title: An Unsupervised Online Spike-Sorting Framework.
abstract: Extracellular neuronal microelectrode recordings can include action potentials from multiple neurons. To separate spikes from different neurons, they can be sorted according to their shape, a procedure referred to as spike-sorting. Several algorithms have been reported to solve this task. However, when clustering outcomes are unsatisfactory, most of them are difficult to adjust to achieve the desired results. We present an online spike-sorting framework that uses feature normalization and weighting to maximize the distinctiveness between different spike shapes. Furthermore, multiple criteria are applied to either facilitate or prevent cluster fusion, thereby enabling experimenters to fine-tune the sorting process. We compare our method to established unsupervised offline (Wave_Clus (WC)) and online (OSort (OS)) algorithms by examining their performance in sorting various test datasets using two different scoring systems (AMI and the Adamos metric). Furthermore, we evaluate sorting capabilities on intra-operative recordings using established quality metrics. Compared to WC and OS, our algorithm achieved comparable or higher scores on average and produced more convincing sorting results for intra-operative datasets. Thus, the presented framework is suitable for both online and offline analysis and could substantially improve the quality of microelectrode-based data evaluation for research and clinical application.
authors.affiliation: * Division of Functional and Restorative Neurosurgery & Division of Translational Neurosurgery, Department of Neurosurgery, and Neuroprosthetics Research Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tuebingen, Otfried-Mueller-Str.45, 72076 Tuebingen, Germany.|‡ Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany.
authors.forename: Simeon
authors.initials: S
authors.lastname: Knieling
authors.affiliation: * Division of Functional and Restorative Neurosurgery & Division of Translational Neurosurgery, Department of Neurosurgery, and Neuroprosthetics Research Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tuebingen, Otfried-Mueller-Str.45, 72076 Tuebingen, Germany.
authors.forename: Kousik S
authors.initials: KS
authors.lastname: Sridharan
authors.affiliation: * Division of Functional and Restorative Neurosurgery & Division of Translational Neurosurgery, Department of Neurosurgery, and Neuroprosthetics Research Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tuebingen, Otfried-Mueller-Str.45, 72076 Tuebingen, Germany.
authors.forename: Paolo
authors.initials: P
authors.lastname: Belardinelli
authors.affiliation: * Division of Functional and Restorative Neurosurgery & Division of Translational Neurosurgery, Department of Neurosurgery, and Neuroprosthetics Research Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tuebingen, Otfried-Mueller-Str.45, 72076 Tuebingen, Germany.
authors.forename: Georgios
authors.initials: G
authors.lastname: Naros
authors.affiliation: † Department for Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research, and German Centre of Neurodegenerative Diseases (DZNE), Eberhard Karls University Tuebingen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Weiss
authors.affiliation: ‡ Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Mormann
authors.affiliation: * Division of Functional and Restorative Neurosurgery & Division of Translational Neurosurgery, Department of Neurosurgery, and Neuroprosthetics Research Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University Tuebingen, Otfried-Mueller-Str.45, 72076 Tuebingen, Germany.
authors.forename: Alireza
authors.initials: A
authors.lastname: Gharabaghi
mesh_terms: D000200:Action Potentials; D000465:Algorithms; D001921:Brain / Q000503:physiopathology / Q000601:surgery; D066264:Datasets as Topic; D046690:Deep Brain Stimulation / Q000379:methods; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology / Q000601:surgery; D010363:Pattern Recognition, Automated / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors
keywords: Online spike-sorting; deep brain stimulation; intra-operative mapping; microelectrode recording; real-time clustering; unsupervised