Ch. 11: Basal ganglia & Cerebellum Flashcards
Hyperkinetic Disorders
- inadequate inhibition from output nuclei
- Ex. Huntington’s Disease
Caudate
- input from prefrontal cortex
- input from thinking brain
- “this is what I want to do”
- cognitive link
Basal Ganglia
- 2 egg shaped clusters of cells at base of brain (lat and ant to thalamus)
- plan/control movement
- make motor plan
5 Components of Basal Ganglia
- caudate
- putamen
- globus pallidus
- subthalamic nucleus
- substantia nigra
Basal ganglia influence on movement
- connects BG to director UMN via motor thalamus (high skill, voluntary movement)
- connect BG to helper UMN via pedunculopontine nucleus (postural movement)
Cerebellum
- inputs to cerebellar cortex
- proprioception and somatosensation via spinocerebellar tract
- has more cells and more complex circuitry than any other part of brain
Substantia Nigra
- part of BG in midbrain
- has compacta that produces dopamine that power the basal ganglia circuit
Subthalamic Nucleus
prossessing functions
4 Functions of Motor Loop
- sequencing movements
- regulate Mm tone
- regulate Mm force
- facilitate/inhibit specific motor synergies
Cerebellar Ataxia
Stance: sway with eyes open/closed Voluntary Movement: ataxic eyes closed Proprioception: Ok Vibration: ok Ankle Reflex: ok
somatosensory ataxia
Stance: sway eyes closed Vol Movement: ok with eyes open Proprioception: impaired Vibration: impaired Ankle reflex: impaired
Cerebellar Treatment
- Slow down movements
- think about moving
- simplify movments
- see and feel movements
Cog Wheel Rigidity
-rigidity with tremor on top
5 basal ganglia functions
- motor loop
- occulomotor loop (direct eye movements)
- executive loop (goal directed behavior)
- behavioral flexibility and control loop (social appropriateness)
- Limbic loop (control emotions)
Huntington’s Disease Sx
Dementia
Chorea (twisting/writhing movements)
Cerebellar Lobes
- Flocculonodular Lobe
- Holds vestibulocerebellum
- Handlebar mustache of cerebellum
Superior Cerebellar Peduncles
- output
- efferent from cerebellum
- messages from correction to UMN of brainstem and cortex
Middle Cerebellar Peduncle
- Afferent
- input to cerebellum from corticopontocerebellar fibers
- gives xerox copy of motor plan to cerebellum
Vestibulocerebellum
- (flocculonodular lobe)
- equilibrium/balance, posture
- compare intended to actual movement for stability/posture
- influences eye movement and postural Mm
Inferior cerebellar Peduncles
- Afferent
- input to cerebellum from spinal cord and brainstem
- what I’m actually doing
Cerebellar Peduncles
- White matter axon bundles from cerebellum to brain stem
- Superior, middle, inferior
Parkinson’s Tx
- dopamine precursors
- surgical procedures
- PT/OT
Hypokinetic Disorders
-Excessive inhibition from output nuclei
Ex. Parkinson’s
Cerebellar Function
- compare actual to intended movement
- adjust actual motor output if there is a discrepancy
Parkinson’s disease
- Death of dopamine producing cells
- decreased dopamine–>BG malfunctions
- increased inhibition of excitatory motor thalamus–>decreased voluntary movement
- increased inhibition to inhibitory pedunculopontine nucleus–>excessive contraction of flex/ext posture muscles
Midline Vermis
control midline/core Mm
Cerebellar vertical divisions
(somatotopic organization)
- midline vermis
- paravernal hemisphere
- lateral hemisphere
Paravernal Hemisphere
control proximal extrmity Mm
Lateral Hemisphere
control distal extremity Mm
hands/feet
Globus Pallidus
Processor
Spinocerebellum
- gross movement of limbs
- midline/core and most proximal Mm
- control ongoing movement via brainstem descending tracts
Huntington’s Disease
-degeneration of BG input modules and cerebral cortex
- dereased inhib of motor thal (excitatory)–>invol Mm contractions
- decreased inhib of pedunculopontine nucleus (inhibitory)–>insufficient contraction of flex/ext postural Mm
Lesions of Spinocerebellum
-ataxic, wide based gait
3 Cerebellar Functional Divisions
- vestibulocerebellum
- spinocerebellum
- cerebrocerebellum
Putamen
- Input: from primary motor cortex and motor planning center
- “this is what I’m doing now and how environment is”
- movement link
Signs of cerebellar disorders
- general hypotonia
- general ataxia
- signs ipsilateral to damage
6 Parkinson’s Signs
- akinesia/hypokinesia
- rigidity (cog wheel)
- freezing
- visuoperceptive impairments
- postural instability
- resting tremor
Cerebrocerebellum
- fine distal voluntary movement
- coordinated voluntary movement
- ability to judge TIME, INTERVALS, and produce accurate RHYTHMS
Lesions of paravermis and cerebrocerebellum
- dysarthria: problem with mechanical production of speech/sounds
- sounds like drunk slurring
Lesions of vestibulocerebellum
- abnormal eye movements
- dysequilibrium
- truncal ataxia
Lesions of Spinocerebellum (cerebrocerebellum)
- dysdiadochokinesia (rapid alternating movements)
- Dysmetria (targets)
- Action tremor
