Prevalence and function of Heschl’s gyrus morphotypes in musicians

Abstract

Morphological variations of the first transverse Heschl's gyrus (HG) in the human auditory cortex (AC) are common, yet little is known about their functional implication. We investigated individual morphology and function of HG variations in the AC of 41 musicians, using structural and functional magnetic resonance imaging (fMRI) as well as magnetoencephalography (MEG). Four main morphotypes of HG were (i) single HG, (ii) common stem duplication (CSD), (iii) complete posterior duplication (CPD), and (iv) multiple duplications (MD). The vast majority of musicians (90%) exhibited HG multiplications (type ii-iv) in either one (39%) or both (51%) hemispheres. In 27% of musicians, MD with up to four gyri were found. To probe the functional contribution of HG multiplications to auditory processing we performed fMRI and MEG with auditory stimulation using analogous instrumental tone paradigms. Both methods pointed to the recruitment of all parts of HG during auditory stimulation, including multiplications if present. FMRI activations extended with the degree of HG gyrification. MEG source waveform patterns were distinct for the different types of HG: (i) hemispheres with single HG and (ii) CSD exhibited dominant N1 responses, whereas hemispheres with (iii) CPD and (iv) MD exhibited dominant P1 responses. N1 dipole amplitudes correlated with the localization of the first complete Heschl's sulcus (cHS), designating the most posterior anatomical border of HG. P2 amplitudes were significantly higher in professional as compared to amateur musicians. The results suggest that HG multiplications occur much more frequently in musicians than in the general population and constitute a functional unit with HG.

Reduced cortical thickness in Heschl's gyrus as an in vivo marker for human primary auditory cortex

“…In recent histological studies, the localization of PAC, deriving from cytoarchitectonic probability maps, could only be approximated to the medial two‐thirds of HG (Morosan et al, ). This approximation seems to be insufficient, especially if considering the HG's high inter‐individual structural variability (Abdul‐Kareem & Sluming, ; Benner et al, ; Campain & Minckler, ) and the weak correlation between macro‐anatomical landmarks of AC with cytoarchitectonic features of PAC while auditory koniocortex shows likewise considerable intersubject variability in location and extent (Morosan et al, ; Rademacher et al, , ; Sweet et al, ; Von Economo & Horn, ). In early histological investigations by Von Economo & Koskinas () and Von Economo & Horn (), PAC has already been found to correspond roughly to the macroscopic landmarks delineated by HG which are conceded to merely posit a region of probability, while cases of PAC extending into areas posterior of HG have been reported by them as well They have suggested that the entire koniocortex (corresponding to area TC) covers the same surface area in both hemispheres, and have noted that the major part of PAC consisting of true koniocortex (corresponding to area TC1) is larger on the left than on the right.…”

“…In parallel to the CTH analyses, segmentation and 3D reconstruction of individual AC was performed based on a stepwise semi‐automatic procedure using BrainVoyager QX software (Figure d). In particular, the superior temporal plane including HG, anterior superior temporal gyrus (aSTG) and planum temporale (PT) was segmented slice‐by‐slice along the Sylvian fissure based on sagittal images, employing standard definitions of the anatomical landmarks of AC (Penhune, Cismaru, Dorsaint‐Pierre, Petitto, & Zatorre, ; Rademacher et al, ; Wong et al, ) and according to established criteria (Benner et al, ; Schneider et al, ; Wengenroth et al, ). Thereby, the HG was defined as the most anterior transverse gyrus within the supratemporal plane located between the first transverse sulcus and Heschl's sulcus (HS).…”

“…Based on the individual segmentation of ACs, the individual structure of HG was systematically parcellated in (a) medial HG (mHG), covering the posteromedial two‐thirds of HG (Figure , blue area), and (b) lateral HG (lHG), covering the remaining lateral part of HG (Figure , green area), including potential CSDs or CPDs according to Schneider et al () and Benner et al (). Thereby, the region of HG was defined to originate medially at the retroinsular region and to extend to the lateral rim of the supratemporal plane (Rademacher et al, ; Schneider et al, ; Wang, ).…”

“…Heschl's gyrus (HG), also known as the anterior transverse temporal gyrus (Penhune, Zatorre, MacDonald, & Evans, ; Destrieux, Fischl, Dale, & Halgren, ), originates medially at the retroinsular region and joins the lateral rim of the supratemporal plane (Rademacher et al, ; Schneider et al, ; Wang, ). Apart from common findings describing single transverse gyri, a multitude of more complex morphological variants of HG have already been observed, namely: sulcus intermedius (SI), indenting partially the transverse gyrus along its mediolateral extension (Penhune et al, ), common stem duplications (CSD), complete posterior duplications (CPD) (Abdul‐Kareem & Sluming, ; Marie et al, ; Marie, Maingault, Crivello, Mazoyer, & Tzourio‐Mazoyer, ; Moerel, De Martino, & Formisano, ), and furthermore multiple duplications (MD) of HG (Benner et al, ; Turker et al, ). Interestingly, the macroscopic gyrification and size of HG have been found to be highly stable already at primary school age (Seither‐Preisler, Parncutt, & Schneider, ).…”

Sing Chinese and tap Tagalog? Predicting individual differences in musical and phonetic aptitude using language families differing by sound-typology

“…The easiest way thus is the learning of a musical instrument to sharpen perceptual-cognitive processing, or to sing, as generally speaking, musicians' Heschl's gyri in the auditory cortex show alterations, more specifically multiplications (Benner et al, 2017) improving auditory abilities allowing them to discriminate pitch variations far better than non-musicians (Schneider et al, 2002). However, auditory models have also argued that primary capacities influence musical aptitude, while secondary musical skills are environmentally shaped by the culture and individual training received (Karma, 1994).…”