Fast or slow? Cellular and molecular adaptations underlying different frequency regimes in spinal motor systems

• Applicant: Professor Dr. Boris Chagnaud
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 333218137

The ability to move is essential for the most important tasks in an animals life: the search for shelter or food and reproductive success. In vertebrates, locomotion is governed by spinal circuits that generate alternating contractions of bilaterally organized skeletal muscles. Independent of locomotor style, such as walking, running, swimming, flying or crawling, highly conserved spinal locomotor circuits, i.e., central pattern generators (CPGs), coordinate the activity of motoneurons innervating the skeletal muscles. While adaptations in the general spinal blueprint circuit between undulating and bi- or quadrupedal moving animals lead to different locomotor patterns, individual motor patterns (e.g. bilaterally alternating skeletal contractions) display widely diverging ranges of frequencies between fast or slowly moving animals. The goal of the proposed study is to investigate, at a network, cellular and molecular level, the mechanisms that enable evolutionarily conserved neuronal circuits to generate widely different frequency regimes. Rattlesnakes offer a unique opportunity to address this question since they produce two different spinal behaviors at distinct frequency ranges. The predominant part of the cord generates low frequency alternating muscle contraction sequences for locomotion (ca. 4-15Hz), whereas the most caudal part of the spinal cord generates high frequency alternating patterns (ca. 80-120 Hz) for acoustic signaling (rattling). The presence of two functionally different spinal systems in one animal provides a unique opportunity to investigate evolutionary adaptations that enable or cause highly diverging frequency regimes without having to consider possible interspecies differences. Using electrophysiological, pharmacological, anatomical and molecular methods, the goal of this proposed study is to elucidate the mechanisms responsible for these widely different frequency regimes at a network, single cell, and molecular level. The general hypothesis is that the general spinal network organization is retained between the two different rattlesnake spinal patterns, and that cellular adaptations lead to the different frequency regimes. This study will help shed light on how neuronal circuits that share a common evolutionary origin can be modified to express different behaviors.Summary: Taking advantage of the presence of slow (locomotion) and fast (rattling system) spinal motor systems in the rattlesnake, the goal of the proposed study is to understand the underlying mechanisms leading to different frequency regimes in neuronal circuits that share a common evolutionary origin.

• DFG Programme: Research Grants
• International Connection: Austria