Effects of sustained, voluntary attention on amplitude and latency of steady-state visual evoked potential: a costs and benefits analysis.
OBJECTIVE
Steady-state visual evoked potentials (VEPs) were recorded to study the mechanisms that underlie visual attention.


METHODS
VEPs were recorded from 1 cycle/degree sinusoidal grating contrast reversed at various temporal frequencies (6-10 Hz). This was displayed in one hemifield. A letter search display was flashed at a random rate in the other hemifield. The subject performed a demanding task on the recording stimulus (attended condition) or on the opposite side stimulus (unattended condition). Alternatively, he/she passively fixated on the fixation point (passive condition).


RESULTS
Relative to the passive condition, attended stimuli elicited enhanced-amplitude and shortened-latency VEP (benefits). Costs (i.e. responses to passive vs. unattended stimuli) were more marked for latency.


CONCLUSIONS
VEP latency may be the key of a priority-based attention mechanism acting at an early level.
Di Russo
F
F
Fondazione Santa Lucia, IRCCS (Centro Ricerche di Neuropsicologia), via Ardeatina 306, 00179 Rome, Italy. fdirusso@uniroma1.it
Spinelli
D
D
D000328:Adult; D001288:Attention / Q000502:physiology*; D003362:Cost-Benefit Analysis; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D014794:Visual Fields / Q000502:physiology