Pantev C, Bertrand O, Eulitz C, Verkindt C, Hampson S, Schuierer G, et al. Specific tonotopic organizations of different areas of the human auditory cortex revealed by simultaneous magnetic and electric recordings

Center of Biomagnetism, Institute of Experimental Audiology University of Münster, Germany.
Electroencephalography and Clinical Neurophysiology 02/1995; 94(1):26-40. DOI: 10.1016/0013-4694(94)00209-4
Source: PubMed

ABSTRACT This paper presents data concerning auditory evoked responses in the middle latency range (wave Pam/Pa) and slow latency range (wave N1m/N1) recorded from 12 subjects. It is the first group study to report multi-channel data of both MEG and EEG recordings from the human auditory cortex. The experimental procedure involved potential and current density topographical brain mapping as well as magnetic and electric source analysis. Responses were compared for the following 3 stimulus frequencies: 500, 1000 and 4000 Hz. It was found that two areas of the auditory cortex showed mirrored tonotopic organization; one area, the source of N1m/N1 wave, exhibited higher frequencies at progressively deeper locations, while the second area, the source of the Pam/Pa wave, exhibited higher frequencies at progressively more superficial locations. The Pa tonotopic map was located in the primary auditory cortex anterior to the N1m/N1 mirror map. It is likely that N1m/N1 results from activation of secondary auditory areas. The location of the Pa map in A1, and its N1 mirror image in secondary auditory areas is in agreement with observations from animal studies.

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    • "Fig. 3. Mean estimated ECD locations for the M100 component (80–130 ms) in left and right hemispheres. M100 dipole sources, with higher frequencies corresponding to more medial coordinates and lower frequencies corresponding to more lateral coordinates (Pantev et al., 1995). While no clear patterns were observed in the left hemisphere, in the right hemisphere the location of the standard sounds showed a pattern consistent with categorical perception: although the acoustic distance between S "
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    ABSTRACT: Previous research in speech perception has shown that category information affects the discrimination of consonants to a greater extent than vowels. However, there has been little electrophysiological work on the perception of fricative sounds, which are informative for this contrast as they share properties with both consonants and vowels. In the current study we address the relative contribution of phonological and acoustic information to the perception of sibilant fricatives using event-related fields (ERFs) and dipole modeling with magnetoencephalography (MEG). We show that the field strength of neural responses peaking approximately 200ms after sound onset co-varies with acoustic factors, while the cortical localization of earlier M100 responses suggests a stronger influence of phonological categories. We propose that neural equivalents of categorical perception for fricative sounds are best seen using localization measures, and that spectral cues are spatially coded in human cortex. Copyright © 2015 Elsevier Inc. All rights reserved.
    Brain and Language 04/2015; 143. DOI:10.1016/j.bandl.2015.02.003 · 3.31 Impact Factor
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    • "It has been less clear how (and whether) these core regions, and their tonotopic gradients, map onto human primary auditory cortex, and onto Heschl's gyrus in particular. Earlier MEG studies (e.g., Pantev et al., 1995), using less accurate dipolebased analysis methods, were interpreted as consistent with a simpler tonotopic arrangement in humans, with a single gradient running low to high, lateral to medial along Heschl's gyrus. Only with the advent of high field fMRI studies (e.g., Formisano et al., 2003) did it become clear that human auditory cortex also exhibited multiple mirror-symmetric high-low-high tonotopic gradients akin to those seen in macaque. "
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    ABSTRACT: A wide variety of evidence, from neurophysiology, neuroanatomy, and imaging studies in humans and animals, suggests that human auditory cortex is in part tonotopically organized. Here we present a new means of resolving this spatial organization using a combination of non-invasive observables (EEG, MEG, and MRI), model-based estimates of spectrotemporal patterns of neural activation, and multivariate pattern analysis. The method exploits both the fine-grained temporal patterning of auditory cortical responses and the millisecond scale temporal resolution of EEG and MEG. Participants listened to 400 English words while MEG and scalp EEG were measured simultaneously. We estimated the location of cortical sources using the MRI anatomically constrained minimum norm estimate (MNE) procedure. We then combined a form of multivariate pattern analysis (representational similarity analysis) with a spatiotemporal searchlight approach to successfully decode information about patterns of neuronal frequency preference and selectivity in bilateral superior temporal cortex. Observed frequency preferences in and around Heschl's gyrus matched current proposals for the organization of tonotopic gradients in primary acoustic cortex, while the distribution of narrow frequency selectivity similarly matched results from the fMRI literature. The spatial maps generated by this novel combination of techniques seem comparable to those that have emerged from fMRI or ECOG studies, and a considerable advance over earlier MEG results.
    Frontiers in Neuroscience 11/2014; 8(368). DOI:10.3389/fnins.2014.00368 · 3.70 Impact Factor
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    • "They observed that the neuron's CF increased toward postero-medial locations, supporting the presence of one tonotopic gradient on human medial HG (Howard et al., 1996). However, using MEG several other tonotopic patterns were observed as well, including one frequency gradient with reversed direction (compatible with the low-to-high gradient in hR; Hari and Mäkelä, 1986) and a mirror symmetric pattern (Pantev et al., 1995; N100m and Pam response reflecting high-to-low and low-to-high pattern when moving from postero-medial to antero-lateral locations, respectively ). Throughout MEG studies, reported gradients are reproducible within an individual but highly variable across individuals (Lütkenhöner et al., 2003). "
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    ABSTRACT: While advances in magnetic resonance imaging (MRI) throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla). Importantly, we illustrate that-whereas a group-based approach to analyze functional (tonotopic) maps is appropriate to highlight the main tonotopic axis-the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e., myelination) as well as of functional properties (e.g., broadness of frequency tuning) is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post-mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions.
    Frontiers in Neuroscience 07/2014; 8:225. DOI:10.3389/fnins.2014.00225 · 3.70 Impact Factor
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