Podcast
Questions and Answers
What type of fibers connect to granule cells in the cerebellar circuitry?
What type of fibers connect to granule cells in the cerebellar circuitry?
- Parallel fibers
- Aminergic fibers
- Mossy fibers (correct)
- Climbing fibers
Which structure serves as a major relay center for sensory information entering the cerebellum?
Which structure serves as a major relay center for sensory information entering the cerebellum?
- Cerebral cortex
- Spinal cord
- Vestibular nuclei
- Inferior olive (correct)
What is the primary function of climbing fibers in cerebellar circuits?
What is the primary function of climbing fibers in cerebellar circuits?
- Direct motor output
- Convey error signals (correct)
- Facilitate muscle contraction
- Regulate sensory input
How many Purkinje cells can one climbing fiber connect to?
How many Purkinje cells can one climbing fiber connect to?
Which part of the cerebellum is responsible for regulating equilibrium and receives input from vestibular nuclei?
Which part of the cerebellum is responsible for regulating equilibrium and receives input from vestibular nuclei?
What is affected when there is an impairment to the Purkinje cells?
What is affected when there is an impairment to the Purkinje cells?
What type of output does the cerebellum provide via Purkinje cells?
What type of output does the cerebellum provide via Purkinje cells?
Which pathway do mossy fibers influence cerebellar output through?
Which pathway do mossy fibers influence cerebellar output through?
Which layer of the cerebellar cortex contains Purkinje cells?
Which layer of the cerebellar cortex contains Purkinje cells?
What neurotransmitter do Purkinje cells primarily use?
What neurotransmitter do Purkinje cells primarily use?
Which type of cell is the only output cell for the cerebellar cortex?
Which type of cell is the only output cell for the cerebellar cortex?
How do granule cell axons interact with Purkinje cells?
How do granule cell axons interact with Purkinje cells?
What type of synapses do basket cells have on Purkinje cells?
What type of synapses do basket cells have on Purkinje cells?
Which are considered the main types of cellular fibers in the cerebellum?
Which are considered the main types of cellular fibers in the cerebellum?
What effect do Golgi cells have on granule cells?
What effect do Golgi cells have on granule cells?
Which structure is formed by Golgi cells axons, granular cell dendrites, and mossy fibers?
Which structure is formed by Golgi cells axons, granular cell dendrites, and mossy fibers?
Which tremor is associated with cerebellar lesions?
Which tremor is associated with cerebellar lesions?
Which of these symptoms is NOT typically associated with basal ganglia lesions?
Which of these symptoms is NOT typically associated with basal ganglia lesions?
What type of movement velocity is noted in cerebellar lesions?
What type of movement velocity is noted in cerebellar lesions?
Which of the following clinical observations would suggest a cerebellar lesion?
Which of the following clinical observations would suggest a cerebellar lesion?
Which symptom is indicative of a basal ganglia lesion?
Which symptom is indicative of a basal ganglia lesion?
What information do the interposed nuclei primarily receive?
What information do the interposed nuclei primarily receive?
Which cerebellar nucleus is the largest?
Which cerebellar nucleus is the largest?
What is the primary function of the rubrospinal tract?
What is the primary function of the rubrospinal tract?
Which cerebellar peduncle contains mostly efferent fibers?
Which cerebellar peduncle contains mostly efferent fibers?
Which of the following accurately describes the connectivity of vestibular nuclei?
Which of the following accurately describes the connectivity of vestibular nuclei?
What type of information is primarily carried by the middle cerebellar peduncle?
What type of information is primarily carried by the middle cerebellar peduncle?
Which type of processing is influenced by the output of deep cerebellar nuclei?
Which type of processing is influenced by the output of deep cerebellar nuclei?
How do the cerebellar nuclei compare functionally to the vestibular nuclei?
How do the cerebellar nuclei compare functionally to the vestibular nuclei?
Which artery supplies the flocculus and medulla?
