Stereoelectroencephalography for continuous two-dimensional cursor control in a brain-machine interface

Abstract

<jats:p>Stereoelectroencephalography (SEEG) is becoming more prevalent as a planning tool for surgical treatment of intractable epilepsy. Stereoelectroencephalography uses long, thin, cylindrical “depth” electrodes containing multiple recording contacts along each electrode's length. Each lead is inserted into the brain percutaneously. The advantage of SEEG is that the electrodes can easily target deeper brain structures that are inaccessible with subdural grid electrodes, and SEEG does not require a craniotomy. Brain-machine interface (BMI) research is also becoming more common in the Epilepsy Monitoring Unit. A brain-machine interface decodes a person's desired movement or action from the recorded brain activity and then uses the decoded brain activity to control an assistive device in real time. Although BMIs are primarily being developed for use by severely paralyzed individuals, epilepsy patients undergoing invasive brain monitoring provide an opportunity to test the effectiveness of different invasive recording electrodes for use in BMI systems. This study investigated the ability to use SEEG electrodes for control of 2D cursor velocity in a BMI. Two patients who were undergoing SEEG for intractable epilepsy participated in this study. Participants were instructed to wiggle or rest the hand contralateral to their SEEG electrodes to control the horizontal velocity of a cursor on a screen. Simultaneously they were instructed to wiggle or rest their feet to control the vertical component of cursor velocity. The BMI system was designed to detect power spectral changes associated with hand and foot activity and translate those spectral changes into horizontal and vertical cursor movements in real time. During testing, participants used their decoded SEEG signals to move the brain-controlled cursor to radial targets that appeared on the screen. Although power spectral information from 28 to 32 electrode contacts were used for cursor control during the experiment, post hoc analysis indicated that better control may have been possible using only a single SEEG depth electrode containing multiple recording contacts in both hand and foot cortical areas. These results suggest that the advantages of using SEEG for epilepsy monitoring may also apply to using SEEG electrodes in BMI systems. Specifically, SEEG electrodes can target deeper brain structures, such as foot motor cortex, and both hand and foot areas can be targeted with a single SEEG electrode implanted percutaneously. Therefore, SEEG electrodes may be an attractive option for simple BMI systems that use power spectral modulation in hand and foot cortex for independent control of 2 degrees of freedom.</jats:p>

Defining Surgical Terminology and Risk for Brain Computer Interface Technologies

“…These systems record electric field potentials from cortical populations within the brain parenchyma itself which includes cortex or deeper brain structures. Similar to ECoG, they access a broad frequency spectrum of dynamical brain activity and can be both output and input BCIs (Wang et al, 2010;Vadera et al, 2013;Li et al, 2017). Current and near-term applications of LFP BCI systems are clinical and research oriented.…”

The stereotactic approach for mapping epileptic networks: a prospective study of 200 patients

“…20 Improved access to the epileptogenic network with 3D electrodes implanted using SEEG methodology, when generalized to other functional networks in the brain, may also have broad ramifications for the future development of brainmachine interfaces. 33 For these reasons, it is evident that the SEEG methodology will serve as an important foundation for ongoing clinical treatment and basic science research into brain networks and the spatiotemporal activity therein, in both physiological and pathological stages.…”

The Potential of Stereotactic-EEG for Brain-Computer Interfaces: Current Progress and Future Directions

“…A number of studies have demonstrated decoding of motor signals for BCI using sEEG. Vadera et al (2013) demonstrate two-dimensional cursor control from depth electrodes implanted in hand and foot cortical areas. While imagined movements were not investigated, this study highlights one of the advantages of sEEG -the opportunity to record foot cortical areas that reside in the longitudinal fissure that cannot be attained with surface measurements.…”