Reliving Experiences Through Memories

We have all heard it before, "I remember that day like it was yesterday." Someone is explaining an important past experience, and he/she claims that every time they think about that time it is like they are reliving it.  However, is that actually possible? Can your memories be so vivid that it is as if you are are experiencing it all over again?  As it turns out, your brain may have a similar activation as you replay the memory to its original activation during the experience.  Dr. Brad Buchsbaum and colleagues conducted a study at Baycrest Rotman's Research Institute which tests whether the brain activates similar areas when bringing up a memory as when the brain perceives the original experience.  The study consisted of 20 adult participants who had to watch 12 videos that were 9 seconds long.  Each video had a variety of different animals, scenery, and sounds, and each video was paired with a stimuli. The participants were told that they would be tested on the videos.  While the participants were viewing the videos, and fMRI was taken so that the activation of their brain can be seen.

After the initial viewing, 9 of those participants were trained in remembering the 12 videos.  During the training, the participants were taught to associate the stimuli with its respected video.  The stimuli would cue the the participant to mentally replay a video.  The memory training took several weeks, but once it was over the participants partook in another fMRI scan.  This time they would mentally replay each one of the video and watch the real videos afterwards.  Buchsbaum found that the perception areas of the brain activated during the original video viewing are correlated with the areas activated for mentally replaying them.  There is an even stronger correlation vice versa which means that if an area is activated in the retrieval of the memory then it is very likely that it was also activated in the perception.

If areas that were used during the perception of an experience are being reactivated in the retrieval of the memory of that experience, then the claim that you remember something so vividly that it is like you are reliving it is not very far off base.  However, the participants were trained to replay the videos for several weeks.  This brings to question how much activation in perception areas is present when replaying a memory that you only experienced one time.  Is it possible to still have a similar re-activation or is it greatly diminished because you were not exposed to the stimuli over and over again?  Perhaps this finding is more applicable to traumatic and/or extremely joyous memories since you are more likely to replay those memories various times.

None the less this study may bring new meaning to testing the accuracy of memory. Since perception areas are reactivated during retrieval, an fMRI can be taken when a person who is "remembering" to see how much activation is taking place.  If there is high activation in the perception areas then it is more likely that the person is accurately remembering the event. Perhaps in the future a techniques such as that can be implemented for criminal identification and court testimonies.  It would be a lie detector in the sense that if the person is not telling the truth their would not be a lot of perception activation.  Although it would not be practical to give a testimony while in an fMRI machine, this study could open the door for finding better techniques to implement a similar way to detect lies.  At least for now when you hear people's vivid memories, you know that their brain is partially reliving that experience.

News Article
Baycrest Centre for Geriatric Care (2012, July 23). Why does a vivid memory 'feel so real?'. ScienceDaily. Retrieved November 15, 2012, 

Study
Bradley R. Buchsbaum, Sabrina Lemire-Rodger, Candice Fang, Hervé Abdi. The Neural Basis of Vivid Memory Is Patterned on Perception. Journal of Cognitive Neuroscience, 2012; : 1 DOI: 10.1162/jocn_a_00253