Ontogeny of the paired-pulse index: a measure of dentate granule cell modulation

In this report the authors present the dentate granule cell population response to paired-pulse stimulation of the perforant path obtained from freely-moving rats at 15, 30, and 90 days of age. The resultant paired-pulse indices (PPIs) indicated that a markedly low level of facilitation and lack of late inhibitory modulation is present in 15 day old rats when compared to the 90 day (adult) group. Values of the PPI obtained from 30 day old rats fall intermediate between the 15 day and adult groups. These results indicate that the PPI can be effectively used as a measure of the maturation of dentate granule cell modulation