title: Classification of prefrontal activity due to mental arithmetic and music imagery using hidden Markov models and frequency domain near-infrared spectroscopy.
abstract: Near-infrared spectroscopy (NIRS) has recently been investigated as a non-invasive brain-computer interface (BCI). In particular, previous research has shown that NIRS signals recorded from the motor cortex during left- and right-hand imagery can be distinguished, providing a basis for a two-choice NIRS-BCI. In this study, we investigated the feasibility of an alternative two-choice NIRS-BCI paradigm based on the classification of prefrontal activity due to two cognitive tasks, specifically mental arithmetic and music imagery. Deploying a dual-wavelength frequency domain near-infrared spectrometer, we interrogated nine sites around the frontopolar locations (International 10-20 System) while ten able-bodied adults performed mental arithmetic and music imagery within a synchronous shape-matching paradigm. With the 18 filtered AC signals, we created task- and subject-specific maximum likelihood classifiers using hidden Markov models. Mental arithmetic and music imagery were classified with an average accuracy of 77.2% +/- 7.0 across participants, with all participants significantly exceeding chance accuracies. The results suggest the potential of a two-choice NIRS-BCI based on cognitive rather than motor tasks.
authors.affiliation: Bloorview Research Institute, Bloorview Kids Rehab, Toronto, Ontario, Canada. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Power
authors.forename: Tiago H
authors.initials: TH
authors.lastname: Falk
authors.forename: Tom
authors.initials: T
authors.lastname: Chau
mesh_terms: D000328:Adult; D003071:Cognition / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology; D016013:Likelihood Functions; D008297:Male; D008390:Markov Chains; D055641:Mathematical Concepts; D009146:Music; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014584:User-Computer Interface