Modulation of Movement: Basal Ganglia and Cerebellum

Question 1

What does the motor cortex do?

Answer 1

Initiation of voluntary movement
Skilled, dexterous movements
Integration of movement with 
- Maintenance of postural stability
- Goals
- Physical environment

Question 2

What kind of motor patterns does the motor cortex coordinate?

Answer 2

Extended patterns of movement

Question 3

Does the motor cortex exert ipsilateral or contralateral control of the body?

Answer 3

Contralateral

Question 4

Where is the motor cortex located?

Answer 4

Pre-central gyrus

Question 5

What happens when areas more rostral to the motor cortex are stimulated?

Answer 5

More complex movements produced

Question 6

What is the topographical mapping of the motor cortex?

Answer 6

Lower limb medial
Upper limb more lateral
- Fingers and hands have large areas
Head and face lateral
- Large area from lips and mouth

Question 7

What areas of the cortex are activated with simple movement?

Answer 7

Pre-central gyrus

Post-central gyrus in similar area

Question 8

What areas of the cortex are activated with complex movement?

Answer 8

Pre-central gyrus
Post-central gyrus in similar area
Pre-motor areas

Question 9

What areas of the cortex are activated with mental rehearsal of complex movment?

Answer 9

Motor association area only

Question 10

What is really represented in the primary motor cortex?

Answer 10

Wherever hand is at start of stimulation of cortex, activation of area of motor cortex moves hand to particular region
Produces ecologically logical movements

Question 11

Describe the experiment that demonstrates what mirror motor neurons are

Answer 11

Neurons would fire when monkeys observed experimenters doing things
These neurons recognised those tasks
When monkey performed same task, same neuron fires as well

Question 12

What do mirror motor neurons recognise?

Answer 12

Same pattern of movements rather than same end goal

Question 13

What is the likely reason for the existence of mirror motor neurons?

Answer 13

How we learn - people and monkeys learn a lot of things by watching

Question 14

Where are the inputs to the primary motor cortex from

Answer 14

Association areas
Somatosensory cortex
Posterior parietal area

Question 15

What does the posterior parietal area do?

Answer 15

Synthesises sensory information into egocentric map

Question 16

Where do the pre-motor areas receive input from?

Answer 16

Posterior parietal areas
Pre-frontal areas responsible for salience of objects and tasks
- Goal driving
- Planning

Question 17

What are the visual streams coming into the motor areas?

Answer 17

Dorsal

Ventral

Question 18

What do the visual streams provide information to the motor cortex on?

Answer 18

Where things are

What things are

Question 19

What types of movement do the visual streams “control”?

Answer 19

Dorsal = where > reach
Ventral = what > grasping - hand shaping

Question 20

What are the functions of the basal ganglia?

Answer 20

Allow selection of complex patterns of voluntary movements
Evaluate success of actions in achieving goals of actions
Initiating movements

Question 21

What is the relationship between the basal ganglia and motor cortex?

Answer 21

Basal ganglia modulate what happens in motor cortex

Question 22

How do the basal ganglia project to the motor cortex?

Answer 22

Only via thalamus

Question 23

Do the basal ganglia project to other cortical regions?

Answer 23

Yes

Question 24

Which basal ganglia is destroyed in Parkinson’s disease?

Answer 24

Substantia nigra

Question 25

With what level of damage to the substantia nigra do clinical signs of Parkinson's disease appear?

Answer 25

80% of neurons lost

Question 26

Why is the substantia pigmented black?

Answer 26

Presence of black pigment melanin in dopaminergic neurons

Question 27

What basal ganglia are affected in Huntington's disease?

Answer 27

Caudate | Lenticular nucleus

Question 28

What are the characteristics of the Parkinsonian gait?

Answer 28

Stooped posture Turning by small shuffling steps Tremor in limbs Bradykinesia

Question 29

What is the role of dopamine in the basal ganglia?

Answer 29

Facilitates pathway of information from basal ganglia to motor cortex

Question 30

What are the characteristics of chorea in Huntington's disease?

Answer 30

Quick irregular involuntary muscle twitches | Hyperactivity of hands, feet, and sometimes entire limb

Question 31

Where does input from the motor cortex come into the basal ganglia?

Answer 31

Striatum

Question 32

How many pathways are there from the basal ganglia to the motor cortex?

Answer 32

Two, via thalamus

Question 33

Describe the direct pathway from the basal ganglia to the motor cortex?

Answer 33

Facilitates movements Selects movement patterns to go together to make coherent motor plan Facilitated by dopamine Removes inhibition

Question 34

Describe the indirect pathway from the basal ganglia to the motor cortex?

Answer 34

Stops movement from happening, especially those that interfere with those that are happening Excites inhibitory neurons to inhibit these pathways Dopamine reduces activity

Question 35

What is the role of having both a direct and indirect pathway?

Answer 35

Movements selected stand out more clearly by inhibiting all others

Question 36

What are the functions of the cerebellum?

Answer 36

Coordinating timing and sequence of muscle actions and movements Maintenance of tone Motor learning Planning sequences of muscle activation for complex movements

Question 37

What inputs does the cerebellum receive?

Answer 37

Copies of motor commands from motor cortex | Ascending information to see how motor command went

Question 38

What does the cerebellum do with the information it receives from the motor cortex and ascending information?

Answer 38

Compares two to adjust movement

Question 39

What cortical structures does the cerebellum link with?

Answer 39

Primary and associated motor cortices

Question 40

What is the gross structure of the cerebellum?

Answer 40

Tightly folded Three lobes Cerebellar peduncles attach it to brainstem

Question 41

Where do fibres in the cerebellar peduncles connect to?

Answer 41

Medulla Pons Midbrain

Question 42

What is the functional organisation of the cerebellum?

Answer 42

Approx medial to lateral

Question 43

What is ataxia?

Answer 43

Inability to appropriately integrate/coordinate movement

Question 44

What happens with a lesion in the cerebellum?

Answer 44

Ataxia

Question 45

Does a unilateral lesion in the cerebellum have a contralateral or ipsilateral effect?

Answer 45

Generally ipsilateral

Question 46

What is anterior lobe syndrome?

Answer 46

Ataxic gait | Loss of inter-limb coordination

Question 47

Why does anterior lobe syndrome occur?

Answer 47

Chronic ethanol toxicity > anterior Purkinje cells in cerebellum preferentially lost

Question 48

How does anterior lobe syndrome progress?

Answer 48

Progression of pathology posterioly involves upper limbs and facial muscle dys-coordination

Question 49

What is posterior lobe syndrome?

Answer 49

``` Dysemtria Dysdiadochokinesia Speech abnormality - Loss of natural rhythm - Slurring across syllables - Overcompensation by explosive speech ```

Question 50

What is dysemtria?

Answer 50

Overshoot in precision speech

Question 51

What is dysdiadochokinesia?

Answer 51

Inability to rapidly alternate movements

Question 52

What is flocculonodular lobe syndrome?

Answer 52

Truncal ataxia - Difficulty walking - In severe cases: difficulty standing and sitting

Question 53

Why are cerebellar lesions ipsilateral to deficits?

Answer 53

One side of cerebellum sends output > crosses midline > info received by contralateral motor cortex Motor cortex sends information to body on contralateral side = double cross