Eklöf-Ljunggren, E., Haupt, S., Ausborn, J., Dehnisch, I., Uhlén, P., Higashijima, S.I., and El Manira, A. (2012) Origin of excitation underlying locomotion in the spinal circuit of zebrafish. Proceedings of the National Academy of Sciences of the United States of America. 109(14):5511-5516.
Neural circuits in the spinal cord transform instructive signals from the brain into well-coordinated locomotor movements
by virtue of rhythm-generating components. Although evidence suggests that excitatory interneurons are the essence of locomotor
rhythm generation, their molecular identity and the assessment of their necessity have remained unclear. Here we show, using
larval zebrafish, that V2a interneurons represent an intrinsic source of excitation necessary for the normal expression of
the locomotor rhythm. Acute and selective ablation of these interneurons increases the threshold of induction of swimming
activity, decreases the burst frequency, and alters the coordination of the rostro–caudal propagation of activity. Thus, our
results argue that V2a interneurons represent a source of excitation that endows the spinal circuit with the capacity to generate