Stephen J Smith Stephen J Smith Stephen J Smith is a Senior Investigator at the Allen Institute for Brain Science. Previously, Dr. Smith was Professor of Molecular and Cellular Physiology at the Stanford University School of Medicine. In 1990, Smith published an article in the journal "Science", which proposed that certain glial cells in the human brain known as astrocytes would be able to communicate through chemical signals, rather than electrical. By utilizing the neurotransmitter glutamate, he was able to show that these cells, which had once been perceived as inert tissue between neurons, in fact were actively communicating with the rest of
Action potential potential. Their joint efforts can be thwarted, however, by the counteracting inhibitory postsynaptic potentials. Neurotransmission can also occur through electrical synapses. Due to the direct connection between excitable cells in the form of gap junctions, an action potential can be transmitted directly from one cell to the next in either direction. The free flow of ions between cells enables rapid non-chemical-mediated transmission. Rectifying channels ensure that action potentials move only in one direction through an electrical synapse. Electrical synapses are found in all nervous systems, including the human brain, although they are a distinct minority. The amplitude of an action