HMN 2026: How Brain implant uses temperature to switch neurons on and off

A research team led by Professor Il-Joo Cho of Korea University College of Medicine has developed a novel brain implant capable of bidirectionally modulating neural activity using temperature, opening new possibilities for next-generation brain-computer interfaces (BCIs) and treatments for neurological disorders.

Current neuromodulation technologies primarily rely on electrical, magnetic, optical, ultrasonic or chemical stimulation. However, many existing approaches are designed either to activate or suppress neural activity in a single direction, limiting their ability to achieve precise, bidirectional control of neural circuits.

Temperature, by contrast, is a physiological factor capable of both increasing and decreasing neuronal activity. This unique characteristic enables both activation and inhibition through a single mode of stimulation. Despite its potential, the practical application of temperature-based neuromodulation has been constrained by the technical difficulty of delivering localized cooling and heating to deep-brain regions.

To overcome these limitations, Cho’s team developed a miniaturized brain implant that combines a thermoelectric (Peltier) device with a silicon-based neural probe. This device can be implanted into deep-brain regions to locally increase or decrease tissue temperature, enabling targeted cooling and heating of neural circuits.

The device also integrates an electrode array for simultaneous thermal stimulation and neural signal recording. This capability enables researchers to directly monitor neural responses while delivering temperature-based modulation.

Published in Advanced Science, experimental findings showed that cooling effectively suppressed neural activity, whereas heating increased it. Notably, the researchers showed that thermal stimulation of the locus coeruleus (LC)—a brain region involved in arousal and attention regulation—not only altered neural activity but also induced corresponding changes in pupil size, including both constriction and dilation.

This technology is expected to contribute significantly to the development of next-generation bidirectional brain-computer interfaces (BCIs). While current BCI systems primarily focus on decoding brain signals to control external devices, future systems are expected to place greater emphasis on delivering sensory information, such as tactile feedback, directly to the brain.

By enabling the selective activation and inhibition of specific neural circuits, the newly developed implant demonstrates strong potential as a core technology for bidirectional BCIs that provide sensory feedback, as well as for closed-loop neuromodulation systems.

“This study introduces a new concept in brain interface technology that enables both activation and suppression of neural activity within a single device,” said Professor Il-Joo Cho, the principal investigator of the study. “We anticipate that this technology will contribute to the advancement of bidirectional BCIs, the restoration of neural function, and development of novel therapeutic approaches for a wide range of neurological and neurodegenerative disorders that remain difficult to address using conventional treatment methods.”

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