Annabelle Singer, associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, learned early how to shape light. As a child wiring theater production lights, she helped illuminate stages. Today, she engineers light for a far more complex system: the human brain.
At the center of Singer’s research is a deceptively simple idea. If Alzheimer’s disrupts the brain’s electrical rhythms, those rhythms may be guided back into sync.
“If you think about the brain as an electrical circuit,” Singer explains, “we can manipulate those electrical signals.”
That perspective reflects a broader shift in how researchers approach neurological disease. Instead of focusing solely on biochemistry, Singer’s work treats the brain as a dynamic electrical system, one that may be tuned through precisely delivered sensory input. In Alzheimer’s disease, where abnormal activity patterns can precede symptoms by decades, that timing could be critical.
“The therapeutic effects we’ve seen often come from chronic stimulation, an hour a day over weeks,” Singer says. These studies have shown that sensory “flicker” stimulation can reduce disease-related pathology, recruit immune responses in the brain, and improve the function of neural circuits involved in memory.
A newer line of research is expanding that vision.
In recent studies, Singer and her team asked what happens immediately when the brain is exposed to these rhythms, not only in patients but also in healthy individuals. This short-term view offers a different lens for understanding how stimulation interacts with cognition in real time.
The answer was not what they expected.
“One of the things we were looking for was whether the stimulation might actually be distracting,” Singer says. “It could have been neutral or even harmful for attention.”
Instead, the team found the opposite. Participants exposed to 40 Hz flickering stimulation performed better on attention tasks. Their brain activity also showed changes associated with heightened alertness.
“Lower delta activity is typically seen when you’re more awake,” she explains. “Seeing that decrease, along with improved task performance, suggests people were more alert and engaged.”
The findings point to a deeper mechanism. Flicker stimulation does not only affect the frequency it is tuned to. It may also influence broader brain networks involved in attention, something researchers had not fully explored before.
“This was the first time we’ve observed changes outside the specific stimulation frequency,” Singer notes. “There may be a lot more going on in the brain than we’ve previously been measuring.”
The implications extend beyond Alzheimer’s disease. Clinical trials, including a Phase 2 study conducted by Cognito Therapeutics, have already shown that sensory stimulation may slow brain atrophy and cognitive decline. These newer findings suggest there could also be applications for improving attention in everyday settings.
“We’ve talked about whether this could be useful for people who need sustained attention, like air traffic controllers or anyone doing long, repetitive tasks,” Singer says.
At the same time, she remains measured about what the technology can do. In an environment filled with constant digital stimulation, attention is shaped by many overlapping factors.
“I don’t know that flicker is going to solve everything we see with attention challenges,” she says. “There are many factors, like multitasking and constant novelty, but it could help in moments where attention naturally fades.”
Just as important, the research offers reassurance for clinical use. If stimulation is delivered daily as a therapy, it must fit seamlessly into people’s lives without disrupting normal cognitive function.
“If this interfered with cognition, that would be a problem,” Singer says. “But if it’s neutral, or even beneficial, that’s incredibly important for how we deliver therapy.”
That usability has already been tested in early clinical work. When Singer approached clinicians at the Emory Brain Health Center to explore human trials, the transition from lab to clinic happened quickly. Within months, a feasibility study was underway. Despite initial skepticism, participants consistently completed an hour-long daily regimen.
“They didn’t love it,” Singer recalls, “but they didn’t say, ‘I’m never going to do it again.’”
Now, as diagnostic tools improve and Alzheimer’s can be detected earlier, Singer is focusing on intervention at earlier stages as well. The goal is to reach patients before significant damage occurs, when the brain may be more responsive to treatment.
Light and sound may seem like simple tools. In Singer’s lab, however, they are becoming precision instruments for restoring rhythm, strengthening attention, and revealing just how adaptable the brain can be when its timing is brought back into balance.
About Holy Shift! Biomedical Breakthroughs Shaping Tomorrow
Host Angela Gill Nelms chats with the brilliant minds behind the research to learn how biomedical engineers are shifting the status quo to drive breakthroughs and improve lives.
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