Bioelectric activity of neonatal mouse cerebral cortex during growth and differentiation in tissue culture

Abstract

Electrophysiologic studies with extracellular microelectrodes demonstrate the development of characteristic bioelectric activity in cultured fragments of mouse cerebral neocortex during their growth and differentiation in vitro. Within the first 2–3 days after explantation, only simple spike potentials can be evoked by electric stimuli. By 4 days, responses of much greater complexity and duration begin to appear in the cultures. Facilitation effects at long test intervals can now be demonstrated and can also be augmented by strychnine. During the following week in culture, bioelectric responses increase in amplitude, complexity and regularity. Barrages of spikes and slow waves occur sporadically as well as in response to electric stimuli. d-Tubocurarine and strychnine may greatly enhance these activities, whereas procaine blocks them at levels which still permit simple spike responses. Simultaneous records of evoked-potential patterns from various regions of the explants suggest maintenance of laminar organization of neural elements parallel to the original surface of the cerebral cortex. This degree of functional integrity may be retained for more than 2 months in vitro. In many respects, the bioelectric properties of cultured cerebral explants are remarkably similar to those of chronic, neuronally isolated slabs of neonatal cerebral cortex in situ. Application of this method to problems of cerebral function at the cellular level are discussed.