The science behind GeoSource 3 source imaging and GTEN 100 Neuromodulation

EGI’s focus has always been on developing the very best research tools — the same tools that we want to use in our own research — and then streamlining and optimizing the workflow to make the technology accessible for our customers. The technology behind EGI’s newest products is based on research conducted in the EGI Science Department in collaboration with researchers at other institutions.

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EGI's new study using GTEN 100 Research System and pulsed protocols showed long-term depression of motor cortex excitability, sustained over 90 minutes following current injection (Luu et al., 2016).

Focus on high resolution and accurate head models for electrical source imaging

EGI scientists, in collaboration with researchers at the Neuroinformatics Center and Psychology Department at the University of Oregon and the Neuroimaging Laboratory at Washington University in St. Louis, have demonstrated that good conductivity estimates and good geometry descriptions in the head model improve the accuracy of source localization (Song et al., 2013). In another study, we showed that a dense array of electrodes with whole head coverage, including the neck and face regions, is critical for accurate source analysis (Song et al., 2015).

Based on this research, we integrated High Density EEG and the best head models into our new GeoSource 3 Research products to create what we believe to be the most accurate source estimation product available. We tested the ability of GeoSource 3 source estimation to identify a small known area of the motor cortex, and were able to show localization to a known anatomical location, as well as comparable results to fMRI studies (Kuo et al., 2014).

Focus on streamlining the process of creating individual head models

To simplify the arduous process of building high-quality individual head models, EGI scientists developed techniques for automatic identification of 7 different head tissues directly from an individual MRI scan, CT scan, and sensor locations, and for performing the cortical surface extraction required for use of the Finite Difference Method (Li, Papademetris, and Tucker, 2016). This work, along with the integration of accelerated computing, makes it possible for GeoSource 3 customers to construct individual FDM models using a step-by-step workflow that takes a fraction of the time normally required for this level of accuracy.

The technology behind GTEN 100 Neuromodulation

In developing the GTEN 100 Neuromodulation technology, EGI incorporated all of the accuracy advantages of using a dense array of electrodes and high-quality head models, and additionally, we applied the reciprocity principle in developing the most accurate planning software for delivering current to a chosen brain target. Our published work in collaboration with Fernandez-Corazza at Universidad Nacional de La Plata, details the importance and benefits of using the reciprocity principle for targeting and compares the reciprocity methods against standard optimization techniques. The research shows that using the reciprocity principle, one can develop a superior method for selecting electrodes for current injection for a given target (Fernandez-Corazza et al., 2016).

EGI’s work is covered by several patents and patents pending. Net Station 5.4, GeoSource 3, and GTEN 100 products are protected by one or more of the following issued US patents: 6,330,470, 6,594,521, and 9,326,699. GeoSource 3 Research products are protected by one or more of the following US patents: 8,478,011.