An Example of Glial Modulation of Neurons
You learn in Chapter 1 that glial cells help modulate synaptic activity by releasing glutamate and by absorbing variable amounts of transmitter (p 41). Now a study has demonstrated a behavioral effect of glial modulation: Regulation of clock neuron activity by astrocytes helps determine daily activity rhythms. The study was done with fruit flies (Drosophila melanogaster), that were geneticallly modified to interfere with their glial cell functioning. Examination of the flies' brains indicated that disabling the glial cells had disrupted transport or release (or both) of a peptide transmitter that is needed for synchronizing the clock neuronal network. Curent Biology (in press 4/14/2011).
The Hidden Brain
Researchers are constantly revising their assessment of the importance of glial cells. This article gives a nice overview of recent discoveries, written in a popular style. Scientific American Mind May/June, 2011, 53-59.
How Neurons Code Information
The nervous system operates in a modular fashion; neurons within a module must process complex information and then pass this refined information on to the next level for further processing. Processing is best done when neurons can do their own thing and fire individually, but passing the information on to the next module works bests when neurons fire in synchrony, rather like a roomful of people shouting the same thing in unison. A new study by researchers at the Center for the Neural Basis of Cognition has provided clues that the nervous system controls these two kinds of activity by the judicious use of inhibition. Over the short term—measured in milliseconds—the inhibition neurons exert on their neighbors keeps them from firing in synchrony. But over a longer period—up to a secondf—they bring firing into synchrony, enhancing communication of the processed information.Proceedings of the National Academy of Sciences, , Vol 108, 5843-5848.