The converse was true of the hippocampal spectra LDK378 cost averages with the beta bandwidth exhibiting a difference favoring all successive presentations over the initial presentation (all t(25) > 3.4; p < 0.0025), and the gamma bandwidth exhibiting no differences (Figure 3B). Thus, although the polarity of the responses differed between the monkey entorhinal cortex and hippocampus, both structures signaled immediate novelty similar to the prominent signal seen in

humans. One of the most prominent task-related signals we have seen in the monkey hippocampus from single cell recording was a strong differentiation between correct and error trials (trial outcome) during the reward and ITI periods of an object-place associative HIF-1 activation learning task (Wirth et al., 2009). Similar trial outcome signals have also been reported by us in the entorhinal cortex during the location-scene association task used in the present study (E.L. Hargreaves, unpublished data). This information can be used to strengthen correct and/or rewarded associations and modify incorrect and/or unrewarded ones during learning. We first asked whether the prominent outcome signals seen at the single unit level of analysis

in monkeys were also reflected in the LFP. For all new stimuli, frequency spectra averages of the “correct” and “error” trials were analyzed during a postresponse trial epoch spanning 1,500 ms across the reward and ITI periods. Multiple regressions generated β values for power of both the gamma and beta bandwidths, which were then compared in group analyses using parametric statistics (Figures 4A and 4B). An additional exclusion criterion was applied to these analyses requiring that sessions had a minimum of seven error responses for adequate weighting of the β coefficients. For the entorhinal cortex, significant differences

between correct and error trials were seen for both the gamma (t(41) = 4.25; p < 0.0001) and beta (t(41) = 3.63; p < 0.0007) bands (Figure 4A). The direction of the Ergoloid difference for both bandwidths favored the error trials with positive β values contrasted to the correct trials negative β values. Consistent with our single unit findings in the hippocampus (Wirth et al., 2009), significant differences between correct and error trial β values were seen for the gamma band (t(24) = 3.09; p < .0036), but not the beta band. Like the entorhinal cortex, the gamma band difference in the hippocampus favored the error trials with positive β values (Figure 4B). To examine trial outcome signals in the human MTL, we analyzed the entorhinal and hippocampal ROIs using the same multiple regression to generate β values for the correct and error trial responses to new stimuli for each subject. We observed significant differences in both the entorhinal cortex (t(30) = 3.19; p < 0.0034; Figure 4C) and hippocampal (t(30) = 4.75; p < 0.0001; Figure 4D) ROIs.