title: Attention induces synchronization-based response gain in steady-state visual evoked potentials.
abstract: When attention is voluntarily directed to a spatial location, visual sensitivity increases at that location. What causes this improved sensitivity? Studies of single neuron spike rates in monkeys have provided mixed results in regard to whether attending to a stimulus increases its effective contrast (contrast gain) or multiplicatively boosts stimulus-driven neural responses (response or activity gain). We monitored frequency-tagged steady-state visual evoked potentials (SSVEPs) in humans and found that voluntary sustained attention multiplicatively increased stimulus-driven population electrophysiological activity. Analyses of intertrial phase coherence showed that this attentional response gain was at least partially due to the increased synchronization of SSVEPs to stimulus flicker. These results suggest that attention operates in a complementary manner at different levels; attention seems to increase single-neuron spike rates in a variety of ways, including contrast, response and activity gains, while also inducing a multiplicative boost on neural population activity via enhanced response synchronization.
authors.affiliation: Department of Psychology and Institute for Neuroscience, Northwestern University, 2029 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Yee Joon
authors.initials: YJ
authors.lastname: Kim
authors.forename: Marcia
authors.initials: M
authors.lastname: Grabowecky
authors.forename: Ken A
authors.initials: KA
authors.lastname: Paller
authors.forename: Krishnakumar
authors.initials: K
authors.lastname: Muthu
authors.forename: Satoru
authors.initials: S
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D003344:Cortical Synchronization; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D013997:Time Factors