Basal Ganglia & Motor Pathways Part II Flashcards
Review: the parts of the Basal Ganglia
- caudaute
- Putamen
- caudate + putamen = stiatum
- Globus Pallidus (internal and external portions)
- subthalamic nuclei
- substatia nigra (pars compata, pars reticularis)
thalmus related: but not part of the BG: just the output for the signals here
Review: Basal Ganglia Pathways
- Baseline
- Direct
- Indirect
- Substania Nigra
Baseline Pathway
- subthalamic nuclei –> glutamate (+) —> globus pallidus (internal) —> GABA (-) —> Thalamus —> cortex = net result is the inhibition of unwanted movements
Direct Pathway
- cortex —> glutamate (+) –> striatum (putamne) —> GABA (-) —> globus pallidus (internal) —> GABA (-) —> thalmus –> cortex = inhibiting the inhibtory pathway: thus allowing movement to begin
direct and indirect work concurrently to make sure proper muscles are working & their opposing forces are not
Indirect Pathway
- cortex —> glutamate (+) —> stritum (putamine) –> GABA (-) —> Globus pallidus (external) —> GABA (-) –> subthalmic nuclei –> glutamate (+) —> GP (internal) —> GABA (-) —> thalmus –> cortex = net result is less movement in the antagonists muscle group or the desiered action
Substantia Nigra Pathway (DA here)
cortex –> glutamate (+)–> substantia nigra (compata) to D1 receptors —> dopamine (+) —> striatum (putamine) –> GABA (-) —> globus pallidus (internal)—> GABA (-) —> thalmu s–> cortex = disinhibitrs een more to allow more muslces to work
problems here with lack of DA result in unwanted movements
what are the NT’s involved in the Basal Ganglia
GABA (inhibitory) released from….
- caudate
- putamen
- globus pallidus
Glutamate (excitatory) released from….
- subthalamic nucleus
- cortex
- thalmus
Dopamine (excitatory) released from….
- substantia nigra (compata)
Dopamin (inhibitor) released from….
- substanta nigra (compacta)
Parkinson’s Disease
- where in the brain does it impact
- symptos
Parkinson’s Disease
- an idopathic dopamine loss in the substanta nigra: pars compacta
Symptoms
- resting tremor
- freezing episodes (@ transitional movements)
- bradykinesia: affecting gross & fine motor
- microphonia, micrographia and dysphaiga (all due to brdaykinesia)
- Festinating Gait: the shuffle
- Dystonia (unwanted movements) & Stiffness (cogwheel rigidity)
- pain
- cognitive, sleep and ANS changes
Parkinson’s Disease
Diagnosis
treatment
Diagnosis
- a diagnosis made from neurologic testing assess the following
- gait
- tone of muscles
- tremor or bradykinesia
- response to DA medications
Treatment
- starts with dopamine agonists: MAO inhibitors
- then progression to levodopa/carbodopa
- PT/OT/SLP help
Effects of Levodopa (Parkinson’s Disease)
Levopdopa: becomes dopamine in the body
Side Effects
- on/off effects: can wain overtime and need more
- side effect: dyskinesias: unwanted movements!!
- drug interactions (Vit B6) & food (proteins slow absorbtion)
Long Term Levodopa
- dyskineas emerge; or a result from ther doses need to battle the progression of parkinsons
can be used with deep brain stiulation (targering GPinternus or STN)
Huntington’s Disease
- what is it
- symptoms and why they present
Huntington’s Disease
- a genetic atrophy of the basal ganglia (specifically the striatum: autosomal dominant genetic condition
- atrophy of basal ganglia = starting with caudate and putamen atrophy
- a GABAergic condtions
- progresses to multiple brain areas as they age
- cholenergic nuerons in striatum also impacted
Symptoms
- it is impacting the Indirect basal ganglia pathway therefore atrophy of GABA and lack of inhibition of unwanted movements: increase unwanted movements
- these movemetns exisit as chorea in face and limbs
- can later include aspects of dementia
Athetoid Cerebral Palsy
- what is it
- symptoms & manifestations
Athetoid CP
- dyskinetic CP: a common form
- a non-progressive perinatal neurological insult
- atheoid CP is resulting of hypoxic injury ro the basal ganglia and thalamus
Symptoms (affects motor first)
- fluctuating hyper/hypotonia
- abnormal posturing
- slow withering (circular) movements of extremities
- increased withering when attempting voluntary moveents
-
Hemiballisums
- what is it
- what causes it
- symptoms
Hemiballisums
- intermittenet, sudden and forceful movements of one extremity
- subthalmaic nucleus most affected area as it is an inhibitio of the thalamus by globus pallidus lessened contorl
causes
- TBI
- CVA
- Infection
Symptoms
