Abstract
The pacemaker nucleus of Gymnotus carapo contains two types of neurons: pacemaker cells which set up the frequency of the electric organ discharge (EOD) and relay cells which convey the command signal to the spinal cord. Direct activation of a single relay cell provides enough excitation to discharge a pool of spinal electromotor neurons and electrocytes, generating a small EOD (unit EOD). Different relay cells generate unit EODs of variable size and waveform, indicating the involvement of different groups of electrocytes. A special technique of EOD recording (multiple air-gap) was combined with intracellular stimulation of relay cells to study the spatial distribution within the electric organ (EO) of the command signal arising from different relay cells. Three types of relay cells could be identified: type I commanding the rostral 10% of the EO, type II which distribute their command all along the EO and type III driving the caudal 30%. Waveform analysis of unit EODs indicates that doubly innervated electrocytes which are the most relevant for attaining the specific EOD waveform, receive a favored command from the pacemaker nucleus.
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Abbreviations
- CV:
-
conduction velocity
- EMF:
-
electromotive force
- EMN:
-
electromotor neuron
- EO:
-
electric organ
- EOD:
-
electric organ discharge
- PN:
-
pacemaker nucleus
- uEOD:
-
unit electric organ discharge
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Lorenzo, D., Sierra, F., Silva, A. et al. Spatial distribution of the medullary command signal within the electric organ of Gymnotus carapo . J Comp Physiol A 173, 221–226 (1993). https://doi.org/10.1007/BF00192980
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DOI: https://doi.org/10.1007/BF00192980