Biology subjects

Abdellahi, M. E. A.

Publications and source records attributed to Abdellahi, M. E. A..

6 recordsLinked to original sources

bioRxiv2024

Disarming emotional memories using Targeted Memory Reactivation during Rapid Eye Movement sleep

Emotional responses are dampened across sleep, and this is thought to be mediated by neural reactivation during Rapid Eye Movement (REM) Sleep. Such reactivation can be triggered by targeted memory reactivation (TMR), a technique in which a tone previously associated with a memory during wake is re-presented during subsequent sleep. Prior work has shown that TMR in REM reduces arousal responses to negative stimuli. The present study builds on this by measuring autonomic responses and brain activity as well as behaviour. Participants rated the arousal of 48 affective images, paired with semantically matching sounds. Half of these sounds were cued during REM in the subsequent overnight sleep cycle. Participants rated the images in a Magnetic Resonance Imaging (MRI) scanner with pulse oximetry 48 hours after encoding, and again after two weeks. Results showed that TMR during REM was also associated with reduced brain activity in the two primary nodes of the Salience Network (SN): the Anterior Insula and dorsal Anterior Cingulate Cortex (dACC), as well as the orbitofrontal cortex, subgenual cingulate, and left amygdala, all of which are known to be important for emotional processing. TMR markedly reduced the emotional heart rate deceleration (HRD) response, and also reduced subjective arousal ratings for highly arousing images, while increasing ratings for less arousing images. We conclude that REM TMR can facilitate a decrease in physiological and neurological responses to arousal. These findings have potential implications for the use of TMR in treatment of depression and anxiety disorders. HighlightsO_LITMR in REM sleep reduces Salience Network responses to emotional pictures. C_LIO_LITMR in REM sleep reduces heart rate deceleration to emotional pictures. C_LIO_LITMR in REM sleep reduces subjective arousal ratings of highly arousing images. C_LIO_LITMR in REM sleep provides a promising potential avenue for treatment of PTSD. C_LI

neuroscience↗

bioRxiv2024

Targeted memory reactivation elicits temporally compressed reactivation linked to spindles

Memories reactivate during sleep, however the properties of such reactivation and its relationship to encoding strength and subsequent memory performance are not well understood. We set out to examine memory reactivations associated with a serial reaction time task (SRTT). 48 human participants performed the SRTT, and then slept in the lab while we deliberately induced reactivation in Slow Wave Sleep (SWS) using a Targeted Memory Reactivation (TMR) design. We detected reactivation after TMR cues using multiclass classification that adapted to sleep data by using sleep activity for training and wake activity for testing. We then examined the temporal properties of reactivation in relation to behavioural performance and sleep spindles. In keeping with the rodent literature, the observed reactivation was 3 to 20 times faster than waking activity. Furthermore, we report an inverted-U shaped relationship between TMR-related behavioural improvement and encoding strength, with very strong and very weak memories benefiting little from cueing while medium-strength memories benefit the most. Finally, reactivation was more frequently observed in trials with high sigma power, supporting the idea that sleep spindles are associated with memory reactivation during sleep. These findings bring us closer to understanding the characteristics of human memory reactivation after TMR, demonstrate when cueing is effective, and provide evidence for the positive relationship between the detectability of reactivation and memory consolidation.

neuroscience↗

bioRxiv2022

Cueing motor memory reactivation during NREM sleep engenders learning-related changes in precuneus and sensorimotor structures

Memory reactivation during Non-Rapid Eye Movement (NREM) sleep is important for memory consolidation but it remains unclear exactly how such activity promotes the development of a stable memory representation. We used Targeted Memory Reactivation (TMR) in combination with longitudinal structural and functional MRI to track the evolution of a motor memory trace over 20 days. We show that repeated reactivation of motor memory during sleep leads to increased precuneus activation 24 h post-TMR. Interestingly, a decrease in precuneus activity over the next 10 days predicts longer-term cueing benefit. We also find both functional and structural changes in sensorimotor cortex in association with effects of TMR 20 days post-encoding. These findings demonstrate that TMR can engage precuneus in the short-term while also impacting on task-related structure and function over longer timescales.

