The most common neural representations for spatial attention encode locations retinotopically, relative to center of gaze. To keep track of visual objects across saccades or to orient toward sounds, retinotopic representations must be combined with information about the rotation of one's own eyes in the orbits. Although gaze input is critical for a correct allocation of attention, the source of this input has so far remained unidentified. Two main signals are available: corollary discharge (copy of oculomotor command) and oculoproprioception (feedback from extraocular muscles). Here we asked whether the oculoproprioceptive signal relayed from the somatosensory cortex contributes to coding the locus of attention. We used continuous theta burst stimulation (cTBS) over a human oculoproprioceptive area in the postcentral gyrus (S1 EYE ). S1 EYE -cTBS reduces proprioceptive processing, causing ∼1° underestimation of gaze angle. Participants discriminated visual targets whose location was cued in a nonvisual modality. Throughout the visual space, S1 EYE -cTBS shifted the locus of attention away from the cue by ∼1°, in the same direction and by the same magnitude as the oculoproprioceptive bias. This systematic shift cannot be attributed to visual mislocalization. Accuracy of open-loop pointing to the same visual targets, a function thought to rely mainly on the corollary discharge, was unchanged. We argue that oculoproprioception is selective for attention maps. By identifying a potential substrate for the coupling between eye and attention, this study contributes to the theoretical models for spatial attention.

Patients suffering from simultanagnosia cannot perceive more than one object at a time. The underlying mechanism is incompletely understood. One hypothesis is that simultanagnosia reflects “tunnel vision,” a constricted attention window around gaze, which precludes the grouping of individual objects. Although this idea has a long history in neuropsychology, the question whether the patients indeed have an abnormal attention gradient around the gaze has so far not been addressed. Here we tested this hypothesis in two simultanagnosia patients with bilateral parieto-occipital lesions and two control groups, with and without brain damage. We assessed the participants' ability to discriminate letters presented briefly at fixation with and without a peripheral distractor or in the visual periphery, with or without a foveal distractor. A constricted span of attention around gaze would predict an increased susceptibility to foveated versus peripheral distractors. Contrary to this prediction and unlike both control groups, the patients' ability to discriminate the target decreased more in the presence of peripheral compared with foveated distractors. Thus, the attentional spotlight in simultanagnosia does not fall on foveated objects as previously assumed, but rather abnormally highlights the periphery. Furthermore, we found the same center–periphery gradient in the patients' ability to recognize multiple objects. They detected multiple, but not single objects more accurately in the periphery than at fixation. These results suggest that an abnormal allocation of attention around the gaze can disrupt the grouping of individual objects into an integrated visual scene.

Spatial attention can be defined as the selection of a location for privileged stimulus processing. Most oculomotor structures, such as the superior colliculus or the FEFs, play an additional role in visuospatial attention. Indeed, electrical stimulation of these structures can cause changes in visual sensitivity that are location specific. We have proposed that the recently discovered ocular proprioceptive area in the human postcentral gyrus (S1 EYE ) may have a similar function. This suggestion was based on the observation that a reduction of excitability in this area with TMS causes not only a shift in perceived eye position but also lateralized changes in visual sensitivity. Here we investigated whether these shifts in perceived gaze position and visual sensitivity are spatially congruent. After continuous theta burst stimulation over S1 EYE , participants underestimated own eye rotation, so that saccades from a lateral eye rotation undershoot a central sound (Experiment 1). They discriminated letters faster if they were presented nearer the orbit midline (Experiment 2) and spent less time looking at locations nearer the orbit midline when searching for a nonexistent target in a letter array (Experiment 3). This suggests that visual sensitivity increased nearer the orbit midline, in the same direction as the shift in perceived eye position. This spatial congruence argues for a functional coupling between the cortical eye position signal in the somatosensory cortex and visuospatial attention.

The oculomotor and spatial attention systems are interconnected. Whereas a link between motor commands and spatial shifts in visual attention is demonstrated, it is still unknown whether the recently discovered proprioceptive signal in somatosensory cortex impacts on visual attention, too. This study investigated whether visual targets near the perceived direction of gaze are detected more accurately than targets further away, despite the equal eccentricity of their retinal projections. We dissociated real and perceived eye position using left somatosensory repetitive transcranial magnetic stimulation (rTMS), which decreases cortical processing of eye muscle proprioceptive inflow and produces an underestimation of the rotation of the right eye. Participants detected near-threshold visual targets presented in the left or right visual hemifield at equal distance from fixation. We have previously shown that when the right eye is rotated to the left of the parasagittal plane, TMS produces an underestimation of this rotation, shifting perceived eye position to the right. Here we found that, in this condition, TMS also decreased target detection in the left visual hemifield and increased it in the right. This effect depended on the direction of rotation of the right eye. When the right eye was rotated rightward and TMS, we assume, shifted perceived gaze direction in opposite direction, leftward, visual accuracy decreased now in the right hemifield. We suggest that the proprioceptive eye position signal modulates the spatial distribution of visual processing resources, producing “pseudo-neglect” for objects located far relative to near the perceived direction of gaze.

The ability to recognize visually one's own movement is important for motor control and, through attribution of agency, for social interactions. Agency of actions may be decided by comparisons of visual feedback, efferent signals, and proprioceptive inputs. Because the ability to identify one's own visual feedback from passive movements is decreased relative to active movements, or in some cases is even absent, the role of proprioception in self-recognition has been questioned. Proprioception during passive and activemovements may, however, differ, and so to address any role for proprioception in the sense of agency, the active movement condition must be examined. Here we tested a chronically deafferented man (I.W.) and an age-matched group of six healthy controls in a task requiring judgement of the timing of action. Subjects performed finger movements and watched a visual cursor that moved either synchronously or asynchronously with a random delay, and reported whether or not they felt they controlled the cursor. Movement accuracy was matched between groups. In the absence of proprioception, I.W. was less able than the control group to discriminate self- from computer-produced cursor movement based on the timing of movement. In a control visual discrimination task with concurrent similar finger movements but no agency detection, I.W. was unimpaired, suggesting that this effect was task specific. We conclude that proprioception does contribute to the visual identification of ownership during active movements and, thus, to the sense of agency.