Extraocular Muscle Afferent Signals Modulate Visual Attention

Abstract

PURPOSE. Extraocular muscle afferent signals contribute to oculomotor control and visual localization. Prompted by the close links between the oculomotor and attention systems, it was investigated whether these proprioceptive signals also modulated the allocation of attention in space. METHODS.A suction sclera contact lens was used to impose an eye rotation on the nonviewing, dominant eye. With their viewing, nondominant eye, participants (n ¼ 4) fixated centrally and detected targets presented at 58 in the left or right visual hemifield. The position of the viewing eye was monitored throughout the experiment. As a control, visual localization was tested using finger pointing without visual feedback of the hand, whereas the nonviewing eye remained deviated. RESULTS.The sustained passive rotation of the occluded, dominant eye, while the other eye maintained central fixation, resulted in a lateralized change in the detectability of visual targets. In all participants, the advantage in speed and accuracy for detecting right versus left hemifield targets that occurred during a sustained rightward eye rotation of the dominant eye was reduced or reversed by a leftward eye rotation. The control experiment confirmed that the eye deviation procedure caused pointing errors consistent with an approximately 28 shift in perceived eye position, in the direction of rotation of the nonviewing eye. CONCLUSIONS.With the caveat of the small number of participants, these results suggest that extraocular muscle afferent signals modulate the deployment of attention in visual space. (Invest Ophthalmol Vis Sci. 2012;53:7004-7009)

Role of Oculoproprioception in Coding the Locus of Attention

“…Furthermore, we have observed alterations in visual sensitivity in conditions that distort the oculoproprioceptive signal. The oculoproprioceptive signal was distorted in the ocular periphery, using passive eye rotation (Balslev, Newman, & Knox, 2012), or centrally, in the somatosensory cortex, after repetitive TMS Balslev, Gowen, & Miall, 2011) or after a focal lesion (Balslev, Odoj, & Karnath, 2013). These previous studies suggest a link between the oculoproprioceptive signal in the somatosensory cortex and spatial attention; however, the nature of this link is still unclear.…”

<p>Children with Dyslexia Have Altered Cross-Modal Processing Linked to Binocular Fusion. A Pilot Study</p>

“…It could also be that the Maddox rod increased the contribution of ocular proprioception by introducing a spatial discrepancy between the two eyes in the dyslexic, a group already identified as ocular balance deficient. 13,14,43 In the present case the Maddox would weaken the ocular balance, already unstable in dyslexics.…”

“…44,45 Even if we did not systematically test children's attention capacity, it should be stressed that participants' performance did not change during the recording session, suggesting a stable attention level and consequently a limited contribution of this factor to the VS However, ocular proprioception modulates the deployment of attention in visual space, shifts visual sensitivity and codes the locus of attention in collaboration with the location of the image on the retinas. 28,43,46 Thus, we cannot totally rule out a potential effect of attention associated with gaze motor control.…”

The distinctive vertical heterophoria of dyslexics

“… 80 , 81 Furthermore, whether it is of ocular or systemic origin, proprioception modulates visual attention. 83 , 84 There is a deficit of this modulation in the dyslexic. 85 This deficit, along with labile VH and torsion, appears to cross the gap between surface and phonological dyslexia.…”