Auditory selective attention during a working memory task with melodies: a MEG study

Working memory and attention are jointly needed in most everyday life tasks and activities. They have however mostly been studied separately. Here we investigate how auditory working memory and selective attention interact using a recently introduced paradigm (MEMAT) that combines a classic working memory paradigm, the delayed-matching-to-sample task, and selective attention, with distractors presented during the encoding phase. All stimuli are four-tone melodies. Twenty-two participants performed the MEMAT task during MEG recordings. We manipulate the difficulty of the memory task and of attentional filtering. When memory task difficulty increases, the amplitude of the CNV in anticipation of the melody to encode increases and the decrease in alpha power during encoding and maintenance in a left fronto-temporal network is reduced. When attentional filtering difficulty increases, the amplitude of the sustained evoked response during encoding increases, whereas the differential processing of relevant and irrelevant sounds in auditory areas is less pronounced, and frontal theta power during encoding and maintenance is higher. In the left auditory cortex, we could directly observe the result of the interaction between auditory memory and attention: the facilitation of relevant sound processing in the easy filtering condition was reduced when the memory task difficulty increased. This pattern mirrors the observed behavioral effects. Overall brain dynamics highlight reciprocal influences of working memory and selective attention processes, in keeping with shared cognitive resources between them.