Neuroplasticity

by Moheb Costandi

Neurons can also be classified according to their electrical properties. For example, basket cells, the interneurons that control closure of the critical period in the visual cortex, are believed to exist in as many as 20 different types, the best known being the “fast-spiking” and “slow-spiking” ones, characterized according to the time frames of their responses. But it turns out that these cells can switch back and forth between fast- and slow-spiking activity, in response to neuronal activity. They appear to be constantly tuned in to neuronal network activity, and to change their firing properties in response by means of a protein that enters the nucleus and regulates the expression of potassium channels, which determine the cell’s firing rate. This suggests that the 20 apparently different types basket cells are actually one and the same, and that they morph along a continuum in an activity-dependent manner. Basket cells form networks that modulate neuronal network activity, and so this identity-switching mechanism could significantly impact neuronal population dynamics by altering the ratio of fast- to slow-spiking cells within a given network of neurons.