The function of photoexcitive neurones in the central ganglia for behavioral activity of the marine mollusc,Onchidium verruculatum

Summary

• 1. The function of the photoexcitive neurones located within the CNS in the marine pulmonate mollusc,Onchidium verruculatum was investigated.

• 2. A light-evoked discharge was recorded from the photoexcitive neurones in the whole animal preparation (Fig. 3).

• 3. Tactile stimuli from the mantle were mediated synaptically to the photoexcitive neurones through the pleuro-parietal nerves of both sides (Fig. 4).

• 4. An attempt was made to confirm the tactile receptive field of the photoexcitive neurones, Ep-2, Bp-3 and Es-1 by stimulating the mantle surface of the animal with brush strokes (Fig. 5).

• 5. It was suggested that sensory inputs which inhibited the photoexcitive neurones were derived from some mechanoreceptors other than tactile receptors within the mantle (Fig. 6).

• 6. A stereotyped response (the mantle-levating reflex) was evoked by tactile stimuli given to the mantle surface. This response could also be elicited by direct electrical stimulation of the photoexcitive neurones (Fig. 8).

• 7. The photoexcitive neurones played a role in regulating the transmission of the tactile sensory information (Fig. 9).

• 8. From these results, it was postulated that the photoexcitive neurones modified the activity level of the mantle-levating reflex.