Emotional arousal ripples across time to bind subsequent episodes in memory

Time unfolds continuously, yet our memories are stored as discrete episodes. Prior work shows that fluctuations between stability and change in an ongoing neutral context facilitates this formation of distinct and memorable events. However, less is known about how shifting emotional states influence these memory processes, despite ample evidence that emotion has a robust influence on non-temporal aspects of episodic memory. Here, we examined if emotional stimuli influence temporal memory for recent event sequences. Participants encoded lists of neutral object images while listening to pure auditory tones. At regular intervals within each list, participants heard emotional positive, negative, or neutral sounds, which served as ‘emotional event boundaries’ that divided each sequence into discrete auditory events. Temporal order memory was tested for neutral item pairs that either spanned an emotional sound (‘boundary-spanning’) or encountered within the same auditory event (‘same-context’). We found that highly arousing boundaries had opposite effects on binding ongoing versus subsequent sequential representations in memory. Specifically, highly arousing emotional sounds tended to lead to worse temporal order memory for boundary-spanning item pairs. By contrast, they led to better temporal order memory for same-context item pairs in the next event. Both of these arousal effects were specific to negative sounds. The carryover effect of negative arousal was also strongest for item pairs encountered closest to the boundary and diminished as the event unfolded. These findings suggest that temporally dynamic emotional states support the temporal integration of mnemonic events, which may contribute to the hyper-episodic nature of negative emotional memories.

A multimodal neuroprosthetic interface to record, modulate and classify electrophysiological correlates of cognitive function

Most mental disorders are characterised by impaired cognitive function and behaviour control. Their often chronic reoccurring nature and the lack of efficient therapies necessitate the development of new treatment strategies. Brain-computer interfaces, equipped with multiple sensing and stimulation abilities, offer a new toolbox, whose suitability for diagnosis and therapy of mental disorders has not yet been explored. Here, we developed a soft and multimodal neuroprosthesis to measure and modulate prefrontal neurophysiological features of neuropsychiatric symptoms. We implanted the device epidurally above the medial prefrontal cortex of rats and obtained auditory event-related brain potentials reflecting intact neural stimulus processing and alcohol-induced neural impairments. Moreover, implant-driven electrical and pharmacological stimulation enabled successful modulation of neural activity. Finally, we developed machine learning algorithms which can deal with sparsity in the data and distinguish effects with high accuracy. Our work underlines the potential of multimodal bioelectronic systems to enable a personalised and optimised therapy.

Sensory attenuation for external events is produced by a competition for attentional resources

A doorbell sounds less loud to us if we ring it ourselves than if someone else pushes the button. Self-produced stimuli appear attenuated to us compared to stimuli generated by others (Weiss et al., 2011). The effect is known as sensory attenuation for external events. Here, we asked whether this effect results from a competition for attentional resources of sensory events. We first tested whether tactile attention is boosted at the time of pushing a button. We presented a button in a virtual reality setup that allowed to manipulate the time of tactile feedback. We found that a tactile impulse was perceived as more intense in the moment the hand pushed the button. In a second experiment, participants pushed a button and estimated the loudness of sounds. We found sensory attenuation for the loudness of the sound only when tactile feedback was provided at the time of reaching the movement goal. In a third experiment, we found that this interaction between a tactile and an auditory event did not occur when the hands remained passive without movement. These data reveal that sensory attenuation for external events occurs because tactile attention is boosted at the time of a button pressing movement, thereby dragging attention from the auditory modality.