Figure 2.
Low activation for complex tones with weak pitch salience in anterior auditory cortex. a, Differential activation maps based on data from five subjects superimposed on averaged anatomy and displayed in an inflated format. Light and dark gray regions correspond to gyri and sulci, respectively. White indicates areas of significant difference (p < 10-3) between conditions that differed in harmonic resolvability and hence in pitch salience. The qualitative center of mass for these areas (indicated by asterisks) had Talairach coordinates of 48.28, -10.52, 3.35 (right hemisphere) and -54.94, -4.83, 2.65 (left hemisphere). No differential activation was found in the contrasts between conditions that differed in F0 or frequency range alone. b, c, Average ± SEM normalized percentage signal change for each tone condition (b) or bandpass-filtered noise bursts (c), relative to silence, within the activation areas shown in a. Within complex-tone stimuli, condition 2, which produced weak pitch salience, elicited the lowest level of activation. Consistent with the interpretation that activity in these are as reflects pitch salience, noise bursts (no pitch) elicited activation levels that were lower than, or comparable with, those produced by the condition of weak pitch salience (c). Unlike the case of tones, different levels of activation for the noise conditions reflected differences in spectral region.