Neuropsychologia 46 (2008) 632–639 Evidence for the role of the right auditory cortex in fine pitch resolution Krista L. Hyde a,b,c,∗ , Isabelle Peretz b,c , Robert J. Zatorre a,c a Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4 b Department of Psychology, University of Montreal, C.P. 6128 succ. Centre-ville, Montreal, Quebec, Canada H3C 3J7 c International Laboratory for Brain, Music and Sound Research (BRAMS), Montreal, Quebec, Canada Received 18 January 2007; received in revised form 4 September 2007; accepted 5 September 2007 Available online 14 September 2007 Abstract The neural basis of human pitch perception is not fully understood. It has been argued that the auditory cortices in the two hemispheres are specialized, such that certain right auditory cortical regions have a relatively finer resolution in the frequency domain than homologous regions in the left auditory cortex, but this concept has not been tested directly. Here, we used functional magnetic resonance imaging (fMRI) to test this specific prediction. Healthy volunteers were scanned while passively listening to pure-tone melodic-like sequences in which the pitch distance between consecutive tones was varied in a parametric fashion. As predicted, brain activation in a region of right lateral auditory cortex, corresponding to the planum temporale, was linearly responsive to increasing pitch distance, even across the fine changes in pitch. In contrast, the BOLD signal at the homologous left cortical region was relatively constant as a function of pitch distance, except at the largest pitch change. The results support the model of relative hemispheric specialization and indicate that the right secondary auditory cortex has a finer pitch resolution than the left. © 2007 Elsevier Ltd. All rights reserved. Keywords: fMRI; Hemispheric functional specialization; Normal brain; Planum temporale 1. Introduction Pitch is the perceptual correlate of acoustic frequency and can be considered along at least two perceptual dimensions, pitch height and pitch chroma (Shepard, 1982). Pitch height, is related to spectral energy distribution and is illustrated by the octave on the keyboard. In contrast, pitch chroma, or the cycle of notes within the octave, provides a basis for acous- tic patterns (melodies). Several studies have investigated the processing of sequential or melodic pitch, which is critical for musical perception, however, its neural correlates are not fully understood. Many findings have shown that musical pitch processing preferentially involves right auditory cortical structures. For example, studies of brain-lesioned patients have shown that the right auditory cortex is critical for melody discrimina- tion (Milner, 1962), perception of missing fundamental pitch ∗ Corresponding author at: McConnell Brain Imaging Center, Montreal Neu- rological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4. Fax: +1 514 398 8949. E-mail address: krista.hyde@mail.mcgill.ca (K.L. Hyde). (Zatorre, 1988), perception of melody in terms of its global contour (Peretz, 1990), direction of pitch change (Johnsrude, Penhune, & Zatorre, 2000), and in using melodic contextual cues in pitch judgments (Warrier & Zatorre, 2004). Consis- tent evidence comes from neuroimaging studies of normal subjects, showing that right secondary auditory regions are cen- tral in various aspects of musical pitch processing, such as in melodic processing (Patterson, Uppenkamp, Johnsrude, & Griffiths, 2002; Zatorre, Evans, & Meyer, 1994), in the mainte- nance of pitch while singing (Perry et al., 1999), and in imagery for tunes (Halpern & Zatorre, 1999). In contrast, left auditory regions seem to be specialized for rapid temporal processing as required in speech (e.g. Belin et al., 1998; Jancke, Wustenberg, Scheich, & Heinze, 2002; Phillips & Farmer, 1990; Zaehle, Wustenberg, Meyer, & Jancke, 2004). Zatorre, Belin, and Penhune (2002) have recently proposed that the auditory system has developed two parallel and com- plementary systems, one in each hemisphere, specialized for differential resolution in the spectral and temporal domains, as a need to optimally process incoming simultaneous spectral and temporal acoustic information from the environment. A similar proposition has been made by Poeppel (2003), who suggested that different time integration windows characterize the left and 0028-3932/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuropsychologia.2007.09.004