Network interactions among sensory neurons.

ANTONIA MARIN BURGIN; LIDIA SZCZUPAK

Orlando

Congreso; Meeting of the society for neuroscience; 2002

Society for Neuroscience

Interactions among primary sensory neurons contribute to the processing of sensory information. Mechanosensory neurons sesitive to touch (T), pressure (P) and nociceptive stimuli (N) in the leech nervous system were studied in isolated ganglia and in body-wall preparations. Stimulation of P and N evoked depolarizing and hyperpolarizing responses in T cells. The relative expression of the two components depended on the duration of the stimuli. One or two spikes in P cells produced, predominantly, a depolarization of the T cells, and increasing number of spikes evoked, predominantly, hyperpolarizing responses. N cells produced more often the hyperpolarization of T cells at any stimulus duration. The synaptic responses evoked by P and N were mediated by interneurons.When T cells fired due to the injection of positive current into the soma (central excitation), concomitant stimulation of P cells inhibited the T cell activity. However, when T cells were excited by light mechanical stimuli applied on the skin (peripheral excitation), stimulation of P cells failed to inhibit the activity of the T cells. The results indicate that the inhibitory synaptic input impinged the T cell at its central branches, at a site proximal to the soma, and away from the spike initiation zone activated by peripheral stimulation.