Neuro 10 - Basal Ganglia and Cerebellum

Question 1

What is the collective term given to the basal ganglia and cerebellum?

Answer 1

Extrapyramidal system

Question 2

Broadly speaking, what is the role of this system>?

Answer 2

checks the movement selected by the motor cortex

Question 3

Where is the basal ganglia located?

Answer 3

white matter in the middle of the brain

Question 4

What are the different parts of the basal ganglia?

Answer 4

Striatum = caudate and putamen
Globus pallidus = external and internal
Substantia nigra
Subthalamic nucleus

Question 5

What is the function of the basal ganglia?

Answer 5

involved in planning and coordinating movement

plans associated movements

Question 6

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

Answer 6

Motor cortex – striatum – putamen – globus pallidus internal segment – substantia nigra pars reticulata

Question 7

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

Answer 7

motor cortex – striatum – putamen – globus pallidus external segment – subthalamic nucleus – globus pallidus internal segment

Question 8

What is the difference in function of the direct and indirect pathways?

Answer 8

direct = excitatory on the motor cortex

indirect = inhibitory on the motor cortex

Question 9

What extra component modulates the function of the direct and indirect pathways?

Answer 9

Nigro-striatal pathway

Question 10

Where do the projections fo to after leaving the basal ganglia?

Answer 10

thalamus

then go to the cortex - supplementary and primary motor areas

Question 11

Describe how the basal ganglia are involved in choosing the correct motor programmes to carry out particular functions.

Answer 11

form a processing loop

enable motor commands via direct pathway

inhibit commands via indirect pathway

Question 12

Connections with which parts of the brain allow the basal ganglia to have a role in enabling various cognitive, executive and emotional programmes?

Answer 12

prefrontal association cortex

Limbic cortex

Question 13

What causes Parkinson’s?

Answer 13

neuronal degeneration of dopaminergic neurones in the substantia nigra pars compacta

progressive depletion of dopaminergic neurones

Question 14

What are the consequences of the loss of dopaminergic neurones in the substantia nigra pars compacta?

Answer 14

connection between the striatum and the substantia nigra pars compacta is lost

so direct pathway is reduced and so excitation of motor cortex reduced

Question 15

State the main signs of Parkinson’s?

Answer 15

bradykinesia
pill rolling tremor
akinesia
hypomimic face
rigidity

Question 16

Describe the Parkinsonian gait.

Answer 16

walking slowly, small steps, shuffling feet

stooped posture

Question 17

What is Huntington’s disease caused by?

Answer 17

Abnormality on Chromosome 4

degeneration of GABAergic neurones in the striatum

Question 18

What are the consequences of loss of GABAergic neurones in the striatum?

Answer 18

inhibitory effect of the indirect pathway is no longer in place

direct pathway is unopposed so the motor cortex is hyperexcitable

Question 19

What are the main signs of Huntington’s disease?

Answer 19

Choreic movements - rapid jerky
hands and face affected first
chorea increased over time until patients totally incapacitated

Question 20

State the 3 lobes of the cerebellum.

Answer 20

Anterior
Posterior
Flocculonodular

Question 21

The cerebellum is divided sagittally into 3 zones. What are they?

Answer 21

Vermis
Intermediate hemisphere
Lateral hemisphere

Question 22

State the three layers of the cerebellar cortex?

Answer 22

Granule cell layer
Purkinje cells
molecular layer

Question 23

Name 3 deep nuclei that are involved in the connections of the cerebellum with other parts of the body.

Answer 23

Fastigial - control of balance and connected with the vestibular nuclei

Interposed and Dentate - both involved in voluntary movement and are connected to the thalamus

Question 24

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

Answer 24

Mossy fibres - from cortex and pons
mossy fibres - from spinocerebellar tract
Climbing fibres - from the inferior olive

Question 25

Functionally the cerebellum is divided into three, What are these divisions.

Answer 25

Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum

Question 26

What is the role of the vestibulocerebellum?

Answer 26

flocculonodular lobe
connected with vestibular nuclei
involved in balance, posture, gait
also coordinating head and eye movements

Question 27

Which parts of the cerebellum are part of the spinocerebellum?

Answer 27

Vermis and intermediate hemispher

Question 28

From where does the spinocerebellum receive inputs?

Answer 28

afferent from axial - vermis

afferent from limbs - intermediate hemisphere

Question 29

What are the roles of the spinocerebellum?

Answer 29

coordination of speech
adjustment of tone
coordination of limb movement

Question 30

Which part of the cerebellum is part of the cerebrocerebellum?

Answer 30

Lateral hemisphere

Question 31

From where does the cerebrocerebellum receive inputs from?

Answer 31

Cortex

- function is for cognitive function, attention and coordiination of skilled movement

Question 32

In summary what are the main functions of the cerebellum?

Answer 32

maintenance of balance and posture
coordination of voluntary movements
motor learning
cognitive functions

Question 33

State 3 syndromes causes by dysfunction of different parts of the cerebellum.

Answer 33

Vestibulocerebellar syndrome
Spinocerebellar syndrome
Cerebrocerebellar syndrome

symptoms associated with functions obviously

Question 34

What behavioural habit is spinocerebellar syndrome associated with?

Answer 34

Chronic alcoholism

Question 35

Describe the symptoms of spinocerebellar syndrome?

Answer 35

abnormal gait and wide based stance

Question 36

Describe the symptoms of cerebrocerebellar syndrome?

Answer 36

arms affected

affects coordinated movements

Question 37

What are the main signs of cerebellar disorders?

Answer 37

ataxia - general impairments in movement
dysmetria - inappropriate force and distance
intention tremor - nose finger tracking
dysdiadochokinesia - inability to perform rapid alternating movements
Scanning speech - staccato

Question 38

State a hereditary and acquired cause of the symptoms listed?

Answer 38

hereditary - friedreich’s ataxia

acquired - multiple sclerosis