Eye dominance predicts fMRI signals in human retinotopic cortex

Abstract

There have been many attempts to define eye dominance in normal subjects, but limited consensus exists, and relevant physiological data is scarce. In this study, we consider two different behavioral methods for assignment of eye dominance, and how well they predict fMRI signals evoked by monocular stimulation. Sighting eye dominance was assessed with two standard tests, the Porta Test, and a 'hole in hand' variation of the Miles Test. Acuity dominance was tested with a standard eye chart and with a computerized test of grating acuity. We found limited agreement between the sighting and acuity methods for assigning dominance in our individual subjects. We then compared the fMRI response generated by dominant eye stimulation to that generated by non-dominant eye, according to both methods, in 7 normal subjects. The stimulus consisted of a high contrast hemifield stimulus alternating with no stimulus in a blocked paradigm. In separate scans, we used standard techniques to label the borders of visual areas V1, V2, V3, VP, V4, V3A, and MT. These regions of interest (ROIs) were used to analyze each visual area separately. We found that percent change in fMRI BOLD signal was stronger for the dominant eye as defined by the acuity method, and this effect was significant for areas located in the ventral occipital territory (V1v, V2v, VP, V4). In contrast, assigning dominance based on sighting produced no significant interocular BOLD differences. We conclude that interocular BOLD differences in normal subjects exist, and may be predicted by acuity measures.Keywords visual cortex; Portus; Miles; amblyopia; V1The concept of eye dominance in normal subjects, i.e., a consistent preference or advantage for using one of the two eyes, is well known and has been discussed for decades [19,23,27]. Nevertheless, the functional significance of eye dominance remains elusive, and, if present, it Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. [15,3]. The lack of consensus has lead several authors to express a rather pessimistic view of the significance of eye dominance: "Other than being the 'preferred' eye in some viewing situations, the sighting dominant eye has no special role for visual or oculomotor processes for the normal population" [19]. NIH Public AccessIn addition to the inconsistencies associated with sighting eye dominance, it has been unclear if this concept would have relevance to the processing of simple visual stimuli in retinotopic areas of visual cortex. One prior fMRI study by Rombouts et al., of 22 subjects found a slightly larger extent of activation in both occipit...

Impact of eye-dominance on pattern reversal visual evoked potentials

“…Imaging studies in this field have conflicting results and the question of cortical asymmetries in processing between dominant and non-dominant eye remains an unresolved issue. [27,28] PRVEPs are non-invasive tools to study the normal ocular dominance and in future with the evolution of the technology, they are likely to provide more qualitative and quantitative information which could contribute to fully understand the functional significance of the visual lateralisation.…”

“…The observer then closes the eyes alternately or slowly draws the thumb/finger back to the head to determine which eye is viewing the object that is the dominant eye. [11,13] …”

Hemispheric differences in electrical and hemodynamic responses during hemifield visual stimulation with graded contrasts

“…The asymmetry between the left and the right visual field has been attributed to stimulus-driven attentional bias or to the functional specialization of the corresponding hemispheres [50]. Ocular dominance has been reported as being related to this asymmetry [51,52].…”

Effect of Ocular Dominance on the Latency and Amplitude of Visual Evoked Potentials

“…The observer than alternates closing the eyes or slowly draws the thumb/finger back to the head to determine which eye is viewing the object ,that is the dominant eye [10].…”

“…For example, a patient will form a hole with his hands and binocularly center an object in that hole. When he alternately occludes either eye, only the dominant eye will still see the same object [10].…”