Human visual response gain increases with arousal
35.16, Sunday, 17-May, 5:15 pm - 7:15 pm, Talk Room 1
Dongho Kim1,2, Savannah Lokey1, Jianfei Guo1, Franco Pestilli3, Sam Ling1,2,4; 1Dept. of Psychological & Brain Sciences, Boston University, 2Center for Computational Neuroscience and Neural Technology, Boston University, 3Dept. of Psychological & Brain Sciences, Indiana University, 4Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
How do states of arousal affect perception? Large gains have been made in characterizing how top-down processes, such as attention, influence vision. However, measurements of the effects of arousal on human perception are relatively limited and the underlying mechanisms remain surprisingly far less understood. Here, we examine the modulatory role of arousal on one of the cornerstones of vision: the contrast response function. To do so, we measured contrast psychometric functions in two groups of subjects. One group – high-arousal – was asked to refrain from eating and drinking for 5 hours prior to the experiment. The other group – low-arousal – was allowed normal access to eating and drinking and was given water prior to the experiment. During the experiment, both groups received drops of water at 80% probability coincident with stimulus presentation, throughout the experiment. Participants performed a fine orientation discrimination task on a grating shown at fixation, which varied in contrast from trial-to-trial. Water during the experiment aroused participants differently depending on deprivation history: when deprived, water drops led to high levels of arousal, when satiated, water drops led to lower levels of arousal. Results reveal that participants in the high-arousal group yielded psychometric functions that saturated (Rmax) significantly higher than the low-arousal group, consistent with an increase in the response gain of the underlying contrast response. However, we found no difference in the semi-saturation constant (C50) between the two groups. These findings are in line with reports from animal models showing a multiplicative effect of alertness on the contrast response function in LGN neurons (Cano et al., 2006). and suggests that arousal alters early visual perception by mitigating suppressive neural activity, thereby boosting neural responsivity and perceptual sensitivity.