Temporal resolution in olfaction III: flicker fusion and concentration-dependent synchronization with stimulus pulse trains of antennular chemoreceptor cells in the American lobster

To understand how chemoreceptor organs may extract temporal information fro m odor plumes, we investigated the frequency filter properties of lobster c hemoreceptor cells. We used rapid stimulation and high-resolution stimulus measurement for accurate stimulus control and recorded extracellular respon ses from chemoreceptors in the lobster lateral antennule in situ. We tested 16 hydroxyproline-sensitive cells with a series often 100-ms pulses at 10, 100 and 1000 mu mol l(-1) at stimulation frequencies from 0.5 Hz to 4 Hz. Receptor cell responses could accurately encode 10 mu mol l(-1), but not 10 0 or 1000 mu mol l(-1) pulses, delivered at rates of 4 Hz. Flicker-fusion f requency and synchronization with the stimulus pulse train were concentrati on dependent: performance rates above 1 Hz became poorer both with increasi ng pulse amplitude and frequency. Flicker fusion frequency was 3 Hz for 100 mu mol l(-1) pulses and 2 Hz for 1000 mu mol l(-1) pulses. Individual cell s showed differences in their stimulus pulse following capabilities, as mea sured by the synchronization coefficient. These individual differences may form a basis for coding temporal features of an odor plume in an across-fib er pattern.