According to recent research from MIT’s Picower Institute for Learning and Memory, the mammal brain does not retain a specific memory in a solitary or even a few locations but in a dispersed, dynamically integrated complex encompassing several brain areas.
When the rodents were moved from one cage to the other, they were subjected to a brief but lasting electrical shock, and the researchers were able to identify the brain regions involved in engram formation.
There were numerous areas that were anticipated to engage in remembering, but there were also those that were not. Using the brains of mice that were either able to encode or remember an electrical zap as a control, the experts were able to exclude areas that may have been affected by behavior unconnected to the zap recollection. In an attempt to rank order 117 cerebral areas that have a high probability of becoming engaged in the complex memory engrams, they used an “engram index.”
Optogenetics is a method of controlling cells stimulated by light flashes in mice that have been genetically modified by experts. A laser flash was administered to certain brain areas to determine whether activating them would artificially duplicate the fear memory response of remaining in place, even in a “neutral” enclosure in which the zap had never happened.
Optogenetic activations of engram complexes of neurons were shown to follow the same characteristics as those seen in normal memory retention.
As the brain stores a single memory over such a large area, experts believe it is rendering remembering more powerful and robust. If just a few parts of the brain are affected by illness, dispersed memories may help us recall the past and make us more resilient to local harm.
The study was published in Nature Communications.