Blue light as a medium to influence oscillatory contraction frequency in physarum

Abstract

Blue light (496 nm; threshold intensity approximately 1500 Lux) induces a transient frequency decrease of oscillatory contraction automaticity in Physarum. Many, but not all specimens react by an increase in the force amplitude of longitudinal contraction. The spectral region of 496 nm provokes a photophobic response of the plasmodia. The blue light reaction of radial and longitudinal contraction activities decreases with increasing distance from the irradiated area. The light-induced decrease in frequency can be used for experimental phase shifting, e.g., when studying the nature and the pathway of signal transmission for the spatial phase synchronization of contractile activities.

Autonomous Pattern Formation of Micro-organic Cell Density with Optical Interlink between Two Isolated Culture Dishes

“…[17,40,41], and Physarum polycephalum [4,15,22]. Since our interlink feedback scheme uses separate culture dishes, we can realize artificial interaction among various target microbes inhabiting different environments.…”

“…Figure 5 shows the temporal evolution of the TMs in two pairs of opposite spokes (indexed as 1 and 9, or 2 and 10, clockwise from the top), obtained in the digital feedback experiments executed under rule combinations (1, 2), (2,3), and (1,4). The imposed rule combination (2, 3) is simultaneously satisfied by only two out of all possible patterns (12870 2 ), whereas the combination (1, 4) cannot be satisfied by any patterns.…”

“…One of the two solutions was achieved at 3680 time steps, but repeatedly deviated from thereafter, revealing that the solution had not been established stably by 4000 time steps. Under the rule combination (1,4), the four TMs continuously fluctuated in a middle range, indicating that the illumination pattern of each dish never converged to a specific pattern.…”

A Would-Be Nervous System Made from a Slime Mold

“…Pioneer articles on photomovement of Physarum reported that plasmodium exhibits the most pronounced negative phototaxis to blue and white light [20,54]. The illumination increase causes changes in the plasmodiumʼs oscillatory activity; the degree of change is inversely proportional to the distance from the light source [71,21]. The exact mechanism of the response to light is as yet unknown.…”

“…Being light sensitive [71,21,2], Physarum could play the role of a primitive eyelike organ. To test this possibility we undertook a series of experiments, one of which is described below.…”