Dentate granule cell population responses to paired-pulse stimulations
applied to the perforant pathway across a range of interpulse interva
ls (IPI) were examined in freely moving rats at 15, 30, and 90 days of
age. The profile of the paired-pulse index (PPI), a measure of the ty
pe and degree of modulation of dentate granule cell excitability, was
shown to change significantly as a function of age.