They were amazed,... Job 32:15
"Studies in brainless slime molds reveal that they use physical cues to decide where to grow.
If you didn’t have a brain, could you still figure out where you were
and navigate your surroundings?
Thanks to new research on slime molds,
the answer may be “yes.” 
Scientists from the Wyss Institute and the Allen Discovery Center have discovered that a brainless slime mold called Physarum polycephalum uses its body to sense mechanical cues in its surrounding environment, and performs computations similar to what we call “thinking” to decide in which direction to grow based on that information.
Scientists from the Wyss Institute and the Allen Discovery Center have discovered that a brainless slime mold called Physarum polycephalum uses its body to sense mechanical cues in its surrounding environment, and performs computations similar to what we call “thinking” to decide in which direction to grow based on that information.
“People are becoming more interested in Physarum because it doesn’t have
a brain but it can still perform a lot of the behaviors that we
associate with thinking, like solving mazes, learning new things, and
predicting events,” said first author Nirosha Murugan.
Slime molds are amoeba-like organisms that can grow to be up to several
feet long, and help break down decomposing matter in the environment
like rotting logs, mulch, and dead leaves. A single Physarum creature
consists of a membrane containing many cellular nuclei floating within a
shared cytoplasm, creating a structure called a syncytium. Physarum
moves by shuttling its watery cytoplasm back and forth throughout the
entire length of its body in regular waves, a unique process known as
shuttle streaming.
The researchers placed Physarum specimens in the center of petri 
dishes
coated with a semi-flexible agar gel and placed either one or three
small glass discs next to each other atop the gel on opposite sides of
each dish.
They then allowed the organisms to grow freely in the dark
over the course of 24 hours, and tracked their growth patterns. For the
first 12 to 14 hours, the Physarum grew outwards evenly in all
directions; after that, however, the specimens extended a long branch
that grew directly over the surface of the gel toward the three-disc
region 70% of the time. Remarkably, the Physarum chose to grow toward
the greater mass without first physically exploring the area to confirm
that it did indeed contain the larger object.
To figure out the missing piece of the puzzle, the
scientists used computer modeling to create a simulation of their
experiment to explore how changing the mass of the discs would impact
the amount of stress (force) and strain (deformation) applied to the
semi-flexible gel and the attached growing Physarum. As they expected,
larger masses increased the amount of strain, but the simulation
revealed that the strain patterns the masses produced changed, depending
on the arrangement of the discs.
“Imagine that you are driving on the highway at night and looking for
a town to stop at. You see two different arrangements of light on the
horizon: a single bright point, and a cluster of less-bright points.
While the single point is brighter, the cluster of points lights up a
wider area that is more likely to indicate a town, and so you head
there,” said co-author Richard Novak, Ph.D., a Lead Staff Engineer at
the Wyss Institute. “The patterns of light in this example are analogous
to the patterns of mechanical strain produced by different arrangements
of mass in our model. Our experiments confirmed that Physarum can
physically sense them and make decisions based on patterns rather than
simply on signal intensity.”
Q: But how was it detecting these strain patterns?
A: The scientists suspected
it had to do with Physarum’s ability to rhythmically contract and tug
on its substrate, because the pulsing 
and sensing of the resultant
changes in substrate deformation allows the organism to gain information
about its surroundings. Other animals have special channel proteins in
their cell membranes called TRP-like proteins that detect stretching,
and co-author and Wyss Institute Founding Director Donald Ingber, M.D.,
Ph.D had previously shown that one of these TRP proteins mediates
mechanosensing in human cells.
When the team created a potent TRP
channel-blocking drug and applied it to Physarum, the organism lost its
ability to distinguish between high and low masses, only selecting the
high-mass region in 11% of the trials and selecting both high- and
low-mass regions in 71% of trials."
SciTechDaily
