Hierarchical control of locomotion by distinct types of spinal V2a interneurons in zebrafish

• Published in: Nature communications Vol. 10; no. 1; pp. 4197 - 12
• Main Authors: Menelaou, Evdokia, McLean, David L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13-09-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 14/19; 14/34; 14/35; 631/378/2632/1823; 631/378/3920; 64/116; 9/74; Amplitudes; Animals; Car pools; Connectivity; Danio rerio; Humanities and Social Sciences; Interneurons; Interneurons - cytology; Interneurons - metabolism; Locomotion; Locomotion - physiology; Morphology; Motor neurons; Motor Neurons - cytology; Motor Neurons - metabolism; Motor task performance; multidisciplinary; Neural networks; Neurons; Neurosciences; Physiology; Science; Science (multidisciplinary); Spinal cord; Spinal Cord - cytology; Spinal Cord - metabolism; Vertebrates; Zebrafish
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-12240-3

In all vertebrates, excitatory spinal interneurons execute dynamic adjustments in the timing and amplitude of locomotor movements. Currently, it is unclear whether interneurons responsible for timing control are distinct from those involved in amplitude control. Here, we show that in larval zebrafish, molecularly, morphologically and electrophysiologically distinct types of V2a neurons exhibit complementary patterns of connectivity. Stronger higher-order connections from type I neurons to other excitatory V2a and inhibitory V0d interneurons provide timing control, while stronger last-order connections from type II neurons to motor neurons provide amplitude control. Thus, timing and amplitude are coordinated by distinct interneurons distinguished not by their occupation of hierarchically-arranged anatomical layers, but rather by differences in the reliability and probability of higher-order and last-order connections that ultimately form a single anatomical layer. These findings contribute to our understanding of the origins of timing and amplitude control in the spinal cord.
V2a excitatory interneurons in the spinal cord are important for coordinating locomotion. Here the authors describe two types of V2a neuron with differences in higher order and lower order connectivity in larval zebrafish.