title: Spatio-temporal patterns of neuronal activity: analysis of optical imaging data using geometric shape matching.
abstract: Optical imaging of neuronal network activity yields information of spatial dynamics which generally is analyzed visually. The transient appearance of spatial activity patterns is difficult to gauge in a quantifiable manner, or may even altogether escape detection. Here, we employ geometric shape matching using Fréchet distances or straight skeletons to search for pre-selected patterns in optical imaging data with adjustable degrees of tolerance. Data were sampled from fluorescence changes of a voltage-sensitive dye recorded with a 464-photodiode array. Fluorescence was monitored in a neuronal network in vitro. Neuronal activity prompting fluorescence fluctuations consisted of spontaneous epileptiform discharges in neocortical slices from patients undergoing epilepsy surgery. The experiments show that: (a) spatial activity patterns can be detected in optical imaging data; (b) shapes such as "mini-foci" appear in close correlation to bioelectric discharges monitored with field potential electrodes in a reproducible manner; (c) Fréchet distances yield more conservative matches regarding rectangular, and less conservative hits with respect to radially symmetric shapes than the straight skeleton approach; and (d) tolerances of 0.03-0.1 are suited to detect faithful images of pre-selected shapes, whereas values >0.8 will report matches with any polygonal pattern. In conclusion, the methods reported here are suited to detect and analyze spatial, geometric dynamics in optical imaging data.
authors.affiliation: Institut für Physiologie, Westfälische Wilhelms Universität, Robert-Koch-Strasse 27a, 48149 Münster, Germany. kohling@uni-muenster.de
authors.forename: R
authors.initials: R
authors.lastname: Köhling
authors.forename: J
authors.initials: J
authors.lastname: Reinel
authors.forename: J
authors.initials: J
authors.lastname: Vahrenhold
authors.forename: K
authors.initials: K
authors.lastname: Hinrichs
authors.forename: E-J
authors.initials: EJ
authors.lastname: Speckmann
mesh_terms: D000465:Algorithms; D001931:Brain Mapping / Q000295:instrumentation* / Q000379:methods*; D004594:Electrophysiology / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology; D005456:Fluorescent Dyes; D006801:Humans; D066298:In Vitro Techniques; D008959:Models, Neurological; D019579:Neocortex / Q000502:physiology*; D055095:Optics and Photonics
chemical_list: D005456:Fluorescent Dyes