Local infrared neural stimulation of non-anesthetized primate brain through a fiber-optic laser-brain interface

Abstract

Infrared neural stimulation (INS) generally represents invasive techniques for modulating brain activity in animals, particularly primates – effective models for human brain research. These invasive techniques offer high spatial resolution by targeting neurons with directly focused laser beams but require intricate surgeries that damage the meninges, limiting studies to short-term acute experiments on anesthetized animals.
We present a minimally invasive practical method for long-term high-resolution laser INS that does not disrupt brain tissue integrity and reduces inflammation risks. The laser radiation is delivered to a selected local area of the cerebral cortex through the optical contact between a flexible optical fiber and the dura mater's outer surface, permitting chronic experiments on non-anesthetized, cognitively intact, physically active primates.
In a multi-day experiment, we analyzed electrophysiological responses of various cortical areas to localized stimulation using modulated infrared laser radiation directed (through the optical fiber) at the primary visual cortex of a rhesus macaque. Electrocorticograms indicated that even low-intensity laser stimulation (below conscious perception thresholds) caused synchronous biopotential changes both at the stimulation site and in certain distant cortical regions, suggesting possibility of complex brain response to local INS.
Thus, the developed INS method using a fiber-optic laser-brain interface enables multi-day chronic INS experiments on non-anesthetized primates, which alows obtaining a great variety of statistically reliable data on neurophysiological responses of cognitively intact primates to targeted high-resolution INS that is impossible with other INS techniques.

Speaker

Alexey Harauzov
Pavlov Institute of Physiology, Russian academy of sciences, Saint Petersburg, Russia
Russia

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