26 — Aberrant cortical activity in multiple GCaMP6-expressing transgenic mouse lines

First off… I am all about this style of Results-section-first writing.

This paper discusses a common transgenic mouse line commonly used in neuroscience studies. This GCaMP6 line is used for a variety of imaging protocols, where the GCaMP6 proteins fluoresce green in the presence of calcium. This is commonly used to detect neural activity, and is widely used in the neuroscience world.

The authors found that these mice underwent “epileptiform events” — waves of excitation that raced across the brain in what looks very similar to epileptic seizures. This is troubling for a bunch of reasons, but one notable fear is this: Because these mice are so widely used in behavioral and high-level cognitive tasks, and these epileptiform events are unexpected in healthy mice, these findings suggest that neuroscience studies in the past may use a skewed model that does not match a “wild-type” mouse as closely as desired.

Because these events rarely manifest as a visible seizure, and the animals do not appear to learn differently or at a different pace than their “normal” peers, these events have not been explored deeply in the past. The authors suggest that caution should be used when using these mice in studies that might be disturbed by this abberant activity.

Currently there is no confirmed mechanism to explain this epileptiform activity.