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Can We Help the Brain Remember with Technology?

Why Memory Matters

Most of us know someone who struggles with memory, whether due to aging, injury, or illnesses such as Alzheimer’s. Scientists have observed that certain brain activities, called neural oscillations (imagine brain cells flashing in rhythmic patterns), often become disrupted in these conditions.
While medications do not always help, new devices that communicate with the brain using tiny electrical pulses (similar to how pacemakers support the heart) are showing promise. These devices are already being used successfully to treat movement problems in Parkinson’s disease. Now, we are asking an important question: can they also help memory?

What We Know About Memory and the Brain

Memory is not a single event but a chain of processes: storing information, keeping it safe, and recalling it later when needed. Each of these steps depends on a network of brain areas working together in rhythm, much like musicians playing in time with each other.
When these connections break down, memory falters. For example, the entorhinal cortex acts as a bridge. In the early stages of Alzheimer’s, this bridge is damaged, disrupting communication with the hippocampus and prefrontal cortex and leading to memory decline.

The Big Idea Behind This Work

Our goal is to restore healthy brain rhythms in real time across entire networks so that both humans and non-human primates (monkeys) can learn and remember more effectively. The vision is to create a kind of “prosthetic for memory.” This would not cure the root causes of disease but could help people maintain quality of life for longer.
What makes this project unique is its focus on controlling three features of stimulation at the same time:

  • Where the stimulation is applied in the brain or body

  • When it is delivered, and in what rhythm

  • At what frequency it targets, corresponding to specific brainwave bands

To tackle these challenges, participants (human or monkey) play a memory game called paired associates learning, which involves matching images to locations. The research brings together three complementary approaches:

  • Using direct brain stimulation in monkeys to understand how specific brain regions and networks support memory

  • Using flashing lights and sound in healthy humans to guide brain rhythms from the outside

  • Using non-invasive electrical nudges on the scalp to target and tune memory-related brain areas in humans

Each of these projects provides a different piece of the memory puzzle.

Directly Stimulating Monkey's Memory Areas
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An illustration of the memory areas of the brain targeted. Hippocampus (red) and entorhinal cortex (blue) are each implanted with an electrode containing 8 contacts, and the prefrontal cortex (yellow) is placed with a electrode array of 55 contacts. Each of these 71 contacts can be used for recording the neural oscillations and stimulation to restore incorrect oscillations to correct ones. Thus, allowing the manipulation of the memory.  

In monkeys, experiments focus on stimulating brain networks directly while they perform memory tasks.

  • Step 1: Fine-tuning stimulation for each brain region while monkeys play memory games

  • Step 2: Expanding to multi-area stimulation, aiming to sync brain circuits together like an orchestra playing in harmony

  • Step 3: Using closed-loop systems that monitor brain activity in real time and stimulate only when memory starts to slip

To test if these rhythms can actually “fix” memory, I temporarily disrupt memory with a safe drug called scopolamine, which mimics some aspects of dementia. I then check whether targeted stimulation can reverse these effects by measuring both behavior and brain signals.
The long-term goal is a fully implantable memory prosthesis. Early trials may involve patients with severe conditions such as epilepsy patients who already have electrodes implanted. Later, this could extend to milder memory problems or early dementia. With millions worldwide affected, the potential impact is huge.

Lights, Sounds, and Memory
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By providing the visual stimulation (aka flashing lights) and/or sound, the brain activity was modified. For visual stimulation a virtual reality headset was used and lights were flashed at low, high, low + high frequencies.   

In parallel, I tested whether brain rhythms can be guided through the senses using flickering lights and rhythmic sounds.
Brainwaves are how neurons coordinate activity. Theta waves link to memory and navigation, while gamma waves support attention and the integration of information. In Alzheimer’s and other memory disorders, these rhythms often lose coherence.
By presenting light and sound at specific frequencies, I can “entrain” brain rhythms and help restore their natural sync. In animal studies, this sensory stimulation even reduced disease-related brain changes.
In human experiments:

  • Volunteers experienced light and sound rhythms tuned to theta (slow) or gamma (fast) waves. Some trials combined both in “nested” stimulation

  • EEG measured whether brainwaves aligned with these rhythms

  • Memory tasks before and after stimulation tested for changes in learning and recall

Key findings:

  • Visual and combined light-sound stimulation reliably boosted brain rhythms, especially in frontal and visual areas

  • Real-time monitoring confirmed effective stimulation

  • Combined theta-gamma stimulation showed signs of helping short-term memory in some participants

  • Pure auditory stimulation was weaker, and nested rhythms did not always outperform single rhythms

Follow-up studies confirmed expected brainwave markers but found 40 Hz visual stimulation did not always improve memory. Sometimes it reduced brainwave patterns linked to memory.
Overall, sensory stimulation is safe, inexpensive, and easy to use. Effects on memory are subtle and vary between individuals, but this approach holds promise as a supportive tool for those with early memory decline.

Electric Nudges for the Brain
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Placing two connected pads (the connected black rectangles) on the scalp and passing changing current leads to generation of electric fields, represented as green and yellow waves, which can stimulate (shown as lighting bolt on surface) the outer surface of the brain, also called as cortex. This method of stimulation is called as tACS (transcranial alternating current stimulation). By using 4 such pads and strategically placing them on scalp such that the two fields interact to simulate a deeper area of the brain, shown as dashed red circle. The process of using the interacting fields for deeper area stimulation is called as tTIS (transcranial temporal interference stimulation).

A third project explores whether gentle, painless electrical currents applied to the scalp can tune brain activity and improve memory. This includes testing in younger adults, older adults, and older adults with cerebral small vessel disease (CSVD).
CSVD is damage to small blood vessels in the brain that can cause cognitive problems and increase dementia risk. It is common worldwide and has limited treatment options.
Unlike implants, scalp stimulation is non-invasive, safe, and accessible. 
The study compares three methods:

  • tACS (transcranial alternating current stimulation), which applies rhythmic currents to the head’s surface

  • tTIS (transcranial temporal interference stimulation), which targets deeper brain areas

  • High-frequency stimulation, using rapid pulses

Participants get personalized brain maps via MRI. During sessions, they wear EEG caps that record brain activity and deliver stimulation. Each session includes real, sham (placebo), and no stimulation to allow direct comparison.

What Were the Measures

  • Changes in memory task performance

  • Shifts in brain activity patterns

  • Differences by age or baseline memory

Why This Matters

Non-invasive brain stimulation could be a practical way to help people maintain memory with age. Comparing methods head-to-head will show which are most effective and for whom.

Looking Ahead

Together, these three projects explore complementary paths:

  • Direct brain stimulation in monkeys to uncover how memory rhythms operate

  • Audiovisual stimulation to gently nudge brain rhythms through the senses

  • Non-invasive electrical stimulation to support memory safely from outside the skull

All share the same mission: to restore the rhythms that memory depends on. While the science is ongoing, there is hope that by guiding brainwaves safely and effectively we may offer people with memory problems not a cure, but more time with their memories.

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