Brainless slime mould
has an external memory
By Ella Davies, BBC Nature
9 October 2012
Slime Mold_Paul Zahl-NG-Getty Images |
clipped article:
"The whole organism is made up of bits of pulsating
tissue, which are constantly expanding and contracting, using a similar mechanism
to our own muscle cells," explained PhD student Christopher Reid.
"Each part changes the speed at which it pulsates
according to what it can sense in the environment around it - for example food,
light or heat - which are detected by chemical receptors on the cell's
surface."
"The pulsating parts are also influenced by the
throbbing of their neighbours within the cell, which means that they can
communicate with each other, to pass information through the organism about
what is happening in the environment outside. The different speeds of
contraction directly influence which direction the cell will then move
in."
"In essence, the
slime mould is memorising where it has been - storing this memory in the
external environment and recalling the information when it later touches the
slime-coated area.
"For a single-celled organism, it has continually
surprised researchers with its abilities, such as solving mazes, anticipating
periodic events, and even making
irrational decisions like we do," he told BBC Nature.
"It is truly a remarkable creature that is redefining
our notions of 'intelligence'."
notes:
Slime mold uses an
externalized spatial “memory” to navigate in complex environments
Chris R. Reid, Tanya Latty, Audrey Dussutour, and Madeleine
Beekman
Behaviour and Genetics of Social Insects Laboratory, School
of Biological Sciences, and Centre for Mathematical Biology, University of
Sydney, Sydney, NSW 2006, Australia; and Centre de Recherches sur la Cognition
Animale, UMR 5169 Centre National de la Recherche Scientifique, Université
Toulouse III, 31062 Toulouse, France
Edited by John G. Hildebrand, University
of Arizona , Tucson , AZ ,
and approved September 7, 2012 (received for review June 24, 2012)
Abstract:
Spatial memory enhances an organism’s navigational ability.
Memory typically resides within the brain, but what if an organism has no
brain? We show that the brainless slime
mold Physarum polycephalum constructs a form of spatial memory by avoiding
areas it has previously explored. This mechanism allows the slime mold to
solve the U-shaped trap problem—a classic test of autonomous navigational
ability commonly used in robotics—requiring the slime mold to reach a
chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the
organism must rely on other methods than gradient-following to escape and reach
the goal. Our data show that spatial
memory enhances the organism’s ability to navigate in complex environments.
We provide a unique demonstration of a spatial memory system in a nonneuronal
organism, supporting the theory that an externalized
spatial memory may be the functional precursor to the internal memory of higher
organisms.
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