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Thomas Kreuz Institute for complex systems, CNR Florence, Italy. Monitoring spike train synchrony. June 2013. Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients
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Thomas Kreuz Institute for complex systems, CNR Florence, Italy Monitoringspike train synchrony June 2013
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance (improved) - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
ISI- and SPIKE-distance Average over time profiles: Instantaneous values Time of previous spike: Time of following spike: Interspike interval: n=1,2 (spike trains)
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
ISI-distance Bivariate (N=2) Kreuz et al., J Neurosci Methods (2007)
ISI-distance Multivariate (N>2): Local pairwise averages Kreuz et al., J Neurosci Methods (2009) Analogous equation holds for SPIKE-distance
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
SPIKE-distance For each corner spike: Interval to nearest spike in other spike train
SPIKE-distance Local weighting (for each spike train separately) Interval to previous spikes: Interval to following spikes: e.g. Kreuz et al., J Neurosci Methods (2011)
SPIKE-distance Averaging and normalization (Time-scale independence): Weighting of relative distances between spike trains: Kreuz et al., submitted (2012)
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
Real-time SPIKE-distance Motivation: • Epilepsy • Brain-Machine Interfaces No following spikes, no ISI Kreuz et al., submitted (2012)
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline
Epilepsy Statistics • ~ 1 % of world population suffers from epilepsy • in Germany ~ 800 000 patients • ~ 70 % can be treated with antiepileptic drugs • ~ 8 % might profit from epilepsy surgery • ~ 22 % cannot be treated sufficiently Epilepsy Center Bonn (Contact: Florian Mormann) • presurgical evaluations: ~ 50 cases / year • invasive evaluations: ~ 15 cases / year
Presurgical evaluation - Localization of seizure generating area (epileptic focus) - current gold standard: EEG recording of seizure origin - exact delineation from functionally relevant areas - estimation of post-operative status (seizure control, neurological deficits, ...) Surgical intervention - tailored resection of epileptic focus Epilepsy Surgery
Hippocampus Amygdala Entorhinal Cortex Medial Temporal Lobe Parahippocampal Cortex
Clinical contacts Microwire recordings in humans • 64 microwires (40 μm diameter) able to • record single-neuron-activity and LFPs • Effective recording bandwidth 1 Hz - 10 kHz • Data provided by Florian Mormann Setup:
Action potentials of individual neurons Quian Quiroga, Scholarpedia (2007)
Example movie Time-resolved spike train distances - (ISI-distance) - SPIKE-distance - Realtime SPIKE-distance Application to multi-unit activity from epilepsy patients Application to continuous data (EEG) Outline