Time and spatial attention: effects of prism adaptation on temporal deficits in brain damaged patients.

Growing evidence indicates that the representations of space and time interact in the brain but the exact neural correlates of such interaction remain unknown. Neuroimaging and neuropsychological studies show that processing of temporal information engages a distributed network in the right hemisphere and suggest a link between deficits in spatial attention and deficits in time perception. In the present study we used the procedure of prismatic adaptation (PA) to directionally manipulate spatial attention in order to explore the effect of attentional deviation on time perception in patients with right (RBD) vs. left (LBD) brain damage. In a first experiment, two groups of RBD and LBD patients and two groups of age-matched healthy subjects were submitted to a time reproduction task before and after rightward or leftward PA (between-group design). In a second experiment RBD and LBD patients were submitted to the same task, before and after rightward and leftward PA (within-group design). RBD but not LBD patients presented a time deficit with a clear tendency to underestimate the real time. PA inducing leftward attentional deviation biased time perception toward an underestimation in RBD patients and controls, while it was ineffective in LBD patients. PA inducing a rightward attentional deviation failed to affect time perception in either group. These results underline the effects of PA on temporal deficits in brain damaged patients. The novel finding is that, while a right hemispheric network is critical for explicit timing, a left hemispheric network is necessary for mediating the effects of prismatic adaptation on spatial and temporal perception.