Basal Ganglia and Motor Control System

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Questions and Answers

Which of the following cortical areas provides primary and secondary somatosensory information to the basal ganglia?

Frontal cortex

Cingulate cortex

Temporal cortex

Parietal cortex (correct)

What is the consequence of the direct pathway in the basal ganglia?

Inhibition of movement

Facilitation of movement (correct)

Processing of visual information

Modulation of emotional status

What is the effect of the dopaminergic nigrostriatal projection?

Facilitation of motor activity (correct)

Modulation of emotional status

Inhibition of motor activity

Processing of auditory information

Which of the following is NOT a source of input to the basal ganglia?

Cerebellum Signup and view all the answers

What is the role of the indirect pathway in the basal ganglia?

Inhibition of movement Signup and view all the answers

Which neurotransmitter is involved in the modulation of the direct and indirect pathways?

Acetylcholine Signup and view all the answers

What is the main input nucleus of the basal ganglia?

Striatum Signup and view all the answers

What is the function of the basal ganglia?

A unified functional unit that works closely with the cerebral cortex and corticospinal motor control system Signup and view all the answers

What is the role of the striatum in the basal ganglia?

Receives input from the cortex Signup and view all the answers

Which of the following pathways involves the projection from the striatum to the globus pallidus external (GPe)?

Indirect pathway Signup and view all the answers

What are the two separate nuclei that make up the Globus pallidus?

Internal and external segments Signup and view all the answers

What is the function of the pars compacta of the Substantia nigra?

Contains dopaminergic cells that project heavily to the striatum Signup and view all the answers

What is the function of the Subthalamic nucleus?

Receives projections from the external segment of the globus pallidus, cerebral cortex, thalamus, and brain stem Signup and view all the answers

What is the function of the internal segment of the Globus pallidus?

Is one of the major output structures of the basal ganglia Signup and view all the answers

What is the function of the Nucleus accumbens?

Participates in emotion regulation Signup and view all the answers

What is the function of the Putamen?

Participates in limb and trunk movement control Signup and view all the answers

What is the primary function of cholinergic striatal interneurons in the basal ganglia?

To decrease motor activity by inhibiting striatal cells of the direct pathway and exciting striatal cells of the indirect pathway Signup and view all the answers

Which of the following is NOT a function of the basal ganglia?

Visual perception Signup and view all the answers

What is the effect of lesions in the substantia nigra?

Parkinson's disease Signup and view all the answers

Which part of the basal ganglia is involved in the planning and programming of movements?

Putamen Signup and view all the answers

What is the role of the basal ganglia in cognitive control of motor activity?

Planning and programming of movements Signup and view all the answers

Which type of movements are characterized by sudden flailing movements of the entire limb?

Hemiballismus Signup and view all the answers

What is the effect of lesions in the caudate nucleus and putamen?

Huntington's chorea Signup and view all the answers

Which of the following is a function of the basal ganglia in motor control?

All of the above Signup and view all the answers

Study Notes

Basal Ganglia

The basal ganglia are a group of nuclei that act as a unified functional unit, closely associated with the cerebral cortex and corticospinal motor control system.

Structure

The basal ganglia consist of four principal nuclei:
- Striatum (input nucleus)
- Globus pallidus (output nucleus)
- Subthalamic nucleus
- Substantia nigra

Striatum

The striatum is the input nucleus of the basal ganglia, receiving afferent projections from the cerebral cortex.
Three subnuclei comprise the striatum:
- Caudate nucleus (participates in eye movement control and cognition)
- Putamen (participates in control of limb and trunk movements)
- Nucleus accumbens (participates in emotions)

Globus Pallidus

The globus pallidus consists of two separate nuclei: the external and internal segments.
The internal segment is one of the major output structures of the basal ganglia, while the external segment is part of their intrinsic circuitry.

Substantia Nigra

The substantia nigra includes two separate nuclei: the pars compacta and pars reticulata.
The pars compacta contains dopaminergic cells that project heavily to the striatum.

Subthalamic Nucleus

The subthalamic nucleus is a small nucleus situated between the thalamus and the substantia nigra.
It receives projections from the external segment of the globus pallidus, the cerebral cortex, thalamus, and brain stem, and sends output to both segments of the globus pallidus and to the substantia nigra pars reticulata.

Basal Ganglia Input

The basal ganglia receive input from:
- Parietal cortex (primary and secondary somatosensory information, secondary visual information)
- Temporal cortex (secondary visual and auditory information)
- Cingulate cortex (limbic and emotional status information)
- Frontal cortex (primary and secondary motor information)
- Prefrontal cortex

Cortico-Basal Ganglia-Thalamocortical Circuits

There are two important pathways through which striatal information reaches the globus pallidus (internal): the direct pathway and the indirect pathway.
The direct pathway facilitates movement, while the indirect pathway inhibits movement.

Functions of Basal Ganglia

The basal ganglia are involved in:
- Voluntary movement
- Postural control
- Control of muscle tone
- Role in arousal mechanism
- Speech
- Cognitive control of motor activity
- Planning and programming of movements
- Timing and scaling of intensity of movements
- Subconscious execution of some movements

Lesions of Basal Ganglia

Lesions of different nuclei can result in:
- Globus pallidus: athetosis (spontaneous writing movements of the hand, arm, neck, and face)
- Putamen: chorea (flicking movements of the hands, face, and shoulders)
- Substantia nigra: Parkinson's disease (rigidity, tremor, and akinesia)
- Subthalamus: hemiballismus (sudden flailing movements of the entire limb)
- Caudate nucleus and putamen: Huntington's chorea (loss of GABA-containing neurons to globus pallidus and substantia nigra)

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Description

Learn about the basal ganglia, its function as a unified motor system, and its association with the cerebral cortex and corticospinal motor control system.