The Future of Targeted Memory Reactivation (TMR)

As a child, I wasn’t always best at school. In fact, I dreaded sitting down to study for tests and had excessive trouble with memorization. My mother used to tell me that if I slept with my notes under my pillow, I would wake up knowing all the information. Regrettably, learning new information is not that simple. While putting notes under your pillow is not going to magically make you smarter when you wake up, it is true that memory is consolidated during sleep. This is why academic institutions discourage students from pulling “all-nighters” or sleeping for periods less than 6 hours. Sleep is a necessary component to enhancing memory storage.

While memory consolidation already occurs during sleep, how can we amplify these already existing mechanisms?

Dr. Iliana Vargas’ research focuses on strengthening individual memories by reactivating them during sleep. During her research, it was found that reminders of smells or sounds during sleep can be used to “target the reactivation and strengthening of individual memories.” Targeted Memory Reactivation (TMR) utilizes sounds and odors to strengthen the already present memory consolidation that occurs during slow wave sleep. The underlying mechanism for the strengthening of memories is referred to as “neural replay”: newly learned information corresponds to a specific pattern of neural firing that then continuously recurs throughout sleep, ultimately strengthening the neural pathways and memories. Aware that memories gain stability during sleep consolidation, Vargas investigated whether “reinstating a learning context (an odor) during slow-wave sleep enhances retrieval of spatial information learned in that context.” The study required subjects to learn 50 images and associate those images with a specific sound and location on a map displayed on the computer screen. For example, an image of a cat would be presented with a meow, while a kettle would be presented with the sound of a whistle. Researchers would then reintroduce the sounds during the non-REM portion of sleep as the participants napped. The results of the study showed that memory processing can be highly specific and that information presented during sleep influences ensuing retrieval of information when awake.

Similarly, Dr. Bjorn Rasch, a biopsychologist at the University of Fribourg in Switzerland, utilized TMR with the memory game Concentration. Subjects were taught to associate images of cards with specific locations presented on a computer screen. Then throughout the study period, researchers released the smell of roses into the environment, essentially linking the odor to the material being learned. Rasch found that those who were exposed to the smell of roses during sleep displayed greater accuracy during the recall period where participants had to remember the placement of the cards.

The use of TMR is important because it may be able to help us alter how we think, advance our abilities when learning new information, and perhaps even lessen trauma associated with past experiences. Focusing on sleep and memory consolidation, Dr. Penny Lewis, a neuroscientist and sleep scientist at Cardiff University in Wales, describes memories as multisensory experiences. The idea that memories are multisensory experiences is clearly seen in both Vargas’ and Rasch’s research, where senses are presented as being powerfully tied to our memories and even propel retrieval of them. While TMR is only in its infancy, it’s potential impact is boundless. Scientists are currently trying to find a relationship between TMR and the process of consolidating emotional memories. Dr. Lewis is attempting to see whether triggering traumatizing events from our past during sleep can make these events less distressing. Participants in Lewis’ study are presented disturbing pictures (i.e. car crashes) with sound cues. Participants find these images less troubling when the memory of the image is reactivated during sleep through TMR. Lewis attributes this phenomenon to the lack of the neurotransmitter noradrenaline during rem sleep. Noradrenaline is responsible for our bodies physiological fear responses, such that of increased heart rate, sweating, and pupil dilation. Lewis believes that replaying the memory of the disturbing images in the absence of noradrenaline, allows the participant to experience the memory without the averse emotional response, and consequently, be able to dissociate the memory from the emotion. While it is too early to draw conclusions regarding the future of TMR, it’s not hard to imagine the use of TMR as a treatment for trauma disorders such as PTSD.

Works Cited

Winkle's, Van. "Targeted Memory Reactivation Will Make You Smarter as You Sleep." Inverse. Inverse, 09 Feb. 2017. Web. 03 May 2017.

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