cerebellum and basal ganglia Flashcards
cerebellum basic functions
coordinates voluntary movements
maintenance of posture and balance
motor learning and adaptation
integration of sensory input to fine-tune motor activity
where is the cerebellum located?
posterior to the cranial fossa above the foramen magnum
inferior to the occipital and temporal lobes
what is the cerebellum covered in?
tentorium cerebelli (dura mater)
what separates the cerebellum from the medulla and pons?
fourth ventricle
how is the cerebellum connected to the brainstem?
superior cerebellar peduncle
middle cerebellar peduncle
inferior cerebellar peduncle
afferent and efferent cerebellar tracts travel through the ____, to and from the ipsilateral cerebellar cortex
peduncles
three lobes of cerebellum
anterior
posterior
flocculonodular
what are the basic functions of the three lobes of the cerebellum?
Anterior lobe: Primarily involved in
coordinating movements of the limbs and
trunk (proprioception).
Posterior lobe: Plays a significant role in fine
motor control, planning, and coordination of
voluntary movements.
Flocculonodular lobe: Associated with
balance and eye movements (vestibular
functions).
what are the hemispheres and vermis of the cerebellum mostly in charge of?
hemisphere: fine motor coodination
vermis: postural adjustments
functional zones of the cerebellum
cerebrocerebellum
spinocerebellum
vestibulocerebellum
lesion in lateral cerebellum would affect the ___
lesion in the vermis would affect the ___
lesion in lateral cerebellum would affect the “LIMBS”
lesion in the vermis would affect the “TRUNK”
symptoms will be ____ to the side of the lesion in the cerebellum
ipsilateral
ataxia
Symptoms of damage to cerebellar pathways and the cerebellum
lesions of the vestibulocerebellum result in (3)
Impaired balance and gait
Marked nystagmus – involuntary eye movements
These symptoms can also occur with damage to the vestibular system.
lesions of the spinocerebellar result in
Impaired gait - often stomping. Lack of proprioceptive information makes patients unsure of where their legs and feet are without visual input.
lesions of the cerebrocerebellum result in (3)
Intention Tremor – amplitude of tremor increases during voluntary movement as the individual gets close to target. Example: trying to touch your nose with your index finger.
Difficulty with skilled movements
“Subtle” nystagmus
The cerebellum is composed of the outer ____ matter (cerebellar cortex) and inner ___ matter (cerebellar
medulla)
outer - gray
inner -white
cerebellum matter
outer:
inner:
outer: gray - cerebellar cortex
inner: white - cerebellar medulla
the cerebellar cortex is made of ___ matter
gray
the cerebellar medulla is made of ___ matter
white
three distinct layers of cerebellar cortex (grey)
molecular layer
purkinjie layer
granule layer
what is the cerebellar medulla composed of (4)?`
mossy fibers
climbing fibers
Purkinje cell axons
deep cerebellar nuclei
what are the only output of the cerebellum?
deep nuclei
Don’t Eat Greasy Food
denate
emboliform
globose
fastigial nucleus
what are the four nuclei of the deep cerebellar nuclei?
denate
emboliform
globose
fastigial nucleus
Don’t Eat Greasy Food
afferent: info to ____ to be ____
cerebellum to be processed
efferent: info ____ cerebellum to ____
leaves cerebellum to help coordinate motor activity
afferent tracts travel mainly thought the ___ and ___ cerebellar peduncles
inferior and middle
Ventral/Anterior Spinocerebellar Pathway
Carries proprioceptive information from muscle spindles, Golgi tendon organs, and joint receptors of lower extremities to cerebellum
Ventral/Anterior Spinocerebellar Pathway
brainstem:
cerebellum:
terminates:
Brainstem: axons cross back over
Cerebellum: Enters through superior cerebellar peduncle
Terminates: Ipsilateral vermal / paravermal cortex
Dorsal/Posterior Spinocerebellar Pathway
brainstem:
cerebellum:
terminates:
Brainstem: remains ipsilateral
Cerebellum: Enters through inferior cerebellar peduncle
Terminates: Ipsilateral cerebellar cortex
Dorsal/Posterior Spinocerebellar Pathway
Carries proprioceptive information from muscle spindles, Golgi tendon organs, and joint receptors of trunk and lower extremities to cerebellum
Friedreich’s ataxia
A hereditary ataxia affecting the spinocerebellar tracts
Multiple sclerosis
Demyelination affecting cerebellar pathways
Cerebellar stroke
Damage to spinocerebellar tracts or associated nuclei
afferent pathways from the cerebral cortex
corticopontocerebellar
cortico-olivocerebellar
cortico-reticulocerebellar
where do the afferent pathways from the cerebral cortex travel through and terminate?
signals through brainstem to cerebellum
corticopontocerebellar pathway
cerebral cortex
pontine nuclei
mossy fibers
cerebellar hemisphere via middle cerebellar peduncle
*enters through middle peduncle
*terminates in the contralateral cerebellar cortex
cortico-olivocerebellar pathway
cerebral cortex
inferior olivary nuclei
climbing fibers
cerebellar hemisphere via inferior cerebellar peduncle
cortico-reticulocerebellar pathway
cerebelar cortex
recticular formation
mossy fibers
cerebellar hemisphere via middle and inferior cerebellar peduncle
*middle and inferior peduncle
*terminates ipsilateral cerebellar cortex
peduncles and termination:
corticopontocerebellar -
cortico-olivocerebellar -
cortico-reticulocerebellar -
corticopontocerebellar -
middle peduncle
contralateral
cortico-olivocerebellar -
inferior peduncle
contralateral
cortico-reticulocerebellar -
inferior & middle peduncle
ipsilateral
efferent pathways from cerebellum (2)
rubrospinal tract
cerebellovestibular tract
where do efferent pathways originate from of the cerebellum?
