Alicia Garrido-Peña, Irene Elices, Rafael Levi, Francisco B Rodriguez, Pablo Varona
Central Pattern Generators (CPG) generate and coordinate motor movements by producing rhythms composed of patterned sequences of activations in their constituent neurons. These robust rhythms are yet flexible and the time intervals that build the neural sequences can adapt as a function of the behavioral context. We have recently revealed the presence of robust dynamical invariants in the form of cycle-by-cycle linear relationships between two specific intervals of the crustacean pyloric CPG sequence and the period [1]. Following the same strategy, the present work characterizes the intervals that build the rhythm and the associated sequence of the feeding CPG of the mollusk Lymnaea Stagnalis. The study entails both the activity obtained in electrophysiological recordings of living neurons and the rhythm produced by a realistic conductance-based model. The analysis reported here first assesses the quantification of the variability of the intervals and the characterization of relationships between the intervals that build the sequence and the period, which allows the identification of dynamical invariants. To induce variability in the CPG model, we use current injection ramps in individual CPG neurons following the stimulation used in experimental recordings in [2]. Our work extends previous analyses characterizing the Lymnaea feeding CPG rhythm from experimental recordings and from modeling studies by considering all intervals that build the sequence [3]. We report the presence of distinct variability in the sequence time intervals and the existence of dynamical invariants, which depend on the neuron being stimulated. The presence of dynamical invariants in CPG sequences, not only in the model but also in two animal species, points out the universality of this phenomena.
Acknowledgements
We acknowledge support from AEI/FEDER PGC2018-095895-B-I00 and TIN2017-84452-R.
References
1\. Elices, I., Levi, R., Arroyo, D., Rodriguez, F. B., and Varona, P. (2019). Robust dynamical invariants in sequential neural activity. _Sci. Rep._ 9, 9048. doi:10.1038/s41598-019-44953-2.
2\. Elliott, C. J., and Andrew, T. (1991). Temporal analysis of snail feeding rhythms: a three-phase relaxation oscillator. _J. Exp. Biol._ 157, 391 LP – 408.
3\. Vavoulis, D. V, Straub, V. A., Kemenes, I., Kemenes, G., Feng, J., and Benjamin, P. R. (2007). Dynamic control of a central pattern generator circuit: a computational model of the snail feeding network. _Eur. J. Neurosci._ 25, 2805–2818. doi:10.1111/j.1460-9568.2007.05517.x.
