Microelectrode analysis of light responses in the brain of the cricket ( Gryllus domesticus ) This research was done during the tenure of a U.S.P.H.S., N.I.M.H. postdoctoral fellowship (H.D.) and was supported by N.S.F. grant GB-1711 to S. S. Fox. For technical assistance we are grateful to Miss Bonnie Cross and Miss Joanna Wirble.

Abstract

Electrical activity in response to light stimuli was recorded from the brain of the cricket ( Gryllus domesticus ) using stainless steel microelectrodes. Four basic types of elements were observed as follows: (1) units which registered ambient light intensity by frequency of firing as well as responding with transient changes in rate to stepwise increases or decreases in intensity; (2) units which fired at a higher frequency in dark than in light; (3) units which fired continuously at low level in light and responded with a transient high frequency burst to light off; and (4) units which responded with a brief burst to on and off, but tended to be “on-dominant” or “off-dominant.” Also observed were synchronized spikes in mushroom body responding primarily to light off, but also on occasion to light on, and often accompanied by single unit responses. The units registering intensity are probably homologous with units showing similar properties recorded from the visual systems of several other arthropods and usually referred to as “sustaining units.” On-off, off, and dark units are also known from other forms. The mushroom body light responses were similar to synchronized spikes recorded in cockroach mushroom body following antennal stimulation.