Neural Circuits and Systems Neuroscience
Author: Martina Radice | Email: radicemarti@gmail.com
Martina Radice1°2°, Federico Yulita1°3°, Lidia Szczupak1°2°
1° Instituto de Fisiología, Biología Molecular y Neurociencias, UBA-CONICET, Argentina.
2° Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
3° Departamento de Física, Universidad de Buenos Aires, Argentina
Central pattern generators (CPGs) are neuronal networks that produce rhythmic behaviors like locomotion. Ex vivo preparations that retain core functionality and produce fictive patterns resembling those in vivo have been essential for studying CPGs.
Leeches have been used to study motor control due to their robust repertoire of motor behaviors executed by a relatively simple body plan and nervous system. On solid surfaces, leeches exhibit crawling, a robust rhythmic motor pattern resulting from waves of elongation and contraction that propagate along the body segments. Fictive crawling can be monitored in the isolated nervous system.
Extracellular recordings of various nerves during fictive crawling enabled single unit identification. Based on their rhythmic activity, units were classified considering whether they fired during the contraction phase, defined by motoneuron DE-3 activity, or during the elongation phase.
To compare ex vivo and in vivo motor patterns, we conducted kinematic measurements in intact leeches during crawling using DeepLabCut. The contraction and elongation duty cycles of specific body regions closely matched motoneuron activity from isolated ganglia of those sections. However, some motor pattern characteristics are not replicated in isolated ganglia due to intersegmental interactions. Combining physiological studies with mathematical models of coupled CPG chains seems essential to better understand how coordinated behavior emerges from the nerve cord.