Intracortical myelination in musicians with absolute pitch: Quantitative morphometry using 7‐T MRI

Abstract

Absolute pitch (AP) is known as the ability to recognize and label the pitch chroma of a given tone without external reference. Known brain structures and functions related to AP are mainly of macroscopic aspects. To shed light on the underlying neural mechanism of AP, we investigated the intracortical myeloarchitecture in musicians with and without AP using the quantitative mapping of the longitudinal relaxation rates with ultra‐high‐field magnetic resonance imaging at 7 T. We found greater intracortical myelination for AP musicians in the anterior region of the supratemporal plane, particularly the medial region of the right planum polare (PP). In the same region of the right PP, we also found a positive correlation with a behavioral index of AP performance. In addition, we found a positive correlation with a frequency discrimination threshold in the anterolateral Heschl's gyrus in the right hemisphere, demonstrating distinctive neural processes of absolute recognition and relative discrimination of pitch. Regarding possible effects of local myelination in the cortex and the known importance of the anterior superior temporal gyrus/sulcus for the identification of auditory objects, we argue that pitch chroma may be processed as an identifiable object property in AP musicians. Hum Brain Mapp 37:3486–3501, 2016. © 2016 Wiley Periodicals, Inc.

Resting state functional connectivity of the ventral auditory pathway in musicians with absolute pitch

“…In our previous study [Kim and Knösche, ], we found a positive correlation between the APS and the cortical myelin content in the right PP. In the current study, we hypothesized a positive relationship between the APS and RSFC of the right PP to a number of cortical areas.…”

“…Of most relevance in the present context, Warren and colleagues demonstrated higher sensitivity to pitch chroma in the PP and higher sensitivity to pitch height in the PT [Warren et al, ]. As mentioned above, the processing of pitch chroma is the essential characteristic of AP [Deutsch, ; Deutsch and Henthorn, ; Kim and Knösche, ; Miyazaki, ; Takeuchi and Hulse, ], which speaks for a specific involvement of the ventral pathway in AP perception, most probably in the early perceptual process. This has been corroborated by the finding of increased intra‐cortical myelination in the right PP of AP possessors [Kim and Knösche, ].…”

“…We found a positive correlation between the AP/APS and RSFC of the right PP. Because we previously found positive a correlation between the AP/APS and cortical myelination (estimated by qR1) [Kim and Knösche, ], there might (but not necessarily) be a direct positive correlation between the myelination and RSFC of the right PP. To confirm this, we tested if the qR1 and RSFC of the right PP are also positively correlated (i.e., one‐side T‐test).…”

“… Abstract Absolute pitch (AP) is the ability to recognize pitch chroma of tonal sound without external references, providing a unique model of the human auditory system (Zatorre: Nat Neurosci 6 () 692–695). In a previous study (Kim and Knösche: Hum Brain Mapp () 3486–3501), we identified enhanced intracortical myelination in the right planum polare (PP) in musicians with AP, which could be a potential site for perceptional processing of pitch chroma information. We speculated that this area, which initiates the ventral auditory pathway, might be crucially involved in the perceptual stage of the AP process in the context of the “dual pathway hypothesis” that suggests the role of the ventral pathway in processing nonspatial information related to the identity of an auditory object (Rauschecker: Eur J Neurosci 41 () 579–585).…”

“…Importantly, a previous rs‐fMRI study reported greater overall (network‐wise) degree centrality (i.e., the average number of edges across all nodes) in AP than in non‐AP musicians [Loui et al, ], suggesting a global reorganization of brain networks. In contrast, in the current study, we tested specific hypotheses on the role of particular anatomical regions that are expected to be involved in the AP‐specific RSN, based on our previous study [Kim and Knösche, ].…”