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
behaviour 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 behaviour.
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 behaviour within --- and health
status of --- living systems