Learn More
The cruciform hypothesis states that if a visual evoked potential component originates in V1, then stimuli placed in the upper versus lower visual fields will generate responses with opposite polarity at the scalp. This diagnostic has been used by many studies as a definitive marker of V1 sources. To provide an empirical test of the validity of the(More)
We used source imaging of visual evoked potentials to measure neural population responses over a wide range of horizontal disparities (0.5-64 arcmin). The stimulus was a central disk that moved back and forth across the fixation plane at 2 Hz, surrounded either by binocularly uncorrelated dots (disparity noise) or by correlated dots presented in the(More)
EEG and MEG have excellent temporal resolution, but the estimation of the neural sources that generate the signals recorded by the sensors is a difficult, ill-posed problem. The high spatial resolution of functional MRI makes it an ideal tool to improve the localization of the EEG/MEG sources using data fusion. However, the combination of the two techniques(More)
Estimating cortical current distributions from electroencephalographic (EEG) or magnetoencephalographic data is a difficult inverse problem whose solution can be improved by the addition of priors on the associated neural responses. In the context of visual activation studies, we propose a new approach that uses a functional area constrained estimator(More)
Using cortical source estimation techniques based on high-density EEG and fMRI measurements in humans, we measured how a disparity-defined surround influenced the responses to the changing disparity of a central disk within five visual ROIs: V1, V4, lateral occipital complex (LOC), hMT+, and V3A. The responses in the V1 ROI were not consistently affected(More)
The cruciform model posits that if a Visual Evoked Potential component originates in cortical area V1, then stimuli placed in the upper versus lower visual field will generate responses with opposite polarity at the scalp. In our original paper (Ales et al., 2010b) we showed that the cruciform model provides an insufficient criterion for identifying V1(More)
We used fMRI-informed EEG source-imaging in humans to characterize the dynamics of cortical responses during a disparity-discrimination task. After the onset of a disparity-defined target, decision-related activity was found within an extended cortical network that included several occipital regions of interest (ROIs): V4, V3A, hMT+ and the Lateral(More)
We introduce a sensitive method for measuring face detection thresholds rapidly, objectively, and independently of low-level visual cues. The method is based on the swept parameter steady-state visual evoked potential (ssVEP), in which a stimulus is presented at a specific temporal frequency while parametrically varying ("sweeping") the detectability of the(More)
The lateral occipital cortex (LOC) activates selectively to images of intact objects versus scrambled controls, is selective for the figure-ground relationship of a scene, and exhibits at least some degree of invariance for size and position. Because of these attributes, it is considered to be a crucial part of the object recognition pathway. Here we show(More)
Studying directional selectivity using neuroimaging in humans is difficult because the resolution is insufficient to directly access directionally selective activity. Here we used motion adaptation of the steady-state visual evoked potential (SSVEP) and source imaging in the frequency domain to detect brain areas that contain direction-selective cells. This(More)