Basal ganglia and cerebellum Flashcards Preview

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Flashcards in Basal ganglia and cerebellum Deck (26):

What are the functions of the motor cortex?

Initiation of voluntary movement

Skilled, dextrous movements

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



Where is the motor cortex located?

Immediately rostral/anterior to the central sulcus


Describe the mapping of the primary motor cortex?

Simple mapping in comaprison to other motor areas

Topographic arrangement

Motor homunculus

Contralteral actions with stimulation 


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

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

eg. SMA and primary sensory cortex


Describe the suggested functions of the motor association areas?

Planning of movements

Performance of more complicated programs or sequences of movements 


What is really represented by the motor cortex?

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


How do cortical motor neurons differ from spinal motor neurons?

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 


Describe the concept of mirror neurons?

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 


Describe the inputs to the motor areas?

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


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

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 


Describe the three main functions of the basal gangli?

1) Selection of complex patterns of voluntary movements

2) Evaluating the success of actions in achieving the goals of those actions

3) Initiating movements


Describe the basic anatomy of the basal ganglia?

Made up of five nuclei

3 in midbrain: caudate, putamen, globus pallidus

1 in diencephalon: subthalamic nucleus

1 in midbrain: substantia nigra 


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

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


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

Caudate and putamen reduced, almost lost



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

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 


Describe the functions of the cerebellum?

Coordinating timing and sequence of movements

Maintenance of muscle tone

Motor learning

Planning sequences of muscle activation for complex movements 


Which parts of the brain does the cerebellum interact with?

Motor cortex



Briefly describe the anatomy of the cerebellum?

Tightly folded

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

Every part the same in terms of cellular structure



Describe the functional organisation of the cerebellum?

Medial to lateral


What is the major consequence of cerebellar lesions?

Ataxic movements

Inability to follow path/route 

Effects are ipsilateral for a unilateral lesion 


Describe the signs of anterior lobe syndrome of the cerebellum?


Ataxic gait

Loss of inter-limb coordination 


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

Chronic ethanol toxicity


Describe the signs of posterior lobe syndrome of the cerebellum?

Dysmetria (overshoot in precision reach)

Dysdiadochokinesia (inability to rapidly alternate movements)

Speech abnormality 


What is flocculonodular syndrome?

Which lobe of the cerebellum is it associated with?

Truncal ataxia (inability to stabilise trunk)

Associated with posterior lobe 


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


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


Describe the role of the cerebellum in learning and adaptation?

Cerebellum is required to make adaptations to motor programs