Cholinergic innervation in the human striatum: a three-compartment model

Area of Science:

• Neuroscience
• Neuroanatomy
• Molecular Biology

Background:

• The mammalian striatum exhibits compartmentalization, with dorsal and ventral regions differing in organization.
• The dorsal striatum is typically described with striosomes and matrix, while the ventral striatum has a more complex structure.
• Understanding striatal compartmentalization is key to deciphering its diverse functions.

Purpose of the Study:

• To characterize the compartmentalization of the human dorsal and ventral striatum.
• To utilize choline acetyltransferase (ChAT) as a marker for striatal compartments.
• To compare ChAT-defined compartments with acetylcholinesterase (AChE) staining patterns.

Main Methods:

• Immunohistochemical staining for choline acetyltransferase (ChAT) in human striatal tissue.
• Image analysis to quantify immunostaining intensity and define compartments (intensely, moderately, weakly stained).
• Comparison of ChAT staining patterns with adjacent acetylcholinesterase (AChE) stained sections and mapping of cholinergic somata.

Main Results:

• Three distinct ChAT-immunostained compartments were identified: intensely, moderately, and weakly stained areas.
• The dorsomedial striatum showed a striosome/matrix organization, while the ventral and lateral striatum displayed a more complex, multi-compartmental pattern.
• Cholinergic somata densities generally correlated with ChAT immunostaining intensity, with notable exceptions in the rostroventral striatum.

Conclusions:

• The human striatum, particularly the ventral portion, exhibits a complex, multi-compartmental organization.
• This complex organization suggests an expanded and more differentiated role for the ventral striatum in the human brain compared to other mammals.
• Differences in cholinergic cell distribution and projection patterns may underlie regional functional specializations within the striatum.