Hamed Azami1, Javier Escudero2, Ali Darzi3, Saeid Sanei4. 1. Institute for Digital Communications, School of Engineering, University of Edinburgh, UK. Electronic address: hamed.azami@ed.ac.uk. 2. Institute for Digital Communications, School of Engineering, University of Edinburgh, UK. Electronic address: javier.escudero@ed.ac.uk. 3. Institute for Research in Fundamental Sciences (IPM), Iran. Electronic address: ali.darzi@ipm.ir. 4. Department of Computing, Faculty of Engineering and Physical Sciences, University of Surrey, UK. Electronic address: s.sanei@surrey.ac.uk.
Abstract
BACKGROUND: The information obtained from signal recorded with extracellular electrodes is essential in many research fields with scientific and clinical applications. These signals are usually considered as a point process and a spike detection method is needed to estimate the time instants of action potentials. In order to do so, several steps are taken but they all depend on the results of the first step, which filters the signals. To alleviate the effect of noise, selecting the filter parameters is very time-consuming. In addition, spike detection algorithms are signal dependent and their performance varies significantly when the data change. NEW METHODS: We propose two approaches to tackle the two problems above. We employ ensemble empirical mode decomposition (EEMD), which does not require parameter selection, and a novel approach to choose the filter parameters automatically. Then, to boost the efficiency of each of the existing methods, the Hilbert transform is employed as a pre-processing step. To tackle the second problem, two novel approaches, which use the fuzzy and probability theories to combine a number of spike detectors, are employed to achieve higher performance. RESULTS, COMPARISON WITH EXISTING METHOD(S) AND CONCLUSIONS: The simulation results for realistic synthetic and real neuronal data reveal the improvement of the proposed spike detection techniques over state-of-the art approaches. We expect these improve subsequent steps like spike sorting.
BACKGROUND: The information obtained from signal recorded with extracellular electrodes is essential in many research fields with scientific and clinical applications. These signals are usually considered as a point process and a spike detection method is needed to estimate the time instants of action potentials. In order to do so, several steps are taken but they all depend on the results of the first step, which filters the signals. To alleviate the effect of noise, selecting the filter parameters is very time-consuming. In addition, spike detection algorithms are signal dependent and their performance varies significantly when the data change. NEW METHODS: We propose two approaches to tackle the two problems above. We employ ensemble empirical mode decomposition (EEMD), which does not require parameter selection, and a novel approach to choose the filter parameters automatically. Then, to boost the efficiency of each of the existing methods, the Hilbert transform is employed as a pre-processing step. To tackle the second problem, two novel approaches, which use the fuzzy and probability theories to combine a number of spike detectors, are employed to achieve higher performance. RESULTS, COMPARISON WITH EXISTING METHOD(S) AND CONCLUSIONS: The simulation results for realistic synthetic and real neuronal data reveal the improvement of the proposed spike detection techniques over state-of-the art approaches. We expect these improve subsequent steps like spike sorting.