Recognition of imagined hand movements with low resolution surface Laplacian and linear classifiers

Fabio Babiloni, Febo Cincotti, Luigi Bianchi, Giada Pirri, José Del R. Millán, Josep Mouriño, Serenella Salinari, Maria Grazia Marciani

Research output: Contribution to journalArticlepeer-review

Abstract

EEG-based Brain Computer Interfaces (BCIs) require on-line detection of mental states from spontaneous EEG signals. In this framework, it was suggested that EEG patterns can be better detected with EEG data transformed with Surface Laplacian computation (SL) than with the unprocessed raw potentials. However, accurate SL estimates require the use of many EEG electrodes, when local estimation methods are used. Since BCI devices have to use a limited number of electrodes for practical reasons, we investigated the performances of spline methods for SL estimates using a limited number of electrodes (low resolution SL). Recognition of mental activity was attempted on both raw and SL-transformed EEG data from five healthy people performing two mental tasks, namely imagined right and left hand movements. Linear classifiers were used including Signal Space Projection (SSP) and Fisher's linear discriminant. Results showed an acceptable average correlation between the waveforms obtained with the low resolution SL and these obtained with the SL computed from 26 electrodes (full resolution SL). More importantly, satisfactorily recognition scores for mental EEG-patterns were obtained with the low-resolution surface Laplacian transformation of the recorded potentials when compared with those obtained by using full resolution SL (82%). These results demonstrated also the utility of linear classifiers for the detection of mental patterns in the BCI field.

Original languageEnglish
Pages (from-to)323-328
Number of pages6
JournalMedical Engineering and Physics
Volume23
Issue number5
DOIs
Publication statusPublished - 2001

Keywords

  • Brain Computer Interface
  • Linear classifiers
  • Signal Space Projection
  • Surface Laplacian

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Psychology(all)

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