Unlabelled: Ambiguous visual stimuli elicit different perceptual interpretations over time, creating the illusion that a constant stimulus is changing. We investigate whether such spontaneous changes in visual perception involve occipital brain regions specialized for processing visual information, despite the absence of concomitant changes in stimulation. Spontaneous perceptual changes observed while viewing a binocular rivalry stimulus or an ambiguous structure-from-motion stimulus were compared with stimulus-induced perceptual changes that occurred in response to an actual stimulus change. Intracranial recordings from human occipital cortex revealed that spontaneous and stimulus-induced perceptual changes were both associated with an early transient increase in high-frequency power that was more spatially confined than a later transient decrease in low-frequency power. We suggest that the observed high-frequency and low-frequency modulations relate to initiation and maintenance of a percept, respectively. Our results are compatible with the idea that spontaneous changes in perception originate from competitive interactions within visual neural networks.
Significance Statement: Ambiguous visual stimuli elicit different perceptual interpretations over time, creating the illusion that a constant stimulus is changing. The literature on the neural correlates of conscious visual perception remains inconclusive regarding the extent to which such spontaneous changes in perception involve sensory brain regions. In an attempt to bridge the gap between existing animal and human studies, we recorded from intracranial electrodes placed on the human occipital lobe. We compared two different kinds of ambiguous stimuli, binocular rivalry and the phenomenon of ambiguous structure-from-motion, enabling generalization of our findings across different stimuli. Our results indicate that spontaneous and stimulus-induced changes in perception (i.e., "illusory" and "real" changes in the stimulus, respectively) may involve sensory regions to a similar extent.
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http://dx.doi.org/10.1523/JNEUROSCI.0242-15.2016 | DOI Listing |
Alzheimers Dement
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Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
Introduction: Women with early bilateral salpingo-oophorectomy (BSO) have greater Alzheimer's disease (AD) risk than women with spontaneous menopause (SM), but the pathway toward this risk is understudied. Considering associative memory deficits may reflect early signs of AD, we studied how BSO affected brain activity underlying associative memory.
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Objectives: To examine quality of maternal and newborn care (QMNC) around childbirth in facilities in Belgium during the COVID-19 pandemic and trends over time.
Design: A cross-sectional observational study.
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State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, China. Electronic address:
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December 2024
Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China.
Dexmedetomidine (DexM), a highly selective α-adrenoceptor agonist, significantly reduces postoperative adverse effects, including sleep and circadian rhythm disruptions. Vasoactive intestinal peptide neurons in the suprachiasmatic nucleus (SCN) regulate the synchronization of circadian rhythms with the external environment in mammals. We investigate the effects of DexM on sleep and circadian rhythms, as well as the underlying mechanisms.
View Article and Find Full Text PDFSci Rep
December 2024
Brain Dynamics Lab, Interdisciplinary Center of Biomedical and Engineering Research for Health, Universidad de Valparaíso, Valparaíso, Chile.
Multi-state metastability in neuroimaging signals reflects the brain's flexibility to transition between network configurations in response to changing environments or tasks. We modeled these dynamics with a Kuramoto network of 90 nodes oscillating at an intrinsic frequency of 40 Hz, interconnected using human brain structural connectivity strengths and delays. We simulated this model for 30 min to generate multi-state metastability.
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