Limits...
Routing of Physarum polycephalum "signals" using simple chemicals.

de Lacy Costello B, Adamatzky AI - Commun Integr Biol (2014)

Bottom Line: Polycephalum did not reach either output and was confined to the input channel.This was regardless of whether a chemoattractant was used in combination with the chemorepellent showing a hierarchy of inhibition over attraction.Polycephalum would move toward one output at the junction, but the direction was randomly selected.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biosensing Technology; University of the West of England; Bristol, UK ; Unconventional Computing Group; University of the West of England; Bristol, UK.

ABSTRACT
In previous work the chemotaxis toward simple organic chemicals was assessed. We utilize the knowledge gained from these chemotactic assays to route Physarum polycephalum "signals" at a series of junctions. By applying chemical inputs at a simple T-junction we were able to reproducibly control the path taken by the plasmodium of P. Polycephalum. Where the chemoattractant farnesene was used at one input a routed signal could be reproducibly generated i.e., P. Polycephalum moves toward the source of chemoattractant. Where the chemoattractant was applied at both inputs the signal was reproducibly split i.e., at the junction the plasmodium splits and moves toward both sources of chemoattractant. If a chemorepellent was used then the signal was reproducibly suppressed i.e., P. Polycephalum did not reach either output and was confined to the input channel. This was regardless of whether a chemoattractant was used in combination with the chemorepellent showing a hierarchy of inhibition over attraction. If no chemical input was used in the simple circuit then a random signal was generated, whereby P. Polycephalum would move toward one output at the junction, but the direction was randomly selected.

No MeSH data available.


Figure 4. Selected results from the implementation of a compound T-shaped junction with 6 possible sites of chemical inputs. The top left hand side image shows the case where farnesene (Activator (A)) is present at both central inputs and also in the input at the top left hand side. This shows that Physarum polycephalum appears to take a “cross country” more direct route toward the correct output configuration. The top right hand side image shows a circuit with the same inputs which is correctly implemented via the channels. The central left hand side image shows a circuit where Farnesene is present at both central inputs, but no chemical input (Neutral (N)) is present at the other inputs. The result is that the Physarum signal remains confined in the central region for an extended period of time > 24 h. The central right hand side image shows a circuit where farnesene is present at only the right hand side central input and also the top right hand side input. The signal is successfully transferred through the circuit The bottom left hand side image shows the case where farnesene is only present at the central right hand side input, whereas the bottom right hand side image shows the same circuit with farnesene at the central left hand side input. In both cases it shows that there is directed transfer through the first part of the circuit then segregation in the central portion for an extended time period.
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Figure 4: Figure 4. Selected results from the implementation of a compound T-shaped junction with 6 possible sites of chemical inputs. The top left hand side image shows the case where farnesene (Activator (A)) is present at both central inputs and also in the input at the top left hand side. This shows that Physarum polycephalum appears to take a “cross country” more direct route toward the correct output configuration. The top right hand side image shows a circuit with the same inputs which is correctly implemented via the channels. The central left hand side image shows a circuit where Farnesene is present at both central inputs, but no chemical input (Neutral (N)) is present at the other inputs. The result is that the Physarum signal remains confined in the central region for an extended period of time > 24 h. The central right hand side image shows a circuit where farnesene is present at only the right hand side central input and also the top right hand side input. The signal is successfully transferred through the circuit The bottom left hand side image shows the case where farnesene is only present at the central right hand side input, whereas the bottom right hand side image shows the same circuit with farnesene at the central left hand side input. In both cases it shows that there is directed transfer through the first part of the circuit then segregation in the central portion for an extended time period.

Mentions: A compound T junction was used for these experiments (see Figure 3). Figure 4. shows selected results from the attempts to implement a more complex routing circuit with a constant P. polycephalum input and potentially six chemical inputs. This work showed that it was possible to route a signal via a specific pathway to a predestined output point. For example in Figure 4. We can see in the top right hand image that the signal is routed through the central junction toward the output on the top right of the image only. In this case the circuit has 3 activator inputs (2 in the central region and 1 at the top left hand side where the final signal exits from) and 3 neutral inputs (no chemical). Thus the signal is routed through 3 outputs all of which were sources of the activator chemical farnesene. Thus the routing circuit is implemented correctly according to the inputs, at the first T-junction we obtain signal splitting at the 2nd T-junction we obtain directed signal transfer. Interestingly in this compound circuit after the first junction the presence of no chemical input at the T-junction on the left hand side does not generate a random signal. This is presumably because there is already activator within the circuit so the termination points of the circuit (at least in the short/medium term) are sources of activator at the various inputs. In the original T-shaped junction experiments, the random signal generation arose from a circuit completely free of activator and inhibitor – thus the signal was not suppressed, or directed.