Which artery supplies the flocculus and medulla?
What is a common cause of rotatory dizziness?
What is a common cause of rotatory dizziness?
Which of the following symptoms is NOT associated with lesions in the lateral cerebellum?
Which of the following symptoms is NOT associated with lesions in the lateral cerebellum?
What does dysmetria indicate during motor tasks?
What does dysmetria indicate during motor tasks?
Which sign is commonly observed in patients with vestibulocerebellar lesions?
Which sign is commonly observed in patients with vestibulocerebellar lesions?
What does the term ‘decomposition’ refer to in cerebellar disorders?
What does the term ‘decomposition’ refer to in cerebellar disorders?
Which of the following is a characteristic sign of cerebellar dysfunction?
Which of the following is a characteristic sign of cerebellar dysfunction?
What type of ataxia results from paravermal lesions?
What type of ataxia results from paravermal lesions?
Which symptom is specifically associated with lesions in the cerebellum?
Which symptom is specifically associated with lesions in the cerebellum?
What movement disorder is characterized by gradual clumsiness and shaking on one side of the body?
What movement disorder is characterized by gradual clumsiness and shaking on one side of the body?
Which of the following describes a characteristic of basal ganglia lesions?
Which of the following describes a characteristic of basal ganglia lesions?
A patient exhibits abnormal eye movements alongside uncoordinated movements on one side. What does this suggest?
A patient exhibits abnormal eye movements alongside uncoordinated movements on one side. What does this suggest?
What type of muscle tone is typically observed in cerebellar lesions?
What type of muscle tone is typically observed in cerebellar lesions?
What is the primary function of the cerebellum?
What is the primary function of the cerebellum?
Which lobe of the cerebellum is located deep to the posterior lobe?
Which lobe of the cerebellum is located deep to the posterior lobe?
Which structure separates the anterior and posterior lobes of the cerebellum?
Which structure separates the anterior and posterior lobes of the cerebellum?
What percentage of brain volume does the cerebellum account for?
What percentage of brain volume does the cerebellum account for?
Which of the following is NOT a function of the cerebellum?
Which of the following is NOT a function of the cerebellum?
Which nuclei in the cerebellum is most medially located?
Which nuclei in the cerebellum is most medially located?
What are folia in the context of cerebellar anatomy?
What are folia in the context of cerebellar anatomy?
Which of the following best describes the functional divisions of the cerebellum?
Which of the following best describes the functional divisions of the cerebellum?
What type of information do the interposed nuclei primarily receive?
What type of information do the interposed nuclei primarily receive?
Which nucleus is the largest among the cerebellar nuclei?
Which nucleus is the largest among the cerebellar nuclei?
Which cerebellar peduncle primarily carries inputs from the pons?
Which cerebellar peduncle primarily carries inputs from the pons?
The primary function of the rubrospinal tract is associated with which of the following?
The primary function of the rubrospinal tract is associated with which of the following?
What type of fibers does the superior cerebellar peduncle primarily contain?
What type of fibers does the superior cerebellar peduncle primarily contain?
Which nuclei receive input from the flocculonodular lobe?
Which nuclei receive input from the flocculonodular lobe?
What is the primary role of cellular output from the deep cerebellar nuclei?
What is the primary role of cellular output from the deep cerebellar nuclei?
Which of the following is true regarding the connectivity patterns of vestibular nuclei?
Which of the following is true regarding the connectivity patterns of vestibular nuclei?
What is the primary function of the spinocerebellum?
What is the primary function of the spinocerebellum?
Which type of fibers primarily project from the cerebrocerebellum?
Which type of fibers primarily project from the cerebrocerebellum?
What structures receive output from the spinocerebellum?
What structures receive output from the spinocerebellum?
Which part of the cerebellum is primarily involved in coordinating fine distal limb movements?
Which part of the cerebellum is primarily involved in coordinating fine distal limb movements?
