Neuroglia: biophysical properties and physiologic function.

The membrane time constant of neocortical glial cells is abolut 385 microseconds, less than one-twentieth the known value for the Betz cell. Glial membrane specific resistance is low (approximately 200 to 500 ohm centimeters squared. Neuroglial cells are ideally suited to buffer the immediate extraneuronal space at areas of synaptic contact against the increases in external potassium ion concentration that accompany postsynaptic and spike activity and to minimize the spread of potassium ions to other pre- and postsynaptic regions.