde transport: inject tracer in the area you want to know what region project to
Small molecule anterograde transport: inject tracer in the area you want to know where it projects to

Question 17

What is cre-recombinase?

Answer 17

a system that can be used to get specific expression of protein or deleting genes in nerve cells

Question 18

How can you make functional assesments of the motor behavoior?

Answer 18

Using optogenetics or DREADDS

Question 19

What are optogenetics?

Answer 19

A method used to control electrical activity in nerve cells using opsins and light activation/inhibition

Question 20

What are DREADDS?

Answer 20

Designer Receptors Exclusively Activated by Designer Drugs