Basal Ganglia and Cerebellum (W6)

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Which two components of the Basal Ganglia are referred to as the "Corpus Striatum?": Caudate and Putamen
There are 5 structures that make up the basal ganglia. Name them.: 1. Caudate nucleus
2. Putamen
3. Globus Pallidus
4. Subthalamic nucleus
5. Substantia Nigra
The lenticulate nucleus is made up of which two structures?: 1. Globus Pallidus
2. Putamen
What are the two divisions of the substantia nigra?: pars reticulata
pars compacta
T/F: Basal ganglia have direct access to spinal cord motor neurons.: FALSE: They must use the thalamus as a "mediator"
Basal Ganglia structures in relation to the internal capsule: The _________ is located medial to the anterior limb of the internal capsule: head of the caudate nucleus
Basal Ganglia structures in relation to the internal capsule: The thalamus is ___________ (med/lat) to the posterior limb of the Internal Capsule.: Medial
Basal Ganglia structures in relation to the internal capsule: The putamen and globus pallidus are __________ to the genu and anterior and posterior limbs of the internal capsule: lateral to the genu and A & P limbs of the internal capsule
Basal Ganglia structures in relation to the ventricular system: The ______________ forms the lateral wall of the lateral ventricle: head and body of the caudate nucleus
Basal Ganglia structures in relation to the ventricular system: The ______________ passes in the roof of the temporal horn of the lateral ventricle.: tail of the caudate nucleus
Which basal ganglia structure forms the lateral walls of the third ventricle?: Thalami
Basal Ganglia Circuitry: The _________ connects the cortex afferents to the caudate and putamen.: Internal and External capsule
Basal Ganglia Circuitry: The lenticular fasciculus runs between the ___1________ and ____2____. The last structure runs directly to the ____3_____.: 1. globus pallidus
2. thalamic fasciculus.
3. Thalamus
Which basal ganglia structure is the principal player in determining proper movement?: Subthalamic Nucleus
Afferent fibers to the subthalamic nucleus come from? Efferent fibers from the subthalamic nucleus go to?: Afferents: GPe (external segment of globus pallidus)
Efferents: GPi (internal segment of the globus pallidus)
Which basal ganglia structure can be functionally lumped together with the globus pallidus?: SNr (substantia nigra, pars reticulata). Common fiber projection to the thalamus.
What is the function of the substantia nigra, pars compacta?: The SNc has dopamininergic neurons: it is an important source of afferents to the caudate and putamen.
What are the two structures that send afferent fibers to the caudate and putamen (corpus striatum)?: 1. Cortex
2. SNc (substantia nigra, pars compacta)
The striatum influences the globus pallidus via 2 pathways: name them and describe their course.: 1. Direct pathway -> striatum to GPi (internal segment of globus pallidus)
2. Indirect pathway -> striatum to GPe to Subthalamic nucleus to GPi.
Levels of activity within the subthalamic nucleus appear to be key in controlling _________________.: the initiation of movement
All output from the striatum can be classified as __________.: Inhibitory (via GABA)
D1 receptors are ___________ and are mainly associated with which pathway? What about D2 receptors?: D1 -> inhibitory, associated with indirect pathway
D2 -> excitatory, associated with direct pathway
What type of interneurons does the striatum contain? are they (+) or (-)?: cholinergic interneurons (use acetylcholine). (+)
Define: 1. akinesia 2. rigidity 3. tremors: 1. loss of the power of voluntary movement. slow to initiate movement
2. resistance to passive movement, stiffness
3. involuntary trembling
Define: 1. Chorea 2. Athetosis 3. Ballism: 1. dance-like involuntary mvmts. of the limbs
2. slow involuntary writhing mvmnt. of fingers & hands.
3. violent jerking or shaking mvmnt. of the limbs
Parkinson's disease is caused by ______________. Describe the state of a brain afflicted with PD.: intrastriatal dopamine depletion.
nigro-striatal dopaminergic projections degenerate, pars compacta depigmented.
