Cholinergic control of striatal GABAergic microcircuits.

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Cholinergic interneurons (CINs) are crucial for striatal function.
• Acetylcholine signaling via muscarinic receptors (mAChRs) is well-known, but postsynaptic nicotinic receptors (nAChRs) on GABAergic interneurons (GINs) are increasingly recognized as critical.
• The precise interconnections between CINs and GINs, and their role in modulating striatal output, remain incompletely mapped.

Purpose of the Study:

• To elucidate the intricate mechanisms by which CINs modulate GINs populations.
• To identify the specific GINs populations involved in CIN-mediated striatal output modulation.
• To investigate the role of presynaptic and postsynaptic mAChRs and nAChRs in CIN-GINs communication.

Main Methods:

• Optogenetics was employed to stimulate and record neuronal activity.
• Electrophysiological techniques were used to study synaptic and electrical coupling.
• Immunohistochemistry was utilized to identify specific interneuron populations, including tyrosine hydroxylase-expressing GINs.

Main Results:

• CINs modulate four distinct GINs populations through a complex interplay of presynaptic and postsynaptic mAChRs and nAChRs.
• Tyrosine hydroxylase-expressing GINs were identified as key players in the disynaptic inhibition of striatal projection neurons (SPNs).
• Heterotypic electrical coupling between tyrosine hydroxylase-expressing GINs and neurogliaform interneurons contributes to SPN inhibition.

Conclusions:

• CINs exert significant control over GINs microcircuits through sophisticated synaptic and heterosynaptic mechanisms.
• The findings reveal a complex regulatory network involving multiple cholinergic receptor types and specific interneuron populations.
• This study advances our understanding of how CINs shape striatal circuits and influence neuronal output.