Awh said that "these findings provide strong evidence that these electrical oscillations in the alpha frequency band play a key role in a person's ability to store a limited number of items in working memory."
"By identifying particular rhythms that are important to memory, we're getting closer to understanding the low-level building blocks of this really limited cognitive ability. If this rhythm is what allows people to hold things in mind, then understanding how that rhythm is generated -- and what restricts the number of things that can be represented -- may provide insights into the basic capacity limits of the mind."
The findings emerged from a basic research project led by Awh and co-author Edward K. Vogel -- funded by the National Institutes of Health -- that seeks to understand the limits of storing information. "It turns out that it's quite restricted," Awh said. "People can only think about a couple of things at a time, and they miss things that would seem to be extremely obvious and memorable if that limited set of resources is diverted elsewhere."
Past work, mainly using functional magnetic resonance imaging (fMRI), has established that brain activity can track the content of memory. EEG, however, provides a much less expensive approach and can track mental activity with much a higher temporal resolution of about one-tenth of a second compared to about five seconds with fMRI.
"With EEG we get a fine-grained measure of the precise contents of memory, while benefitting from the superior temporal resolution of electrophysiological measures," Awh said. "This EEG approach is a powerful new tool for tracking and decoding mental representations with high temporal resolution. It should provide us with new insights into how rhythmic brain activity supports core memory processes."