What type of information does the vestibulocerebellum primarily integrate?
What type of information does the vestibulocerebellum primarily integrate?
Which nuclei does the spinocerebellum project its output to?
Which nuclei does the spinocerebellum project its output to?
What role do the branches of the basilar and vertebral arteries play in cerebellar function?
What role do the branches of the basilar and vertebral arteries play in cerebellar function?
Which cerebellar region primarily processes auditory and vestibular information?
Which cerebellar region primarily processes auditory and vestibular information?
Which type of cell extends axons that are inhibitory to granule cells?
Which type of cell extends axons that are inhibitory to granule cells?
What is the primary neurotransmitter utilized by Purkinje cells?
What is the primary neurotransmitter utilized by Purkinje cells?
In which layer of the cerebellar cortex are basket cells primarily found?
In which layer of the cerebellar cortex are basket cells primarily found?
What is the relationship between granule cells and Purkinje cells in terms of synaptic interaction?
What is the relationship between granule cells and Purkinje cells in terms of synaptic interaction?
What distinguishes Purkinje cells from other neuronal cell types in the cerebellar cortex?
What distinguishes Purkinje cells from other neuronal cell types in the cerebellar cortex?
Which type of cell in the cerebellar cortex is known to have a dense dendritic branching structure and receives excitatory input?
Which type of cell in the cerebellar cortex is known to have a dense dendritic branching structure and receives excitatory input?
What is the role of mossy fibers within the cerebellar circuitry?
What is the role of mossy fibers within the cerebellar circuitry?
What effect do stellate cells have on Purkinje cells in the cerebellar cortex?
What effect do stellate cells have on Purkinje cells in the cerebellar cortex?
Study Notes
Cerebellar Nuclei
- Interposed Nuclei are made up of the Globose and Emboliform nuclei.
- They receive input from the intermediate zone of the cerebellum and cerebellar afferents carrying sensory information:
- Spinal
- Proximal somatosensory
- Auditory
- Visual
- The Interposed Nuclei project to the contralateral red nucleus, which is the origin of the rubrospinal tract.
- The Dentate Nucleus is the largest cerebellar nucleus.
- It receives input from the medulla and projects to the contralateral red nucleus and the ventrolateral (VL) thalamic nucleus.
Vestibular Nuclei
- Located in the rostral Medulla and caudal Pons
- Receive input from the flocculonodular lobe and the vestibular labyrinth
- Project to various motor nuclei and originate the vestibulospinal tracts
Cerebellar Peduncles
- Form the walls of the fourth ventricle
- Inferior Cerebellar Peduncle
- Restiform Body: Contains spinocerebellar fibers
- Justirestiform: Contains vestibulocerebellar fibers
- Middle Cerebellar Peduncle
- Brachium Pontis: Contains massive connections to the pons
- Superior Cerebellar Peduncle
- Brachium Conjunctivum: Contains anterior spinocerebellar fibers and cerebellothalamic fibers
Inferior Cerebellar Peduncle
- Carries afferent fibers from the medulla and efferent fibers to the vestibular nuclei
- Posterior spinocerebellar
- Vestibulocerebellar
- Primarily carries input
Middle Cerebellar Peduncle
- Connects with the pons
- Carries afferent fibers
- Primarily carries input
Superior Cerebellar Peduncle
- Carries efferent fibers from the cerebellar nuclei and afferent fibers from the spinocerebellar tract
- Connects with the midbrain, primarily carrying output
Microanatomy of the Cerebellum
- Has unique circuits that allow for temporal and spatial processing of information
- The deep cerebellar nuclei receive excitatory output from the cerebellum that is influenced by:
- Excitatory inputs from afferent collaterals
- Inhibitory influences of efferent cells
- Temporal processing is achieved through timing variances
- Spatial processing is achieved through various body components
Cerebellar Cellular Anatomy
- Has three cell layers:
- Molecular Layer
- Purkinje Cell Layer
- Granule Cell Layer
Neuronal Cell Types
- Purkinje
- Granule
- Basket
- Stellate
