Perceptual restoration fails to recover unconscious processing for smooth eye movements after occipital stroke

Abstract

Visual pathways that guide actions do not necessarily mediate conscious perception. Patients with primary visual cortex (V1) damage lose conscious perception but often retain unconscious abilities (e.g. blindsight). Here, we asked if saccade accuracy and post-saccadic following responses (PFRs) that automatically track target motion upon saccade landing are retained when conscious perception is lost. We contrasted these behaviors in the blind and intact fields of 8 chronic V1-stroke patients, and in 8 visually-intact controls. Saccade accuracy was relatively normal in all cases. Stroke patients also had normal PFR in their intact fields, but no PFR in their blind fields. Thus, V1 damage did not spare the unconscious visual processing necessary for automatic, post-saccadic smooth eye movements. Importantly, visual training that recovered motion perception in the blind field did not restore the PFR, suggesting a clear dissociation between pathways mediating perceptual restoration and automatic actions in the V1-damaged visual system.

Pre-saccadic enhancement of target stimulus motion influences post-saccadic smooth eye movements

“…It appears that PFR, as a smooth eye movement, follows the same distinction from perception. A recent study from our lab investigating recovery of motion perception in cortically-blind patients with V1 lesions found that improvements in perception did not correlate with any recovery of PFR in the blind fields, even when perception recovered to normal levels (Kwon et al, 2022). In fact, they found no significant PFR in blind-fields, suggesting that it must rely on motion signals that pass through area V1.…”