Neuroprosthetic electrode implants being used by US military-funded tests may become the next solution for memory loss prevention. Presumably, the implants have the capability to simulate the electrical patterns that are responsible for creating and storing memories.
This two-part project by the Defense Advanced Research Projects Agency is being managed by researchers from the University of Southern California (USC) and another team from the University of Pennsylvania (Penn).
Long-term memory is translated from short-term memory when the latter is accessed from its storage in the hippocampus for a short period after its point of storage. In this process the brain sends a signal from the region of the hippocampus called CA3 onto another region called CA1. Theodore Berger of USC believes that recreating signals sent to CA1 will help in memory restoration.
Using signal patterns recorded from participants who have epilepsy and who have been implanted with the electrodes, the USC team used the CA1 cell patterns as basis to create an algorithm that predicts the CA3 patterns. Tests of the algorithm, by far, have shown 80% accuracy.
In terms of application, stimulation of CA1 cells is the target to work around any damage to CA3 cells.
The challenge in this assumption lies in cases where the CA1 cells have extensive damage so that stimulation of these cells by CA3 signals may not be sufficient to implement memory mimicking.
On the part of the Penn team stimulation of the hippocampus housing, called the medial temporal lobe, is found to allow revival of memories that are fading. However, the same stimulation performed on a healthy brain results to a worsening of the memory.
The team created their algorithm on the basis of recorded brain activity from 28 individuals. Using this stimulation, performance is boosted by as much as 140% when testing the participants with words that are easily forgotten.
Both teams will perform further testing to refine the methods. Added research is also required to determine the explanation for how memory is recovered and why stimulation of the brain's regions assists in this.
