September 24, 2023

The brain is an electrical organ. Everything that is going on there is the result of millivolts switching from one neuron to another in certain patterns. This increases the tempting possibility that, if we ever deciphered them, we could electrically adjust these patterns to treat neurological disorders – from Alzheimer’s to schizophrenia – or even to optimize desirable traits like intelligence and resilience.

Of course, the brain is so complex and difficult to access that it is much easier to imagine than to do. However, a couple of studies published in the journal Nature Medicine in January show that electrical stimulation can treat compulsive urges and symptoms of depression with surprising speed and precision. By mapping the participants’ brain activity in response to certain sensations, the researchers were able to personalize the stimulation and change moods and habits far more directly than is possible through therapy or medication. The results also showed the extent to which symptoms that we tend to classify as a single disorder – depression, for example – may include electrical processes that are unique to each person.

In the first study, a team from the University of California at San Francisco surgically implanted electrodes in the brain of a woman whose severe depression had proven resistant to other treatments. For 10 days, they delivered impulses through the electrodes to different areas of the brain at different frequencies and had the patient record her level of depression, anxiety and energy on an iPad. The influence of certain impulses was significant and nuanced. “Within a minute, she would say,” I feel like I’m reading a good book, “says Katherine W. Scangos, psychiatrist and lead author of the study, who described the effect of a different pulse as” less cobwebs and cotton. ”

The researchers also recorded what kind of immediate brain activity coincided with periods of low mood or energy. The aim was to use these responses to control the placement of another set of electrodes that would provide what is known as deep brain stimulation – a technique that allows neurons to restore their loss of function by zapping them with a steady, high-frequency electrical pulse. So far, it has been most commonly used to treat movement disorders such as Parkinson’s. It has also shown promise for depression. “But because different people experience depression differently, there are likely multiple neural circuits involved,” says Scangos. She and her colleagues wondered if a “more personal approach” could make treatment more effective. Based on their mapping of the patient’s brain activity, they programmed the electrodes in such a way that they recognize their depressive states and, in response, emit stimulation, similar to how a pacemaker acts on the heart. This experimental treatment is continued over the long term when the patient goes about her daily life.

Deep brain stimulation is too invasive to use except in extreme circumstances. In the second study, however, the researchers used a non-invasive technique called transcranial AC stimulation to deliver electrical pulses through electrodes on the participants’ scalps. The aim was to curb compulsive behavior. Previous studies have shown that the frontal orbital cortex, an area in the brain’s reward network, may play a role in enhancing such behaviors by viewing them as beneficial. So the researchers attached the electrodes to 64 volunteers and recorded the number of hertz that their orbital frontal cortex fired when they won a financial reward in a game.

It was crucial that the frequency varied slightly from person to person. Using this personal frequency, the researchers stimulated the same area in each participant for 30 minutes a day for five days in a row. They found that this reduced the number of compulsive behaviors among the volunteers by an average of nearly 30 percent over the next three months. (None of the volunteers had a diagnosis of obsessive-compulsive disorder. However, all reported varying degrees of repetitive tendencies, and those whose symptoms were most intense showed the greatest relief.) The researchers hypothesized that the stimulation helped the orbital frontal cortex hold You contribute to the optimal rhythm and thus improve coordination with other areas of the reward network.

The results confirmed the idea that personalized brain stimulation requires not only determining the right target area, but also the right rhythm. “The neural code – it’s frequency specific,” says Robert MG Reinhart, one of the study’s authors and director of the Laboratory for Cognitive and Clinical Neuroscience at Boston University. “The information processing channel in the brain is just like a channel you can tune into on the radio.” The study also showed that traits such as compulsiveness existed on a spectrum. At present, a person who is troubled but not disabling by these traits may not seek treatment, especially if accompanied by side effects, as is often the case with medication. However, brain stimulation could one day fix all kinds of conditions that we are now inaccurately targeting with drugs, says Reinhart. “If you want to go futuristic, you can imagine someone zapping themselves to get over a transatlantic flight. What people use coffee for today. “

Psychiatrists won’t be Prescribing brain stimulation to the masses anytime soon. However, by identifying the neural circuitry that leads to certain symptoms and showing that changes in the timing of their fire can alter those symptoms, they offer new ways to think about psychiatric disorders. “There’s still a lot of stigma about depression that many patients feel,” Scangos says. The subject of her study was no exception: “The fact that there was such an immediate response when we stimulated made her feel like I was not doing anything wrong. There is something in my brain that can be addressed. “

Labeling a collection of symptoms with a diagnostic label such as “depression” is useful as it helps doctors more effectively find successful treatment, which is currently a lengthy process of trial and error. “The million dollar question is how to tailor the best treatment for the patient and how to avoid treatments that don’t work,” says Helen Mayberg, neurologist and director of the Nash Family Center for Advanced Circuit Therapeutics at the Icahn School of Medicine on Mount Sinai; She was co-author of a commentary on the two studies. As neuroscientists map the brain activity of more and more patients, they are nearing the opportunity to offer a series of tests that show Scangos says, “If you have this type of depression, this drug is your best response.”

If we could address these symptoms head-on, we could ultimately get rid of the diagnostic categories altogether, says Alvaro Pascual-Leone, medical director of the Wolk Center for Memory Health at Hebrew SeniorLife and professor of neurology at Harvard Medical School. Instead of using a standard label for depression or obsessive-compulsive disorder, according to Pascual-Leone, doctors could instead ask, “What is the disability symptom this person is exhibiting?” And then treat them specifically.

Currently, these studies offer everyone additional evidence that “our brains are made of plastic,” says Shrey Grover, graduate student and co-author of the study at Boston University. “And we can rewire the brain in a number of ways.” These include psychotherapy and pharmacology. Our neural activity also changes when we learn; it changes as we get older. This means that we can improve the way our minds work at any point in our life, even without advanced technology.

However, the plasticity of the brain makes it all the more puzzling that certain psychological states are so difficult to dispel. Research into personalized brain stimulation also explores the bigger question of why moods or habits that are mild or awkward in some people – such as a careful review of a tax form or a deep sadness about the death of a loved one – are chronic and debilitating in others. “There is nothing that is right in this matter,” says Reinhart. “It’s like the water is flowing in the sink and you can mop the floor, but nobody turns off the tap.”

Kim Tingley is a contributing writer for the magazine.