Pushing attention to one side: Force field adaptation alters neural correlates of orienting and disengagement of spatial attention

Abstract

Sensorimotor adaptation to wedge prisms can alter the balance of attention between left and right space in healthy adults, and improve symptoms of spatial neglect after stroke. Here we asked whether the orienting of spatial attention to visual stimuli is affected by a different form of sensorimotor adaptation that involves physical perturbations of arm movement, rather than distortion of visual feedback. Healthy participants performed a cued discrimination task before and after they made reaching movements to a central target. A velocity‐dependent force field pushed the hand aside during each reach, and required participants to apply compensatory forces toward the opposite side. We used event‐related potentials (ERPs) to determine whether electroencephalography (EEG) responses reflecting orienting (cue‐locked N1) and disengagement (target‐locked P1) of spatial attention are affected by adaptation to force fields. After adaptation, the cue‐locked N1 was relatively larger for stimuli presented in the hemispace corresponding to the direction of compensatory hand force. P1 amplitudes evoked by invalidly cued targets presented on the opposite side were reduced. This suggests that force field adaptation boosted attentional orienting responses toward the side of hand forces, and impeded attentional disengagement from that side, mimicking previously reported effects of prism adaptation. Thus, remapping between motor commands and intended movement direction is sufficient to bias ERPs, reflecting changes in the orienting of spatial attention in the absence of visuo‐spatial distortion or visuo‐proprioceptive mismatch. Findings are relevant to theories of how sensorimotor adaptation can modulate attention, and may open new avenues for treatment of spatial neglect.

Gradual exposure to Coriolis force induces sensorimotor adaptation with no change in peripersonal space

“…Both groups recovered a reach precision close to baseline after four trials during POST-rotation and endpoint errors vanished with the same temporal pattern whatever the type of perturbation. Overall, adaptation to the new gravito-inertial force field appeared, in the present study, to have a similar effect on the sensorimotor system as in previous studies 27 , 36 , 37 , 52 , 59 , even though the mechanisms underlying sensorimotor adaptation might differ according to whether the perturbation is introduced gradually or abruptly 50 , 69 .…”

“…Therefore, reachability judgments were obtained before and after the action control system was updated as in our previous experiments 26 , 33 . Considering that previous studies reported that adaptation to gradually-altered limb dynamics also induces after-effects 36 , 50 , 52 , 53 , we predicted that exposure to gradual change in the Coriolis force would result in sensorimotor adaptation revealed by post-rotation after-effects on reaching movements, as typically observed after exposure to an abrupt change in Coriolis force. As mentioned before, such change typically influences the representation of the peripersonal space 26 , 33 , which was predicted here to not significantly differ between the pre-gradual rotation and the post-gradual rotation phases.…”

“…While sensorimotor adaptation to a gradually-modified force field has been widely explored using robotic devices 48 – 52 , no study has yet investigated, to our knowledge, how the sensorimotor system adapts to a gradually-increased force field induced by a platform rotation. The consequence of such perturbation on the representation of the peripersonal space therefore also remains unknown.…”