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Synaptic organization of the globus pallidus
1Department of Neurology, Harvard Medical School, Boston, Massachusetts.
Journal of Electron Microscopy Technique
|November 1, 1988
Summary
The globus pallidus features diverse neurons and axon terminals, primarily using GABA. Its unique synaptic structure may enable thalamic disinhibition via neostriatal activation.
Area of Science:
- Neuroscience
- Cellular Biology
- Neuroanatomy
Background:
- The globus pallidus is a key component of the basal ganglia circuitry.
- Understanding its synaptic organization is crucial for deciphering motor control and related functions.
Purpose of the Study:
- To review and synthesize current knowledge on the synaptic organization of the globus pallidus.
- To detail the types of neurons, fibers, axon terminals, and their relationships within the globus pallidus.
Main Methods:
- Review of studies using Nissl stains, Golgi impregnations, lesion degeneration, immunohistochemistry, and anterograde axonal labeling.
- Inclusion of ultrastructural data from various species.
- Analysis of neuronal morphology, dendritic arborizations, and axonal bouton types.
Main Results:
- The globus pallidus contains principal efferent neurons (GABAergic) and a smaller population of cholinergic neurons.
- Three prevalent types of axonal boutons (I, II, III) form synaptic contacts, with type I originating from neostriatal neurons (GABA/enkephalin positive).
- Synaptic architecture is characterized by dendrites ensheathed by axons, with infrequent triadic synapses.
Conclusions:
- The globus pallidus exhibits a complex synaptic organization with distinct neuronal populations and input sources.
- The inhibitory nature of striatopallidal and pallidothalamic connections suggests a mechanism for thalamic disinhibition upon neostriatal activation.