Michele Deodato^1,2 (), Vincenzo Romei², Jason Samaha³; ¹New York University Abu Dhabi, ²University of Bologna, ³University of California Santa Cruz

EEG alpha oscillations are thought to impose pulsed inhibition, producing rhythmic fluctuations in neural excitability with clear sensory consequences. Numerous studies show that visual events are more likely to be perceived near the excitatory phases of the alpha cycle (typically around the trough) and suppressed near the peak, suggesting that alpha rhythms define temporal windows of enhanced sensory processing. The aperiodic structure of the EEG power spectrum has independently been linked to cortical excitation–inhibition (E/I) balance and correlates with alpha power, implying overlapping circuit-level mechanisms. Recent evidence indicates that multiple measures of temporal processing are predicted not only by individual alpha frequency and phase but also by the aperiodic exponent. For example, visual temporal fusion thresholds are jointly predicted by alpha dynamics and aperiodic activity: faster alpha rhythms correspond to finer temporal resolution, whereas flatter aperiodic slopes correspond to broader integration windows and shallower psychometric functions. These influences are partially independent, with both periodic and aperiodic EEG components contributing unique variance to perceptual timing. Here, we replicate these findings in a new dataset and propose a novel mechanistic account that unifies periodic and aperiodic effects through a common process. We suggest that global shifts in excitation–inhibition alter alpha-cycle dynamics such that a greater portion of each cycle falls below the excitability threshold required for sensory processing. This mechanism results in a compression of the high-excitability phase that shortens the effective temporal integration period without requiring changes in the frequency of rhythmic inhibition. This unified account provides a robust, replicable framework for understanding how cortical inhibition shapes the temporal structure of visual perception.