%0 Journal Article %J Journal of Neural Engineering %D 2014 %T A general method for assessing brain–computer interface performance and its limitations. %A Jeremy Jeremy Hill %A Häuser, Ann-Katrin %A Gerwin Schalk %K brain-computer interface %K information gain %K information transfer rate %K Neuroprosthetics %K performance evaluation %X Objective. When researchers evaluate brain–computer interface (BCI) systems, we want quantitative answers to questions such as: How good is the system's performance? How good does it need to be? and: Is it capable of reaching the desired level in future? In response to the current lack of objective, quantitative, study-independent approaches, we introduce methods that help to address such questions. We identified three challenges: (I) the need for efficient measurement techniques that adapt rapidly and reliably to capture a wide range of performance levels; (II) the need to express results in a way that allows comparison between similar but non-identical tasks; (III) the need to measure the extent to which certain components of a BCI system (e.g. the signal processing pipeline) not only support BCI performance, but also potentially restrict the maximum level it can reach. Approach. For challenge (I), we developed an automatic staircase method that adjusted task difficulty adaptively along a single abstract axis. For challenge (II), we used the rate of information gain between two Bernoulli distributions: one reflecting the observed success rate, the other reflecting chance performance estimated by a matched random-walk method. This measure includes Wolpaw's information transfer rate as a special case, but addresses the latter's limitations including its restriction to item-selection tasks. To validate our approach and address challenge (III), we compared four healthy subjects' performance using an EEG-based BCI, a 'Direct Controller' (a high-performance hardware input device), and a 'Pseudo-BCI Controller' (the same input device, but with control signals processed by the BCI signal processing pipeline). Main results. Our results confirm the repeatability and validity of our measures, and indicate that our BCI signal processing pipeline reduced attainable performance by about 33% (21 bits/min). Significance. Our approach provides a flexible basis for evaluating BCI performance and its limitations, across a wide range of tasks and task difficulties. %B Journal of Neural Engineering %V 11 %8 03/2014 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/24658406 %N 026018 %R 10.1088/1741-2560/11/2/026018 %0 Journal Article %J Epilepsy Behav %D 2014 %T Proceedings of the Fifth International Workshop on Advances in Electrocorticography. %A A L Ritaccio %A Peter Brunner %A Gunduz, Aysegul %A Hermes, Dora %A Hirsch, Lawrence J %A Jacobs, Joshua %A Kamada, Kyousuke %A Kastner, Sabine %A Robert T. Knight %A Lesser, Ronald P %A Miller, Kai %A Sejnowski, Terrence %A Worrell, Gregory %A Gerwin Schalk %K Brain Mapping %K brain-computer interface %K electrical stimulation mapping %K Electrocorticography %K functional mapping %K Gamma-frequency electroencephalography %K High-frequency oscillations %K Neuroprosthetics %K Seizure detection %K Subdural grid %X

The Fifth International Workshop on Advances in Electrocorticography convened in San Diego, CA, on November 7-8, 2013. Advancements in methodology, implementation, and commercialization across both research and in the interval year since the last workshop were the focus of the gathering. Electrocorticography (ECoG) is now firmly established as a preferred signal source for advanced research in functional, cognitive, and neuroprosthetic domains. Published output in ECoG fields has increased tenfold in the past decade. These proceedings attempt to summarize the state of the art.

%B Epilepsy Behav %V 41 %P 183-92 %8 12/2014 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/25461213 %R 10.1016/j.yebeh.2014.09.015 %0 Journal Article %J Epilepsy & Behavior %D 2013 %T Proceedings of the Fourth International Workshop on Advances in Electrocorticography. %A A L Ritaccio %A Peter Brunner %A Nathan E. Crone %A Gunduz, Aysegul %A Hirsch, Lawrence J. %A Kanwisher, Nancy %A Litt, Brian %A Kai J. Miller %A Morani, Daniel %A Parvizi, Josef %A Ramsey, Nick F %A Richner, Thomas J. %A Tandon, Niton %A Williams, Justin %A Gerwin Schalk %K Brain Mapping %K Brain–computer interface %K Electrocorticography %K Gamma-frequency electroencephalography %K High-frequency oscillations %K Neuroprosthetics %K Seizure detection %K Subdural grid %X The Fourth International Workshop on Advances in Electrocorticography (ECoG) convened in New Orleans, LA, on October 11–12, 2012. The proceedings of the workshop serves as an accurate record of the most contemporary clinical and experimental work on brain surface recording and represents the insights of a unique multidisciplinary ensemble of expert clinicians and scientists. Presentations covered a broad range of topics, including innovations in passive functional mapping, increased understanding of pathologic high-frequency oscillations, evolving sensor technologies, a human trial of ECoG-driven brain–machine interface, as well as fresh insights into brain electrical stimulation. %B Epilepsy & Behavior %V 29 %P 259–68 %8 11/2013 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/24034899 %N 2 %R 10.1016/j.yebeh.2013.08.012 %0 Journal Article %J Epilepsy Behav %D 2012 %T Proceedings of the Third International Workshop on Advances in Electrocorticography. %A A L Ritaccio %A Beauchamp, Michael %A Bosman, Conrado %A Peter Brunner %A Chang, Edward %A Nathan E. Crone %A Gunduz, Aysegul %A Disha Gupta %A Robert T. Knight %A Leuthardt, Eric %A Litt, Brian %A Moran, Daniel %A Ojemann, Jeffrey %A Parvizi, Josef %A Ramsey, Nick %A Rieger, Jochem %A Viventi, Jonathan %A Voytek, Bradley %A Williams, Justin %A Gerwin Schalk %K Brain Mapping %K brain-computer interface %K Electrocorticography %K Gamma-frequency electroencephalography %K high-frequency oscillation %K Neuroprosthetics %K Seizure detection %K Subdural grid %X The Third International Workshop on Advances in Electrocorticography (ECoG) was convened in Washington, DC, on November 10-11, 2011. As in prior meetings, a true multidisciplinary fusion of clinicians, scientists, and engineers from many disciplines gathered to summarize contemporary experiences in brain surface recordings. The proceedings of this meeting serve as evidence of a very robust and transformative field but will yet again require revision to incorporate the advances that the following year will surely bring. %B Epilepsy Behav %V 25 %P 605-13 %8 12/2012 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/23160096 %N 4 %R 10.1016/j.yebeh.2012.09.016