Directional Electrical Spiking, Bursting, and Information Propagation in Oyster Mycelium Recorded with a Star-Shaped Electrode Array

TL;DR

The study addresses how electrical activity in fungal mycelium is spatially organized and propagated. Using a star-shaped electrode array to record spontaneous activity in Pleurotus ostreatus on wood-shavings, it analyzes spikes, bursts, inter-channel correlations, and propagation delays across three sessions. The findings reveal strong directional heterogeneity, clustered bursting, and locally constrained coupling, along with slow, direction-dependent propagation of bursts, supporting the view that the mycelium functions as a distributed excitable medium. This has implications for understanding fungal physiology and for developing biohybrid sensing and unconventional information-processing approaches.</n>

Abstract

Electrical activity in fungal mycelium has been reported in numerous species and experimental contexts, yet its spatial organisation and propagation remain insufficiently characterised. In this study we investigate the spatiotemporal structure of electrical potential dynamics in oyster mushroom (\textit{Pleurotus ostreatus}) mycelium colonising a wood-shavings substrate. Electrical signals were recorded using an eight-channel star-shaped differential electrode array providing angular resolution around a central region of colonised substrate. We analyse spike statistics, bursting behaviour, inter-channel correlations, and event-based propagation delays. The results reveal strong directional heterogeneity in spiking frequency and amplitude, clustered bursting dynamics, partial and localised coupling between channels, and reproducible propagation patterns across spatial sectors. Electrical bursts originate preferentially in specific directions and recruit other regions with with characteristic delays ranging from seconds to minutes to hours. These findings support the interpretation of fungal mycelium as a spatially extended excitable medium capable of slow, distributed electrical signalling and signal integration.

Figures (15)

• Figure 1: Schematic of the electrode arrangement used for electrical recordings. Eight differential recording channels (1--8) were positioned at fixed locations within a substrate colonised by oyster fungi. The channels form an ordered spatial array, allowing comparison of spike onset times across neighbouring and non-neighbouring electrodes. This configuration enables detection of temporal delays and directional propagation of electrical activity along the mycelial network.
• Figure 2: Examples of electrical spiking activity recorded on different channels. Each panel shows raw electrical potential over a representative six-hour window for channels 1, 4, and 8, respectively. Spikes appear as slow, high-amplitude excursions occurring on time scales of minutes to hours. Differences in timing across channels illustrate spatiotemporal structure of the electrical activity.
• Figure 3: Mean spike rate (events/min) by directional channel, aggregated across all recording sessions. Error bars denote standard deviation between experiments. Electrical spiking is strongly anisotropic, with order-of-magnitude differences between directions and substantial inter-session variability.
• Figure 4: Polar representation of mean spike rate by direction, aggregated across all experiments. The star-electrode arrangement reveals pronounced angular anisotropy of electrical activity within the mycelial network.
• Figure 5: Spike amplitude distributions by direction, pooled across all recording sessions. Amplitude statistics differ substantially between directions, indicating that spatial sectors of the mycelial network operate in distinct electrical regimes.