Spatiotemporal dynamics of brightness coding in human visual cortex revealed by the temporal context effect
Hao Zhou,
Matthew Davidson,
Peter Kok,
Li Yan McCurdy,
Floris P. de Lange,
Hakwan Lau,
Kristian Sandberg
Affiliations
Hao Zhou
Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, 8000, Denmark; Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, China; Sino-Danish Center for Education and Research, Beijing, 100190, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; Corresponding author., 15 Datun Road, Chaoyang District, Beijing, China.
Matthew Davidson
Department of Psychology, Columbia University, New York, NY, 10027, USA
Peter Kok
Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Kapittelweg 29, 6525, EN Nijmegen, the Netherlands; Wellcome Centre for Human Neuroimaging, University College London, London, WC1N 3BG, UK
Li Yan McCurdy
Department of Psychology, Columbia University, New York, NY, 10027, USA; Interdepartmental Neuroscience Program, Yale University, New Haven, CT, 06520, USA
Floris P. de Lange
Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Kapittelweg 29, 6525, EN Nijmegen, the Netherlands
Hakwan Lau
Department of Psychology, Columbia University, New York, NY, 10027, USA; Department of Psychology, University of California, Los Angeles, Los Angeles, 90095, USA; Brain Research Institute, University of California, Los Angeles, Los Angeles, 90095, USA; Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong
Kristian Sandberg
Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, 8000, Denmark; Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, 8450, Hammel, Denmark; Corresponding author., Palle Juul-Jensens Boulevard 82. building NBG/10G, 10G-4-06, 8200, Aarhus N, Denmark.
Human visual perception is modulated by both temporal and spatial contexts. One type of modulation is apparent in the temporal context effect (TCE): In the presence of a constant luminance patch (a long flash), the perceived brightness of a short flash increases monotonically with onset asynchrony. The aim of the current study was to delineate the neural correlates of this illusory effect, particularly focusing on its dynamic neural representation among visual cortical areas. We reconstructed sources of magnetoencephalographic (MEG) data recorded from observers (6 male and 9 female human adults) experiencing the TCE. Together with retinotopic mapping, signals from different occipital lobe areas were extracted to investigate whether different visual areas have differential representation of the onset vs. offset synchronized short flashes. From the data, TCE related responses were observed in LO and V4 in the time window of 200–250 m s, while neuronal responses to physical luminances were observed in the early time window at around 100 m s across early visual cortex, such as V1 and V2, also in V4 and VO. Based on these findings, we suggest that two distinct processes might be involved in brightness coding: one bottom-up process which is stimulus energy driven and responds fast, and another process which may be broadly characterized as top-down or lateral, is context driven, and responds slower. For both processes, we found that V4 might play a critical role in dynamically integrating luminances into brightness perception, a finding that is consistent with the view of V4 as a bottom-up and top-down integration complex.
