Brain-computer interface (BCI) technology has great potential for improving the quality of life for neurologic patients. This study aimed to use PET mapping for BCI-based stimulation in a rat model with electrodes implanted in the ventroposterior medial (VPM) nucleus of the thalamus. Methods: PET imaging studies were conducted before and after stimulation of the right VPM. Results: Stimulation induced significant orienting performance. 18 F-FDG uptake increased significantly in the paraventricular thalamic nucleus, septohippocampal nucleus, olfactory bulb, left crus II of the ansiform lobule of the cerebellum, and bilaterally in the lateral septum, amygdala, piriform cortex, endopiriform nucleus, and insular cortex, but it decreased in the right secondary visual cortex, right simple lobule of the cerebellum, and bilaterally in the somatosensory cortex. Conclusion: This study demonstrated that PET mapping after VPM stimulation can identify specific brain regions associated with orienting performance. PET molecular imaging may be an important approach for BCIbased research and its clinical applications. Br ain-computer interface (BCI) technology has gained great visibility in the past few years as it merges the fields of biorobotics and neuroscience. Clinically, it is a promising therapeutic strategy for the restoration of sensory and motor function in patients with neurologic disorders (1,2). Because of the technical advancement of implantable microelectrodes and processing electronics, the initial achievement of remote control of an animal's orienting performance has been succeeded by repeated training during artificial introduction of electrical commands into the somatosensory cortical and medial forebrain bundles (3). During the training, rats learn to interpret remote brain stimulation as instructions directing their trajectory of locomotion. Recently, our group demonstrated a novel control method by which direct stimulation of the ventroposterior medial (VPM) nucleus of the thalamus can initiate orienting performance in freely roaming rats without repeated training sessions. Supplemental Video 1 shows an example of this BCI-guided rat navigation. In the directions indicated by the arrows, the rat in the video was instructed to climb a slope, cross a bridge, and turn left or right (4). VPM is known as a somatosensory relay station that takes sensory information being input from individual whiskers and projects it to the primary somatosensory cortex (5). However, it is unclear which brain regions are involved in the orienting performance induced by VPM stimulation. Thus, we hypothesized that by using a PET molecular imaging approach to map the brain, we could explore the VPM stimulation-related orienting function and identify the specific cerebral activation pattern. In the present study, we conducted PET imaging on a freely moving rat model before and after VPM stimulation. To our knowledge, this was the first PET imaging study on BCIbased stimulation in a rat model with electrodes implanted in the VPM.
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