- Golgi
Purkinje Cell Layer
- Purkinje Cells
- Possess extensive dendritic trees that extend into the molecular layer with numerous spines
- Axons synapse with the deep cerebellar nuclei, and are the only axons to leave the cerebellar cortex
- Modify the output of the cerebellum
- Secrete GABA, an inhibitory neurotransmitter
- Purkinje cells are the ONLY output cells of the cerebellar cortex
Granule Cells
- Axons project to the folia, where they bifurcate and form the parallel fibers
- Higher density of parallel fibers relative to a Purkinje cell
- Form excitatory synapses with Purkinje cells
Basket Cells
- Located in the molecular layer
- Dendrites extend into the superficial molecular layer and receive excitatory input from parallel fibers
- Axons extend across folia (perpendicular to parallel fibers) and send a collateral branch to Purkinje cells
- Inhibitory
Stellate Cells
- Located in the Molecular Layer
- Axons extend across the folia perpendicular to parallel fibers
- Receive excitatory input from parallel fibers
- Form inhibitory synapses with Purkinje cells
- Have a discrete influence on dendrites
Golgi Cells
- Located deep to the Purkinje cells
- Dendrites extend to the molecular layer
- Excitatory connections with parallel fibers
- Axons enter the granule layer
- Inhibitory to granule cells
Cerebellar Glomerulus
- A complex synaptic structure formed by:
- Golgi cell axons
- Granule cell dendrites
- Mossy fibers
Cerebellar Cellular Fibers
- There are four fiber types:
- Mossy fibers (vast majority)
- Climbing fibers (olivocerebellar)
- Parallel fibers (terminals of granule cells)
- Fibers from:
- Hypothalamus
- Pontine raphe nuclei
- Locus ceruleus
Mossy Fibers
- Excitatory afferent fibers that determine the output of Purkinje fibers
- Formed by efferent axons from:
- Pontine nuclei
- Spinal cord
- Vestibular nuclei
- Reticular formation (Brainstem)
- Synapse with granule cell dendrites
- Form excitatory connections within glomeruli
- One mossy fiber connects to 600 granule cells, which in turn connect to greater than 5000 Purkinje cells
Climbing Fibers
- Formed by afferent axons from:
- Inferior olivary nucleus (medulla)
- Olivary nuclei act as a major staging area for motor and sensory information entering the cerebellum
- Enter through the inferior cerebellar peduncle
- Synapse with Purkinje cell dendrites
- Collateral branches form excitatory connections with the deep cerebellar nuclei
- Slow firing rate, strong enough to initiate an action potential
- Open calcium channels affecting the metabolism of the Purkinje cell
- The mechanism responsible for motor learning
- One climbing fiber can connect to as many as 300 Purkinje cells
Cerebellar Circuits
- Mossy fibers influence cerebellar output via two pathways:
- A direct pathway to the cerebellar nuclei
- A less direct pathway through the cerebellar cortex
- Climbing fibers are thought to convey error signals to the Purkinje cells
- Excitatory inputs from:
- Granule cells (parallel fibers)
- Mossy fibers
- Climbing fibers
- Aminergic fibers
- Inhibitory inputs from:
- Purkinje cells
- Stellate and basket cells
- Golgi cells
Afferent-Efferent Communication
- The inferior olive serves as a relay center for sensory information into the cerebellum
- Descending input via the cortex and spinal cord
- The cerebellum analyzes the afferent information, which is compared to planned movement and sensory experiences, sending error signals for online adjustments of movements
- Output from the cerebellum via Purkinje cells:
- Refinement of motor activities
- Impairment to Purkinje cells and the inferior olive causes:
- Ataxia
- Loss of coordination
- Dysphagia
- Dysarthria
Functional Divisions
- Based on connections made within the CNS:
- Vestibulocerebellum
- Spinocerebellum
- Cerebrocerebellum
Vestibulocerebellum
- Functional name for the Flocculonodular lobe
- Receives afferent input from:
- Vestibular Nuclei
- Vestibular apparatus
- Projects to:
- Vestibular nuclei
- Output reaches lower motor neurons (LMNs) via:
- Vestibulospinal tract
- Regulates equilibrium
- Example: When a person reaches for a book from a high shelf, the vestibulocerebellum provides anticipatory contraction of lower limb and back muscles to maintain balance.
