Lecture 10 NROB60 Question And Answer

These flashcards cover key concepts from the lecture on the functional anatomy of the cerebellum and basal ganglia, providing a comprehensive review tool for the exam.

What is the primary function of the pyramidal system?

To carry descending signals from upper motor neurons in the motor cortex to the brainstem or spinal cord.

What are the two main tracts of the corticospinal pathway?

Lateral corticospinal tract (distal movements) and anterior corticospinal tract (proximal movements).

Where do upper motor neurons innervate lower motor neurons?

In the ventral horns of the spinal cord.

What does the reticulospinal tract primarily do?

Coordinates axial and proximal limb muscles to stabilize posture during movements.

How does the basal ganglia influence movement?

It helps to initiate and terminate movements and controls unwanted movements.

What do the structures of the cerebellum and basal ganglia have in common?

Both are involved in the regulation of upper motor neuron activity.

What is the hallmark of cerebellar damage?

Difficulty producing smooth, well-coordinated movements.

What are the three major functional divisions of the cerebellum?

Spinocerebellum, cerebrocerebellum, vestibulocerebellum.

What characteristic symptoms result from chronic alcohol abuse affecting the cerebellum?

Wide and staggering gait due to degeneration of the anterior spinocerebellum.

What type of neurons are found predominantly in the striatum of the basal ganglia?

Medium spiny neurons (MSNs).

What neurotransmitter do Purkinje cells predominantly release?

GABA.

What type of input do Purkinje cells receive?

Excitatory input from parallel fibers from granule cells and climbing fibers from the inferior olive.

What is the function of the fastigial nucleus in the cerebellum?

Involved in balance and sends axons to vestibular nuclei.

What does the term 'decomposition of movement' refer to?

The breakdown of smooth, skilled movements into individual segments.

What happens when dopaminergic neurons in the substantia nigra degenerate?

It leads to reduced voluntary movement and is a hallmark of Parkinson's disease.

What are the clinical signs of Huntington’s disease?

Hyperkinesia, chorea, and cognitive deficits.

What is the functional implication of the cerebellum's ipsilateral control?

The right cerebellum controls the right side of the body and vice versa.

How do cerebellar inputs from the spinal cord differ from those from the cortex?

Spinal cord inputs remain ipsilateral, while cortical inputs cross midline.

What are basket and stellate cells in the cerebellum?

Types of inhibitory interneurons that modulate the activity of Purkinje cells.

What are the outputs from the deep cerebellar nuclei?

They project to motor nuclei of the thalamus and contribute to motor control.

What does EMG stand for and what does it measure?

Electromyography; it measures muscle activity.

What are the two types of inputs to the striatum in the basal ganglia?

Glutamatergic (excitatory) inputs from the cortex and dopaminergic inputs from the substantia nigra.

What is the main difference between direct and indirect pathways in the basal ganglia?

The direct pathway facilitates movement, while the indirect pathway inhibits movement.

What pathology causes tremor at rest and rigidity in patients?

Parkinson's disease due to degeneration of dopaminergic neurons.

How does the cerebellum assist in motor learning?

By detecting motor errors and making adjustments during movements.

What visual representation can be used to monitor neuronal firing patterns?

Raster plots.

What is the relationship between the cerebellum and the basal ganglia?

Both are critical in regulating and refining motor output.

What type of signals does the cerebellum correct during movement?

Motor errors between intended and actual movements.

What results from connections between cerebellar outputs and thalamic inputs?

Regulation of upper motor neurons for motor control.

What happens when there is damage to the cerebellum?

Errors in motor coordination, balance, and movement smoothness.

What type of neuron is primarily involved in the cortico-striatal-thalamic circuit?

Medium spiny neurons (MSNs).

What mechanism increases motor cortex excitability?

Dopamine release in the basal ganglia decreasing inhibitory output.

How does the reticulospinal tract function in postural stability?

