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

doi:10.1016/j.isci.2020.101409

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

iScience. 2020 Sep 1;23(9):101409. doi: 10.1016/j.isci.2020.101409. eCollection 2020 Sep 25.

Authors

Shinichiro Okamoto^{1

2

3}, Jaerin Sohn⁴, Takuma Tanaka⁵, Megumu Takahashi^{1

3}, Yoko Ishida¹, Kenta Yamauchi^{1

2}, Masato Koike^{1

2}, Fumino Fujiyama⁶, Hiroyuki Hioki¹

Affiliations

¹ Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
² Advanced Research Institute for Health Sciences, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
³ Department of Neuroscience, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
⁴ Division of Cerebral Circuitry, National Institute for Physiological Sciences, 5-1 Higashiyama Myodaiji, Okazaki, Aichi 444-8787, Japan.
⁵ Graduate School of Data Science, Shiga University, 1-1-1 Banba, Hikone, Shiga 522-8522, Japan.
⁶ Laboratory of Neural Circuitry, Graduate School of Brain Science, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0394, Japan.

Abstract

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.

Keywords: Biological Sciences; Cellular Neuroscience; Neuroscience.