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Flashcards in Basal ganglia and cerebellum Deck (26)
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1
Q

What are the functions of the motor cortex?

A

Initiation of voluntary movement

Skilled, dextrous movements

Integration of movement with maintenance of postural stability and the physical envrionment

2
Q

Where is the motor cortex located?

A

Immediately rostral/anterior to the central sulcus

3
Q

Describe the mapping of the primary motor cortex?

A

Simple mapping in comaprison to other motor areas

Topographic arrangement

Motor homunculus

Contralteral actions with stimulation

4
Q

Which areas of the brain are active in more complex motor movements?

A

In addition to primary motor area, areas outside of it are stimulated with more complex movements

eg. SMA and primary sensory cortex

5
Q

Describe the suggested functions of the motor association areas?

A

Planning of movements

Performance of more complicated programs or sequences of movements

6
Q

What is really represented by the motor cortex?

A

The types of movements that we actually need to perform

eg. bringing hand to chest to examine something or hand to face to eat something

7
Q

How do cortical motor neurons differ from spinal motor neurons?

A

In cortex, neurons have different functional allocations

Neurons for particular types of tasks

Not like spinal cord, where neuron must be active if muscle is active

8
Q

Describe the concept of mirror neurons?

A

Neurons respond to seeing a movement performed, as well as performing that movement ourselves

Preparatory, as well as a way of encoding the means by which a goal would be achieved

Important for motor learning

9
Q

Describe the inputs to the motor areas?

A

Primary motor cortex: inputs from association areas and somatosensory cortex, particularly other parts of parietal cortex that synthesise higher order representations of our environment

Premotor areas: from high level representation of environment, as well as prefrontal areas, which suggests that prefrontal areas are telling us about the value/salience/meaning of things

10
Q

Describe how motor pathways relate to visual pathways in the brain?

A

Dorsal pathway = where = reaching

Ventral pathway = what = grasping

Two motor pathways that feed into different areas of the motor cortex and association areas, and integrate behaviour about an object that we see to perform a goal

11
Q

Describe the three main functions of the basal gangli?

A

1) Selection of complex patterns of voluntary movements
2) Evaluating the success of actions in achieving the goals of those actions
3) Initiating movements

12
Q

Describe the basic anatomy of the basal ganglia?

A

Made up of five nuclei

3 in midbrain: caudate, putamen, globus pallidus

1 in diencephalon: subthalamic nucleus

1 in midbrain: substantia nigra

13
Q

How are the basal ganglia affected in Parkinson’s disease?

A

Loss of dopaminergic neurons in substantia nigra > inability to initiate movement

14
Q

How are the basal ganglia affected in Huntington’s disease?

A

Caudate and putamen reduced, almost lost

15
Q

Describe the general principles of the pathways through the basal ganglia?

A

Two pathways by which the motor cortex connects back with itself

Direct pathway: selects patterns of motor activity

Indirect pathway: suppresses other movements, especially similar ones

Dopamine is critical

16
Q

Describe the functions of the cerebellum?

A

Coordinating timing and sequence of movements

Maintenance of muscle tone

Motor learning

Planning sequences of muscle activation for complex movements

17
Q

Which parts of the brain does the cerebellum interact with?

A

Motor cortex

Brainstem

18
Q

Briefly describe the anatomy of the cerebellum?

A

Tightly folded

Three main lobes with three connections to brainstem (superior, middle and inferior peduncles)

Every part the same in terms of cellular structure

19
Q

Describe the functional organisation of the cerebellum?

A

Medial to lateral

20
Q

What is the major consequence of cerebellar lesions?

A

Ataxic movements

Inability to follow path/route

Effects are ipsilateral for a unilateral lesion

21
Q

Describe the signs of anterior lobe syndrome of the cerebellum?

A

Ataxic gait

Loss of inter-limb coordination

22
Q

What is a major cause of anterior lobe syndrome in the cerebellum?

A

Chronic ethanol toxicity

23
Q

Describe the signs of posterior lobe syndrome of the cerebellum?

A

Dysmetria (overshoot in precision reach)

Dysdiadochokinesia (inability to rapidly alternate movements)

Speech abnormality

24
Q

What is flocculonodular syndrome?

Which lobe of the cerebellum is it associated with?

A

Truncal ataxia (inability to stabilise trunk)

Associated with posterior lobe

25
Q

On which side of the body do unilateral cerebellar lesions present?

Why?

A

Cerebellar lesions present ipsilaterally

Due to double cross

Output from cerebellum crosses over and projects to motor thalamus or brainstem and to cortex in crossed pathway

Damage to cerebellum > affects contralateral part of cerebrum > affects ipsilateral side of body

26
Q

Describe the role of the cerebellum in learning and adaptation?

A

Cerebellum is required to make adaptations to motor programs