EEG measures of consolidation of visual perceptual learning during wakefulness are distinct from consolidation during sleep

Visual perception is malleable in response to training, called visual perceptual learning (VPL). Thus, improvements on one VPL task must be consolidated to resist retrograde interference from subsequent training. Previous findings have shown that, during post-training REM sleep, the power of EEG theta-band oscillations, as well as a lower excitation-dominance between excitatory and inhibitory neurotransmitters (E/I), were each reliably related to learners' abilities to resist such retrograde interference. Notably, while consolidation of VPL also occurs during wakefulness, the underlying neural mechanisms of the consolidation of VPL during wakefulness have yet to be fully characterized. Here, we tested whether theta power and EEG-based E/I balance similarly indexed increased resistance to interference in awake humans. Participants were trained with one texture discrimination task (TDT) set and rested for one hour (post-training rest). During the rest period, posterior EEG was recorded. Training on a second set of TDT was then completed, which has the potential to interfere with the learning from the first TDT. While previously reported results linked higher interference to lower theta power during post-training REM sleep, we did not observe evidence for such a relationship in theta power. Instead, we found a similar link between higher interference and lower alpha power during post-training rest (contralateral to trained hemifield; ρ = .45). While the lower E/I balance measured by neurotransmitters was linked to increased resistance to interference during post-training REM sleep previously, the lower E/I balance measured by EEG was linked to increased susceptibility to interference during an awake post-training rest period (theta-band ρ = .47; alpha-band ρ = .36). These suggest that while consolidation during REM sleep is associated with inhibition, consolidation during wakefulness is associated with excitation. Neural mechanisms for the consolidation of VPL are thus likely to differ between wakefulness and sleep.