Handling complex metadata in neurophysiological experiments

Technological progress in neuroscience allows to record from tens to hundreds of neurons simultaneously, both in vitro and in vivo, using various recording techniques and stimulation methods. In addition, recordings can be performed under more or less natural conditions in (almost) freely behaving animals. To disentangle the relationship between behavior and neuronal activity, it is necessary to document animal training, experimental procedures, and details of the setup along with the recorded neuronal and behavioral data. In consequence, electrophysiological experiments become increasingly complex. Given these various sources of complexity, the availability of all experimental metadata is of extreme relevance for reproducible data analysis and correct interpretation of results.In order to provide metadata in an organized, human- and machine-readable way, an XML based file format, odML (open metadata Markup Language), was proposed [1]. We here demonstrate the usefulness of odML for data handling and analysis in the context of a complex behavioral experiment with neuronal recordings from a large number of electrodes delivering massively parallel spike and LFP data [2]. We illustrate the conceptual design of an odML metadata structure and offer templates to facilitate the usage of odML in different laboratories and experimental contexts. In addition, we demonstrate hands-on the advantages of using odML to screen large numbers of data sets according to selection criteria relevant for subsequent analyses. Well organized metadata management is a key component to guarantee reproducibility of experiments and to track provenance of performed analyses