Routing of Physarum polycephalum "signals" using simple chemicals.

de Lacy Costello B, Adamatzky AI - Commun Integr Biol (2014)

Figure 4. Selected results from the implementation of a compound T-shaped junction with 6 possible sites of chemical inputs. The top left hand side image shows the case where farnesene (Activator (A)) is present at both central inputs and also in the input at the top left hand side. This shows that Physarum polycephalum appears to take a “cross country” more direct route toward the correct output configuration. The top right hand side image shows a circuit with the same inputs which is correctly implemented via the channels. The central left hand side image shows a circuit where Farnesene is present at both central inputs, but no chemical input (Neutral (N)) is present at the other inputs. The result is that the Physarum signal remains confined in the central region for an extended period of time > 24 h. The central right hand side image shows a circuit where farnesene is present at only the right hand side central input and also the top right hand side input. The signal is successfully transferred through the circuit The bottom left hand side image shows the case where farnesene is only present at the central right hand side input, whereas the bottom right hand side image shows the same circuit with farnesene at the central left hand side input. In both cases it shows that there is directed transfer through the first part of the circuit then segregation in the central portion for an extended time period.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: Figure 4. Selected results from the implementation of a compound T-shaped junction with 6 possible sites of chemical inputs. The top left hand side image shows the case where farnesene (Activator (A)) is present at both central inputs and also in the input at the top left hand side. This shows that Physarum polycephalum appears to take a “cross country” more direct route toward the correct output configuration. The top right hand side image shows a circuit with the same inputs which is correctly implemented via the channels. The central left hand side image shows a circuit where Farnesene is present at both central inputs, but no chemical input (Neutral (N)) is present at the other inputs. The result is that the Physarum signal remains confined in the central region for an extended period of time > 24 h. The central right hand side image shows a circuit where farnesene is present at only the right hand side central input and also the top right hand side input. The signal is successfully transferred through the circuit The bottom left hand side image shows the case where farnesene is only present at the central right hand side input, whereas the bottom right hand side image shows the same circuit with farnesene at the central left hand side input. In both cases it shows that there is directed transfer through the first part of the circuit then segregation in the central portion for an extended time period.
Mentions: A compound T junction was used for these experiments (see Figure 3). Figure 4. shows selected results from the attempts to implement a more complex routing circuit with a constant P. polycephalum input and potentially six chemical inputs. This work showed that it was possible to route a signal via a specific pathway to a predestined output point. For example in Figure 4. We can see in the top right hand image that the signal is routed through the central junction toward the output on the top right of the image only. In this case the circuit has 3 activator inputs (2 in the central region and 1 at the top left hand side where the final signal exits from) and 3 neutral inputs (no chemical). Thus the signal is routed through 3 outputs all of which were sources of the activator chemical farnesene. Thus the routing circuit is implemented correctly according to the inputs, at the first T-junction we obtain signal splitting at the 2nd T-junction we obtain directed signal transfer. Interestingly in this compound circuit after the first junction the presence of no chemical input at the T-junction on the left hand side does not generate a random signal. This is presumably because there is already activator within the circuit so the termination points of the circuit (at least in the short/medium term) are sources of activator at the various inputs. In the original T-shaped junction experiments, the random signal generation arose from a circuit completely free of activator and inhibitor – thus the signal was not suppressed, or directed.

Bottom Line: Polycephalum did not reach either output and was confined to the input channel.This was regardless of whether a chemoattractant was used in combination with the chemorepellent showing a hierarchy of inhibition over attraction.Polycephalum would move toward one output at the junction, but the direction was randomly selected.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biosensing Technology; University of the West of England; Bristol, UK ; Unconventional Computing Group; University of the West of England; Bristol, UK.

ABSTRACT
In previous work the chemotaxis toward simple organic chemicals was assessed. We utilize the knowledge gained from these chemotactic assays to route Physarum polycephalum "signals" at a series of junctions. By applying chemical inputs at a simple T-junction we were able to reproducibly control the path taken by the plasmodium of P. Polycephalum. Where the chemoattractant farnesene was used at one input a routed signal could be reproducibly generated i.e., P. Polycephalum moves toward the source of chemoattractant. Where the chemoattractant was applied at both inputs the signal was reproducibly split i.e., at the junction the plasmodium splits and moves toward both sources of chemoattractant. If a chemorepellent was used then the signal was reproducibly suppressed i.e., P. Polycephalum did not reach either output and was confined to the input channel. This was regardless of whether a chemoattractant was used in combination with the chemorepellent showing a hierarchy of inhibition over attraction. If no chemical input was used in the simple circuit then a random signal was generated, whereby P. Polycephalum would move toward one output at the junction, but the direction was randomly selected.

No MeSH data available.