Flexible contrast gain control in the right hemisphere.
This study investigates whether the right hemisphere has more flexible contrast gain control settings for the identification of spatial frequency. Right-handed participants identified 1 and 9 cycles per degree sinusoidal gratings presented either to the left visual field-right hemisphere (LVF-RH) or the right visual field-left hemisphere (RVF-LH). When luminance contrast was randomized across a wide range (20-60%), performance gradually improved with contrast in the LVF-RH. Conversely, performance in the RVF-LH was disrupted and saturated for 20 and 60% of contrast, respectively, leading to a LVF-RH advantage for these contrast levels. When contrast was blocked or randomized for a smaller range (30-50%), the LVF-RH advantage was diminished. Flexible contrast gain control is needed when contrast is randomized across a wide range, but not when it is blocked or randomized across a smaller range. The results therefore suggest that the right hemisphere is able to process spatial frequency information across a wider range of contrast levels than is the left hemisphere.
Okubo
Matia
M
Department of Psychology, University of Melbourne, Australia. mokubo@unimelb.edu.au
Nicholls
Michael E R
ME
D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008027:Light; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology* / Q000528:radiation effects; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology* / Q000528:radiation effects