Mapping pitch representation in neural ensembles with fMRI.

Functional magnetic resonance imaging (fMRI) in humans and macaques allows a test of the hypothesis that there is a specialized neural ensemble for pitch within auditory cortex: a pitch center. fMRI measures the blood oxygenation level-dependent (BOLD) response related to regional synaptic activity (Logothetis et al., 2001). The distinction between synaptic activity and spike firing, and species differences encourage caution when comparing BOLD activity in humans and macaques to recordings from single neurons in ferret and marmoset in the previous mini-review. The BOLD data provide support for the pitch-center concept, with ongoing debate about its location.