- Supplies:
- Middle Cerebellar Peduncle
- Superior Cerebellar Peduncle
- Deep Cerebellar Nuclei
- Cerebellar White Matter
- Infarction causes:
- Limb and Gait Ataxia
- Abnormal saccades
- Nystagmus
Anterior Inferior Cerebellar Artery
- Supplies:
- Medulla and Pons
- Inferior Middle peduncle
- Inferior Peduncle
- Flocculus
- Vermis
- Inferior Cerebellar Cortex
- Infarctions cause:
- Limb and gait ataxia
Posterior Inferior Cerebellar Artery
- Supplies:
- Dorsolateral Medulla
- Inferior/Posterior Vermis
- Inferolateral surface of the cerebellum
- Dentate Nucleus
- Infarctions cause:
- Rotatory dizziness
- Nausea and vomiting
- Imbalance
- Nystagmus
Cerebellum Clinical Disorders
- Cerebellar lesions affect the ipsilateral side of the body
- Signs of Cerebellar Dysfunction:
- Ataxia/Ataxic Gait
- Nystagmus
- Dysdiadochokinesia
- Dysmetria
- Decomposition of Movement
- “Intentional tremor”
Ataxia
- Area Involved: Any lesion causes ataxia
- Ataxia is characterized by voluntary, normal-strength, jerky, and inaccurate movements
- Vermal and flocculonodular lesions lead to truncal ataxia
- Paravermal lesions result in gait and limb ataxia
- Lateral cerebellar lesions cause hand ataxia
Testing for Speed and Accuracy
- Finger to finger or finger to nose can be used to test
- Demonstrates intentional tremor
Vestibulocerebellar Lesions
- Signs:
- Ataxic Gait
- Patient will fall toward the side of the lesion
- Nystagmus
- Vertigo
- Emesis
- Ataxic Gait
Spinocerebellar/Cerebrocerebellar Lesions
- Dysdiadochokinesia – loss of timing between agonist and antagonist
- Cannot perform rapid alternating movements
- Sequence of individual muscle contraction is impaired
- Dysmetria – performance deteriorates as the motor act progresses
- Different than intention tremor
- Hypermetria – forceful rebound of limb
- Decomposition – performance of motor activity by moving only one joint at a time because of an inability to control the entire movement
- Helps improve movement
- Ataxia – disruption in the precision of motor acts
Videos
- Abnormal Coordination Exam:
- Hand Rapid Alternating Movements Dysdiadochokinesia
- https://www.youtube.com/watch?v=ylcWsoBOGzk
- Dysmetria
- Abnormal Coordination Exam: Finger-to-nose
Comparison of basal ganglia and cerebellum
- Spinocerebellar receives sensory input
Comparison of lesions in basal ganglia versus cerebellum
| Basal Ganglia | Cerebellum |
|---|---|
| Resting tremor | Intention tremor |
| Bradykinesia or hypokinesia | Normal velocity of movement |
| Hyperkinesia | No hyperkinesia |
| Rigidity | Hypotonia |
| No ataxia | Ataxia |
| Secondary disequilibrium | Loss of equilibrium |
| No nystagmus | Nystagmus |
Clinical Case
- A 47 year old woman presents with increasing right-sided clumsiness and shaking.
- Symptoms began gradually 4 months ago.
