Sleep is essential for the modulation of neural functions as well as for preserving physiological balance. However, there is a lack of high-temporal and spatial resolution tools to study the detailed information encoding mechanisms of neurons in deep brain regions over sleep–wake states. In particular, although the regulatory role of the ventral tegmental area (VTA) in sleep–wakefulness has been preliminarily revealed, direct electrophysiological evidence is lacking. To this end, this study fabricated a multi-channel, high-stability microelectrode array (MEA), and adopted a mixed electrochemical co-deposition strategy of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and polydopamine (PDA) to achieve synergistic improvements in the electrode interface. The resulting PEDOT:PSS/PDA coating markedly decreased the impedance from 2085.66 ± 248.87 kΩ (bare Pt) to 28.03 ± 3.25 kΩ, enhanced the charge storage capacity, improved mechanical stability and biocompatibility, and increased the signal-to-noise ratio to 11.61. The coating-modified MEA was implanted into the VTA of mice, enabling stable long-term monitoring of local field potentials (LFPs) and spikes. In parallel, electroencephalography (EEG) and electromyography signals were simultaneously acquired. Through cellular-level neural signal analysis, three neuronal populations with state-specific firing patterns were identified as sleep-responsive, wake-responsive, and state-independent neurons. Further analysis of LFPs revealed that, compared with EEG, they were more sensitive to changes in sleep state and exhibited stronger state-dependent oscillation patterns. This study not only provides new cellular-level evidence for the involvement within the VTA for sleep–wake control, but also presents a general strategy for constructing high-performance, long-term stable neural–electrode interface coatings.
Miao et al. (Wed,) studied this question.