Role of visuo-spatial working memory in path integration disorders in neglect

This paper investigates the relationship between memory deficits and navigational ability in neglect. In recent studies (Piccardi et al., 2008a, 2010; Bianchini et al., 2010), a dissociation was found in visuo-spatial memory for peripersonal/reaching space and visuo-spatial memory for navigational space, suggesting that the latter is processed by a specific system devoted to storing environmental information for navigational purposes (Piccardi et al., 2010). Specific deficits have also been described in neglect patients in navigational tasks requiring to memorize and retrieve a target location in a real environment. In order to analyze the relation between visuo-spatial memory for different type of space (reaching vs navigational) and its relation with navigational processes, in the present study, we compared the performance of right brain-damaged patients with and without neglect on visuo-spatial memory both in peripersonal/reaching (Corsi Block-Tapping test) and in navigational (Walking Corsi test Laser) space with performances on navigational tests (a human version of the Morris Water Maze). Results indicate that a specific deficit in navigational working memory affects navigational ability in neglect patients. Indeed, neglect patients' difficulty in using path integration to navigate in the environment is directly correlated with a deficit in visuo-spatial working memory. These results support the existence of a specific memory system devoted to representing environmental information for navigational purposes and separate from visuo-spatial memory systems, which stores information in peripersonal/reaching space.