Try to recall a conversation without hearing it in your head. It’s difficult, because sound impacts our memory formation. That’s why we forget the milk at the store, and leave without the one thing we came for: we heard the instructions, but we didn’t really listen.
Maintaining a sound in your mind’s ear—that is, how we imagine it, keep hearing it, and retrieve it after it’s gone—is called auditory working memory.
This cognitive capacity to keep sounds in mind for a short period of time was the focus of a paper published in Neuron by a team at McGill University’s Brain Imaging Centre. The study tested the efficacy of a non-invasive brain therapy called transcranial magnetic stimulation, or TMS. Using a hand-held device placed against the scalp, the researchers positioned the targeted, oscillating pulses (at 5 Hz) into the brain in order to stimulate nerve cells.
The group found some surprising results. TMS seemed to directly improve the working memory of 17 participants in a recall task. Participants were asked to recognize a melody when the order of notes played back was reversed. After TMS treatment, they were able to remember the series of sounds quicker, and more accurately.