Brain & Behaviour #7

Front 1

What does the cerebellum do?

Back 1

- receives and interprets proprioceptive information
- Coordinates balance and is tightly linked to the vestibular nuclei
- Coordinates fine movement, eye hand coordination
- Predicts the sensory consequences of movement

Front 2

Describe the anatomy of the cerebellum

Back 2

- Lies over the 4th ventricle
- can be divided into three lobes (anterior, posterior, flocculonodular)
- Vermis lies centrally, nodule is the most anterior part of the vermis
- Cerebellar tonsils lie superior to foramen magnum on inferior surface of cerebellum
- connected to brainstem via three cerebellar peduncles

Front 3

What do the cerebellar afferents dealing with vestibular information do?

Back 3

1. Help orient eye movements during locomotion
2. Provide information of the position of the head and body in space

Front 4

What do the cerebellar afferents dealing with proprioceptive information do?

Back 4

Unconscious proprioception

Front 5

What fibers are involved in proprioceptive cerebellar afferents?

Back 5

From muscle spindles: Ia, II
From Golgi tendons: Ib

Front 6

What do the cerebellar afferents dealing with cortical information do?

Back 6

- Cortex projects to pontine nuclei, which projects to cerebellar hemispheres
- pontocerebellar tract through MCP
- Deals with fine motor control of upper extremity, dexterous hand movement, hand eye coordination

Front 7

What is the archicerebellum responsible for?

Back 7

archicerebellum = vestibulocerebellum
responsible for: Trunk control

Front 8

What is the paleocerebellum responsible for?

Back 8

paleocerebellum = spinocerebellum
responsible for: Syngeristic movements of extremities

Front 9

What is the neocerebellum responsible for?

Back 9

neocerebellum = cerebrocerebellum
responsible for: coordination of intricate and complex movements
(topographical representation of the extremities, areas for eye movement and speech

Front 10

What do lesions in the FN lobe of the cerebellum result in?

Back 10

1. trunk ataxia
2. Nystagmus

Front 11

What do lesions in the anterior lobe of the cerebellum result in?

Back 11

1. Affects spinocerebellar input (i.e. the synergistic movement of the extremities)
2. Gait ataxia

Front 12

What do lesions to the neocerebellum do?

Back 12

1. problems with fine coordination of movement
2. Dysdiadokinesia: An inability to perform rapidly alternating movements
3. Dysmetria: inability to coordinate a movement of the extremities.

Front 13

what are the main functions of the basal ganglia?

Back 13

- modulation of voluntary motor activity
- Three parallel circuits
1. Motor circuit controls body and eye movements
2. Associatiative circuit involved in higher level cognitive function
3. Limbic circuit involved in emotional and motivational processing

Front 14

What activities does the basal ganglia encode for?

Back 14

1. Decision to move
2. Direction of movement
3. Amplitude of movement
4. Motor expression of emotions
5. Making movements and behaviours more efficient (proceduralization)

Front 15

Explain the direct pathway of the release-inhibition model of thalamic control

Back 15

The direct pathway releases the UMN from their tonic inhibition, leading to an increase in motor output
The direct pathway facilitates target orientated movement

Front 16

Explain the indirect pathway of the release-inhibition model of thalamic control

Back 16

- counter balances the direct pathway
- puts a brake on the normal function of the direct pathway, resulting in a reduction of motor output
- The indirect pathway inhibits potentially competing movements

Front 17

Define: Ballism

Back 17

- Hyperkinetic disorder
- Characterized by sudden uncontrolled flinginmovements of the extremities.

Front 18

What is the underlying pathophysiology of ballism?

Back 18

A loss of the subthalamic nucleus (STN)
results in;
1) loss of excitatory fibres projecting to the Globus pallidus
2) This results in less inhibitory output from the GPi to the thalamus
3) therefore there is more excitatory output from thalamus to cortex and more motor output overall.

Front 19

What are the characteristics of Huntington's Disease?

Back 19

Deficits in cognition, behaviour and a characteristic hyperkinetic movement disorder

Front 20

What is the pathophysiology of Huntington's Disease?

Back 20

There is a degeneration of the striatum (caudate + putamen) as well as degeneration of temporal and frontal association corticies
- This results in a disinhibition of the output to the cortex and there is more excitation from the thalamus to the cortex overall.

Front 21

D1 receptors from the SN provide what type of input to the direct pathway?

Back 21

Excitatory - they enhance the input from the cortex

Front 22

D2 receptors from the SN provide what type of input to the indirect pathway?

Back 22

Inhibitory - results in a net loss of output from the thalamus, resulting in less cortical stimulation and less cortical output.

Front 23

What is Parkinson's?

Back 23

A motor disorder characterized by a decrease or loss of movement.

Front 24

What is Parkinson's do to?

Back 24

The loss of movement in Parkinson's is due to a degeneration of DA neurons in the substantia nigra.

Front 25

what are the treatment options for PD?

Back 25

1. L-Dopa
2. Deep brain stimulation of the subthalamic nucleus (STN).