✍ Scribed by George Camougis; Hedwig Kasprzak
No coin nor oath required. For personal study only.
Responses to illumination of the eyes of the crayfish were studied by gross recording from one of the circumesophageal connectives. Two-thirds of the spontaneous activity a t this level of the CNS consists of ascending activity, which is eliminated by cutting a connective posterior to the recording electrode. A n average of about eight fibers in a connective responded to 1 sec illumination of the homolateral eye. The fibers were of four types: pure-on units, on-sustained units, on-and-off units and pure-off units. The average latency was 74 msec for the on-response and 26msec for the off-response. The latency of responses to 10 Fsec flashes of increasing intensity shortened from 72 to 52msec. This was demonstrated to be mainly a peripheral effect since ERG latency showed a parallel reduction while the ERG-connective response interval remained more nearly constant at 40-50 msec. ERG amplitude, frequency, and usually the duration of the connective spike discharge increased at greater stimulus intensities, yet the average number of responding fibers was greatest at intermediate intensities. The results indicate minimal processing of response patterns by the brain.
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