title: The effect of task-irrelevant visual backgrounds on human transcranial magnetic stimulation-evoked electroencephalography responses and cortical alpha activity.
abstract: Brain responses evoked by transcranial magnetic stimulation (TMS) in task-free experimental contexts are known to depend on psychophysiological states such as sleep, vegetative state and caffeine-induced arousal. Much less is known about how TMS-evoked responses depend on task-irrelevant steady perceptual input. Here, we examined ongoing alpha activity and the mean amplitude of EEG potentials in response to occipitally applied TMS as a function of task-irrelevant visual backgrounds. Responses to TMS were robustly modulated by photographs of natural scenes and man-made environments. These effects began as early as during the N100 and continued for several hundred milliseconds after the stimulation. There was also a more general effect of background along with other stimuli, such as blank backgrounds, sinusoidal gratings and moving dot-patterns. This effect was observable from ongoing alpha activity as well. Based on these results we conclude that different types of steady perceptual input modulate visual cortex reactivity and/or connectivity and it is possible to measure these modulations by combining TMS with electroencephalography.
authors.affiliation: Institute of Public Law, University of Tartu, Kaarli puietsee 3, Tallinn, 10119, Estonia.
authors.forename: Renate
authors.initials: R
authors.lastname: Rutiku
authors.forename: Anu
authors.initials: A
authors.lastname: Einberg
authors.forename: Kuniyasu
authors.initials: K
authors.lastname: Imanaka
authors.forename: Talis
authors.initials: T
authors.lastname: Bachmann
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D013647:Task Performance and Analysis; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception
keywords: connectivity; evoked potentials; transcranial magnetic stimulation; visual cortex; visual image categories