A Lightweight Drive Implant for Chronic Tetrode Recordings in Juvenile Mice

We're interested in understanding how the brain operates at a network level. This method is our attempt to explore the development of brain networks to identify developmental alterations in age dependent diseases like autism, schizophrenia or bipolar disorder. The silicon probe technology provides a simpler, more consistent method to record network activity in vivo.

But despite this, chronic tetra recordings do offer some advantages over silicon probes, such as simultaneously recording over a broader spatial distribution of brain regions. Chronic recordings pose a unique challenge to in vivo electrophysiology due to several factors, including gliosis at the recording sites, movement of the recording site over time or failure of the attachment method. Our recent work demonstrated that the sweeps encoded by the theta oscillation of the hippocampus during active movement of the animal every hundred milliseconds or so iteratively cycle forward, prospectively evaluating possible future states and backwards retrospectively evaluating prior actions.

Performing these in vivo recordings in juvenile mice poses several engineering challenges due to the small size of the mice, their relative weakness and the lack of development in their skull. Our methodology overcomes these limitations and allows us to chronically record network level activity daily in the developing mouse brain. Besides recording chronically in juvenile mice, our method allows us to record from up to 16 distinct bilateral brain regions irrespective of the spatial relationship of those regions.

These developments will allow us to identify how networks establish functional communication across developments, both in the healthy brain and in mouse models of neurodevelopmental disorders, like autism spectrum disorders.