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Mapping tonotopic organization in human temporal cortex: representational similarity analysis in EMEG source space.

Su L, Zulfiqar I, Jamshed F, Fonteneau E, Marslen-Wilson W - Front Neurosci (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, University of Cambridge Cambridge, UK ; Department of Psychology, University of Cambridge Cambridge, UK.

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.

No MeSH data available.


Related in: MedlinePlus

(A,B) The distribution of center frequencies (in Hz) for all vertices in bilateral superior temporal cortex (A, left hemisphere and B, right hemisphere). (C,D) The distributions of the standard deviation (SD) of the Gaussian tuning curve, expressed in frequency band units, for all vertices in bilateral temporal cortex (C, left; D, right).
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Figure 6: (A,B) The distribution of center frequencies (in Hz) for all vertices in bilateral superior temporal cortex (A, left hemisphere and B, right hemisphere). (C,D) The distributions of the standard deviation (SD) of the Gaussian tuning curve, expressed in frequency band units, for all vertices in bilateral temporal cortex (C, left; D, right).

Mentions: Figures 6A,B show the distributions of preferred frequencies for all vertices in bilateral superior temporal cortex, summarizing the results compiled over the 200 ms from stimulus onset. These distributions are very similar for the two hemispheres although the right hemisphere shows a small shift toward higher frequencies. The peak of the distribution on the left is at around 250–350 Hz, which is in the range of the fundamental frequency of the female voice (the stimuli were recorded by a female speaker). The peak for the right hemisphere was slightly higher, at 450 Hz. The distribution of frequency preferences for both hemispheres was bimodal with a second (much reduced) peak centered at around 900–1000 Hz, likely reflecting the harmonic formant structures in speech. This result suggests that the majority of the area sampled (extending well beyond primary auditory cortex as standardly defined) responded most strongly to the predominant frequencies in the voice range (200–2000 Hz). Note that this did not mean an absence of responses to higher frequencies, as can be seen by the peak frequency plots provided in Figure 8.


Mapping tonotopic organization in human temporal cortex: representational similarity analysis in EMEG source space.

Su L, Zulfiqar I, Jamshed F, Fonteneau E, Marslen-Wilson W - Front Neurosci (2014)

(A,B) The distribution of center frequencies (in Hz) for all vertices in bilateral superior temporal cortex (A, left hemisphere and B, right hemisphere). (C,D) The distributions of the standard deviation (SD) of the Gaussian tuning curve, expressed in frequency band units, for all vertices in bilateral temporal cortex (C, left; D, right).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228977&req=5

Figure 6: (A,B) The distribution of center frequencies (in Hz) for all vertices in bilateral superior temporal cortex (A, left hemisphere and B, right hemisphere). (C,D) The distributions of the standard deviation (SD) of the Gaussian tuning curve, expressed in frequency band units, for all vertices in bilateral temporal cortex (C, left; D, right).
Mentions: Figures 6A,B show the distributions of preferred frequencies for all vertices in bilateral superior temporal cortex, summarizing the results compiled over the 200 ms from stimulus onset. These distributions are very similar for the two hemispheres although the right hemisphere shows a small shift toward higher frequencies. The peak of the distribution on the left is at around 250–350 Hz, which is in the range of the fundamental frequency of the female voice (the stimuli were recorded by a female speaker). The peak for the right hemisphere was slightly higher, at 450 Hz. The distribution of frequency preferences for both hemispheres was bimodal with a second (much reduced) peak centered at around 900–1000 Hz, likely reflecting the harmonic formant structures in speech. This result suggests that the majority of the area sampled (extending well beyond primary auditory cortex as standardly defined) responded most strongly to the predominant frequencies in the voice range (200–2000 Hz). Note that this did not mean an absence of responses to higher frequencies, as can be seen by the peak frequency plots provided in Figure 8.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, University of Cambridge Cambridge, UK ; Department of Psychology, University of Cambridge Cambridge, UK.

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.

No MeSH data available.


Related in: MedlinePlus