Spatial resolution of EEG cortical source imaging revealed by localization of retinotopic organization in human primary visual cortex

Abstract

The aim of the present study is to investigate the spatial resolution of electroencephalography (EEG) cortical source imaging by localizing the retinotopic organization in the human primary visual cortex (V1). Retinotopic characteristics in V1 obtained from functional magnetic resonance imaging (fMRI) study were used as reference to assess the spatial resolution of EEG since fMRI can discriminate small changes in activation in visual field. It is well-known that the activation of the early C1 component in the visual evoked potential (VEP) elicited by pattern onset stimuli coincides well with the activation in the striate cortex localized by fMRI. In the present experiments, we moved small circular checkerboard stimuli along horizontal meridian and compared the activations localized by EEG cortical source imaging with those from fMRI. Both fMRI and EEG cortical source imaging identified spatially correlated activity within V1 in each subject studied. The mean location error, between the fMRI-determined activation centers in V1 and the EEG source imaging activation peak estimated at equivalent C1 components (peak latency: 74.8 ± 10.6 ms), was 7 mm (25% and 75% percentiles are 6.45 mm and 8.4 mm, respectively), which is less than the change in fMRI activation map by a 3° visual field change (7.8 mm). Moreover, the source estimates at the earliest major VEP component showed statistically good correlation with those obtained by fMRI. The present results suggest that the spatial resolution of the EEG cortical source imaging is can correctly discriminate cortical activation changes in V1 corresponding to less than 3° visual field changes.

Top-down effects on early visual processing in humans: A predictive coding framework

“…Notwithstanding these limitations, the classical model as proposed by Jeffreys and Axford (1972a) still forms the basis of our current understanding of the C1 (Clark et al, 1995;Di Russo et al, 2002;Fu et al, 2008;Im et al, 2006;Kelly et al, 2008;Martinez et al, 1999;Pourtois et al, 2004;Pourtois et al, 2008;Vanni et al, 2004). As a potential indicator of very early activity in human primary visual cortex, the C1 has repeatedly been used to assess whether early stages of stimulus processing may be shaped by topdown factors, i.e.…”

“…the frontal eye-field, FEF) and extrastriate visual areas are already active at the peak latency of this earliest VEP component (Bullier, 2001;Foxe and Simpson, 2002;Thorpe et al, 1996), the basic assertion that what Jeffreys and Axford (1972a) termed "C. I" has its principal sources in primary visual cortex has stood the test of time (Clark et al, 1995;Di Russo et al, 2002;Fu et al, 2005;Fu et al, 2008;Im et al, 2006;Kelly et al, 2008;Martinez et al, 1999;Pourtois et al, 2004;Pourtois et al, 2008;Proverbio et al, 2010). The basic model proposed by Jeffreys and Axford (1972a) convincingly explains the most striking feature of the C1, which may also be the reason why the provisional name stuck: the C1 component reverses its polarity depending on whether the upper or lower visual field is stimulated, distinguishing it from later visual ERP components, such as the P1 or the N1.…”

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

“…272,279,282 Co-registration of data acquired through high-density EEG and/or MEG recordings with structural neuroimaging, such as MRI, provides information about brain activity with spatial resolutions comparable to those of fMRIespecially when guided by fMRI-determined regions of interest for a particular brain state or function. [283][284][285][286][287][288] Additionally, most EEGbased recording systems are relatively inexpensive and portable, compared with currently available structural and functional neuroimaging technologies, making them easily deployable in both clinical and naturalistic (i.e., sports, in-theater) settings. The combination of high temporal resolution, reasonable spatial resolution, flexibility of use, portability, and relatively low cost make clinical electrophysiological techniques appealing methods with which to evaluate persons with TBI and disturbances in psychological health.…”

Challenging the estimation of cortical activity from MEG with simulated fMRI-constrained retinotopic maps

“…[10]. The intricate functional and anatomical organization of the human visual system is a challenge to EEG and MEG imaging [4], whose spatial resolution is usually considered on the order of the centimeter and rapidly degrades with distance to sensors. Here we report on the performances of recent forward and inverse MEG image models in the difficult context of neural responses within the visual cortex.…”