Standards for data acquisition and software‐based analysis of in vivo electroencephalography recordings from animals. A TASK1‐WG5 report of the AES/ILAE Translational Task Force of the ILAE

Abstract

SUMMARY Electroencephalography (EEG) - the direct recording of the electrical activity of populations of neurons - is a tremendously important tool for diagnosing, treating, and researching epilepsy. While standard procedures for recording and analyzing human EEG exist and are broadly accepted, no such standards exist for research in animal models of seizures and epilepsy – recording montages, acquisition systems, and processing algorithms may differ substantially among investigators and laboratories. The lack of standard procedures for acquiring and analyzing EEG from animal models of epilepsy hinders the interpretation of experimental results and reduces the ability of the scientific community to efficiently translate new experimental findings into clinical practice. Accordingly, the intention of this report is twofold: 1) to review current techniques for the collection and software-based analysis of neural field recordings in animal models of epilepsy, and 2) to offer pertinent standards and reporting guidelines for this research. Specifically, we review current techniques for signal acquisition, signal conditioning, signal processing, data storage, and data sharing, and include applicable recommendations to standardize collection and reporting. We close with a discussion of challenges and future opportunities, and include a supplemental report of currently available acquisition systems and analysis tools. This work represents a collaboration on behalf of the International League Against Epilepsy (ILAE)- American Epilepsy Society (AES) Translational Research Task Force (TASK1-Workgroup 5), and is part of a larger effort to harmonize video-electroencephalography interpretation and analysis methods across studies using in vivo and in vitro seizure and epilepsy models.

Methodological standards and interpretation of video‐electroencephalography in adult control rodents. A TASK1‐WG1 report of theAES/ILAETranslational Task Force of the ILAE

“…Digital EEG systems convert the recorded waveforms into a series of numerical values, a process known as analog‐to‐digital conversion. The rate at which waveform data are sampled is known as the sampling rate and, as a rule, should be at least twice the highest frequency of interest; for example, for a sampling rate of 250 Hz, frequency reconstruction (i.e., power spectrum analysis) is possible up to 125 Hz (see Nyquist frequency in Data and in the report of the TASK1‐WG5 group) …”

“…Additional details for the advantages and disadvantages of referential and bipolar montages are available in the TASK1‐WG5 paper Recommendation: In small animals such as rodents, use of referential montages (e.g., Fig.…”

“…The rate at which waveform data are sampled is known as the sampling rate and, as a rule, should be at least twice the highest frequency of interest; for example, for a sampling rate of 250 Hz, frequency reconstruction (i.e., power spectrum analysis) is possible up to 125 Hz (see Nyquist frequency in Data S1 and in the report of the TASK1-WG5 group). 36 Standard filters used to read routine clinical EEG are a low-frequency filter of 0.5-1.0 Hz and a high-frequency filter of 70 Hz. However, slower (e.g., infraslow waves < 0.2 Hz) or higher-frequency rhythms may be of interest in specific research studies.…”

Methodological standards and functional correlates of depth in vivo electrophysiological recordings in control rodents. A TASK1‐WG3 report of the AES/ILAE Translational Task Force of the ILAE

“…Visual analysis of biological signals is often used as a first‐pass measure for eliminating periods with prominent noise or artifact, and is the gold standard for detecting relevant EEG features such as seizures . However, for high‐throughput processing, MATLAB (MathWorks, Natick, MA, U.S.A.) or R (Free Software Foundation, Boston, MA, U.S.A.) programs can be used for this purpose, keeping in mind that the sensitivity and specificity of automated methods may be limited due to variability of physiological/pathological processes.…”

Harmonization in preclinical epilepsy research: A joint AES/ILAE translational initiative

“…The TASK1‐WG3 group addresses the methodologies and interpretation of depth electrophysiologic in studies in vivo in adult rodent controls, whereas the TASK1‐WG4 group focuses on in vitro electrophysiologic studies . The TASK1‐WG5 group proposes standards for data acquisition and analysis for the electrophysiologic recordings . Among the future goals of the TF will be to propose an agreement on terminology and classification of abnormal vEEG and electrophysiologic patterns and behaviors, similar to the classification systems that exist for humans.…”