On Harnessing the Electroencephalogram for the Musical Braincap

The braincap, as described in 3001: The Final Odyssey, the concluding edition of Arthur C. Clarke’s science Ž ction classic, is the ultimate humancomputer interface: it connects the brain to a system that is able to read thoughts and upload new information. The wearer can in minutes acquire new skills that would otherwise take years to master. Currently, however, a system that uploads information into the brain cannot exist outside the realm of science Ž ction, although machines that can read signals from the brain are becoming present-day reality. Furthermore, we should soon be able to control all sorts of devices by our thoughts alone. In 1998, a paper presented at the 9th European Congress of Clinical Neurophysiology already reported impressive advances in research on an electroencephalogram-based system to control a prosthetic hand (Guger and Pfurtscheller 1998). More recently, scientists at Brown University reported the development of a brain-computer interface for a system whereby a monkey controlled a cursor on a computer screen (Turner 2002). At Ž rst, the monkey used a joystick to move the cursor. After a while, the joystick was disconnected, and the monkey, who had not realized this, continued moving the cursor by means of tiny electrical signals emanating from an electrode implanted on the monkey’s motor cortex (the main brain area for motor control). We are interested in developing thoughtcontrolled musical devices, and to this end we are currently working on the design of a musical braincap. We are developing technology to interface the brain with music systems and compositional techniques suitable for thought control. This article focuses on extracting and harnessing tiny electrical brain signals from electroencephalograms (EEGs) that can be captured with electrodes on the scalp. We present three experiments whose results provide the basis for building systems to automatically detect information in the electroencephalogram associated with musical mental activities. Then, we describe how these results are currently being embedded in the design of the musical braincap. Before we present the experiments, we brie y introduce the growing Ž eld of BrainComputer Interfaces (BCI), followed by an introduction to the EEG and the signal processing techniques we employed to harness it. Before we continue, it is necessary to clarify the meaning of the expression ‘‘thought control.’’ In Eduardo Reck Miranda,* Ken Sharman,† Kerry Kilborn,‡ and Alexander Duncan§ *Computer Music Research—Neuroscience of Music Group, School of Computing, Communications, and Electronics, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA, United Kingdom [email protected] † Instituto Tecnológico de Informática Universidad Politécnica de Valencia, Camino de Vera s/n, 46071 Valencia, Spain [email protected] ‡Department of Psychology University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, United Kingdom [email protected] §The Sun Centre Prades, 48160 St. Martin de Boubaux, France [email protected] On Harnessing the Electroencephalogram for the Musical Braincap