What type of reflexes would a patient with PD have?: Normal reflexes
Huntington's disease is caused by ___________. What is observed in this brain?: caused by intrastriatal GABA depletion due to degeneration of the striatum. Cortical atrophy is observed
Describe the activity of the subthalamic nucleus in a PD patient versus an HD patient: PD -> subthalamic nuclei neurons are more active
HD -> subthalamic nuclei neurons are less active
What would cause hemiballismus?: a subthalamic stroke. One subthalamic nucleus is obliterated resulting in contralateral hemiballismus
What is the inheritance of Huntington's disease?: autosomal dominant
The thalamus can be divided into 3 main portions when viewed from above. Name them. What separates these?: 1. Anterior
2. Medial
3. Lateral
internal medullary lamina separates the portions. (white matter)
When the thalamus is viewed from the lateral side there are 5 divisions in the ventral tier. Name them.: 1. Medial Geniculate Body
2. Lateral Geniculate Body
3. Ventral Posterior Nucleus
4. Ventral Lateral Nucleus
5. Ventral Anterior Nucleus
The medial geniculate body mediates _________ afferents, while the lateral geniculate nucleus mediates ______ efferents.: auditory
visual
Which portion of the thalamus are the VPL and VPM found in?: Ventral Posterior Nucleus
In which portion of the thalamus are cerebellum efferents and basal ganglia afferents found?: VLN (Ventral Lateral Nucleus)
In which portion of the thalamus are some of the basal ganglia afferents found?: VAN (Ventral Anterior Nucleus)
In which portion of the thalamus are somatosensory afferents found?: VPN (Ventral Posterior Nucleus)
Why has the cerebellum been called a "comparator?": Because it compensates for errors in voluntary mvmnts. by comparing intention (from cortex) with performance (from ascending sensory systems)
Where is the vermis of the cerebellum found?: In the midline (vermis means worm, therefore the vermis looks like a worm)
There are 3 lobes of the cerebellum. Name them: 1. Anterior lobe
2. Posterior lobe
3. Flocculonodular lobe
Which fissure separates the anterior lobe from the posterior lobe in the cerebellum?: The primary fissure
Which fissure separates the posterior lobe from the flocculonodular node?: The posterolateral fissure
The inferior cerebellar peduncle connects the __________ to the cerebellum.: medulla and spinal cord
The middle cerebellar peduncle connects the _________ to the cerebellum.: basilar (ventral) pons
The superior cerebellar peduncle connects the cerebellum to the ________.: midbrain and thalamus
Which cerebellar peduncles contain efferent and afferent fibers?: 1. Inferior and Middle Peduncles -> afferent
2. Superior peduncle -> efferent
The cerebellum is divided into 3 functional subdivisions. Name them: 1. vestibulocerebellum (flocculonodular lobe)
2. spinocerebellum (medial)
3. cerebrocerebellum (lateral)
What is the function of the vestibulocerebellum?: governs eye movements and equilibrium during stance and gait
What is the function of the spinocerebellum?: controls posture and gross coordination
What is the function of the cerebrocerebellum?: coordinates refined or skilled movements
A lesion in which portion of the cerebellum would result in nystagmus?: vestibulocerebellum - lesion manifests as vestibular symptoms
What is the arbor vitae?: "tree of life," the internal white matter of the cerebellum
There are 3 cortical layers of the cerebellum. Name them from outside to in.: 1. Molecular layer (mostly fibers)
2. Purkinje cell layer
3. Granule cell layer
There are 4 pairs of deep nuclei in the cerebellum. Name them from lateral to medial.: 1. Dentate
2. Emboliform
3. Globose
4. Fastigal
"Don't Eat Greasy Food"
Which 2 deep nuclei of the cerebellum are often combined and known as "interposed nuclei?": emboliform and globose nuclei
Which nuclei of the cerebellum are associated with the spinocerebellum? How about the cerebrocerebellum?: Spinocerebellum -> Emboliform, Globose, Fastigal
Cerebrocerebellum -> Dentate
A cerebellar hemisphere recieves ascending sensory information from the ___________ side of the body. (ipsi/contra): ipsilateral
A cerebellar hemisphere recieves motor command information from the __________ cortex. (ipsi/contra): contralateral
it is then relayed and decussates at the pons.
