Motor Control and Movement Disorder

Question 1

Voluntary Movements

Answer 1

Purposeful and goal-directed
Learned
Complex actions

Question 2

Reflexive Movements

Answer 2

Involuntary/rapid/stereotyped

Caused by spinal cord, peripheral nerves and muscles

Question 3

Rhythmic Motor Patterns

Answer 3

Combination of voluntary and reflexive movements
Intention/initiation: voluntary
Once initiated become repetitive and reflexive

Question 4

3 Principles of Motor Control: 1. Hierachical Organisation

Answer 4

High: strategy: goal of movement: neo cortex and basal ganglia
Middle: tactic: muscle contractions arranged to achieve a goal: motor cortex and cerebellum
Low: execution: activation of motor neurons and adjustment of posture: brain stem and spinal cord

Question 5

3 Principles of Motor Control: 2. Sensory Input Guides Motor Control

Answer 5

Strategies: sensory info generates mental image of body and relationship to environment
Tactics: decisions based on memory of sensory into from past experiences
Execution: maintains posture, muscle length and tension around voluntary movement

Question 6

3 Principles of Motor Control: 3. Learning Changes the Locus of Sensorimotor Control

Answer 6

Conscious vs. automatic
After practice, lower levels perform learned tasks with little higher involvement
Fewer brain areas used for well learned tasks than new tasks

Question 7

Brain Areas Involved in Highest Level Motor Movements

Answer 7

Strategy
Posterior parietal cortex (PPC) and prefrontal cortex (PFC) send signals to…
Area 6 (premotor cortex) and then,,,
Area 4 (primary motor cortex, MC)

Question 8

Posterior Parietal Cortex in Movement Control

Answer 8

Generates a mental body image of the body and surrounding environment
Somatosensory, proprioceptive and visual info

Question 9

Prefrontal Cortex in Movement Control

Answer 9

Evaluates external world and initiates voluntary reaction in anticipation of consequences
Decision making

Question 10

Neglect and RH

Answer 10

Lesions to RH posterior parietal cortex (PPC) causes abnormalities of body image and spatial relations

Question 11

Contralateral Neglect

Answer 11

Deficit in attention paid to one side of the visual field

Question 12

Apraxia

Answer 12

Inability to…
Carry out learned movements when verbally instructed
Imitate movements

Question 13

Ready, Set, Go! Paradigm

Answer 13

Ready: PFC, PPC, brain centres control attention and awareness
Set: supplementary motor area (SMA), primary motor area (PMA), movements strategies devised and held until executed
Go: primary motor cortex (MC), basal ganglia

Question 14

Mirror Neurons (Rizzolati et al, 2001)

Answer 14

Suggested that mirror neurons play a role in imitating behaviour
Indirect evidence from fMRI show that they’re likely found in humans

Question 15

MC Inputs and Outputs

Answer 15

Inputs: cortical areas and thalamus
Outputs: spinal cord, brain stem

Question 16

Stimulation of MC Neurons

Answer 16

Brief stimulation - brief body movements
Prolonged stimulation (e.g. 0.5 secs) - complex species typical movements towards target position

Question 17

Lateral Descending Pathways

Answer 17

Initiate voluntary movement of distal musculature

Question 18

Corticospinal Tract

Answer 18

2/3- MC areas to spinal cord

1/3- somatosensory info from periphery to brain

Question 19

Rubrospinal Tract

Answer 19

Smaller tract
MC areas to red nucleus to spinal cord
Tract crosses after it synapses with the red nucleus

Question 20

Lesion Studies on Tracts

Answer 20

Lawrence & Kuypers (1968)
Animal studies
Lesion of 1: paralysis and recovery
Lesion of 1 and 2: paralysis without recovery

Question 21

Ventromedial Descending Pathways

Answer 21

Controls and maintains posture and certain reflex movements

Question 22

Vestibulospinal Tracts and Tectospinal Tracts

Answer 22

Keep head balanced
Turn head in response to stimuli
VST: keep eyes stable when body moves
TST: orientation response

Question 23

Pontine and Medullary Reticulospinal Tract

Answer 23

PRT: stabilise posture, resists gravity
MRT: liberation of antigravity muscles from reflex control

Question 24

Basal Ganglia in Motor Control

Answer 24

Movement initiation and planning
Sequence of movement triggered by MC and BG
BG can be responsible for remainder of action e.g. practised skills
Selects motor program and keeps it offline until signal

Question 25

Basal Ganglia Loop

Answer 25

Cerebral cortex
Through a few more areas then signals reach thalamus and midbrain
Signals from thalamus to motor and prefrontal areas of cerebral cortex
Loops produce excitatory and inhibitiry output to final areas of the loop
Mink (1996) function is motor selection and inhibition of actions

Question 26

Rigidity in PD

Answer 26

Muscle tone increases providing constant resistance to passive movement of joints

Question 27

Resting Tremor in PD

Answer 27

Most common symptom, usually asymmetric

Caused by decreased dopamine input into BG which has connections to many cortical areas

Question 28

Medication for PD

Answer 28

L-DOPA - stops dopamine passing blood-brain barrier

Deep brain stimulation (DBS) - surgical procedure treating disabling symptoms

Question 29

Motor Control Loops: Cerebellum

Answer 29

Motor skill learning and establishing new motor programs

Fine motor coordination/balance and muscle tone/ timing

Question 30

Motor Skill Learning Stages

Answer 30

Initial stage: individual response performed under conscious control
After practice: responses become continuous sequences of action w/o conscious regulation
Transfer from higher to lower levels of motor system

Question 31

Feedback/Feed-Forward Solutions in Cerebellum

Answer 31

Negative feedback and the adjustment of them leads to feed-forward solutions
Due to re-evalution, predictions

Question 32

2 Hemispheres of the Cerebellum

Answer 32

2 hemispheres connected by the vermis

Each hemisphere controls ipslateral movements

Question 33

Damage of the Cerebellum

Answer 33

Similar symptoms of alcohol abuse

Left cerebellar tumour: steady on right leg but not right leg, swayed right in standing position

Question 34

Cerebellar Patients

Answer 34

Ataxia - uncoordinated/inaccurate movements
Intention tremor - tremor at endpoint of deliberate movements
Problems clapping hands, speaking, writing, typing etc - problems motor learning