ON ELECTRICAL CORRELATES OF PHYSARUM POLYCEPHALUM SPATIAL ACTIVITY: CAN WE SEE PHYSARUM MACHINE IN THE DARK?

Abstract

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye, which spans sources of nutrients with its protoplasmic network. In a very simple experimental setup we recorded electric potential of the propagating plasmodium. We discovered a complex interplay of short range oscillatory behavior combined with long range, low frequency oscillations which serve to communicate information between different parts of the plasmodium. The plasmodium's response to changing environmental conditions forms basis patterns of electric activity, which are unique indicators of the following events: plasmodium occupies a site, plasmodium functions normally, plasmodium becomes "agitated" due to drying substrate, plasmodium departs a site, and plasmodium forms sclerotium. Using a collective particle approximation of Physarum polycephalum we found matching correlates of electrical potential in computational simulations by measuring local population flux at the node positions, generating trains of high and low frequency oscillatory behavior. Motifs present in these measurements matched the response "grammar" of the plasmodium when encountering new nodes, simulated consumption of nutrients, exposure to simulated hazardous illumination and sclerotium formation. The distributed computation of the particle collective was able to calculate beneficial network structures and sclerotium position by shifting the active growth zone of the simulated plasmodium. The results show future promise for the non-invasive study of the complex dynamical behavior within — and health status of — living systems.

Sounds synthesis with slime mould of Physarum Polycephalum

“…The model uses the multi-agent approach introduced by Jones whereby simple, low-level interactions within a multi-agent collective generate emergent transport networks, which exhibit the network minimisation behaviors seen in Physarum [26] . We use a modification of the model introduced by Adamatzky and Jones in order to cater for foraging, growth and adaptation behavior of the plasmodium, and its reaction to attracting and repelling sources [15] . Fig.…”

“…Physarum polycephalum produces electrical activity: the movement of intra-cellular components inside the plasmodium's body and its protoplasmic tubes, and migration of the plasmodium over a substrate, produce electricity that can be measured with electrodes [13,14] . Recently Adamatzky and Jones [15] studied the electrical activity of such plasmodium and they found patterns of electrical activity, which uniquely characterise the plasmodium's spatial dynamics and physiological state. Different measurements of electrical potentials, or voltages, indicated when the plasmodium occupied and when it left specific sites of its substrate.…”

Music with Unconventional Computing: A System for Physarum Polycephalum Sound Synthesis

“…If recorded in isolated zones of colonisation over the duration of it being active, patterns emerge that correlate to spatial activity and environmental conditions. Adamatzky and Jones have examined such patterns and have reported that they can be used to denote the plasmodium's behaviour and physiological state [6].…”

Towards a slime Mould-FPGA interface

“…Indeed, in Ref. [17], Adamatzky and Jones suggest that certain patterns in plasmodial activity may serve to communicate instructions between different parts of the organism. For a more comprehensive review of the electrical properties of the P. polycephalum plasmodium, please see Ref.…”

“…The P. polycephalum plasmodium has been demonstrated to respond to stimuli such as application of physical pressure [7], chemical gradients [5] and alterations in environmental temperature [18] in a characteristic fashion. Furthermore, morphological transformations into different life cycle forms also tend to be accompanied by an archetypal pattern of electrical activity [17]. The mechanisms underlying these responses are complex, but are essentially reflections of how the plasmodium responds to the stimulus.…”