Spatiotemporal analysis of the cortical sources of the steady‐state visual evoked potential

Abstract

Abstract:This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874 -886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing. Hum Brain Mapp 00: 000 -000, 2006.

A crossmodal crossover: Opposite effects of visual and auditory perceptual load on steady-state evoked potentials to irrelevant visual stimuli

“…In line with previous SSEP studies (Di Russo et al, 2007;Ding et al, 2006;Parks et al, 2011), SSEP amplitudes evoked by the unattended (visual) stimulus stream tended to be largest at posterior electrodes located over the occipital lobes for visual stimuli, and at frontal electrodes for auditory stimuli (see Figure 3). On the basis of these observations, we analysed the visual stimulus SSEPs at a group of three occipital electrodes (O1, Oz, and O2), and the auditory stimulus SSEPs at a group of three frontal electrodes (F1, Fz, and F2).…”

“…SSEPs are cyclical oscillations of activity in sensory cortical areas evoked by a repeatedly presented or flickering stimulus stream (Di Russo et al, 2007;Heinrich, 2010;Picton et al, 2003;Toffanin et al, 2009;Vialatte et al, 2010). Such oscillations are evoked by both visual and auditory stimulation (e.g., Keitel et al, 2011;Saupe et al, 2009).…”

Lateralized electrical brain activity reveals covert attention allocation during speaking

“…Whereas the N2pc can shift between locations every 100 ms in a certain type of visual search task (Woodman and Luck, 1999), SSVEPs have been estimated to increase in amplitude only after 600-800 ms relative to the onset of an attention-directing cue (Müller et al, 1998b). Furthermore, the neuronal generators of the components differ: whereas the N2pc has been localized to V4 and the lateral occipital complex (Hopf et al, 2000(Hopf et al, , 2006Praamstra and Oostenveld, 2003), associated with intermediate and higher levels of the visual processing pathway, SSVEPs have been localized to primary visual cortex, V1 (Di Russo et al, 2007), associated with very early visual processing. Ultimately, there is a difference in functional role: whereas the N2pc is thought to reflect the focusing of attention on an item (e.g., Luck, 2012), SSVEPs are thought to reflect a gain-control mechanism that enhances the discriminability of attended stimuli (e.g., Müller et al, 1998b).…”

Attentional bias to affective faces and complex IAPS images in early visual cortex follows emotional cue extraction

“…Importantly, SSVEP amplitude increases significantly when a flickering stimulus is attended compared to when that stimulus needs to be ignored (Morgan 1996;Müller et al 1998;Müller et al 2006). The generators of the SSVEP to low-level stimuli that are presented at higher frequency rates have consistently been found in early visual areas, including primary visual cortex (Di Russo et al 2007; Müller et al 2006). Thus, the SSVEP of low-level stimuli flickering at high frequency rates allows investigation of neural attention-emotion interactions at an early sensory processing stage.…”