Scientists recovered forgotten memories with magnetic stimulation
The study shows that short-term memories maintain the possibility of being retrieved even if the neurons associated with them are not active. This shows that the brain continues to process latent words even though there is no continuous activation of neurons.
As scientists have proven, our memory is little like a recorder that stores information and allows us to retrieve it. Rather, it is a creative act that responds to our survival needs. Each time we remember something, we expose our memories to the possibility that they are modified, and that often means that what we remember from the past does not always coincide with what actually happened.
In addition to long-term memory, humans make use of a working memory, which serves to deal with the tasks of the moment and that combines in making decisions with what we already know. This week, in the journal Science, a group of researchers from the Universities of Notre Dame and Wisconsin has tried to advance a little more in understanding the operation of this type of memory and has even been able to manipulate it with transcranial magnetic stimulation.
To analyze what happens in our brain and how we use short-term memory in our daily lives, the scientists performed a series of experiments. First, they presented the study volunteers with three types of stimuli: faces, words, or moving points. Through a fMRI system, a type of MRI that allows real-time brain activity to be observed, they identified the regions of the brain involved in the processing of each stimulus. In this way, they identified areas that only processed one type of stimulus.
We then presented to the volunteers two of the three stimuli and waited some time to finally offer one of the two stimuli. Thus, the subject was being told that what they were going to ask about later had to do with the face and made it focus on the face and stop paying attention to the word. Measuring brain activity, they observed that apparently the part devoted to word processing from working memory had been disabled, but it was not quite so. When the subject knew that after the face they could offer another clue that could be words, they were able to recover the memory through impulses of transcranial magnetic stimulation on the specific area of the brain that processed the words.
This shows that the brain continues to process words latently even though there is no continuous activation of neurons. This would run counter to the current theory that such neurons should remain active to maintain short-term memory. If the memory is going to be relevant to the subject, it can be recovered.
This idea that there is latent information could be used with stimulation protocols to try to manipulate the degree of representation of this kind of memories to consolidate in the longer term. Among other things, understanding the functioning of this type of memory could serve to better understand the habits that protect us from the cognitive deterioration associated with aging. The possibility of employing noninvasive brain stimulation to improve memory functioning in the elderly is a hopeful goal, but the science is still far from make it happen.