Wykes, R.C., Masvidal-Codina, E., Guimera-Brunet, A., Garrido, J.A. Clinical and Translational Medicine; 12(7): e968. 2022. 10.1002/ctm2.968
There is growing interest in examining oscillations and brain signals outside traditional EEG bands (0.3–80 Hz), as these regimes contain useful electrographic biomarkers for the diagnosis, monitoring and prognosis of neurological disorders and injuries. These include high gamma (80–200 Hz), ripples and high-frequency oscillations (HFOs) (200–500 Hz), as well as infraslow oscillations (<0.1 Hz) and ultraslow potential shifts (UPS). In particular, UPS have remained poorly explored in clinical settings with the notable exception of the Co-Operative Studies on Brain Injury Depolarizations (COSBID) consortium, and specialist epilepsy surgical centres. This is due to the associated technical difficulties recording such slow potentials that require DC-coupled amplifiers and highly stable electrodes. However, UPS include clinically relevant events including preseizure DC shifts (1–3 mV), and large (tens of millivolt) spreading depolarisations (SD) which are thought to play an important role in brain injury and contribute to the pathophysiology associated with migraine with aura, stroke and epilepsy. Therefore, the ability to record and map a wide range of brain signals, from UPS to single units, using the same electrophysiological array will greatly advance our understanding of brain diseases and aid the clinical management of patients with diverse neurological disorders and injuries. Therefore, development of improved electrophysiological devices capable of detecting and mapping wide bandwidth signals with high-fidelity and spatial resolution is warranted.