the four deep cerebellar nuclei
*via superior cerebellar peduncle
Efferent tracts originate from the four deep cerebellar nuclei and travel mainly via the
superior cerebellar peduncle
The tracts of the fastigial nucleus travel via the
inferior cerebellar peduncle
cerebellorubral tract pathway
Globose & emboliform nuclei →
superior cerebellar peduncle →
red nucleus →
rubrospinal trac
*tone of contralateral skeletal muscles
cerebellothalamic tract pathway
Dentate nucleus →
superior cerebellar peduncle →
thalamic nuclei →
primary motor cortex
*Contralateral motor coordination
Cerebellovestibular tract pathway
Fastigial nucleus →
inferior cerebellar peduncle →
bilateral vestibular nuclei →
vestibulospinal tract
*Coordination of balance and saccadic ocular movements
from the vestibular nuclei, output is transmitted via (2)
- The vestibulospinal tracts to spinal motor neurons, which control postural muscles.
- Brainstem circuits involved in the vestibulo-ocular reflex (VOR) for stabilizing gaze
basal ganglia are a group of nuclei that lie where?
beneath the cortex
basal ganglia are a group of ___ that lie beneath the cortex
nuclei
Basal ganglia are a group of nuclei. These structures form a network of WHAT to regulate motor, cognitive, and emotional functions?
input, output, and modulatory components to regulate motor, cognitive, and emotional functions.
components of the basal ganglia (4)
striatum
globus pallidus
subthalamic nucleus
substantia nigra
components of the striatum (basal ganglia) - 3
- Caudate nucleus
- Putamen
- Nucleus accumbens
components of the globus pallidus (basal ganglia)
- Globus Pallidus Externus (GPe)
- Globus Pallidus Internus (GPi)
components of the substantia nigra (basal ganglia)
- Substantia Nigra Pars Compacta (SNc)
- Substantia Nigra Pars Reticulata (SNr)
Caudate nucleus:
Putamen:
Nucleus accumbens:
Caudate nucleus: planning and executing movement
Putamen: movement regulation
Nucleus accumbens: interface between limbic system and basal ganglia (motivation/reward processing)
globus pallidus interna vs externa (role)
interna: Major output nucleus of basal ganglia; inhibits the thalamus to regulate movement
external: Relay and modulator in the indirect pathway; inhibits the STN and other nuclei
globus pallidus interna vs externa (direct/indirect)
interna: direct/indirect
externa: indirect
globus pallidus interna vs externa (output targets)
interna: thalamus, brainstem
externa: subthalamic nucleus, globus pallidus interna
Subthalamic Nucleus (STN), an excitatory structure in the basal ganglia that uses ___
glutamate
Substantia Nigra Pars Reticulata (SNr): Uses ___ to inhibit unwanted signals, helping control eye movements and muscle activity for smooth, purposeful actions
GABA
Substantia Nigra Pars Compacta (SNc): Releases ____ to regulate emotions, learning, motivation, and decision-making, linking reward signals to motor actions.
dopamine
hormones?
Subthalamic Nucleus (STN):
Substantia Nigra Pars Reticulata (SNr):
Substantia Nigra Pars Compacta (SNc):
Subthalamic Nucleus (STN): glutamate
Substantia Nigra Pars Reticulata (SNr): GABA
Substantia Nigra Pars Compacta (SNc): dopamine
basal ganglia functional circuitry (function)
Direct pathway:
Indirect pathway:
Direct pathway: Facilitating movement
Indirect pathway: Inhibiting unwanted movements.
The balance of activity between the direct and indirect pathways is modulated by ___
dopamine
basal ganglia direct pathway main function
increase in motor activity (excitatory)
pathway of the basal ganglia direct pathway
Motor cortex activation →
glutamate release →
striatum stimulation →
GABA release →
inhibition of Gpi →
inhibition of GABA release →
thalamus disinhibition →
premotor cortex stimulation →
muscle activation →
↑ movement
basal ganglia direct pathway excitatory or inhibitory?
excitatory
basal ganglia indirect pathway excitatory or inhibitory?
inhibitory
function of basal ganglia indirect pathway
decrease motor activity
*modulation of the disinhibitory effect of the direct pathway
sequence of basal ganglia indirect pathway
Motor cortex activation →
glutamate release →
stimulation of striatum →
GABA release →
inhibition
of Gpe →
inhibition of GABA release →
↓ inhibition (activation) of subthalamic nucleus →
glutamate release →
stim. of substantia nigra (pars reticularis) & Gpi →
GABA release →
inhibition of thalamus →
inhibition of premotor cortex →
deactivation of muscles →
↓ movement
Degeneration in Nigrostriaital pathway =
decreased dopamine
Parkinson’s Disease
- Overactivity of the indirect pathway
- Reduced stimulation of the direct pathway
*Loss and impairment of melanated dopaminergic neurons
*substantia nigra is NOT dark
symptoms of Parkinson’s Disease (6)
- Initial symptom is typically a tremor in fingers or hands
- Bradykinesia- slowed movement
- Stiff/rigid muscles
- Gait abnormalities
- Posture instability
- Loss of automatic movements
Huntington disease
Degeneration of striatum
Huntington’s disease symptoms (6)
- Mood changes
- Cognitive decline
- Movement problems
- Chorea- random spasmastic movements
- Difficulty speaking and swallowing
- Huntington’s is always fatal, there is no cure
