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Tom Bullock, James Elliott, Priscilla Rosila Mares, Lena Nalbandian, Barry Giesbrecht; Feature-selective coding is attenuated during sustained attention. Journal of Vision 2016;16(12):599. doi: 10.1167/16.12.599.
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Adaptive, goal-directed behavior requires a cognitive system that supports sustained attention during prolonged tasks. Failures of sustained attention in these tasks can occur and can have very serious consequences in the real world. To investigate the neural mechanisms underpinning these failures, we recorded electroencephalography (EEG) while participants (n=3) engaged in a continuous target detection task. Participants monitored a stream of flickering (30Hz) oriented Gabors (8 possible orientations) for rare long-duration targets (1133ms) presented amongst short-duration (800ms) standards. When a target was detected, participants indicated whether it was oriented left or right of 90°. In three conditions, the stimuli were presented at fixation, distributed across 8 peripheral locations, or fixed at a single peripheral location for the block. Each task consisted of 24 blocks (3.67 min/block). Target detection performance declined from the start of each block (mean=.83, SEM=.05) to the end (mean=.69, SEM=.09). To investigate the neural markers of the performance decline, the blocks were split in half and then an inverted encoding modeling technique was used to estimate orientation- and location-selective tuning functions from the spatially distributed neural activity measured across the scalp (Garcia et al. 2013; Foster et al., 2015). Tuning functions were estimated using power at the steady-state evoked response frequency to the flickering stimuli (SSVEP), in theta (4-7Hz), and in alpha (8-13Hz). The peak amplitude of the SSVEP-based orientation-selective responses was smaller in the second half compared to the first half of the block in the central fixation condition (mean power (SEM)=.12 (.06) vs. .23 (.05)) and in the peripheral-distributed condition (.02 (.01) vs. .10 (.01)). In contrast, location-selective responses in theta, alpha and the SSVEP were unchanged over the block. These data suggest that performance declines during a demanding sustained attention task co-occur with attenuated feature-selective responses in human visual cortex.
Meeting abstract presented at VSS 2016
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