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 pulses are reportedly not painful.)
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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.
“The most exciting aspect is that we found a causal link between brain and behavior,” Philippe Albouy, one of the study’s co-authors, told The Daily Beast. “TMS is easy to control because the stimulation is focused. When you’re targeting a given brain region, you’re sure that you’re hitting that region.”
TMS was recently granted FDA-approval to treat depression, and the treatment is covered by some health insurance plans. The McGill University study focused on theta wave activity in the auditory dorsal stream, a pathway in the brain that helps us process speech. The group also compared the data to the control condition of TMS at 5 Hz with non-rhythmic pulses. The participants’ brain activity was simultaneously tracked with two technologies: a massive, cocoon-like magnetoencephalography (MEG) scanner, which records the magnetic fields produced by ‘brain waves’; and an electroencephalogram (EEG), a cap-like set of small discs (electrodes) pasted all over the scalp to track the brain’s electrical activity.
“This means that we can use brain activity as a marker for later interventions,” Albouy said. “That’s the interesting part.”
The study’s results suggest broader clinical applications, according to Albouy. TMS, a “relatively painless” tool that doesn’t require anesthesia or hospitalization, has the potential to treat other patients who have deficits in working memory, such as people with Parkinson’s disease or Alzheimer’s disease, or children and adults with ADHD.
“I think you can say that this method could apply to almost everything,” Albouy said. “The only thing is that you have to define a brain marker to a given task. The task can be what you want. It could be attention, visual perception, or memory. Once you have this marker and the region of interest, then you can apply rhythmic stimulation during the task in order to improve performance.”
Though TMS is an emerging, experimental technology, some studies have shown—though at times with mixed results—that the technique has the potential to improve the lives of people with autism and post-traumatic stress disorder (PTSD), and those who struggle with addiction, and chronic pain. A similar study in Science by a team of researchers at the University of Wisconsin-Madison demonstrated that TMS can help us remember: Recent memories can be brought back, and recalled.
Yet researchers haven’t found a way to help participants sustain their improved working memory. Typically, their performance plummets after leaving the TMS machine behind.
Albouy’s team is working on this problem. He’s currently developing a study with HIV-positive patients who are coping with memory deficits.
“We are trying to see if we can observe any after effects. Then, we will apply it to a clinical population, step by step,” Albouy said. “We’re trying to find some patterns. It’s a promising approach.”
The TMS technique described in the study has the potential to be ready for clinical applications in as soon as a year (next spring), Albouy said. “I’m not sure. I can’t really predict it. We are really in the early stages of this approach, so it’s difficult to predict,” he said.
Another future path for research is how sound impacts long-term, rather than working, memory. Evocative or emotionally-charged sounds can change what we can remember—and what we forget. Sound can take over what we think and how we feel. It’s how a song takes you back. It’s how accents move through families and time zones. It’s anticipating the pause before someone tries to pronounce your last name. (The author's last name, for example, “Beebe,” is pronounced bee-bee, like two insects buzzing.) It’s the lilt in the voice of the person you love, the music of how they talk or laugh or scream or sing.
