Neural dynamics of retrieval suppression in abolishing item-specific cortical pattern of unwanted emotional memories

When reminded of an unpleasant experience, people often try to exclude the unwanted memory from awareness in an effort to forget it, a process known as retrieval suppression. Yet, how fast can individual memories be targeted and controlled, and the neural dynamics in modulating cortical traces of individual memories, remain elusive. Here, using multivariate decoding analyses on time-domain and time-frequency-domain EEGs, we found that retrieval suppression of aversive memories was distinct from retrieval and passive viewing, when given a reminder. Specifically, early elevation of mid-frontal theta power during the first 500 ms distinguished retrieval suppression from passive viewing, suggesting that suppression recruited early active control processes. On an item-level, we could discern activities relating to individual memories during active retrieval-initially, based on perceptual responses to reminders (0-500 ms) and later, via the reinstatement and maintenance of the target aversive scenes (500-3000 ms). Critically, suppressing retrieval significantly weakened (during 420-600 ms) and eventually abolished these item-specific cortical patterns till cue disappeared (1200-3000 ms), suggesting the successful exclusion of the unwelcome memory from awareness. Suppression of item-specific cortical patterns bore behavioral consequences in predicting subsequent episodic forgetting. These findings provide unique insight into the neural dynamics underlying the control of unwelcome memories: upon perceiving an unwelcome reminder, people rapidly deploy inhibitory control to truncate retrieval within 500 ms, which likely terminate the reminder-to-memory conversion at around 500 ms that would ordinarily arise through hippocampal pattern completion. We concluded that both rapid and sustained control are critical in abolishing cortical patterns of individual memories, limiting unwelcome awareness, and precipitating later forgetting.

Caution for liver injury after bariatric surgery: logistic regression of risk factors for early elevation of liver enzymes after surgery

The reasons for the influence of bariatric surgery (BS) on the early abnormal increase of liver enzymes and liver injury remain unclear. We found abnormal elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in liver chemistry early after BS. To investigate the risk factors for early elevation of ALT and AST after BS, we performed a regression analysis of 177 patients who underwent BS at our center. Follow-up data before and after BS were collected and divided into two groups according to whether ALT and/or AST increased and exceeded the clinical threshold one month after BS. Logistic regression analysis was used, and independent risk factors were screened. Waist circumference (WC) before BS was an independent risk factor (P < 0.05) for increased ALT and AST after BS, but other factors (P > 0.05), such as sex, type of BS, or body mass index (BMI), were not. The cutoff of WC to predict abnormal elevation of ALT and AST after BS was 117.35 cm (sensitivity, 0.75; specificity, 0.62) and 113.65 cm (sensitivity, 0.88; specificity, 0.48), respectively. WC is an independent risk factor for early liver injury after BS. Long-term liver-related follow-up is necessary.