Relating Structure to Function: Heschl's Gyrus and Acoustic Processing

Abstract

The way in which normal variations in human neuroanatomy relate to brain function remains largely uninvestigated. This study addresses the question by relating anatomical measurements of Heschl’s gyrus (HG), the structure containing human primary auditory cortex, to how this region processes temporal and spectral acoustic information. In this study, subjects’ right and left HG were identified and manually indicated on anatomical MRI scans. Volumes of gray matter, white matter and total gyrus were recorded, and asymmetry indices were calculated. Additionally, cortical auditory activity in response to noise stimuli varying orthogonally in temporal and spectral dimensions was assessed and related to the volumetric measurements. A high degree of anatomical variability was seen, consistent with other reports in the literature. The auditory cortical responses showed the expected leftward lateralization to varying rates of stimulus change and rightward lateralization of increasing spectral information. However, the present data are the first to explicitly link anatomical variability of auditory cortex to individual differences in the way that cortex processes acoustic information. Specifically, larger volumes of left HG were associated with larger extents of rate-related cortex on the left, and larger volumes of right HG related to larger extents of spectral-related cortex on the right. This finding is discussed in relation to known microanatomical asymmetries of HG, including increased myelination of its fibers, and implications for language learning are considered.

Hemispheric association and dissociation of voice and speech information processing in stroke

“…The ROI classification was performed by an expert neuro-radiologist (AF) with 12 years of experience, and following a detailed protocol 1 adapted from the International Stroke Trial III (Whiteley et al, 2006). Regions of Interest (ROI) considered were the middle/inferior frontal gyrus (involved in gender categorization (Fecteau, et al, 2005, Charest et al, 2012, Heschl's gyrus (also called Transverse Temporal gyrus -involved in language learning and spectral/pitch information processing (Warrier et al, 2009), the superior temporal gyrus (anterior/posterior, involved in general auditory processes but also voice perception, Belin, et al, 2004), the insula (involved in central auditory functions, in particular temporal resolution and sequencing (Bamiou et al, 2006) and the amygdala-hippocampal complex (involved in memory and emotional voice perception (Johnstone et al, 2006;Rama et al, 2004).…”

Human Primary Auditory Cortex Follows the Shape of Heschl's Gyrus

“…This distinction affects a broad literature that uses anatomical criteria to estimate the size of human PAC (and the adjacent planum temporale) in relation to brain laterality, language and music abilities, and auditory-related pathologies, including dyslexia, autism, and schizophrenia (for review, see Abdul-Kareem and Sluming, 2008). By current convention, only the anterior division of duplicated HGs is included in PAC measurements (Rademacher et al et al, 1993;Penhune et al, 1996;Leonard et al, 2001;Schneider et al, 2002;Emmorey et al, 2003;Wong et al, 2008;Gage et al, 2009;Schneider et al, 2009;Warrier et al, 2009;Hubl et al, 2010) with the posterior division assigned instead to the planum temporale (Dorsaint-Pierre et al, 2006). The criteria proposed by Penhune et al (1996) (to consider only the anterior division as part of PAC if there is an SI extending half the length of HG) would wrongly exclude the posterior division of PAC (the entire hA1 subfield) in 7 out of 20 of our cases.…”

Sensitivity of Newborn Auditory Cortex to the Temporal Structure of Sounds

“…This multi-time-resolution hypothesis has been modified based on growing experimental evidence (Poeppel et al, 2008). For example, Boemio et al (2005) support these assumptions by demonstrating that right versus left superior temporal cortex shows greater blood oxygenation level-dependent (BOLD) signal changes in response to slow (150 -300 ms) acoustic modulations (Overath et al, 2008;Warrier et al, 2009). Rapid temporal transitions, however, are processed bilaterally, leading to symmetrical activation of left and right auditory cortices.…”