BRAin INfrared STimulation combined with Optical and electrical Recording using Microelectrode arrays based devices – BRAINSTORM

Functional mapping of the connectivity of the brain is an essential procedure for neurosurgeons aiming for maximal resection of a brain tumor, while minimizing damage to the eloquent cortex. Being able to delineate the location of critical cortical areas in individual patients allows the surgeon to preserve sensorimotor and cognitive functions. Direct electrical stimulation is a commonly used technique by neurosurgeons to map eloquent structures of the brain during surgeries like brain tumor resections. Having a precise and rapid way to map the brain during such procedures would allow surgeons to improve the extent of resection while preserving the eloquent and essential structures of the brain. The spatial precision offered now by electrical stimulation is not sufficient for neurosurgeons and an improvement of that resolution would be welcome in such medical applications.
If several methods exist for functional mapping, however, none are capable of delivering fast, label free mapping of the cortex with millimeter precision. Recently, a new neuronal modulation method has emerged based on the use of infrared radiation exposure. Since its first application in the last decade, infrared neuronal modulation proved its efficacy in the central nervous system as well as in the peripheral nervous system in both stimulating and inhibiting neuronal activity. Even though the underlying mechanism of such stimulation is still not fully elucidated, this method and its subsequent stimulation effect, originating from a photothermal interaction, is nevertheless being applied in new prototypes developed for clinical applications for cochlear implantable devices. Compared to optogenetics or other optical methods, it does not depend on genetic modification or any other exogenous absorbers. Furthermore, the spatial selectivity remains high since only the irradiated area is stimulated, and compared to electrical stimulation, it is a contact free method that causes no artefacts and thus can be used simultaneously with the recording of neuronal activity.
Thus, infrared neuronal modulation appears as a good candidate to deliver fast, label free mapping of the cortex with millimeter precision. Its few applications to the brain tissue and the low knowledge of the subsequent interaction is however not sufficient to go towards the development of clinical tools for neurosurgeons. This project aims therefore to develop the fundamental knowledge on the interaction between the infrared radiation and the brain tissue, leading to neuronal stimulation, to go towards new surgical tools.