Surround modulation in visual motion processing studied with the motion after effect and fMRI

Abstract

Surround modulation in visual motion areas was studied with the static MAE and fMRI. Stimuli were composed of a luminance defined central motion area, with a surround that could be static during adaptation or moving. Static surround attributes (MAE Experiments 1-3) could involve colour and could change between adaptation and test. Changing surround attributes from luminance to colour or vice versa between adaptation and test reduced the MAE. Colour changes between adaptation and test caused a greater MAE reduction than luminance contrast changes. In fMRI Experiments 4-6, surround modulation was tested through BOLD activity evoked within ROIs. These were defined as motion selective areas of cortex that had some retinotopic organisation and corresponded topographically to the foveally located central part of the stimulus. Voxels directly activated by the surround were excluded from the ROIs. Width and velocity of rings defining the centre-surround stimuli either controlled for the cortical magnification factor (M-scaled) or did not.EThOS - Electronic Theses Online ServiceGBUnited Kingdo