THE ISOLATED AND PERFUSED BRAIN OF THE GUINEA-PIG IN-VITRO

We describe here an isolated and perfused in vitro adult guinea-pig wh ole brain preparation which is an extension of the previously describe d in vitro brainstem - cerebellum preparation. Viability was tested by the analysis of trans-synaptic responses along the visual pathways fo llowing the electrical stimulation of the optic nerve or the optic rad iations. The evoked field potentials were recorded in the dorsal later al geniculate, the superior colliculus and the visual cortex. The dist ribution of extracellular currents was studied using current source de nsity analysis, in order to determine the amplitude, time course and s patial organization of the synaptic activity at these sites. The study indicates that field potentials were very similar to those described in vivo. These data demonstrate the survival of a complex adult sensor y system in vitro and suggest that this preparation can be used for th e analysis of multisynaptic circuits in the mammalian brain.