Propagation of electrical spike trains in substrates colonised by oyster fungi

Abstract

We investigate electrical signalling in substrates colonised by oyster fungi using long-term, multi-channel electrophysiological recordings. Electrical ac-tivity was recorded continuously for approximately fifteen days using a linear array of eight differential electrode channels sampled at 1 Hz. Slow electrical spikes with durations from tens of seconds to tens of minutes and millivolt-scale amplitudes were identified, and spike trains exhibited highly variable inter-spike intervals on time scales of minutes to hours. Analysis of temporal relationships between channels reveals directional propagation of electrical activity along the electrode array, with delay distributions between adjacent channels showing pronounced positive peaks and a monotonic lead-lag order-ing across channels. Median delays of approximately 180 s between channels separated by approximately 2 cm correspond to an estimated propagation speed of about 0.7 cm/min (approximately 40 cm/h). Control analyses us-ing temporally shuffled spike trains indicated its biological origin. These re-sults demonstrate that electrical activity in oyster fungi propagates through the mycelial network as slow travelling signals consistent with ionic wave dynamics.