By making anticipatory adjustments to stabilize posture.

What is the role of the cerebellar output to the brainstem motor systems?

To modify activity of lower motor neurons.

What neurophysiological change is observed in Purkinje cells during movement?

Their activity changes based on ongoing movement and modulation.

What pattern do the activity of cells in the deep cerebellar nuclei reflect?

It reflects excitatory input received from climbing and mossy fibers.

What does degeneration of medium spiny neurons lead to in Huntington’s disease?

Reduced inhibitory output and hyperexcitability of upper motor neurons.

What is ataxia and how is it related to cerebellar function?

Loss of coordination due to cerebellar damage.

What role do climbing fibers play in the cerebellum?

They provide powerful excitatory inputs to Purkinje cells.

What are the main components of the extrapyramidal system?

Reticulospinal tract and rubrospinal tract.

What is the function of the vestibulocerebellum?

To coordinate balance and postural adjustments.

What role do inhibitory interneurons play in the cerebellum?

They modulate the activity of Purkinje cells via GABA.

How does the structure of the cerebellum aid in its function?

Its layered organization allows for precise processing of motor information.

What is the significance of somatotopic maps in the cerebellum?

They help represent body surface areas and motor coordination.

What is the role of mossy fibers in cerebellar inputs?

They relay information from various sources into the granule cells.

What pathological changes characterize cerebellar ataxia?

Jerky and imprecise movements, frequently overshooting or undershooting targets.

What role does the globus pallidus have in the basal ganglia?

It is involved in sending inhibitory signals to the thalamus to regulate movement.

How do cerebellar projections differ from other motor pathways?

They do not have direct access to lower motor neurons.

What neurotransmitter is commonly released by climbing fibers?

Glutamate.

What happens to the cerebellum's function when it is damaged?

It results in disrupted motor coordination and increased motor errors.

How do deep cerebellar nuclei contribute to cerebellar output?

They provide output signals to the thalamus and brainstem that modulate motor activity.

What clinical implications arise from cerebellar dysfunction?

Motor disorders and the ability to execute coordinated activities.

What is the significance of the Purkinje cell layer in the cerebellum?

It is crucial for inhibitory outputs to deep cerebellar nuclei.

What type of lesions did the lectures discuss concerning sensory pathways?

Unilateral lesions that cause specific sensory deficits and clues for localization.

How does the basal ganglia control eye movements?

Through its projections to the superior colliculus.

What output fibers connect the cerebellum to the motor thalamus?

Deep cerebellar nuclei axons connect to motor thalamic nuclei.

What symptoms would one expect from damage to the spinocerebellum?

Loss of muscle tone and impaired coordination.

What are the differences between D1-type and D2-type MSNs?

D1-type MSNs are part of the direct pathway, facilitating movement; D2-type MSNs are part of the indirect pathway, inhibiting movement.

How does the cerebellum aid in motor error correction?

By comparing intended movements with actual movements and making real-time adjustments.

What are the overarching roles of the cerebellum and basal ganglia together?

Together, they fine-tune motor control, learning, and coordination.

How do alterations in descending pathways affect voluntary movement?

They can lead to conditions like Parkinson's and Huntington's diseases.

What defines the term 'extrapyramidal' in neurology?

Refers to motor pathways that do not pass through the medullary pyramids.

What benefits does recovering from cerebellar lesions provide?

Recovery can lead to compensatory adaptations in motor function.

What role does proprioception play in cerebellar function?

It provides feedback necessary for the cerebellum to adjust movements accurately.

How are the anatomical divisions of the cerebellum functionally related?

Each division corresponds to different aspects of motor control and function.

What is the role of the inferior olive in the cerebellar circuitry?

It provides critical input to climbing fibers that influence Purkinje cells.

What does it mean for a neuron to be GABAergic?

It releases GABA as its primary neurotransmitter, acting inhibitory.

What aspects of movement do the basal ganglia influence?

