Top-down modulation: bridging selective attention and working memory

Abstract

Selective attention, the ability to focus our cognitive resources on information relevant to our goals, influences working memory (WM) performance. Indeed, attention and working memory are increasingly viewed as overlapping constructs. Here, we review recent evidence from human neurophysiological studies demonstrating that top-down modulation serves as a common neural mechanism underlying these two cognitive operations. The core features include activity modulation in stimulus-selective sensory cortices with concurrent engagement of prefrontal and parietal control regions that function as sources of top-down signals. Notably, top-down modulation is engaged during both stimulus-present and stimulus-absent stages of WM tasks; that is, expectation of an ensuing stimulus to be remembered, selection and encoding of stimuli, maintenance of relevant information in mind and memory retrieval.

Figure 1. Correlation between WM performance and early neural measures of selective activity modulation in visual cortices during encoding

A. Grand-average ERP waveform showing early activity modulation, and B. significant differences in P1 amplitude based solely on WM goals (FM-O vs SM-O). C, Participants with greater attentional modulation of P1 amplitude (~100ms post-stimulus presentation) show greater subsequent memory of encoded stimuli (R=0.45, p<0.05). Face memory-overlap (FM-O), Scene memory-overlap (SM-O), Face memory (FM), Scene memory (SM). Error bars represent standard error of the mean. Asterisks denote significant difference (single p<0.05, double p<0.001). Modified from [30].

Figure 2. Site of rTMS and relationship between rTMS-induced changes in P1 modulation and WM accuracy

A. Functional connectivity analysis revealed a PFC region associated top-down modulation, the right inferior frontal junction (IFJ), which was identified in each individual and served as the site for rTMS. B. Participants with greater rTMS-related change in P1 modulation also exhibited a greater change in WM accuracy. Δ = sham – actual rTMS. Modified from [36].