- Examination findings:
- Normal somatosensation, autonomic function, and muscle strength
- Normal coordination on the left side
- Abnormalities on the right side:
- Slow and uncoordinated rapid alternating movements
- Intention tremor during finger-to-nose and heel-to-shin tests
- Right dysmetria on finger-to-nose test
- Abnormal involuntary eye movements
- Question 1:
- Location of lesion (structure and which side): The lesion is located on the right side of the Cerebellum.
Cerebellum
- Location: Posterior to the brainstem, inferior to the cerebrum
- Size: Accounts for 10% of brain volume
- Neuron Concentration: Contains over 50% of the neurons in the brain
- Structure: Two hemispheres separated by the vermis, contains folia (small ridges)
Cerebellar Lobes
- Flocculonodular Lobe: Located deep to the posterior lobe, touches the brainstem
- Anterior Lobe: Superior and separated from the posterior lobe by the primary fissure
- Posterior Lobe: The largest lobe
Cerebellar Nuclei
- Fastigial Nucleus: Most medially located, receives input from the vermis and vestibular, proximal somatosensory, auditory, and visual information. Projects to the vestibular nuclei and reticular formation.
- Interposed Nuclei: Includes globose and emboliform nuclei. Receives input from the intermediate zone and spinal, proximal somatosensory, auditory, and visual information. Projects to the contralateral red nucleus.
- Dentate Nucleus: Largest of the nuclei, receives afferent fibers from the medulla and projects to the contralateral red nucleus and ventrolateral thalamic nucleus.
Cerebellar Peduncles
- Inferior Cerebellar Peduncle: Restiform body (spinocerebellar fibers), mainly carries inputs
- Middle Cerebellar Peduncle: Massive connections to the pons via the brachium pontis, mainly carries inputs
- Superior Cerebellar Peduncle: Brachium conjunctivum, contains mainly efferent fibers.
Cerebellar Cellular Anatomy
- Three Cell Layers: Molecular layer, Purkinje cell layer, and granule cell layer
- Unique Circuits: For temporal and spatial processing of information, coordination of movement
- Excitatory Output: Of deep cerebellar nuclei is influenced by excitatory inputs of afferent collaterals and inhibitory influences of efferent cells
Neuronal Cell Types
- Purkinje Cells: Extensive dendritic tree, only output cells for the cerebellar cortex, axons synapse with the deep cerebellar nuclei, use GABA as neurotransmitter
- Granule Cells: Axons project to the folia and form parallel fibers, excitatory synapses with Purkinje cells.
- Basket Cells: Found in the molecular layer, axons extend across folia and send collateral branches to Purkinje cells, inhibitory synapses.
- Stellate Cells: Found in the molecular layer, axons extend across the folia, inhibitory synapses on Purkinje cells.
- Golgi Cells: Deep to the Purkinje cells, axons enter the granule layer, inhibitory to granule cells.
Cerebellar Functions
- Balance and Posture Maintenance: The vermis and flocculonodular lobe are essential for coordinating balance and posture
- Voluntary Movement Coordination: The spinocerebellum and cerebrocerebellum are responsible for coordinating limb movements
- Motor Adaptation and Learning: The cerebellum plays a crucial role in learning new motor skills
- Cognitive Functions: Recent research suggests the cerebellum plays a role in cognitive functions such as language and attention
Clinical Case
- Lesion Location: Based on the symptoms, the lesion is likely located in the right cerebellar hemisphere.
- Clinical Manifestations: Right sided clumsiness and shaking, intention tremors, dysmetria, abnormal involuntary eye movements are consistent with cerebellar dysfunction.
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Description
This quiz covers the structure and function of the cerebellar nuclei, including the Interposed and Dentate nuclei, as well as the Vestibular nuclei located in the brainstem. Understand their inputs, outputs, and the significance of cerebellar peduncles in motor control. Perfect for students studying neuroscience and neuroanatomy.
