Lapses of attention, in the form of delayed responses to salient stimuli, increase in frequency for some but not all persons after sleep deprivation (SD). To identify patterns of task-related brain activation that might explain differences in vulnerability to SD, we performed fMRI on participants during a visual, selective attention task. We analyzed the correct responses in a trial-by-trial fashion to model the effects of response time. Stimulus contrast was varied to modulate perceptual difficulty. Attentional lapses and low-contrast stimuli were independently associated with increased signal in fronto-parietal regions associated with biasing attention. Sleep-deprived vulnerable individuals showed reduced top down fronto-parietal signal across all levels of image contrast and this reduction was particularly significant during lapses. There was concurrent reduction in extrastriate cortex and thalamus activation. Non-vulnerable persons showed a trend towards higher top-down biasing of attention and preserved visual cortex activation during SD lapses. A major contributor to performance degradation in SD appears to be a reduction in top-down biasing of attention that is independent of task difficulty.
Copyright 2010 Elsevier Inc. All rights reserved.