iScience (Sep 2020)

Overlapping Projections of Neighboring Direct and Indirect Pathway Neostriatal Neurons to Globus Pallidus External Segment

  • Shinichiro Okamoto,
  • Jaerin Sohn,
  • Takuma Tanaka,
  • Megumu Takahashi,
  • Yoko Ishida,
  • Kenta Yamauchi,
  • Masato Koike,
  • Fumino Fujiyama,
  • Hiroyuki Hioki

Journal volume & issue
Vol. 23, no. 9
p. 101409

Abstract

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Summary: Indirect pathway medium-sized spiny neurons (iMSNs) in the neostriatum are well known to project to the external segment of the globus pallidus (GPe). Although direct MSNs (dMSNs) also send axon collaterals to the GPe, it remains unclear how dMSNs and iMSNs converge within the GPe. Here, we selectively labeled neighboring dMSNs and iMSNs with green and red fluorescent proteins using an adeno-associated virus vector and examined axonal projections of dMSNs and iMSNs to the GPe in mice. Both dMSNs and iMSNs formed two axonal arborizations displaying topographical projections in the dorsoventral and mediolateral planes. iMSNs displayed a wider and denser axon distribution, which included that of dMSNs. Density peaks of dMSN and iMSN axons almost overlapped, revealing convergence of dMSN axons in the center of iMSN projection fields. These overlapping projections suggest that dMSNs and iMSNs may work cooperatively via interactions within the GPe.

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