This raises the tantalising possibility that, should we ever decode those patterns, we could electrically adjust them to treat neurological dysfunction — from Alzheimer’s to schizophrenia — or even optimise desirable qualities like intelligence and resilience.
Of course, the brain is so complex, and so difficult to access, that this is much easier to imagine than to do. A pair of studies published in January in the journal Nature Medicine, however, demonstrate that electrical stimulation can address obsessive-compulsive urges and symptoms of depression with surprising speed and precision. Mapping participants’ brain activity when they experienced certain sensations allowed researchers to personalise the stimulation and modify moods and habits far more directly than is possible through therapy or medication. The results also showed the degree to which symptoms that we tend to categorise as a single disorder — depression, for example — may involve electrical processes that are unique to each person.
In the first study, a team from the University of California, San Francisco, surgically implanted electrodes in the brain of a woman whose severe depression had proved resistant to other treatments. For 10 days, they delivered pulses through the electrodes to different areas of the brain at various frequencies and had the patient record her level of depression, anxiety and energy on an iPad. The impact of certain pulses was significant and nuanced. “Within a minute, she would say, ‘I feel like I’m reading a good book,’” says Katherine W. Scangos, a psychiatrist and the study’s lead author. The patient described the effect of another pulse as “less cobwebs and cotton.”
The researchers also recorded what type of unmediated brain activity coincided with periods of low mood or energy. The aim was to use those responses to guide the placement of another set of electrodes that would deliver what is known as deep-brain stimulation — a technique that can restore lost function to neurons by zapping them with a consistent, high-frequency electrical pulse. To date, it has been employed most commonly to treat movement disorders, like Parkinson’s. It has also shown promise for depression. “But because depression presents differently in different people, it likely involves multiple neural circuits,” Scangos says. She and her colleagues wondered if a “more personalised approach” might make the treatment more effective. Based on their mapping of the patient’s brain activity, they programmed the electrodes to detect her depressed states and deliver stimulation in response, much the way a pacemaker acts on the heart. That experimental treatment will continue long term as the patient goes about her daily life.
Deep-brain stimulation is too invasive to use except in extreme circumstances. But in the second study, researchers used a non-invasive technique called transcranial alternating current stimulation to deliver electrical pulses through electrodes placed on participants’ scalps. The goal was to try to curb obsessive-compulsive behaviours. Past studies have suggested that the orbital frontal cortex, an area in the brain’s reward network, might play a role in reinforcing such behaviours, by regarding them as beneficial. So the researchers attached the electrodes to 64 volunteers and recorded the frequency in hertz at which their orbital frontal cortex fired when they won a monetary reward in a game. The findings reinforced the idea that personalised brain stimulation requires determining not just the right area to target but also the right rhythm at which to do so. The study also illustrated that traits like compulsivity exist on a spectrum. Currently, a person for whom those traits are bothersome but not disabling might not seek treatment, particularly if it comes with side effects, as medications often do. Brain stimulation, though, could one day remedy all kinds of conditions we now target inexactly with drugs.
Tingley is a writer for the NYT magazine
The New York Times