- contralater motor pathway affected as the cortex ipsilated to the affected subthalamtic nuclei is stimualted
Cerebellum
- overview of the function
- blood supply
- location within the brain
- anatomy (fissures and lobes)
Cerebellum: for coordination and balance; smoothing of movements
Location: sits behind and inferior to the cortex; directly behind the pons of the BS
Blood Supply: superior cerebelar artery & PICA & AICA
Anatomy
- Vermus = middle (worm-like) – inferior-most aspect = nodule
- Primary Fissure = separates the anterior lobe from the posterior lobe
- horizontal fissure = separates into superior and inferior aspects (not important)
- Flocculucus = a flap of cerebellum which sits lateral to the medualla
Lobes
- anterior lobe
- posterior lobe
- smaller - flocculonodular lobe
a gyrus = folium & white matter pathways = arbor vitae
Names of the Regions of the Cerebelleum & their coordinating Function
Lateral Hemispheres (either side of the vermus) = Cerebrocerebellum = Neocerebellum
- motor planning, specifically motor planning of the gate
Spinocerebellum = Paleocerebellum = Vermis & Paravermis
- posture
- some aspect of the gait
Vestibulocerebellum = Floculonodular = Archicerebellum
- balance
- eye movements
Names and Pathways of the Cerebellar Peducles
peducles = connect the cerebellum to the brainstem= allow the signal to enter/leave the cerebellum to relay the signal
Superior Cerebellar Peduncle
- from cerebellum –> CONTRALATERAL red nucleus
- (then from contralat. RN –> inferior olivary in medulla, thalamus and cortex)
- myleinated axons carrying efferent signals (motor)
- note: some afferent fibers enter here too
Middle Cerebellar Peduncle
- afferent pathways into the cerebellum FROM the contralatera pontine nuclei FROM the cortex
- so cortex, pontine fibers, cross, into middle cerebellar
- afferent: sesnsory
- some fibers of effernt will pass here too
Inferior Cerebellar Pathways
- afferent pathways into the cerebellum from the CONTRALATERAL inferior olive
- afferent pathways into cerebellum from the IPSILATERAL posterior spinocerebellar tracts
- some efferent will pass here
Names and Pathways of the Deep Cerebellar Nuclei
where is their input coming from
where is thier output going
Fastigial
Globose
Emboliform
globose + emboliform = interposed
Dentate
all cerebellar output will pass through these deep nuclei (and probably leave via the superior cerebellar peduncle) EXCEPT: the flocculonodular node will go directly to the vestibular nuclei
Dentate Nucleus: input came from the lateral cerebellar hemisphere (motor planning) –> to the dentate –> to the SCP –> contralat red nucleus –> thalamus –> cortex
Interposed Nucleus: input from the paravermis (coordination) –> to the interposed —> to the SCP –> contralat red nucleus –> SC
Fastigial: input from vermis ( posture, motor control jaw, balance) —> to fastigal —> SCP –> multiple targets (verstibular nuclei gets most)
Afferent Cerebellar Projections
- where are they entering the cerebellum from
- where do thye go within the cerebellum
afferent projections usually enter the cerebellum from the inferior or middle cerebellar peduncle
From MCP
- corticopontinecerebellar fibers run here (from cortex)
- corticopontine fibers: synapse on the ponteine nuclei and then cross through MCP as pontocerebellar fibers
From ICP
- multiple afferent pathways arise from BS and pass through the ICP
- posterior spinocerebellar tract passes here on ipsilateral side (anterior Spinocere. go to the SCP)
- olivocerebellar tract passes here from the contralat olive (coming from multiple visual pathways before)
what are the spinocerebellar tracts
- where do they go
- what do they do
the goal of all spinocerebellar tracts is to get to the ipsilateral cortex of the spincerebellum area of cerebellum
from spine –> cerebellum
Anterior Spincerebellar Tract
- responsible for: proprioception from L2 and down
- synapse in the dorsal horn & cross here –> then ascend through the tract to the midbrain
- decussate AGAIN and enter the cerebellum through the SCP (unique: sensory coming through SCP)
- two crosses: means the control is still ipsilateral
Posterior Spinocerebellar Tract
- responsible for: proprioception from trunk and lower limbs
- ascends ipsilaterally through gracilis fasciculus –> enters cerebellum through ICP
Cuneocerebellar Tract
- responsible for: proprioception from upper limbs
- ascend ipsilaterally in cuneatus faciculus –> cerebellum through the ICP
