High-bandwidth, low-profile, long-term wireless EEG telemetry allows for optogenetic entrainment of natural cortical oscillations in freely-moving rats

Abstract Recording of whole-brain or multi-unit neuronal activity in the rodent brain is a powerful and widely used technique in neuroscience research. However, the acquisition of data from freely-moving animals is subject to a range of compromises. If a high bandwidth of data digitisation is needed, animals will either need to be tethered to the acquisition system or any telemetry used will have a short working battery life. For freely-moving experiments, especially those requiring careful behavioural measurements, such tethers and/or headstages incorporating e.g. optogenetic stimulation systems may prove to be confounding or limiting in the experiments which may be performed. Here we present the refinement and deployment of a wirelessly-charged, self-contained EEG telemeter at high data bandwidths (2kHz) with integrated optogenetic stimulator (473nm) and fully subcutaneous fibre routing and implantation. This approach has allowed for rats to be recorded long-term (6 months) without requiring device explants, charging or maintenance, with an outward appearance identical to an unimplanted rodent. We have demonstrated the use of this system to stimulate cortical networks at a range of frequencies in freely-moving and acutely-anaesthetised rats allowing for the boosting or entrainment of physiological oscillations at will.