Archive for The Paramecium

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Posted in Scientific with tags , , , , , on February 25, 2009 by dejavouz

paramecium1

“If we are to believe that neurons are the only things that control the sophisticated actions of animals, then the humble paramecium presents us with a profound problem.

For she swims about her pond with her numerous tiny hair like legs – the cilia – darting in the direction of bacterial food which she senses using a variety of mechanisms, or retreating at the prospect of danger, ready to swim off in another direction. She can also negotiate obstructions by swimming around them.

Moreover, she can apparently even learn from her past experiences – though this most remarkable of her apparent faculties has been disputed by some. How is this achieved by an animal without a single neuron or synapse? Indeed, being but a single cell, and not being a neuron herself, she has no place to accommodate such accessories.

Yet there must indeed be a complicated control system governing the behaviour of a paramecium – or indeed other one-celled animals like amoebas – but it is not a nervous system. The structure responsible is apparently part of what is referred to as the cytoskeleton. As its name suggests, the cytoskeleton provides the framework that holds the cell in shape, but it does much more.

The cilia themselves are the endings of the cytoskeletal fibres, but the cytoskeleton seems also to contain the control system for the cell, in addition to providing ‘conveyer’ belts for the transporting of various molecules from one place to another. In short, the cytoskeleton appears to play a role for the single cell rather like a combination of skeleton, muscle system, legs, blood circulatory system and nervous system all rolled into one!

It is the cytoskeleton’s roll as the cells ‘nervous system’ that will have the main importance for us here. For our own neurons are themselves single cells, and each neuron has its own cytoskeleton! Does this mean that there is a sense in which each individual neuron might itself have something akin to its own ‘personal nervous system’?

This is an intriguing issue, and a number of scientists have been coming round to the view that something of this general nature might actually be true (see Stuart Hameroff pioneering 1987 book Ultimate Computing: Biomolecular Consciousness and Nanotechnology; Also Hameroff and Watt (1982) and numerous articles in the new journal nanobiology)”

Sir Roger Penrose

Mathematical Physicist and Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute, University of Oxford and Emeritus Fellow of Wadham College.

Excerpt from “Shadows of the Mind”

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