Basal Ganglia and Cerebellum

Question 1

What are the basal ganglia

Answer 1

Basal ganglia are found in the CNS and are comprised of a load of nuclei sitting deep within the cerebral hemispheres

Question 2

What are the basal ganglia formed of

Answer 2

Substantia nigra pars compacta - produces dopamine

Striatum - formed of caudate nucleus and putamen

Globus pallidus - internal and external components. Medial to putamen

Subthalamic nucleus - below thalamus

Question 3

Describe the structure of the striatum

Answer 3

Striatum is formed of the caudate nucleus and putamen

Caudate nucleus is a C-shaped structure found in walls of lateral ventricles

Caudate nucleus and putamen are joined by strands of grey matter with gaps between the strands created by the internal capsule

Question 4

What forms the lentiform nucleus

Answer 4

Globus pallidus and putamen

Question 5

What does the basal ganglia communicate with and what does it control via this communication

Answer 5

Basal ganglia communicates with the motor cortex via the thalamus

Basal ganglia increases cortical activity by increasing the thalamic activity

Question 6

What are the functions of the basal ganglia

Answer 6

Basal ganglia helps select most appropriate action/movement to carry out a behaviour

Has a role in cognition and mood/higher mental functions

Basal ganglia regulates ipsilateral motor cortex -> have contralateral signs

Question 7

What are the two pathways in the basal ganglia and what do they cause

Answer 7

Direct pathway - reinforces appropriate movements -> excitatory. Dopamine acts on D1 receptors

Indirect pathway - edits out inappropriate movements -> inhibitory. Dopamine acts on D2 receptors

Question 8

Describe the structure of the cerebellum and where it is found

Answer 8

Cerebellum is found above the 4th ventricle

Cerebellum is formed of two hemisphere connected by a vermis

Communicates with the CNS via the cerebellar peduncles

Question 9

What are the functions of the cerebellum

Answer 9

Allows coordination of movements and enables sequencing of movements

Helps decide most appropriate sequence of movements to perform an action

Question 10

What are the inputs and outputs to the cerebellum

Answer 10

Cerebellum receives input from ipsilateral spinal cord and contralateral sensory cortices

Cerebellum sends outputs to the contralateral motor cortex

This means cerebellum deals with the ipsilateral side of the body -> signs of damage are on ipsilateral side

Question 11

What are the signs of cerebellar damage

Answer 11

Dysdiadochokinesia

Ataxia - unsteady gait

Nystagmus

Intention tremor

Slurred speech - dysarthria

Hypotonia