Dissociable functional cortical topographies for working memory maintenance of voice identity and location.

In order to ascertain whether the neural system for auditory working memory exhibits a functional dissociation for spatial and nonspatial information, we used functional magnetic resonance imaging and a single set of auditory stimuli to study working memory for the location and identity of human voices. The subjects performed a delayed recognition task for human voices and voice locations and an auditory sensorimotor control task. Several temporal, parietal, and frontal areas were activated by both memory tasks in comparison with the control task. However, during the delay periods, activation was greater for the location than for the voice identity task in dorsal prefrontal (SFS/PreCG) and parietal regions and, conversely, greater for voices than locations in ventral prefrontal cortex and the anterior portion of the insula. This preferential response to the voice identity task in ventral prefrontal cortex continued during the recognition test period, but the double dissociation was observed only during maintenance, not during encoding or recognition. Together, the present findings suggest that, during auditory working memory, maintenance of spatial and nonspatial information modulates activity preferentially in a dorsal and a ventral auditory pathway, respectively. Furthermore, the magnitude of this dissociation seems to be dependent on the cognitive operations required at different times during task performance.