Washington, October 24 : Psychologists at the University of
Pennsylvania have for the first time pinpointed brain waves that
distinguish false memories from the real ones.

The new findings are significant because they may help improve
researchers’ understanding of how memory works, and lead to a new
strategy to enable epilepsy patients retain cognitive function.

The researchers recorded brain activity from 52 neurosurgical
patients being treated for drug-resistant epilepsy, in order to test
whether distinct patterns of electrophysiological activity prior to a
response can distinguish true from false memories.

The patients were asked to perform a verbal free-recall task while
researchers used an array of implanted electrodes and intracranial
electroencephalographic recordings to locate where in their brains the
seizures originated.

For the verbal free-recall task, the patients studied lists of
words, which they were asked to recall at a later stage. It was found
that the participants recalled some numbers of correct items, and also
made a small number of errors while recalling words that had not
appeared on the target list.

As the patients performed the memory game, the researchers observed
electrical activity in their brains to determine whether specific brain
waves were associated with successfully storing and retrieving
memories.

It was found that a fast brain wave called the gamma rhythm
increased as the participants studied a word that they would later
recall. The same waves, whose voltage rises and fall between 50 and 100
times per second, also rose in the half-second prior to participants
correctly recalling an item.

Lead author Per B. Sederberg, a former Penn neuroscientist who is
now performing post-doctoral research at Princeton University, says
that the analysis reveals that the same pattern of gamma band
oscillatory activity in the hippocampus, prefrontal cortex and left
temporal lobe that predicts successful memory formation also re-emerged
at retrieval, distinguishing correct from incorrect responses.

According to led investigator Michael Kahana, a professor of
psychology in Penns School of Arts and Sciences, retrieval of true
memories induced a distinct pattern of gamma oscillations in the brain
as compared to retrieval of false memories.

He said that gamma waves actually predicted whether or not an item
that was about to be recalled was previously studied. In other words,
one could see a difference in brain activity just prior to remembering
something that had and had not actually happened.

The researchers say that the new findings may provide a clearer
picture of how to assist people suffering from epilepsy. They say that
identifying the neural signatures of successful memory storage and
retrieval can help neurosurgeons reduce the cognitive deficits that
might result from epilepsy surgery.

The study has been published online in the journal Psychological Science. (ANI)