Volitional Control of Steady State Visual Evoked Potentials Using Auditory Feedback

Brain computer interfaces (BCIs) have been creating a direct link between human thought and computer input for nearly 40 years. However, these interfaces are often slow and difficult to use because of the noisy, low-bandwidth, nature of measurements of brain activity. This is particularly true in non-invasive techniques such as electroencephalography (EEG), which measures electrical potentials in the brain. In this work, we will use perceptual feedback to enhance the strength of one such potential, the steady state visually evoked potential (SSVEP). The SSVEP is a natural electrical entrainment in the primary visual cortex as a response to a repetitive visual stimulus modulated at 3.5 to 75Hz. This phenomenon is largely considered to be a passive response, but it has been shown that the strength of the signal can be modified through feedback. In our experiment, we use an audible tone as feedback to the participant, with frequency proportional to the strength of the SSVEP. The participant learns to control their SSVEP through controlling the audible tone. We demonstrate the efficacy of this technique and discuss it's potential for increasing the performance of SSVEP-based BCIs.