Naming and gesturing spatial relations: evidence from focal brain-injured individuals

Spatial language helps us to encode relations between objects and organize our thinking. Little is known about the neural instantiations of spatial language. Using voxel-lesion symptom mapping (VLSM), we tested the hypothesis that focal brain injured patients who had damage to left frontal-parietal peri-Sylvian regions would have difficulty in naming spatial relations between objects. We also investigated the relationship between impaired verbalization of spatial relations and spontaneous gesture production. Patients with left or right hemisphere damage and elderly control participants were asked to name static (e.g., an apple on a book) and dynamic (e.g., a pen moves over a box) locative relations depicted in brief video clips. The correct use of prepositions in each task and gestures that represent the spatial relations were coded. Damage to the left posterior middle frontal gyrus, the left inferior frontal gyrus, and the left anterior superior temporal gyrus were related to impairment in naming spatial relations. Production of spatial gestures negatively correlated with naming accuracy, suggesting that gestures might help or compensate for difficulty with lexical access. Additional analyses suggested that left hemisphere patients who had damage to the left posterior middle frontal gyrus and the left inferior frontal gyrus gestured less than expected, if gestures are used to compensate for impairments in retrieving prepositions.