They influence initiation, amplitude, and direction of movements.

What are potential outcomes of direct and indirect pathways’ interactions in movement disorders?

Imbalances can lead to either excessive movement (Huntington's) or insufficient movement (Parkinson's).

What is the overall physiological significance of the cerebellar circuitry?

It forms integrated control pathways for coordinating and refining movement.

How do excitation and inhibition interact within cerebellar circuits?

Excitation from mossy and climbing fibers must balance with inhibition from Purkinje cells.

What is the significance of identifying different Purkinje cell types?

Different types likely have unique functions and responses in motor control.

Why is it clinically relevant to understand the basal ganglia's pathways?

It aids in diagnosis and treatment of movement disorders.

What criteria can differentiate between types of cerebellar ataxia?

Assessment of movement smoothness, appropriateness, and correction during tasks.

How do cerebellar outputs contribute to the learning of new motor skills?

They facilitate adjustments based on real-time sensory feedback.

What specific anatomical structures make up the basal ganglia?

Striatum (caudate and putamen), globus pallidus, corona radiata, substancia nigra.

What is the effect of cerebellar lesions on gait?

Altered gait patterns characterized by instability and lack of coordination.

How does the cerebellum process sensory information?

It synthesizes inputs from various sensory systems to guide motor output.

What characterizes the input-output processing in the cerebellar internal circuitry?

Modulation of output signals to ensure accurate and coordinated movement.

What condition is defined by difficulties in initiating and executing movements?

Parkinson's disease.

How does the composition of the cerebellum differ from the cerebrum?

The cerebellum contains more neurons despite its smaller size.

What clinical challenges arise from medium spiny neuron degeneration?

Heightened levels of involuntary movements and disrupted motor control.

What does hypokinesia refer to in the context of Parkinson's disease?

The reduced ability to initiate movements.

What is the feedback loop between the cerebellum and locomotor patterns?

Cerebellar outputs adjust motor commands to improve movement precision.

What is the anatomical layout of the cerebellar cortex?

Three layers: molecular layer, Purkinje cell layer, and granule cell layer.

How do visual tracking errors manifest as a symptom of cerebellar dysfunction?

Inability to smoothly follow moving targets due to impaired coordination.

What impact does cerebellar function have on hand-eye coordination?

Directly associated with adjustments made during visually-guided actions.

What vital roles do fastigial and dentate nuclei serve?

Fastigial nucleus is involved in balance; dentate nucleus is involved in voluntary movements.

What does cerebellar processing of motor commands ensure?

Ensures that movements are smooth, precise, and adapted based on feedback.

What role does the output signal of the cerebellum have on motor control?

It modulates motor activity by providing corrective feedback to upper motor neurons.

What do the basal ganglia help determine in the context of motor actions?

Initiation, modulation, and inhibition of various movements.

What is meant by 'motor learning' in terms of cerebellar function?

The process through which the cerebellum adjusts future movements based on previous performance.

How is muscle tone affected by the cerebellar circuits?

Cerebellar circuits help regulate and maintain muscle tone during movements.

What is a key functional aspect of the purkinje cells in the cerebellum?

Inhibiting deep cerebellar nuclei to refine motor outputs.

How does chronic alcohol consumption alter cerebellar processing?

Leads to structural degeneration and impaired coordination of movement.

What is seen in cerebellar ataxia that distinguishes it from other motor disorders?

Inconsistent and erratic movement patterns without direct involvement of sensation loss.

How does the cerebellum impact postural adjustments?

It continuously processes sensory feedback to adapt posture before and during movements.

In terms of functionality, why is the cerebellum considered the 'little brain'?

Due to its complex architecture that fine-tunes motor control and coordination.

Why is the reticulospinal tract important during complex motor tasks?

It prepares the body and adjusts posture in anticipation of voluntary movements.

How does feedback from the cerebellum affect future movements?

It generates error correction signals that refine motor strategy for upcoming movements.