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Audiovisual processing was studied in a functional magnetic resonance imaging study using the McGurk effect. Perceptual responses and the brain activity patterns were measured as a function of audiovisual delay. In several cortical and subcortical brain areas, BOLD responses correlated negatively with the perception of the McGurk effect. No brain areas with positively correlated BOLD responses were found. This was unexpected as most studies of audiovisual integration use additivity and super additivity - that is, increased BOLD responses after audiovisual stimulation compared with auditory-only and visual-only stimulation - as criteria for audiovisual integration. We argue that brain areas that show decreased BOLD responses that correlate with an integrated audiovisual percept should not be neglected from consideration as possibly involved in audiovisual integration.
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http://dx.doi.org/10.1097/WNR.0b013e328340cc47 | DOI Listing |
Multivariate pattern analysis (MVPA) methods are a versatile tool to retrieve information from neurophysiological data obtained with functional magnetic resonance imaging (fMRI) techniques. Since fMRI is based on measuring the hemodynamic response following neural activation, the spatial specificity of the fMRI signal is inherently limited by contributions of macrovascular compartments that drain the signal from the actual location of neural activation, making it challenging to image cortical structures at the spatial scale of cortical columns and layers. By relying on information from multiple voxels, MVPA has shown promising results in retrieving information encoded in fine-grained spatial patterns.
View Article and Find Full Text PDFInvest Ophthalmol Vis Sci
September 2025
fMRI unit, Department of Neurology, Hadassah Medical Organization and Faculty of Medicine, The Hebrew University of Jerusalem, Ein Karem, Jerusalem, Israel.
Purpose: Behavioral and electrophysiological studies have shown that vision is slower under scotopic conditions (dark, activating only rods) than photopic conditions (light, activating only cones). However, slower scotopic processing cannot be solely explained by findings that rod signals are slower than cone signals, and it is unknown whether temporal processing differences persist in cortex. Flickering stimuli have previously been used in functional MRI (fMRI) studies to probe photopic cortical temporal sensitivity.
View Article and Find Full Text PDFbioRxiv
August 2025
Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905.
The human brain dynamically adapts to hypoxia, a reduction in oxygen essential for metabolism. The brain's adaptive response to hypoxia, however, remains unclear. We investigated dynamic functional connectivity (FC) in healthy adults under acute hypoxia (FiO = 7.
View Article and Find Full Text PDFbioRxiv
August 2025
Early Life Imaging Research Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
Human cortical development leading up to and around birth is crucial for lifelong brain function. Cortical activity can be studied using BOLD fMRI, however, previously limited sensitivity and spatial specificity has constrained understanding of how its emergence relates to functional cortical circuitry and neurovascular development at the mesoscale. To resolve this, we used ultra-high-field 7 Tesla MRI to acquire submillimetre resolution BOLD-fMRI data from 40 newborns and 4 adults.
View Article and Find Full Text PDFCommun Med (Lond)
August 2025
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.
Background: Central mechanisms may play a role in the success of bariatric surgery (BS), the treatment of choice for refractory obesity. We hypothesize that central dopaminergic receptor function in striatal brain regions is a pivotal mechanism in the success of BS.
Methods: We conducted a cross-sectional study to investigate central dopamine type 2 and 3 receptors (D2/3 R) within striatal brain regions in successful weight loss (WL) through BS.