a cerebellar hemisphere sends information back to the _______ motor cortex via the thalamus. (ipsi/contra): contralateral
a cerebellar hemisphere is responsible for regulation of movement on the ________ side of the body. (ipsi/contra): ipsilateral
Name the 2 cerebellar afferent pathways to the cerebrocerebellum.: 1. pontocerebellar fibers
2. olivocerebellar fibers
How do pontocerebellar fibers get to the cerebrocerebellum? What kind of information do they carry?: via the middle cerebellar peduncle. they carry information from sensory and motor cortices.
the pontocerebellar fibers recieve information from the cortex __________, then they project fibers _________ to the cerebrocerebellum. (ipsi/contra): recieve ipsilaterally
project contralaterally
What information do the olivocerebellar fibers transmit?: info from spinal cord, brainstem and cortical sources
Describe the pathway of the olivocerebellar fibers.: from inferior olivary nucleus (which recieves and integrates info) to the contralateral cerebellar cortex via the inferior cerebellar peduncle
There are 5 afferent pathways that end in the spinocerebellum. Name them.: 1. DSCT
2. Cuneocerebellar tract
3. VSCT
4. Olivocerebellar fibers
5. Trigeminocerebellar fibers
The DSCT, cuneocerebellar, olivocerebellar and trigeminocerebellar all project to the spinocerebellum via the ____________.: inferior cerebellar peduncle
The VSCT projects to the spinocerebellum via the ____________.: superior cerebellar peduncle
There are 2 pathways that project onto the vestibulocerebellum. Name them.: 1. vestibulocerebellar fibers
2. olivocerebellar fibers
There are two kinds of vestibulocerebellar fibers. What are they called and what is the difference?: 1. primary vestibulocerebellar afferents bypass vestibular nuclei & go directly to cerebellum. Secondary vestibulocerebellar afferents go through the nuclei
How do the vestibulocerebellar fibers project to the vestibulocerebellum?: via the juxtarestiform body
Purkinje cells are ___________(+) or (-). Which neurotransmitter do they release?: (-) inhibitory
release GABA
Purkinje cells are large: they are the primary way from the ____________ to the _____________.: cerebellar cortex to the deep nuclei
Purkinje neurons of the flocculonodular lobe project to the _____________ via the _____________.: lateral vestibular nucleus
juxtarestiform body
Climbing fibers come from the ___________ and are ___ (+) or (-) to Purkinje cells and deep nuclei.: inferior olive
(+)
Mossy fibers come from __________ and are (+) to the ________ and _________.: everywhere but the inferior olive
deep nuclei and granule cells
The fastigal nucleus recieves input from the Purkinje neurons and projects ____1___ to the ____2____ via the ___3_____.: 1. bilaterally
2. vestibular complex
3. juxtarestiform body
The Globose, Emboliform & Dentate nuclei all recieve input from Purkinje cells and project to the ____1____ and _____2____ via the ______3__.: 1. red nucleus
2. ventrolateral thalamic nucleus
3. superior cerebellar peduncle
Define: ataxia: inability to coordinate the muscles in voluntary movement (catch all term)
Define: past pointing: a systemic drift (to one side) of a directed movement. This is a vestibulocerebellar symptom
What type of tremor is specific to cerebellar disorders?: intention tremor
Define: dysmetria: inability to stop a mvmt at a desired point. (reach for coffee cup on table can't stop)
Define: decomposition of movements: movements broken down into its constituent parts
Define: dysdiadochokinesia: inability to perform rapid alternating movements
What is masking of cerebellar signs?: When there is a lesion in a cerebellar pathway but it is hidden in a CST lesion. (ie. paralysis)

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