[smart (OP)]

Cognitive behaviours of single cell organisms:

Protozoans, like Physarum, can escape mazes and solve problems; and Paramecium can swim, find food and mates, learn, remember and have sex, all without synaptic connections.

How do single cells manifest intelligent behaviour?

http://www.sciencedirect.com/science/article/pii/S1571064513001188

[chris]

I think it depends, to an extent, on how you define "intelligence"; relative to Einstein, an amoeba is not intelligent.

What single celled organisms do is to follow a set of biochemical instructions that are written into them when they form. Bacteria decorate their external surfaces with receptors and effector molecules; one influences the action of the other. So when a stimulus is present, the bugs respond. But is this intelligence? I would argue that it's not, it's merely evolution equipping these simple creatures with an effective and efficient survival strategy.

[puppypower]

Cognitive behaviours of single cell organisms:

Protozoans, like Physarum, can escape mazes and solve problems; and Paramecium can swim, find food and mates, learn, remember and have sex, all without synaptic connections.

How do single cells manifest intelligent behaviour?

http://www.sciencedirect.com/science/article/pii/S1571064513001188

One critical thing common to neurons, and all cell surfaces, is cationic pumping. All cells pump and exchange Sodium; Na+ and Potassium; K+ cations. They will all accumulate Na+ on the outside surface and K+  on the inside. This ATP energy intensive action sets up a membrane potential. It also sets up an entropy potential due to the segregation of the cations.

The potential energy in the membrane potential is used to drive the movement of materials across the membrane. As the membrane protein use the energy stored within the local membrane potential, the two ions reverse, locally, to reflect the energy change; new equilibrium. They get pumped again to reset the potential.

In many ways, any cell surface is a 2-D synaptic network shell. Neurons do this in 3-D, allowing more complexity. The synaptic analogies, for the 2-D surface of a single cell, is done on a small local scale, all over the surface, using transport enzymes and receptors. These act like the synapses of neurons induces as a  consequence of energy intensive protein activities reversing the cations. For example, if food is on one side of the cell, the 2-D surface synapses will fire more on that side using food specific receptors. This translates to mobility direction.

With neurons and synapses, neurotransmitters are used to fire and inhibit the firing of the synapse. In the case of a cell surface, there is much more variety of neurotransmitter analogies for the synaptic analogous. These are connected to what the environment can dish out and what the cell can interact with. It has the same impact as a neurotransmitter, but locally, near the receptors and transporters.

Na+ and K+ ions have different impacts on water. Na+ is kosmotropic, while K+ is chaotropic. Na+ will create more order in water than water creates by itself, while K+ creates more chaos in water than water creates for itself. The local movement of ions, in and out, of the 2-D surface, alters the potential of the local surface water, inside and outside the  cell. The result, on the inside, is information transfer through the water, to remove the non equilibrium potential. It will take a reasonable amount of surface activity for this information to reach the DNA. This prevents the cell from over reacting to isolated false positives.