Concentration-dependent effects of nicotine on air-puff-evoked compound extracellular responses in the abdominal ganglion of Acheta domesticus

The cercal system of crickets provides a tractable preparation for examining how cholinergic modulation changes sensory-evoked activity in an identified mechanosensory pathway. Here, extracellular recordings from abdominal ganglion preparations of Acheta domesticus were used to test concentration-dependent effects of local nicotine application on responses evoked by air-puff stimulation of the cerci. Nicotine was applied at 0.0001, 0.01, 1, and 10 mM and compared with a 0 mM Ringer procedural control. The recordings were analyzed as compound extracellular signals using raw trace visualization, within-preparation changes in RMS signal power, event-based response metrics, and exploratory frequency-domain features. Raw non-normalized traces and event-based measures indicated the clearest alteration at 10 mM nicotine, where fewer threshold-crossing events were detected per stimulus but higher median compound post-stimulus deflections and response areas were observed. RMS signal power increased after application in all groups, including the procedural control, and nicotine groups did not differ significantly from the control after correction for multiple comparisons. Frequency-domain analysis showed nicotine-associated redistribution of compound signal power, with the strongest descriptive effects at 10 mM. Together, these findings suggest that high-concentration nicotine alters the structure and detectability of air-puff-evoked compound extracellular responses, consistent with mixed excitatory and desensitizing actions at insect nicotinic acetylcholine receptors. The results should be interpreted at the preparation and signal-power level rather than as direct measures of firing rate or neuronal oscillations.