Another change in the picture

As I have pointed out in previous postings, there are important new discoveries about the brain every month or so. This time we have a whole new signaling pathway in the brain. This involves new knowledge of biochemistry, physiology and anatomy. This is not a minor addition to knowledge of the brain.

ScienceDaily reports (here) on the paper: (Sakry, Neitz, Singh, Frischknecht, Marongiu, Binamé, Perera, Endres, Lutz, Radyushkin, Trotter, Mittmann; Oligodendrocyte Precursor Cells Modulate the Neuronal Network by Activity-Dependent Ectodomain Cleavage of Glial NG2; PLoS Biology, 2014; 12 (11)).

There are a number of glia cell types. Oligodendrocytes are the glia that myelinate axons by wrapping around them, insulating and speeding transmission along the axons. They develop from a precursor cell – but this precursor is a wide spread, stable and significant (5-8%) cell type in the brain. The OPC (oligodendrocyte progenitor cells) were shown, a few years ago, to form synapses with neurons and to receive signals from neurons through these synapses, but this was thought to be a one-way communication.

“We have now discovered that the precursor cells do not only receive information via the synapses, but in their turn use these to transmit signals to adjacent nerve cells. They are thus an essential component of the network,” explained Professor Jacqueline Trotter… Classically, neurons have been considered as the major players in the brain. Over the past few years, however, increasing evidence has come to light that glial cells may play an equally important role. “Glial cells are enormously important for our brains and we have now elucidated in detail a novel important role for glia in signal transmission,” explained Professor Thomas Mittmann…

A signal from the neuron results in reactions in the OPC that releases a fragment of a protein (NG2) into the local environment where it affects neighbouring neurons’ synapses altering their electrical activity. “The role of NG2 in this process became apparent when the researchers removed the protein: neuronal synaptic function is altered, modifying learning and disrupting the processing of sensory input that manifests in the form of behavioral changes in test animals.

The way brain networks function is much more complex than our models and less understood than we assumed. I believe there will be many more surprises.

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