Neuro 9: Basal Ganglia + cerebellum

Question 1

collective term given to the basal ganglia and cerebellum =

Answer 1

• Extrapyramidal system

Question 2

what is the role of the extrapyramidal system?

Answer 2

monitors / Checks that movement selected by motor cortex = correct

Question 3

What are the different parts of the basal ganglia?

Answer 3

• Striatum = caudate + putamen
• Globus Pallidus = external segment (GPext) + internal segment (GPint)
• Substantia Nigra = pars compacta (SNc) + pars reticulata (SNr)
• Subthalamic Nucleus

Question 4

What is the function of the basal ganglia?

Answer 4

• Plans + coordinates movement
• Involved in associated movements (e.g arms swinging when walking)
• Contributes to smoothness of complex action
• Involved in moderating + coordinating movements

Question 5

Describe the structure of the direct pathway in the basal ganglia.

Answer 5

• Fibres from motor cortex –>goes to striatum –> then goes from putamen of striatum –> globus pallidus (INTERNAL SEGMENT)+ substantia nigra (PARS RETICULATA)

Question 6

Describe the structure of the indirect pathway in the basal ganglia.

Answer 6

• Fibres from motor cortex –> goes to striatum –> then goes from putamen (EXTERNAL SEGMENT) –> subthalamic nucleus –> Globus pallidus internal segment

Question 7

is direct pathway in basal ganglia inhibitory or excitatory?

Answer 7

excitatory

Question 8

is indirect pathway in basal ganglia inhibitory or excitatory?

Answer 8

Inhibitory

Question 9

Where do the projections go after leaving the basal ganglion structures

Answer 9

• Goes to thalamus –> then the cortex + primary motor area

Question 10

State the main signs of Parkinson’s disease.

Answer 10

• Bradykinesia = Inability/delay in executing movements
• Hypomimic face = Loss of facial expression
• Tremor
• Rigidity

Question 11

What is Huntingdon’s disease caused by?

Answer 11

HTT gene –> CAG repeats

• on Chr 4
• due to degeneration of GABAergic neurones in striatum

Question 12

what are symptoms of huntington’s disease?

Answer 12

• Choreic movements = Rapid Jerking movements
• Starts with hand + face –> then whole body
• Later on patients will develop congnititve decline + dementia

Question 13

State the 3 lobes of the cerebellum.

Answer 13

• Anterior
• Posterior
• Flocculonodular

Question 14

State the 3 layers of the cerebellar cortex.

Answer 14

• Granule cell layer
• Purkinje cells
• Molecular layer

Question 15

What are the 3 sources of input into the cerebellum and what do they connect with?

Answer 15

• Mossy fibres –> from cortex + pons
• Mossy fibres –> from spinocerebellar tract
• Climbing fibres –> from inferior olive

Question 16

Functionally, the cerebellum can be divided in three. What are these three divisions?

Answer 16

• Vestibulocerebellum
• Spinocerebellum
• Cerebrocerebellum

Question 17

What is the role of the vestibulocerebellum

Answer 17

• Connected to vestibular nuclei
• Involved in balance / posture / regulation of gait
• Involved in head movement coordination with eye movement

Question 18

What are the roles of the spinocerebellum

Answer 18

• Coordinates speech
• Adjusts muscle tone
• Coordinates limb movement

Question 19

In summary, what are the four main functions of the cerebellum?

Answer 19

• Maintains balance + posture
• Coordinates voluntary movements
• Motor learning
• Cognitive functions

Question 20

What behavioural habit is spinocerebellar syndrome associated with?

Answer 20

• Chronic alcoholism

Question 21

Describe the symptoms of spinocerebellar syndrome.

Answer 21

• Unsteady gait

- Wide based stance

Question 22

Describe the symptoms of cerebrocerebellar syndrome.

Answer 22

• Damage –> affects mainly arms
• Affects coordinated movements
• Speech – hesitant + slow

Question 23

From where does the cerebrocerebellum receive inputs and what are its main functions?

Answer 23

• Receives projections from cortex
• Major function = coordination of skilled movements / cognitive function / attention / languaging processing / emotional control