title: Evoked potentials in the dentate gyrus reflect the retention of past sensory events.
abstract: Averaged sensory evoked potentials were recorded from the outer molecular layer of the dentate gyrus (OM AEP) in freely moving rats trained to criterion performance in a two-tone differential discrimination paradigm. OM AEPs showed consistent fluctuations in amplitude based on the acquired significance of the tone through their association with reward (CS+) or non-reward (CS-). However, the relationship between tone significance and OM AEP configuration was dependent upon the sequence of trials preceding the evoked potential, irrespective of whether the potential was evoked by a CS+ or CS-. Specifically, when the preceding sequence contained an increased number of CS- trials, the amplitude of the initial negative component (N1) of the OM AEP was increased, while that of the slower (N2) component was reduced; conversely, when the preceding sequence contained an increased number of CS+ trials, the amplitude of N1 was reduced, while that of N2 was increased. The results suggest that the transmission of sensory information into the dentate gyrus is biased by prior experience.
mesh_terms: D000818:Animals; D004193:Discrimination Learning / Q000502:physiology; D005072:Evoked Potentials, Auditory; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D010897:Pitch Discrimination / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012153:Retention, Psychology / Q000502:physiology*