ELECTRIC ORGAN DISCHARGE FREQUENCY-MODULATION EVOKED BY WATER VIBRATION IN GYMNOTUS-CARAPO

1. The electric organ discharge (EOD) frequency modulations evoked by brief water vibration were analysed in the pulse-type fish Gymnotus carapo. 2. The response consisted of a transient increase of the EOD frequency at short latency (30 msec). Response profiles were characteristic of the specimen and relatively independent on stimulus intensity. 3. Conversely, they were dependent on stimulation sequence, showing a rapid decrement along successive stimuli and high temporal discrimination. 4. The brief latencies indicate a relatively simple neural circuit. 5. The response may be an electrolocation enhancement strategy for the detection of moving objects based on "sampling" the periphery at a higher frequency.