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Altered dynamics of visual contextual interactions in Parkinson's disease
- Source :
- NPJ Parkinson's Disease, npj Parkinson's Disease, Vol 5, Iss 1, Pp 1-8 (2019)
- Publication Year :
- 2019
-
Abstract
- Over the last decades, psychophysical and electrophysiological studies in patients and animal models of Parkinson’s disease (PD), have consistently revealed a number of visual abnormalities. In particular, specific alterations of contrast sensitivity curves, electroretinogram (ERG), and visual-evoked potentials (VEP), have been attributed to dopaminergic retinal depletion. However, fundamental mechanisms of cortical visual processing, such as normalization or “gain control” computations, have not yet been examined in PD patients. Here, we measured electrophysiological indices of gain control in both space (surround suppression) and time (sensory adaptation) in PD patients based on steady-state VEP (ssVEP). Compared with controls, patients exhibited a significantly higher initial ssVEP amplitude that quickly decayed over time, and greater relative suppression of ssVEP amplitude as a function of surrounding stimulus contrast. Meanwhile, EEG frequency spectra were broadly elevated in patients relative to controls. Thus, contrary to what might be expected given the reduced contrast sensitivity often reported in PD, visual neural responses are not weaker; rather, they are initially larger but undergo an exaggerated degree of spatial and temporal gain control and are embedded within a greater background noise level. These differences may reflect cortical mechanisms that compensate for dysfunctional center-surround interactions at the retinal level.
- Subjects :
- 0301 basic medicine
Parkinson's disease
genetic structures
Surround suppression
Electroencephalography
Stimulus (physiology)
lcsh:RC346-429
Article
Visual processing
03 medical and health sciences
Cellular and Molecular Neuroscience
chemistry.chemical_compound
0302 clinical medicine
Medicine
Diagnostic markers
Visual system
lcsh:Neurology. Diseases of the nervous system
Sensory Adaptation
medicine.diagnostic_test
business.industry
Retinal
medicine.disease
Electrophysiology
030104 developmental biology
Neurology
chemistry
Neurology (clinical)
business
Neuroscience
030217 neurology & neurosurgery
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- NPJ Parkinson's Disease, npj Parkinson's Disease, Vol 5, Iss 1, Pp 1-8 (2019)
- Accession number :
- edsair.doi.dedup.....3a89d3129a2832d1e9309923e29910f3