In a development that has the potential of ushering in a paradigm shift in how degenerative brain diseases are treated, researchers have broken new ground in using ultrasound to precisely target multiple brain areas at the same time, opening the door to precision treatment of conditions ranging from Alzheimer's to epilepsy. The same technology that created the first baby photos may soon revolutionise how we treat brain diseases—without surgery or medicines. 

A research team from ETH Zurich, the University of Zurich, and New York University has created what they call a "holographic" ultrasound approach that can stimulate three to five distinct brain points simultaneously through the skull without the need for surgery. This is a major improvement over prior single-point ultrasound approaches.

"Given that the brain operates in networks, it's easier to activate or inhibit a brain network if you stimulate it at multiple points simultaneously," explains Professor Daniel Razansky, who conducted the study. The researchers demonstrated this in mice using a specialised hood outfitted with hundreds of ultrasonic transducers. 

The technology functions similarly to how light waves generate holograms. Researchers can establish precise focal areas in the brain by precisely organising hundreds of ultrasound pulses to interfere with one another. 

The actual originality of this "holographic" ultrasound approach is how its key benefits are inextricably linked. Its precise targeting of individual brain networks, rather than entire regions, is fundamentally responsible for increased safety. By dispersing the influence over numerous sites, the method can achieve the desired neuronal modulation with far less overall ultrasonic intensity, lowering the danger of overheating or tissue injury. This safety is enhanced by the capacity to monitor in real time, which provides immediate visual proof of activated networks. This establishes an important feedback loop, allowing researchers to confirm that the stimulation is precise and limited to the specified targets, ensuring that the intervention is as controlled as it is effective. 

The multi-point technique allows researchers to employ substantially lower ultrasonic intensity than single-spot stimulation. "The less intense the ultrasound, the safer this process is for the brain," says Razansky. Earlier approaches frequently had an all-or-nothing problem—too weak and nothing happened, too strong and you risk injuring brain tissue or blood arteries. 

While the exact mechanisms are still being studied, researchers believe that ultrasonic pulses mechanically alter proteins on neurone surfaces that regulate ion transport into cells. These short pulses result in minor temperature rises while potentially triggering or inhibiting brain activity. 

Political constraints have blocked funding from the United States National Institutes of Health to overseas collaborators, creating uncertainty in the research. Despite this, the team intends to continue its work using alternative financing sources. 

The next stage is to test the technique in animal models of brain illnesses such as Alzheimer's, epilepsy, depression, and Parkinson's. "We rely on animals for our research," Razansky explains. "We first need to learn how to control the intervention and ensure it is safe and effective."