Human cortical responses to contrast modulations of visual noise
| Autor: | William A. Simpson, Denis M. Parker, Julie Calvert, Velitchko Manahilov |
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| Rok vydání: | 2005 |
| Předmět: |
Male
Light media_common.quotation_subject Luminance Contrast Sensitivity Visual evoked potentials Psychophysics medicine Image noise Humans Contrast (vision) Latency (engineering) Vision Ocular Visual Cortex media_common Brain Mapping Scalp Second-order vision Sensory Systems Ophthalmology Electrophysiology Visual cortex medicine.anatomical_structure Sensory Thresholds Evoked Potentials Visual Female Spatial frequency Psychology Neuroscience Photic Stimulation |
| Zdroj: | Vision Research. 45:2218-2230 |
| ISSN: | 0042-6989 |
| DOI: | 10.1016/j.visres.2005.02.012 |
| Popis: | We studied visual evoked potentials (VEPs) elicited by second-order contrast modulations of binary dynamic noise and first-order luminance modulations. Using a 3-point Laplacian operator centred on Oz, we found that contrast modulations of both low and higher spatial frequencies elicited a negative component whose latency was about 200 ms. The latency of this component was significantly longer than that of the early Laplacian components to first-order luminance modulations. These findings could be due to slower first-stage linear filters and additional processing stages of the second-order pathway. The topographical analysis of scalp recorded VEPs to central and half-field stimulation has suggested that the responses to second-order patterns are likely to be generated by neuronal structures within the primary visual cortex which may have inputs from extrastriate neurons via feedback connections. |
| Databáze: | OpenAIRE |
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