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. 2021 Apr 23;144(5):1590–1602. doi: 10.1093/brain/awab044

Figure 4.

Figure 4

IEDs and effect on memory performance. (A) Example raw tracing and spectrogram of a detected IED. Scale bars = 25 µV, 125 ms. (B) Left: IEDs recorded in any brain region during encoding predicted a 4% decreased odds of remembering (OR = 0.96, CI = 0.93–0.99, P = 0.002, F-test). IEDs in any brain region during cued recall trended towards decreased odds of remembering (P = 0.0760, F-test). Right: IEDs occurring in the right hemisphere predicted a 9% decreased odds of remembering (P = 0.0002, F-test). There was no difference in odds of remembering for IEDs in the left hemisphere during encoding, or either hemisphere during recall. Error bars represent 95% confidence intervals. (C) Relationship between block size, IQ, and IED rate. Subjects varied in performance, ranging between 1 and 10 stimuli presented per block, larger sets indicating superior task performance across patients. There was a trend towards a negative correlation between IED rate and log set size [r(13) = −0.49, P = 0.06]. (D) Odds of successful memory for IEDs occurring during encoding and recall, by brain region. Mean odds of successful memory per IED occurring during encoding (left) and cued recall (right). Error bars represent 95% CI. Odds < 1 indicate a decreased odds of successful remembering if an IED occurred during the trial. After correction for multiple comparisons, a significant decrease in remembering occurs for IEDs in hippocampus [red, encoding: OR = 0.85, CI = 0.77–0.94), F(1,6221) = 10.5, P = 0.001; recall: OR = 0.75, CI = 0.67–0.85, F(1,5956) = 21.8, P < 0.001]. (E) Odds of successful memory for IEDs occurring in selected brain regions, by 500 ms time bin. Mean odds of successful memory per IED occurring during encoding (left), demonstrate that odds of remembering are further decreased by 25–52% if IEDs occurred in hippocampus, parahippocampal gyrus, and temporal pole occur between 500–2000 ms. During recall (right), mean odds of successful memory per IED in hippocampus decreased by 41% when IEDs occurred between 1000 ms and 2000 ms after stimulus presentation. Error bars represent 95% CI. Significant changes indicated by an asterisk (P < 0.05, F-test).