We questioned whether improvements in maintenance-related neural interactions and working-memory behavior might be due to the stimulation having enhanced perceptual attention immediately after target onset, which could in turn boost the fidelity of the target representation stored in working memory. To test this idea, we examined alpha power suppression immediately after target presentation because this EEG signature is thought to index the release of inhibition to facilitate task-relevant processing 92. If the exogenous stimulation enhanced working memory via a gating-by-inhibition attention mechanism, we should find greater target-locked posterior alpha suppression after active relative to sham stimulation in older adults. a, Target-locked time-frequency representations of total power from occipital and parietooccipital electrodes during memory blocks following sham stimulation in younger minus older adults reveal a significant age-related deficit in alpha suppression (t 82 = 3.154, P = 0.002, d z = 0.688), suggesting that older adults were unable to functionally disinhibit task-relevant areas as efficiently as younger adults during the perceptual analysis of real-world objects. b, However, this age-related deficit in alpha suppression remained significant even after older adults received active stimulation (t 82 = 2.766, P = 0.007, d z = 0.604). c, No changes to alpha power were observed between sham and active stimulation in older adults (t 41 = 0.733, P = 0.468, d z = 0.113). The results showing age-related dysfunction in alpha rhythms during perceptual analysis align with work on the selective attention deficits in aging 96–98. However, unlike the neural interactions of theta-gamma PAC and theta phase synchronization during memory maintenance, this earlier signal during stimulus processing was not influenced by the HD-tACS and is thus an unlikely candidate for underlying the stimulation-induced performance benefit observed in older adults. Topographies show the spatial distribution of the power responses during the 8–14 Hz, 100–400 ms post-target analytic window, indicated by the white dashed box. Between-group comparisons used independent two-tailed t-tests (n = 84). Within-group comparisons used paired sample two-tailed t-tests (n = 42).