Peripheral and intraspinal feedback is required to shape and update the output of spinal networks that execute motor behavior. We report that lumbar dI2 spinal interneurons in chicks receive synaptic input from afferents and premotor neurons. These interneurons innervate contralateral premotor networks in the lumbar and brachial spinal cord, and their ascending projections innervate the cerebellum. These findings suggest that dI2 neurons function as interneurons in local lumbar circuits, are involved in lumbo-brachial coupling, and that part of them deliver peripheral and intraspinal feedback to the cerebellum. Silencing of dI2 neurons leads to destabilized stepping in P8 hatchlings, with occasional collapses, variable step profiles and a wide-base walking gait, suggesting that dI2 neurons may contribute to the stabilization of the bipedal gait.
Bibliographical noteFunding Information:
to AK from the Israel Science Foundation (grant No. 1400/16), the USʹIsrael Binational
Science Foundation (grant No. 2017/172) and the Avraham and Ida Baruch endowment fund.
The authors thank Haya Falk for PRV purification; Alona Katzir, Cole Bendor, Mevaseret Avital, Sapir Shevah, Eitan Yisraeli, Ruth Segal, Fedaa Bazan and Eden Kimchi for technical assistance; Nadav Yayon for assistance with the light sheet microscopy; and Michael O?Donovan for comments on the manuscript. This work was supported by grants to AK from the Israel Science Foundation (grant No. 1400/16), the US?Israel Binational Science Foundation (grant No. 2017/172) and the Avraham and Ida Baruch endowment fund.
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- Neuronal circuits
- Spinal cord
- Spinocerebellar tract