Full activation pattern mapping by simultaneous deep brain stimulation and fMRI with graphene fiber electrodes

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Simultaneous deep brain stimulation (DBS) and functional magnetic resonance imaging (fMRI) are crucial for understanding brain connectivity and DBS therapies.
• Previous DBS-fMRI studies were limited by MRI artifacts from electrodes, obstructing large brain areas and preventing comprehensive activation mapping.
• Subthalamic nucleus (STN) DBS is a key therapy for Parkinson's disease, but its full network effects require advanced imaging.

Purpose of the Study:

• To develop novel MRI-compatible DBS electrodes for artifact-free simultaneous DBS-fMRI.
• To investigate the full brain activation patterns elicited by STN-DBS in a Parkinsonian rat model.
• To explore the frequency-dependent modulation of brain networks by STN-DBS.

Main Methods:

• Fabrication of graphene fiber (GF) electrodes with high charge-injection capacity and minimal MRI artifact at 9.4T.
• Performing simultaneous DBS-fMRI experiments using GF electrodes targeting the STN in Parkinsonian rats.
• Analyzing blood-oxygenation-level-dependent (BOLD) responses across the basal ganglia-thalamocortical network.

Main Results:

• GF electrodes demonstrated minimal MRI artifacts, enabling visualization of previously obstructed brain regions.
• STN-DBS induced robust, frequency-dependent BOLD responses throughout the basal ganglia-thalamocortical network.
• Novel, detectable responses in regions beyond the primary motor pathways were observed, indicating modulation of non-motor circuits.

Conclusions:

• Graphene fiber electrodes overcome limitations of traditional DBS electrodes in fMRI studies.
• DBS-fMRI with GF electrodes provides unprecedented, full activation pattern maps of STN-DBS.
• This technique offers critical insights into the neuromodulatory mechanisms of DBS for Parkinson's disease and other neurological disorders.