Fig. 2.

Significant voxels from the three contrasts used in the analysis, co-registered on to the left (A) and right (B) lateral MRI templates that are available in the image analysis software (SPM99b). The threshold was set at P < 0.00001 uncorrected, excluding clusters with <50 adjacent voxels. At this threshold, the activations were confined to the temporal lobes. Each contrast was centred around zero, and the ordinate of each plot is the mean size of the effect for each condition ± standard error of the mean, within the peak voxel. The coordinates of the peak voxel (x, y and z) in the stereotaxic space of SPM99b, and the Z-score, are shown at the head of each plot. (A) Left temporal lobe. The contrast {(Sp + VCo + RSp) – RVCo}, colour-coded in red, showed (1) the left superior temporal gyrus, both lateral and anterior to the primary auditory cortex, and (2) a separate region in the posterior superior temporal sulcus. The contrast {(Sp + VCo) – (RSp + RVCo)}, colour-coded in yellow, showed clear separation of intelligible from non-intelligible stimuli in the anterior superior temporal sulcus (3a). In the mid-superior temporal sulcus (3b), the response profile to the stimuli appeared to be transitional between the profiles in the posterior and anterior superior temporal sulcus. This ‘transition’ pattern may reflect a change in response to the rotated speech stimuli, but could also arise as a result of the smoothing applied to the data. (B) Right temporal lobe. The only significant voxels were revealed by the contrast {(Sp + RSp) – (VCo + RVCo}, colour-coded in white. They were located in the lateral superior temporal gyrus, anterior to the primary auditory cortex.