How Ocular Dominance and Binocularity Are Reflected by the Population Receptive Field Properties

Abstract

PURPOSE. The neural substrate of binocularity and sighting ocular dominance in humans is not clear. By utilizing the population receptive field (pRF) modeling technique, we explored whether these phenomena are associated with amplitude and pRF size differences. METHODS. The visual field maps of 13 subjects were scanned (3-T Skyra) while viewing drifting bar stimuli. Both eyes (binocular condition), the dominant eye and the nondominant eye (two monocular conditions) were stimulated in separate sessions. For each condition, pRF size and amplitude were assessed. Binocular summation ratios were calculated by dividing binocular by mean monocular values (amplitude and pRF size). RESULTS. No differences in pRF size were seen between the viewing conditions within each region, that is, either between binocular and monocular or between dominant and nondominant viewing conditions. Binocular amplitudes were higher than the monocular amplitudes, but similar among the dominant and nondominant eyes. Binocular summation ratios derived from amplitudes were significantly higher than one (~1.2), while those ratios derived from pRF size were not. These effects were found in all studied areas along the visual hierarchy, starting in V1. CONCLUSIONS. Neither the amplitude nor the pRF size show intereye difference and therefore cannot explain the different roles of the dominant and the nondominant eyes. Binocular, as compared to monocular vision, resulted in higher amplitudes, while receptive fields' sizes were similar, suggesting increased binocular response intensity as the basis for the binocular summation phenomenon. Our results could be applicable in imaging studies of monocular disease and studies that deal with nondisparity binocularity effects.

GABAergic inhibition in the human visual cortex relates to eye dominance

“…Only a handful of studies have investigated the relationship between eye dominance and visual cortex BOLD-signal change and it is fair to say that the results have so far been inconclusive, partly due to differences in how eye dominance was assigned. Greater BOLD-activation in V1 has been found during DE versus NDE stimulation 34 , 35 , whereas others find no difference 36 . In these studies, eye dominance was assigned using other approaches, such as ‘sighting dominance’.…”

Relation of contrast sensitivity with binocularity, eye dominance and interpupillary distance in healthy adults

“…In addition to the studies reporting that DE is better in visual acuity, CS and color vision functions, there are also studies reporting different outcomes [9,10] [11,20]. It has been stated that binocular vision provides not only stereopsis but also a wide range of vision by the effect of summation and that binocular vision reduces detection threshold as compared with monocular vision [22,23]. Deficiency in CS summation has been reported in some ocular patient groups such as those with intermittent exotropia and those with multiple sclerosis with optic neuritis [24,25].…”

GABAergic inhibition in the human visual cortex relates to eye dominance

“…Only a handful of studies have investigated this relationship and it is fair to say that the results have so far been inconclusive, partly due to differences in how eye dominance was assigned. Greater BOLD-activation in V1 has been found during DE versus NDE stimulation [33][34][35], whereas others find no difference [36].…”