Dissociating Aspects of Temporal and Frequency Processing: A Functional ERP Study in Humans

An event-related potential (ERP) study was conducted, in order to dissociate brain functions associated with temporal information processing and processing of frequency information. Twelve participants were presented with both a temporal generalization and a pitch generalization task. In both tasks, exactly the same set of stimuli was presented to prevent stimulus-specific influences on ERP patterns. Participants had to decide whether or not an auditory stimulus matched a previously memorized standard stimulus, either with respect to pitch or duration. Analysis of ERPs revealed an increased negativity for the temporal discrimination task at fronto/central electrode sites. This effect was observed between 150 msec and 1,000 msec. At posterior sites, however, there was an increased positivity between 500 and 1,000 msec for the temporal generalization task. The differential topological activation patterns suggest more pronounced utilization of executive working- memory ressources for processing of temporal than for processing of pitch information.