The influence of repeated natural stimulation upon discharge patterns of mitral cells of the goldfish olfactory bulb

Summary

• 1. The responses of goldfish mitral cells were analysed by extracellular recording. The stimulus was a rectangular pulse of odour of at least 30 s duration. Every cell was stimulated at least 40 times with the same stimulus in order to investigate changes of the responses in the course of the stimulus repetitions.

• 2. The most common response to a single stimulus pulse was an initial phasic activity increase or decrease (about 3–5 s) followed by a fairly constant mean activity maintained during the pulse.

• 3. The activity during the stimulus-free period (at least 30 s) between two stimulus periods usually began with a phasic reaction (about 3–5 s) followed by an interval of fairly constant activity.

• 4. In 37 of 51 cases the responses to single stimuli were reproducible over all runs of the experiment.

• 5. In 14 recordings the single run responses were not reproducible. They rather showed (a) abrupt changes from the first to the second run or (b) slow changes that extended over up to 30 runs. Every pattern of this kind became reproducible after a certain number of runs. The activity changes during the first runs can therefore be attributed to a process that leads to a more pronounced response to a repeated stimulus.