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Abstract:
Abstract: Mismatch negativity (MMN) is an
electrophysiological marker of pre-attentive processing that occurs
automatically to a change in a stream of auditory stimuli. It is
known that it can be enhanced by attention, but it occurs
regardless of whether subjects are actively oriented to it or not.
Although the role of MMN in sleep is currently controversial,
little is known about its change with attentional state such as
drowsiness, sleep deprivation and diurnal cycle. Subjects engaged
in a controlled 48-hour passive sleep deprivation protocol.
Throughout the continuous vigil, participants were periodically
tested on a battery of 3 computerized reaction-time experiments,
each probing a different facet relating to the visual attentional
span. MMN to harmonic pitch stimuli was also recorded at 3 fixed
intervals. Over the 48-hour vigil, negative priming, popout and
flanker effects were found to be robust with no variation in
spotlight size. A general gradual increase in reaction time and a
similar decrease in accuracy characterized the negative priming and
flanker paradigms. Curiously, the vigil affected the inhibition and
facilitation effects differently on the behavioral experiments. The
electrophysiological results showed a conspicuous decrease in
amplitude of MMN at both 24 and 36 hours into the vigil thereby
questioning the common view regarding MMN as being
attention-independent and resource-free.
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