Long-term modulation of cardiac activity induced by inhibitory control over emotional memories

Abstract

Efforts to exclude past experiences from conscious awareness can lead to forgetting. Memory suppression is central to affective disorders, but we still do not really know whether emotions, including their physiological causes, are also impacted by this process in normal functioning individuals. In two studies, we measured the after-effects of suppressing negative memories on cardiac response in healthy participants. Results of Study 1 revealed that efficient control of memories was associated with long-term inhibition of the cardiac deceleration that is normally induced by disgusting stimuli. Attempts to suppress sad memories, by contrast, aggravated the cardiac response, an effect that was closely related to the inability to forget this specific material. In Study 2, electroencephalography revealed a reduction in power in the theta (3–8 Hz), alpha (8–12 Hz) and low-beta (13–20 Hz) bands during the suppression of unwanted memories, compared with their voluntary recall. Interestingly, however, the reduction of power in the theta frequency band during memory control was related to a subsequent inhibition of the cardiac response. These results provide a neurophysiological basis for the influence of memory control mechanisms on the cardiac system, opening up new avenues and questions for treating intrusive memories using motivated forgetting.

EEG evidence that morally relevant autobiographical memories can be suppressed

“…Autobiographical memory intrusions were associated with a significant increase in parietal alpha/beta (8-30Hz) power compared to non-intrusion trials, around 2500-3500ms post-stimulus onset. This result contrasts with some previous findings that intrusions decreased rather than increased oscillatory power compared to successful suppression (Castiglione et al, 2019; Legrand et al, 2020). However, those prior effects were generally observed earlier in time and tended to have more frontal topographies than the intrusion effect found in the present study.…”

“…This effect began around 500 to 1000ms after the reminder appeared and was sustained for as long as the reminder was presented on the screen (3500ms). This broadband and sustained desynchronisation effect resembles the oscillatory correlates of successful memory suppression described in previous research with simpler episodic memories (Crespo-García et al, 2021; Ketz et al, 2014; Legrand et al, 2020; Lin et al, 2021; Quaedflieg et al, 2020; Waldhauser et al, 2015).…”

“…Although such stimuli are useful for achieving experimental control and for understanding the core processes involved in the task, they do not address how people control retrieval of more complex, self-relevant, and emotional memories in everyday life. There is extant behavioural and neuroimaging literature on suppression of emotional words/picture memories (e.g., Chen et al, 2012; Depue et al, 2007; Gagnepain et al, 2017; Joormann et al, 2009; Legrand et al, 2020), but because of the lack of self-relevance of those materials, they arguably do not elicit strong motivation for memory control. Research using more complex stimuli suggests that people can suppress unpleasant self-relevant information (Benoit et al, 2016; Noreen et al, 2014) and autobiographical memories (Noreen et al, 2016; Noreen & Macleod, 2013; Stephens et al, 2013).…”

“…Previous EEG oscillation studies indicate that sustained memory control is associated with a decrease in oscillatory power for suppressed compared to retrieved memories across theta (~4-7Hz), alpha (~8-12Hz), and beta (~13-30Hz) frequency bands. It has been suggested that parietal theta power reductions reflect reduced recollection of the associated memory 1 , whereas sustained maintenance of cognitive control to ensure that the memory does not enter awareness is reflected by alpha/beta band reductions (Depue et al, 2013; Legrand et al, 2020; Quaedflieg et al, 2020; Waldhauser et al, 2015).…”

Prefrontal-hippocampal interactions supporting the extinction of emotional memories: the retrieval stopping model

“…These effects suggest persisting aftereffects of prefrontal control on the amygdala and its affective representations. Consistent with this possibility, retrieval stopping reduces physiological responses to scenes after suppression [ 37 , 57 , 59 ]. These affective attenuation effects likely reflect modulation by right LPFC.…”