Saccadic eye movement strategies in patients with homonymous hemianopia

Abstract

Infrared oculographic recordings from three patients with hemianopia due to an occipital lesion showed that these patients employed a consistent set of (presumably unconscious) compensatory strategies to find and fixate objects. For targets in the blind hemifield, patients at first used a staircase strategy consisting of a series of stepwise saccadic search movements. This is safe but slow. When retested later, one patient had adopted a more efficient strategy employing one large saccade calculated to overshoot the target. Other strategies for finding targets in the blind hemifield were employed in response to specific situations presented by our experiments: a predictive strategy using past experience to anticipate where the target would be found, and special strategies for recovering a lost target and for awaiting the reappearance of the target. To fixate targets in the seeing hemifield, our subjects undershot the target to prevent losing it in the blind hemifield, then held it off-fovea on the seeing side of the macula.

Impaired visual search in patients with unilateral neglect: an oculographic analysis

“…This is reflected in the higher proportion of fixations and longer durations in the far-left quartile band and the tendency to look even beyond the boundaries of the left boundary of the board. These findings conform well with the data reported previously for hemianopic patients on similar types of tasks [30,51,67].…”

Human Dorsolateral Prefrontal Cortex Is Not Necessary for Spatial Working Memory

“…Yet, the accuracy of the first saccade and the accuracy of the final position before feedback likely reflect different aspects of WM. They do have different developmental trajectories (Luna et al, 2004), different profiles of adaptation (Srimal and Curtis, 2010), and different patterns of dysfunction in schizophrenia (Krappmann and Everling, 1998). Because PCS patients made normal visually guided saccades, we can rule out basic visual and motor impairments, including transforming external visual targets into saccade plans.…”

“…This controversy has existed for decades (Curtis and D'Esposito, 2004) and continues to drive theoretical questions about the role of the PFC in WM (Sreenivasan et al, 2014;D'Esposito and Postle, 2015). For instance, research questions whether the PFC actively stores WM representations or directs attention to representations stored in sensory cortices (Lebedev et al, 2004;Emrich et al, 2013;Ester et al, 2015;Pasternak et al, 2015). In the current study, our goal was to resolve the discrepancies between the prevailing animal model of human WM and evidence from human neuroimaging studies (Fig.…”

Structure-Function Correlation in Hemianopic Vision Loss in Children Aged 3-6 Years Using OCT and SVOP, and Comparison with Adult Eyes

“…Previous studies reported 3 stages of saccadic patterns in patients with hemianopia: first a staircase pattern (hypometric saccades), then an overshoot (hypermetric), and finally predictive saccades [24][25][26]. The increased number of dysmetric saccades to the blind side indicates first adaptive mechanisms: hypometric saccades represent a strategy to approach the target in small steps, which is safe, but slow [24][25][26].…”