neuroscience↗

bioRxiv2021

Targeting targeted memory reactivation: characteristics of cued reactivation in sleep

Targeted memory reactivation (TMR) is a technique in which sensory cues associated with memories during wake are used to trigger memory reactivation during subsequent sleep. The characteristics of such cued reactivation, and the optimal placement of TMR cues, remain to be determined. We built an EEG classification pipeline that discriminated reactivation of right- and left-handed movements and found that cues which fall on the up-going transition of the slow oscillation (SO) are more likely to elicit a classifiable reactivation. We also used a novel machine learning pipeline to predict the likelihood of eliciting a classifiable reactivation after each TMR cue using the presence of spindles and features of SOs. Finally, we found that reactivations occurred either immediately after the cue or one second later. These findings greatly extend our understanding of memory reactivation and pave the way for development of wearable technologies to efficiently enhance memory through cueing in sleep.

neuroscience↗

bioRxiv2021

Targeted memory reactivation in human REM sleep elicits recurrent, temporally compressed reactivation

Several studies show that memories are reactivated during non-rapid eye movement (NREM) sleep, but the question of whether equivalent reactivation can be detected in rapid eye movement (REM) sleep is hotly debated. To examine this, we used a technique called targeted memory reactivation (TMR) in which sounds are paired with learned material in wake, and then re-presented in subsequent sleep to trigger reactivation. We then used machine learning classifiers to identify reactivation in REM related to the encoded wake activity. The reactivation we measured was mediated by high theta activity and was sometimes temporally compressed and sometimes dilated compared to wakeful experience. Reactivation strength positively predicted overnight performance improvement. These findings provide the first evidence for wake-like memory reactivation in human REM sleep after TMR.

neuroscience↗

bioRxiv2020

Targeted memory reactivation of a serial reaction time task in SWS, but not REM, preferentially benefits the non-dominant hand

Targeted memory reactivation (TMR) is a technique by which sounds paired with learned information can be used to cue neural reactivation of that information during sleep. While TMR in slow-wave sleep (SWS) has been shown to strengthen procedural memories, it is unclear whether TMR in rapid eye movement (REM) sleep, a state strongly associated with motor consolidation, provides equivalent benefit. Furthermore, it is unclear whether this technique influences dominant and non-dominant hands equally. We applied TMR of a two-handed serial reaction time task (SRTT) during either SWS or REM in thirty-two human right handed adults (sixteen female) to examine the impact of stimulation in each sleep stage on right (dominant) and left hands. While TMR in SWS led to strong benefits in reaction times and sequence-specific skill, equivalent cueing in REM led to no benefit at all, suggesting that reactivation in this sleep stage is not important for the SRTT. Event-related potentials elicited by TMR cues for left and right hand movements differed significantly in REM, but not SWS, showing that these cues are at least processed in REM. Interestingly, TMR benefits were apparent only in the non-dominant hand, potentially due to the weaker performance measured in this hand at the outset. Overall, these findings suggest that memory replay in SWS, but not REM, is important for consolidation of the SRTT, and TMR-cued consolidation is stronger in the non-dominant hand. Significance statementTargeted memory reactivation (TMR) in sleep leads to memory consolidation, but many aspects of this process remain to be understood. We used TMR of a bimanual serial reaction time task to show that behavioural benefit is only observed after stimulation in SWS, even though electrophysiology shows that the TMR cues are processed in REM. Importantly, TMR selectively benefitted the non-dominant hand. These findings suggest that TMR in REM does not benefit this serial reaction time task, and that TMR in SWS preferentially consolidates weaker memory traces relating to the non-dominant hand.

neuroscience↗