Abstract
Purpose:
Last year (ARVO, 2013) we reported a surprising relationship between two seemingly independent sensory modalities, namely human vision and pain. Specifically, adults’ ability to tolerate heat and pressure pain was negatively correlated with performance on tests of spatial contrast sensitivity (CS). However, this effect was found in a very small sample of adults who were tested repeatedly in order to reduce intra-subject variability. To better evaluate the robustness of this effect, and to explore the possible neural mechanisms that may underlie sensory interactions, we evaluated the relationship between pain and both spatial and temporal vision within a much larger group of young adults.
Methods:
Three measures of spatial contrast sensitivity (FACT, Vector Vision, Rabin) and both temporal photopic and mesopic flicker fusion thresholds were assessed binocularly in 105 healthy young adults (M = 23 y; 62 females, 43 males). Within the same session, adults’ threshold and tolerance to both contact heat (arm) and pressure pain (pinky finger) was also assessed.
Results:
Analyses revealed strong correlations between all measures of spatial CS and heat pain tolerance (all r > - 0.65), although results for pressure pain were more modest. More specifically, those who showed lower tolerance for heat pain (i.e., were more sensitive to pain) also showed higher levels of spatial contrast sensitivity. Conversely, temporal measures of critical flicker fusion thresholds appeared uncorrelated with pain threshold or tolerance.
Conclusions:
These results provide further evidence that human adults show a relationship between heat pain sensitivity and spatial vision, but not between pain and the present measures of temporal vision. Given that dopamine is heavily involved in both the processing of pain as well as spatial information in the visual cortex, this raises the interesting possibility that the observed co-variation in sensitivity may be explained by dopaminergic involvement.
Keywords: 478 contrast sensitivity •
730 temporal vision •
641 perception