Brain–Computer Interfaces - Index of

BCIs Based on Signals from Between the Brain
and Skull
Jane E. Huggins
1 Introduction
This chapter provides an introduction to electrocorticogram (ECoG) as a signal
source for brain–computer interfaces (BCIs). I first define ECoG, examine its advantages
and disadvantages, and outline factors affecting successful ECoG experiments
for BCI. Past and present BCI projects that utilize ECoG and have published results
through early 2008 are then summarized. My own ECoG work with the University
of Michigan Direct Brain Interface project is described in detail, as the first and
(at the time of writing) longest running targeted exploration of ECoG for BCI.
The well established ECoG research at the University of Washington is described
only briefly, since Chapter “A Simple, Spectral-change Based, Electrocorticographic
Brain–Computer Interface” in this volume provides a first-hand description. This
chapter concludes with a few thoughts on the growth of BCI research utilizing ECoG
and potential future applications of BCI methods developed for ECoG.
2 Electrocorticogram: Signals from Between the Brain and Skull
The commands for a BCI must come from the collection of individual cells that
make up the brain. Observation and interpretation of the activity of each of the
billions of individual cells is obviously impossible with current technology and
unlikely to become possible in the near future. BCI researchers must therefore
choose either to observe activity from a small percentage of single cells or observe
the field potentials from groups of cells whose activity has been combined by the filtering
affect of brain tissue and structures such as the brain’s protective membranes,
the skull, and the scalp. Field potentials can be observed using electrodes in a wide
J.E. Huggins (B)
University of Michigan, Ann Arbor, MI, USA
e-mail: janeh@umich.edu
B. Graimann et al. (eds.), Brain–Computer Interfaces, The Frontiers Collection,
DOI 10.1007/978-3-642-02091-9_13, C○ Springer-Verlag Berlin Heidelberg 2010
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