Broad decreases in low-frequency power that accompany increased attention must coexist with the band-limited increases in theta oscillatory power that underlie successful episodic and spatial memory. This is precisely why theta oscillations are detectable during high-attention states in memory tasks (i.e. successful encoding/retrieval), either via analytic corrections for the tilt or with contrasts that compare one high-attention state to another high-attention state. Moreover, the presence of memory-related, band-limited theta power yields detectable increases in long-range theta connectivity even as overall measures of spectral power decrease.
