Abstract
Visuo-spatial cueing improves information processing in normally-sighted subjects. This benefit becomes apparent particularly at threshold conditions, e.g. at low stimulus contrast. Patients with visual field defects after cerebral lesions face a similar situation in areas of residual vision (ARVs) at the border of the blind region. Therefore, a special cueing procedure was designed to help those patients shift their focus of attention at the visual field border. We wished to determine whether residual vision could be enhanced by the cue during perimetric testing (short-term effects) and during visual restitution training (long-term effects), respectively.
A group of 23 patients with post-genicular lesions of the visual system were examined with two types of campimetric tests: visual field tests (detection of white light spots without cueing) and attention field tests (analogue procedure with attentional cueing using a Posner paradigm). We found a significant short-term increase of stimulus detection and decrease of reaction times in valid trials of the attention field test and less pronounced unspecific benefits in invalid trials. The gain induced by the cue depended upon the size of areas of residual vision.
Long-term effects of attention were investigated in a training study including 19 patients. We compared effects of conventional visual restitution training and attention field training (with visuo-spatial cueing) on the recovery of visual function. In the complete group of patients, training induced a significant increase of stimulus detection and a shift of the visual field border towards the blind field. With respect to differential effects of the two treatment conditions, we found that the cue in the attention field training changed spatial and temporal patterns of visual field recovery.
Thus, visuo-spatial attention activates residual vision of brain-lesioned patients not only on a short-term scale but also influences long-term neuronal plasticity.