Tracking an intracellular computer.

Tracking an intracellular computer

Under the molecularly-thin skin of every neuron lies a web of protein filaments collectively known as the cytoskeleton. Its growing list of cellular duties includes structural support, transporting chemicals from one place in the neuron to another, and coordinating cell division, growth and morphology. If Steen Rasmussen of Los Alamos National Laboratory, Stuart Hameroff of the University of Arizona College of Medicine in Tucson and their co-workers are right, the cytoskeleton also serves as an intracellular nervous system that processes molecular-level information. Since the cytoskeleton influences synapse dynamics, it may even have a role in cognitive processes, Hameroff says.

These scientists and several other research groups conjecture that the cytoskeleton's grid-like structure, and its orderly way of disintegrating and rebuilding, may enable it to act as an intracellular computer. One variation of the idea identifies the computer inputs as cellular states such as temperature and the concentrations of various molecules. The cytoskeleton processes these states, or inputs, by changing its own molecular structure. These culminates in outputs such as changes in the cell's shape. Sophisticated but preliminary computer simulations of the cytoskeleton's fluctuating architecture suggest that real cytoskeletons may be able to process, respond to adapt to molecular inputs the way the simulated ones appear to do, Rasmussen says.