Dissociable Functional Cortical Topographies for Working Memory Maintenance of Voice Identity and Location

Abstract

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.

Domain specificity in the primate prefrontal cortex

“…Furthermore, recordings in monkeys performing spatial delayed response tasks have shown that the DLPFC contains neurons activated by auditory or visual spatial cues (KikuchiYorioka & Sawaguchi, 2000). Evidence for a DLPFC auditory spatial-processing domain has also been shown in human imaging studies (Bushara et al, 1999;Rama et al, 2004). In one study, maintenance of spatial and nonspatial information preferentially activated dorsal and ventral prefrontal regions, respectively (Rama et al, 2004).…”

Working memory as an emergent property of the mind and brain

“…In contrast to the studies reviewed in the previous paragraph, there have also been several reports demonstrating PFC working memory-related activity that is largely, but not entirely, overlapping for different stimulus domains (Gruber & von Cramon, 2003;Manoach et al, 2004;Rama et al, 2004;Rama, Sala, Gillen, Pek, & Courtney, 2001;Sala et al, 2003). Courtney and colleagues have interpreted these results as suggesting an organizational scheme of graded degrees of segregation and overlap of working memory storage functions of the PFC (e.g., Courtney, 2004).…”

Exploring the extent and function of higher-order auditory cortex in rhesus monkeys

“…Evidence from both monkeys and humans had already suggested that there were multisynaptic corticocortical pathways in audition paralleling those in vision (Bruce et al, 1981;Wang et al, 1995;Andersen, 1997;Romanski et al, 1999;Rauschecker and Tian, 2000;Clarke et al, 2002;Kaiser et al, 2003;Rama et al, 2004;For review see, Shroeder and Fox, 2005). The metabolic mapping study not only lends strong support to that notion, but also allows simultaneous visualization of the territory occupied by all three of these proposed pathways.…”