A practical procedure for real-time functional mapping of eloquent cortex using electrocorticographic signals in humans

Abstract

Functional mapping of eloquent cortex is often necessary prior to invasive brain surgery, but current techniques that derive this mapping have important limitations. In this paper, we demonstrate the first comprehensive evaluation of a rapid, robust, and practical mapping system that uses passive recordings of electrocorticographic (ECoG) signals. This mapping procedure is based on the BC12000 and SIGFRIED technologies that we have been developing over the past several years. In our study, we evaluated ten epilepsy patients from four different institutions and compared the results of our procedure to the results derived using electrical cortical stimulation (ECS) mapping. The results show that our procedure derives a functional motor cortical map in only a few minutes. They also show a substantial concurrence with the results derived using ECS mapping. Specifically, compared to ECS maps, a next-neighbor evaluation showed no false negatives, and only 0.46% and 1.10% false positives for hand and tongue maps, respectively. In summary, we demonstrate the first comprehensive evaluation of a practical and robust mapping procedure that could become a new tool tor planning or invasive brain surgeries.

The reliability of neuroanatomy as a predictor of eloquence: a review

“…The relationships between these various mapping techniques have been the subject of numerous studies, including comparisons between ESM and PET, 6 ESM with functional MR imaging, 39 ECoG and ESM, 10 ECoG with functional MR imaging, 26,32 optical imaging and functional MR imaging, 11,38,41 electroencephalography with functional MR imaging, 31 and functional MR imaging with single units and local field potentials. 32,35 Ultimately, for clinical relevance and implementation, each technique will have to be evaluated relative to patient outcomes.…”

“…With current technologies and implementation, preoperative and intraoperative mapping techniques besides ESM at best provide a framework within which to map the exposed brain but cannot replace ESM. 10,39 Further discussion of studies comparing the various mapping signals is beyond the scope of this review but are critical for gaining insight into the physiological basis of and the relationship between the different modalities. The salient point is that while all signals are related, there are inherent differences in modalityspecific maps that must be considered.…”

Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

“…One specific real-time application based on BCI2000, SIGFRIED 10 , demonstrates that ECoG recordings are also valuable for functional mapping, showing substantial concurrence with the results derived using electrocortical stimulation mapping.…”

“…The reward is that ECoG signals, and in particular amplitudes in the high gamma frequency range (70-110Hz), are highly valuable. Not only do they provide scientific insight into the neural correlates of cognitive, sensory and motor processes 1-4 at a both high spatial and temporal resolution, but brain-computer interfacing studies in ECoG have also shown the method's great promise as a basis for neuroprosthetic applications 6,7,10 .…”

Classification of ECoG Motor Image using Fusion Technique

“…ECoG brain signals are advantageous when used with BCI systems compared to EEGs which include increased spatial resolution, signal bandwidth and larger signal amplitude. So, independent signals are differentiated over a frequencies range -on neighbouring electrodes -using procedures with motor and sensory imagery [4,5]. Traditionally, motor imagery was resorted to as it was felt to be more accessible and reliable EEG signal.…”