Interaction of neurons at the level of cell bodies in the snail CNS. Heterogeneity of the neuroactive environment.

Experiments on the CNS of snail Lymnaea stagnalis in which a cell isolated from the serotonin cluster PeA was used as a mobile sensor neuron demonstrated the presence of neuroactive factors at the surface of the cellular "cortex" of the pedal ganglion. Apart from the previously known factor serotonin, effective concentrations of a factor suppressing the electrical activity of PeA were found at this site, along with a depolarizing factor which, unlike serotonin, narrowed PeA action potentials. The ability of these factors to control the electrical activity of the sensor neuron demonstrates the possible involvement of chemical agents in the intercellular space of the "cortex" in neuronal signaling.