Attentional cues potentiate recovery of fine direction discrimination in cortically-blind patients

摘要

Background. Visual perceptual training in cortically-blind (CB) fields improves performance on trained tasks, recovering vision at previously blind locations. However, contrast sensitivity and fine discrimination remain abnormal, limiting the usefulness of recovered vision in daily life. Here, we asked whether it is possible to overcome residual impairment in fine direction discrimination (FDD) performance by training CB subjects with endogenous, feature-based attention (FBA) cues. Methods. Nine CB subjects were recruited and underwent coarse direction discrimination (CDD) training, followed by FDD training with an FBA cue. Following completion of each training protocol, we tested FDD thresholds at blind-field locations and corresponding intact-field locations, with both neutral and valid FBA cues. T-tests were used to assess significance of differences in FDD thresholds attained after different types of training. Results. Subjects who trained using CDD tasks were able to attain FDD thresholds of 26?±5.5?° (average?±SEM). Training FDD without cues attained FDD thresholds of 18?±3.8 deg, not significantly different from those attained following CDD training (26?±5.5; p0.1). Following FDD training with FBA cues, FDD thresholds measured with valid FBA cues (5.4?±1.3?°) were significantly lower than thresholds attained following FDD training without FBA cues (p=0.02) or CDD training (p=0.01). Moreover, FDD thresholds at blind-field locations for subjects trained and measured with FBA cues were statistically indistinguishable from thresholds at intact-field locations measured with FBA cues (p=0.054) or with neutral FBA cues (p=0.4). Even when measured using neutral FBA cues, FDD thresholds at the blind-field locations trained with FBA cues (9.8?±0.2?°) were significantly lower than following CDD (p=0.02). Lastly, intact-field thresholds were lower when tested with (3.1?±0.3?°) than without (4.3?±0.7?°) FBA cues (p=0.03). Conclusion. Mechanisms governing FBA appear to be intact and functional in CB subjects. Importantly, training with FBA can be leveraged to recover normal, fine visual discrimination performance at trained, blind-field locations.