Abstract
In the superficial layer of macaque monkey V1, many neurons have stronger responses to light decrements (OFF responses) than light increments (ON responses) [Yeh et al., 2009]. This OFF-over-ON bias is evident when V1 receptive fields are mapped with sparse noise, but is weaker with dense noise (i.e. Hartleys, Ringach et al., 1997). One possible mechanism for the mismatch between sparse- and dense-noise maps is the difference in ON and OFF response gains from the input to the output layers of V1 under the two different mapping conditions. In this study, we focused on how the change in ON and OFF response gains might affect the similarity between the sparse- and dense-noise maps of the same neuron. On average, the response strength of the ON subfield should be increased to approximately two times of its origin (1.93+0.19; mean+S.E.M.) to reach the possibly highest receptive-field similarity (RFS, cross-correlation between the two maps). The sole change in the response gain of ON subfield increased the RFS by 66% (From 0.35 to 0.58), and it could account for approximately 81.4% of the overall differences between the two maps. Overall, these results suggest that either a selectively feedforward model (OFF is stronger than ON) [Xing et al., 2010] or a structural network with a greater ON-subfield overlapping in the input layer (Paik & Ringach, 2011; 2012) might contribute to the dark dominance in the superficial layer of V1.
Meeting abstract presented at OSA Fall Vision 2012