Flash pattern recognition in fireflies.

A theory has been developed which explains the use of time intervals in an animal communication system. The theory is based upon the observation of female Photinus macdermotti firefly responses to artificial male flash sequences. An explanation for time discrimination in a firefly brain is proposed as follows. Upon receiving the flash from the male, the female firefly generates a response function composed of three intervals: initial inhibition or total blocking; acceptance; and long-term inhibition. This response function and discrimination bias generated by the short term memory, together with background noise, determine the firefly response time window. The female will answer only if the subsequent male's flash is received during this time window. Short-term memory is used for sensitivity adjustment, whenever sharp change is introduced in the triggering sequence. If the firefly is flashing under favorable conditions, she adjusts herself into a flashing mood and will flash once, even if the triggering changes towards marginal conditions. If the firefly is receiving a wrong input flash sequence, she will enter a non-flashing mood and will not flash on a first good interval. At high frequencies, the firefly blocks her input for a constant period after every flash. It is shown that the flash sequences predicted by the theory are in very good agreement with actual observed female firefly responses to artificial male flash sequences.