Daniel Himmelstein

Physarum polycephalum

BBC Journal Clublink to source

link to source

plasmodium

• vegetative state

• acellular

• multinuclear

• protoplasmic veins (tubules)

link to source

Ball et al. J Exp Bot. 2011

1,000-1,300 Mya

700-1,000 Mya

Chernikova et al. Biology Direct. 2011

Nakagaki et al. Nature 2000

finds shortest path

hour 4 hour 8time 0

Maze Solving

coats entire agar plasmodium retracts

Tokyo Railway

Tero et al. Science 2010

Tero et al. Science 2010

Tero et al. Science 2010

• efficiency• fault tolerance• cost

Actual Rail Network Slime Tubule Network

Navigation Schemes

reactive

• immediate environment

• efficient

• novel exploration

global

• span entire search space

• map precedes solution

• no internalized memory

Slime mold uses an externalized spatial “memory” to navigate in

complex environments.Chris R. Reid, Tanya Lattya, Audrey Dussutour, and Madeleine Beekman

PNAS October 23, 2012 vol. 109 no. 43 17490-17494

Extracellular Slime Avoidance?

391

40

< 0.001

Slime Coated Agar Blank

1822

40

0.636

716

23

0.93

24 trials120 hours

Does extracellular slime function as a navigational aid?

blank(trail perceivable)

slime coated(trail masked)

glucose plasmodium

investigate the ability of the plasmodium to navigate around the trap and reach the glucose

blan

k ag

ar

39 hours

71 hours

slim

e co

ated

aga

r

Mean Speed of Plasmodium

50

0.345

2.5

millimeters per hour

Proportion Finding Goal

96%

33%

< 0.001

Mean Time to Reach Goal

800

0.012

40

hours

excluding trials over 120 hours

Mean Distance Traveled

5000

< 0.001

250

millimeters

Mean Time Spent in Trap

500

0.016

25

hours

Mean Time Spent on own slime trail

400

0.042

20

hours

13 trials 16 trials

measurement p-value

time to reach goal 0.374distance travelled 0.471

speed 0.889

blan

k ag

ar

39 hours

71 hours

slim

e co

ated

aga

r

first conclusion: extracellular slime avoidance provides a navigational benefit

• choice of 120 hour cutoff

• avoids extracellular slime for non-navigational reasons

• do navigational benefits hold across a variety of complex environments

• how are competing stimuli balanced

• “storage and retrieval of information relating to past events”

• Spatial

• Externalized

• Collective

• Functional precursor

second conclusion: extracellular slime avoidance is a form of memory

Memory

• epigenetic processes (chromatin structure)

• vernalization (chromatin remodeling records length of winter)

• immune response (antibodies)

• evolution (stored adaptations)

• ants (pheromone trails)

• sticky notes

“storage and retrieval of information relating to past events”

Memory

• epigenetic processes (chromatin structure)

• vernalization (chromatin remodeling records length of winter)

• immune response (antibodies)

• evolution (stored adaptations)

• ants (pheromone trails)

• sticky notes

“internal storage and retrieval of information relating to past events”

Memory

• epigenetic processes (chromatin structure)

• vernalization (chromatin remodeling records length of winter)

• immune response (antibodies)

• evolution (stored adaptations)

• ants (pheromone trails)

• sticky notes

“storage and retrieval of information relating to personal past events”

The End: Questions