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

Abstract

SUMMARY In vivo electrophysiological recordings are widely used in neuroscience research and video-electroencephalography (vEEG) has become a mainstay of preclinical neuroscience research, including studies of epilepsy and cognition. Studies utilizing vEEG typically involve comparison of measurements obtained from different experimental groups, or from the same experimental group at different times, in which one set of measurements serves as “control”, and the others as “test” of the variables of interest. Thus, controls provide mainly a reference measurement for the experimental test. Control rodents represent an undiagnosed population, and cannot be assumed to be “normal” in the sense of being “healthy.” Certain physiological EEG patterns seen in humans are also seen in control rodents. However, interpretation of rodent vEEG studies relies on documented differences in frequency, morphology, type, location, behavioral state dependence, reactivity and functional or structural correlates of specific EEG patterns and features between control and test groups. This paper will focus on the vEEG of standard laboratory rodent strains with the aim of developing a small set of practical guidelines that can assist researchers in the design, reporting, and interpretation of future vEEG studies. To this end, we will: 1) discuss advantages and pitfalls of common vEEG techniques in rodents and propose a set of recommended practices and 2) present EEG patterns and associated behaviors recorded from adult rats of a variety of strains. We will describe the defining features of selected vEEG patterns (brain-generated or artifactual) and note similarities to vEEG patterns seen in adult humans. We will note similarities to normal variants or pathological human EEG patterns and defer their interpretation to a future report focusing on rodent seizure patterns.

[18F]GE180 positron emission tomographic imaging indicates a potential double‐hit insult in the intrahippocampal kainate mouse model of temporal lobe epilepsy

“…2,42 In our study, saline-injected mice did not exhibit signs of SE, but moderate increases in TSPO expression compared to baseline values were evident throughout the brain for approximately 1 week after surgery. 47 Nevertheless, sham surgery alone did not lead to spontaneous recurrent convulsant or electrographic seizures in this model. Severe penetrating traumatic brain injury is associated with later epilepsy development in a major proportion of clinical patients, 43,44 and mild traumatic brain injury is also associated with an increased risk for unprovoked epileptic seizures.…”

A companion to the preclinical common data elements and case report forms for rodent EEG studies. A report of the TASK3 EEG Working Group of the ILAE/AES Joint Translational Task Force

“…Background activity means the EEG background that is not associated with target events (e.g., baseline or interictal background if seizures are observed). Background activities and state‐dependent patterns similar to those observed in control populations in humans can also be observed in rodents, although some differences in maturation or pattern morphology can be seen . In addition, sleep EEG can be divided into the slow wave‐based non–rapid eye movement sleep stage (slow wave sleep or NREM) and the paradoxical sleep‐based rapid eye movement sleep stage (REM).…”

“…If frequencies of multiple bandwidths exist, each of them may be reported. We have used here the same nomenclature of frequency bands used also to characterize the frequencies in the human EEG studies (e.g., delta, theta, alpha, and beta), as agreed in the earlier reports of the ILAE/AES Joint Translational Task Force . However, the frequency range of specific physiologic or pathologic rhythmic activities may differ among humans and rodents .…”

“…To indicate which, in our opinion, elements are important to include, we have attempted to indicate the level of importance of data in the CDE chart as “high,” “moderate,” and “optional”; that is, which data should be minimally or preferably documented in CRF modules. It is suggested that elements that have high or moderate priority are the minimal essentials would be useful to be included in the standardized protocols The CDEs proposed as “high” priority are shown in Table . We realize that community feedback will be essential in this prioritization and will be sought (see accompanying editorial in this special issue for the process).…”

“…This manuscript of the ILAE/AES Joint Translational TF introduces the preclinical CDEs organized into case report forms (CRFs) for preclinical studies utilizing electroencephalography (EEG), video‐EEG (vEEG), or electrophysiologic recordings in rodents. The recently published reports of the TASK1 groups of ILAE/AES Joint Translational TF outline some of the methodologic and reporting practices for the acquisition, interpretation, and analysis, including software‐based, of EEG performed in experimental control rodents . In addition, readers may refer to additional considerations on reporting experimental methods and welfare of animals used for epilepsy research reported by Lidster et al.…”