Week 12: Cerebellum and Basal Ganglia

What part of the brain is "the error detector-movement corrector"

Cerebellum

3 major functions of cerebellum

Synergy of movement

Maintenance of upright posture

Maintenance of tone

The cerebellum also works with emotional and social functions, what does this mean?

Regulation of social behaviors and creating/storing emotional memories

The cerebellum also works with cognitive functions, what does this mean?

Goal-directed behavior, language optimization (right hemi), visuospatial function (left hemisphere)

What is the medial portion of the cerebellum known as?

Vermis

What are the 3 functional regions of cerebellum?

Lateral hemispheres, intermediate portion, vermis

What is the function of the lateral hemispheres of cerebellum?

Motor planning for distal extremities (involves lateral corticospinal tract)

What is the function of the intermediate hemispheres of cerebellum?

Distal limb coordination (involves lateral corticospinal tract, rubrospinal tract)

What is the function of the vermis and flocculonodular lobe?

Proximal limb/trunk coordination, balance and vestibuloocular reflexes

What are the motor pathways influences by the vermis and flocculonodular lobe?

Anterior corticospinal tract, reticulospinal tract, vestibulospinal tract, tectospinal tract, medial longitudinal fasciculus

What are the deep cerebellar nuclei?

Dentate

Emboliform

Globose

Fastigial

Where does the dentate nuceli receive input from?

Lateral regions

Where does the emboliform nuclei receive input from?

Intermediate regions

Where does the globase nuclei receive input from?

Intermediate regions

Where does the fastigial nuclei receive input from?

Medial regions

What is the vestibular nuclei?

In the brainstem, functions in some way like deep cerebellar nuceli; recieves input from inferior vermis and flocculi

What are the two main synaptic inputs of the cerebellum?

Mossy fibers and climbing fibers (both excitatory)

Where do the mossy fibers and climbing fibers synapse?

Onto purkinje cells

What is the output from the cerebellar cortex?

Purkinje axons to deep cerebellar and vestibular nuclei (inhibitory)

How do the deep cerebellar nuclei and vestibular nuclei convey outputs?

Information from the cerebellum to other regions through excitatory outputs

Pathways from cerebellum are ____________ crossed...what does this mean?

Double; means they cross twice so remain ipsilateral

What is the dorsal spinocerebellar tract responsible for?

Leg proprioceptors, goes to inferior cerebellar peduncle

What is the ventral spinocerebellar tract responsible for?

Leg interneurons, goes to superior cerebellar peduncle

What is the rostral spinocerebellar tract responsible for?

Arm interneurons, goes to superior and inferior cerebellar peduncles

What is the cuneocerebellar tract responsible for?

Arm proprioceptors, goes to inferior cerebellar peduncles

Midline lesions of cerebellum cause what?

Unsteady gait (truncal ataxia) and eye movement abnormalities

Lateral lesions of cerebellum cause what?

Limb ataxia (appendicular ataxia)

Ataxia is _________ to side of lesion

ipsilateral

What is dysrhythmia?

Abnormal timing

What is dysdiadochokinesia?

Inability to perform rapid alternating movements

What is dysmetria?

Abnormal trajectories, over/undershooting

What is a wide-based, unsteady, "drunk" gait in reference to?

Truncal ataxia

What is an intention tremor and what type of ataxia is it seen in?

Patient attempts to move limb toward target, but has irregular/oscillating movements in multiple planes; appendicular ataxia

How to test truncal ataxia?

Standing rhomberg/sharpened rhomberg; tandem rhomberg

How to test appendicular ataxis?

Finger to nose (UE), heel to shin (LE)

SCA infarct sxs

Mainly ataxia with little to no brainstem signs

PICA infarct sxs

Ataxia + vertigo, nausea/vomiting, horizontal nystagmus, appendicular ataxia, truncal ataxia, headache

AICA infarct sxs

Ataxia + unilateral hearing loss

Swelling of the cerebellum can cause what and how?

Hydrocephalus; due to increased ICP by compressing into the 4th ventricle

Initial presentation of cerebellar hemorrhage

GI symptoms of nausea/vomiting

Other sxs of cerebellar hemorrhage?

Headache, nausea/vomiting, ataxia, and nystagmus

What is the striatum?

Caudate and putamen nucleus connected by striations

The series of nuclei in basal ganglia:

Caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra

What is the lenticular nucleus?

Putamen and globus pallidus

Input connections of basal ganglia:

From the cortex via the striatum

How does the basal ganglia transfer its output to the thalamus?

Via globus pallidus and substantia nigra

Thalamus is _________ to cortical motor areas

Excitatory

When basal ganglia releases __________ to thalamus, it inhibits the thalamus

GABA

Indirect pathway leads to ___________ of thalamus, therefore ________ movement

Inhibition; reducing

Direct pathway leads to __________ of thalamus, therefore __________ movement

Stimulation; producing

Which basal ganglia pathway causes GABA to be released to the thalamus therefore reducing movement?

Indirect

What are the four total channels by basal ganglia?

Motor channel

Oculomotor channel

Prefrontal channel

Limbic channel

What is the motor channel?

Regulation of movement

What is the oculomotor channel?

Regulation of eye movements

What is the prefrontal channel?

Cognitive processes

What is the limbic channel?

Regulation of emotions and motivational drives

What is dyskinesia?

General term; abnormal movement

What is akinesia?

Absence of movement

What is bradykinesia?

Slowed movements

What is hypokinesia?

Decreased amount of movements

What is rigidity?

Increased resistance to passive movement of a limb

What is athetosis?

Writhing, worm-like movements

What is chorea?

Irregular, jerky movements

What is dystonia?

Sustained contractions of agonist and antagonist

What is a tremor?

Oscillatory movements (commonly resting tremor with BG lesions)

What is Parkinson's disease caused by?

Idiopathic, neurodegenerative condition caused by a loss of dopaminergic neurons in substantia nigra

Classic triad of parkinson's:

Resting tremor, rigidity, and bradykinesia

True Parkinson's responds well to what medication?

Levodopa (L-dopa)

Parkinson's disease has an ____________ onset of symptoms

Asymmetrical

What age does Parkinson's onset occur at and which gender more effected?

~40-70 years old, males

Non-movement Parkinson's disease symptoms

Apathy, anxiety, anosmia, breathing difficulty, constipation or nausea, cognitive changes, depression, fatigue, hallucinations, pain, sleep disorders

In Parkinson's disease, which pathway takes over?

Indirect

How does atypical Parkinson's (aka Parkinsonism) present?

Symmetrical onset of symptoms, rapid disease progression, lack of resting tremor, early postural instability/gait disturbances, poor response to L-dopa

What is seen in MSA Parkinsonism?

Large autonomic failure (orthostatic hypotension, erectile dysfunction, urinary incontinence)

What is seen in progressive supranuclear palsy Parkinsonism?

Most common; early postural instability, dementia, dysarthria, dysphagia, supranuclear gaze palsy, limited vertical eye movements

What is seen in dementia with Lewy bodies Parkinsonism?

Prominent psychiatric symptoms early on

What is seen in corticobasal degeneration Parkinsonism?

Asymmetrical symptoms, limb dystonia, apraxia, alien limb syndrome, sensory deficits, dementia

Huntington's disease is a __________ disorder

Genetic

Huntington's disease causes progressive atrophy of what nucleus?

Caudate nucleus

How is Huntington's disease described?

Abnormal body movements (chorea, eye movements), emotions, and cognition

Age of onset for Huntington's disease:

30-50 years old, initially have subtle chorea and behavioral disturbances

In Huntington's disease, which pathway takes over?

Direct