Neuro 9: Basal Ganglia + cerebellum Flashcards
collective term given to the basal ganglia and cerebellum =
- Extrapyramidal system
what is the role of the extrapyramidal system?
monitors / Checks that movement selected by motor cortex = correct
What are the different parts of the basal ganglia?
- Striatum = caudate + putamen
- Globus Pallidus = external segment (GPext) + internal segment (GPint)
- Substantia Nigra = pars compacta (SNc) + pars reticulata (SNr)
- Subthalamic Nucleus
What is the function of the basal ganglia?
- Plans + coordinates movement
- Involved in associated movements (e.g arms swinging when walking)
- Contributes to smoothness of complex action
- Involved in moderating + coordinating movements
Describe the structure of the direct pathway in the basal ganglia.
- Fibres from motor cortex –>goes to striatum –> then goes from putamen of striatum –> globus pallidus (INTERNAL SEGMENT)+ substantia nigra (PARS RETICULATA)
Describe the structure of the indirect pathway in the basal ganglia.
- Fibres from motor cortex –> goes to striatum –> then goes from putamen (EXTERNAL SEGMENT) –> subthalamic nucleus –> Globus pallidus internal segment
is direct pathway in basal ganglia inhibitory or excitatory?
excitatory
is indirect pathway in basal ganglia inhibitory or excitatory?
Inhibitory
Where do the projections go after leaving the basal ganglion structures
- Goes to thalamus –> then the cortex + primary motor area
State the main signs of Parkinson’s disease.
- Bradykinesia = Inability/delay in executing movements
- Hypomimic face = Loss of facial expression
- Tremor
- Rigidity
What is Huntingdon’s disease caused by?
HTT gene –> CAG repeats
- on Chr 4
- due to degeneration of GABAergic neurones in striatum
what are symptoms of huntington’s disease?
- Choreic movements = Rapid Jerking movements
- Starts with hand + face –> then whole body
- Later on patients will develop congnititve decline + dementia
State the 3 lobes of the cerebellum.
- Anterior
- Posterior
- Flocculonodular
State the 3 layers of the cerebellar cortex.
- Granule cell layer
- Purkinje cells
- Molecular layer
What are the 3 sources of input into the cerebellum and what do they connect with?
- Mossy fibres –> from cortex + pons
- Mossy fibres –> from spinocerebellar tract
- Climbing fibres –> from inferior olive
Functionally, the cerebellum can be divided in three. What are these three divisions?
- Vestibulocerebellum
- Spinocerebellum
- Cerebrocerebellum
What is the role of the vestibulocerebellum
- Connected to vestibular nuclei
- Involved in balance / posture / regulation of gait
- Involved in head movement coordination with eye movement
What are the roles of the spinocerebellum
- Coordinates speech
- Adjusts muscle tone
- Coordinates limb movement
In summary, what are the four main functions of the cerebellum?
- Maintains balance + posture
- Coordinates voluntary movements
- Motor learning
- Cognitive functions
What behavioural habit is spinocerebellar syndrome associated with?
- Chronic alcoholism
Describe the symptoms of spinocerebellar syndrome.
- Unsteady gait
- Wide based stance
Describe the symptoms of cerebrocerebellar syndrome.
- Damage –> affects mainly arms
- Affects coordinated movements
- Speech – hesitant + slow
From where does the cerebrocerebellum receive inputs and what are its main functions?
- Receives projections from cortex
- Major function = coordination of skilled movements / cognitive function / attention / languaging processing / emotional control
