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Single cells, proteins & ions
Single cells, proteins & ions
Single
cell organisms and neurons
Based on Michael Marshall, New Scientist, 3
September 2011, referring to work by Dirk Fasshauer, Xinjiang Cai and Harold
Zakon
Important components of neurons are shown to be already
apparent in early single-cell organisms. Dirk Fasshauer et al, University of
Lausanne have found the important neural proteins, Munc18 and syntaxin1 in
simple single-cell aquatic organisms called choanoflagellates. The interaction
between the two proteins in these organisms was the same as in neurons. These
proteins are found in every neuron and control the release of
neurotransmitters. Thus this system looks to have evolved in single-cell
organisms even before multicellular life had emerged.
Another researcher,
Xinjiang Cai at Duke University found that these single-cell organisms had the
same calcium channels as neurons, while Harold Zakon at the University of Texas
discovered the organism had the same sodium ion channels that neurons use to
transmit signals along their membranes. Further research showed further
proteins in these organisms that were the same as those used by neurons to
process incoming signals.
The significance for consciousness studies of
these discoveries may lie in the apparent capacities of individual cells
including neurons. Single cells organisms demonstrate many of the capacities of
navigation, feeding and avoidance of predators that are seen in multicellular
animals, despite not being linked up into nervous systems. Without necessarily
suggesting that single cells organisms are conscious, these discoveries at
least hint at the possibility of individual neurons supporting the
sophisticated activity of consciousness, rather than merely acting as dumb
switches.
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