Wednesday, 3 June 2009

14. Formal inversion in C. elegans - E.

Connectogram for amphid

All the sensory neurons are listed in rows and all the interneurons in columns. Each dot represents a chemical connection site identified by White et al. (1986) on a sensory neuron and each small square surrounding a dot represents a corresponding connection site similarly identified on an interneuron.

The small diagram on the left shows the plotting key: TO the left and TO the right in upper quadrants and FROM the left and FROM the right in lower quadrants.

If you now look at the two yellow squares, where the taste circuitry begins, you will see that the two (red) connections from the left sensory neuron to the right interneuron are one-way and that the opposite connection (from the right sensory neuron to the left interneuron) is two-way or circular.

Note that such circular left/right connection patterns (red sites, one above the other and within the same grid square) occur in four places in key circuits.

Two of these are concerned with the main taste circuit initiated by the ASE neurons: the above-mentioned yellow square (ASER-AIBL) example and another at ASER-AIAL.

Another is concerned with the main smell circuit initiated by the AWC neurons: namely at AWCR-AIYL.

The other is concerned with the main thermosensation circuit initiated by the AFD neurons: at AFDL-AINR.

Newcomers to C. elegans data will by now have begun to appreciate the value of the Minimal Model Brain (and its Minimal Model 'Thoughts') at this very early stage in our quest to understand the many mysteries of our own brains and minds. In the next post we shall return to the main demonstration taste circuit.

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