Propagation of activity within the hippocampal dentate gyrus

Objectives: To investigate the spread of excitation in the dentate gyrus with stimulation of stratum granulosum at different sites. Methods: Data were sampled from fluorescence changes of the voltage-sensitive dye RH 795 incorporated into cellular membranes after electric stimulation and recorded with a 464-photodiode array in a neuronal network in vitro. The decrease of fluorescence of the sensitive dye depends on the level of cell-excitation. Results: The experiments showed that stimulation of the crest of the stratum granulosum evoked activity in this entire layer and in the hilus. The inner edge of the ectal…