Internal-switches of a central pattern generator for scratching in the cat
Gutiérrez-Ojeda J, Hernández LF, De la Torre Valdovinos B, Huidobro N, Manjarrez E
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, México
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Abstract
The spinal neurons exhibit an ON-OFF and OFF-ON firing activity related to the central pattern generator (CPG) (Cuellar et al., 2018, Front Cell Neurosci 12:68). However, this activity was only examined around the “postural stage” of fictive scratching, disregarding the firing behavior during and at the end of the scratching episodes. Here we extended such observations to include the analysis of the whole episodes. The scratching episodes were divided into three stages: “before,” “during,” and “after.” We found the following firing patterns associated with the whole scratching episodes at those stages: 1)ON-OFF-ON, 2)OFF-ON-OFF, 3)ONstart-OFF-ONend, 4)OFFstart-ON-OFFend, 5)ON-OFF-OFF, and 6)OFF-OFF-ON. Because these patterns resemble “switches” or “gates” turning ON or OFF the flow of firing electrical activity, we suggest that they could be useful to develop new models of neural computation for the central pattern generator.
Methods
The experiments were performed in two decerebrate and paralyzed cats, following the National Institutes of Health Guide for the Care and Use of Laboratory Animals (85–23) and the Mexican regulations (NOM-062-ZOO-1999). We recorded the cord dorsum potentials from L4 to S1 segments to identify the spinal region with maximal activity during scratching. Then, we registered the intraspinal multiunit activity in that region. We also recorded the electroneurographic signals from the flexor and extensor nerves. Finally, we employed spike sorting software to select the unitary spikes from 743 neurons.
Results
Conclusion
The firing patterns of CPG neurons during scratching resemble “switches” or “gates” turning ON or OFF the electrical firing activity. We suggest that they could help develop new models of neural computation for the central pattern generator.
References
Cuellar et al. (2018) The spinal neurons exhibit an ON-OFF and OFF-ON firing activity around the onset of fictive scratching episodes in the cat. Frontier in Cellular Neuroscience.
Tapia et al. (2013) Reticular activating system of a central pattern generator: premovement electrical potentials. Physiological Reports, e00129.
Fig. 1 Experimental montage. Left panel, AgCl electrode array to record the cord dorsum potentials along the L4-S1 spinal segments. Right panel, intraspinal multiunit recordings in the region of maximal electrical activity from the cord dorsum.
Fig 2. Firing patterns of spinal neurons associated with scratching. The dashed magenta lines indicate the beginning and end of the scratching episodes. These patterns resemble “switches” or “gates” turning ON or OFF the flow of firing electrical activity around the scratching episodes.
Fig. 3 We show the firing rate according to each scratching stage (”before, “during” and “after”).
Fig 4. Detailed segmentation of the scratching episodes into nine parts to appreciate the neuronal firing rate changes during the following three patterns: ONstart-OFF-ONend, OFFstart-ON-OFFend, and ON-OFF-OFF.
Fig. 5. Hypothetical model of the central pattern generator for scratching.