| Autor: |
Arshavsky, Yu. I., Orlovsky, G. N., Panchin, Yu. V., Pavlova, G. A. |
| Zdroj: |
Experimental Brain Research; November 1989, Vol. 78 Issue: 2 p398-406, 9p |
| Abstrakt: |
In previous work carried out on the isolated pedal ganglia of the pteropod mollusc Clione limacina we described the activity of a neuronal element (type 12 neuron) and looked into its role in the locomotor rhythm generation (Arshavasky et al. 1985d). As we learned subsequently, the activity was recorded from the neuron axon passing in the pedal ganglia, while the neuron soma was located in the pleural ganglia and consequently was cut off in the course of pedal ganglia isolation. It thus became necessary to reinvestigate the properties of this neuron and its role in locomotory rhythm generation by using less reduced preparation of the central nervous system. The following results were obtained. (1) Each pleural ganglion contains only one neuron of this type, this cell is thus to be considered as the identified neuron. The neuron's axon reaches into the pedal ganglion via the pleuro-pedal connective. Then the axon divides into two branches terminating in the lateral regions of both pedal ganglia. The neurons 12 from the left and right pleural ganglia have no direct connections with one another; their synchronous operation in the locomotor cycle is determined by common inputs. (2) The electrical properties of an intact neuron 12 and one without a soma are about the same. In either case the neuron generates “plateau” potentials, i.e., it may persist for a long time in the depolarized state. Plateau potentials can be induced by a depolarizing current pulse or by an EPSP, and terminated by hyperpolarizing current or by an IPSP. The neuron input resistance drops about twofold during generation of the plateau potential. (3) Recording of the neuron 12 in the pleural ganglia showed that its activity during “fictive swimming” does not differ from that of somadeprived axon recorded in the isolated pedal ganglia. The neuron generates a plateau potential in the V-phase of the locomotor cycle (definitions for the phases of the cycle were given in Arshavsky et al. 1985b). This potential is triggered by an EPSP evoked by subgroup 8d pedal neurons. The plateau potential terminates in the D-phase under the influence of an IPSP evoked by group 7 neurons. The effects of the neuron 12 on other neuronal elements of the locomotor generator in pedal ganglia do not depend on the presence of the cell soma either. (4) The pedal ganglia locomotor generator sometimes generates an “anomalous rhythm” when normal cycles alternate with reduced ones in which the activity of some groups of neurons is inhibited. Simultaneous recording from two neurons 12 demonstrated that the alternating rhythm generation was caused by the anomalous behaviour of one of the neurons 12: the neuron persisted in the depolarized state for one cycle and a half and not for half a cycle, as during the normal operation of the locomotor generator. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Full text from SpringerLink