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Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners.

Dietrich S, Hertrich I, Ackermann H - PLoS ONE (2015)

Bottom Line: Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension.By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1.Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

View Article: PubMed Central - PubMed

Affiliation: Department of General Neurology, Hertie Institute for Clinical Brain Research, Center for Neurology, University of Tübingen, Hoppe-Seyler-Str. 3, D-72076 Tübingen, Germany.

ABSTRACT
In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

No MeSH data available.


Volumes of interest used for the model space definition.Location of the domain in which blind subjects showed their individual peak coordinates (yellow) within cytoarchitectonic masks of (A) pulvinar (Pv), (B) supplementary motor area (pre-SMA), (C) primary visual area (V1), and (D) primary auditory area (A1). Note the Pv peaks did neither overlap with MGN (light blue) nor lateral geniculate nucleus (LGN) (dark blue). All selected structures overlaid on a T1 template.
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pone.0132196.g002: Volumes of interest used for the model space definition.Location of the domain in which blind subjects showed their individual peak coordinates (yellow) within cytoarchitectonic masks of (A) pulvinar (Pv), (B) supplementary motor area (pre-SMA), (C) primary visual area (V1), and (D) primary auditory area (A1). Note the Pv peaks did neither overlap with MGN (light blue) nor lateral geniculate nucleus (LGN) (dark blue). All selected structures overlaid on a T1 template.

Mentions: FMRI time series were extracted from activation peaks in the above described four regions (right A1, Pv, V1, and left pre-SMA see Fig 2). Because local maxima of activation differ across subjects, time series extraction relied on individually adjusted coordinates by using a combination of functional and anatomical constraints: (i) an individual significance level of p < 0.05 uncorrected, (ii) maximum distance from group peak (see covariance analysis of [10]) of 4 mm Pv, and 8 mm for A1, V1, pre-SMA), (iii) location within the respective cytoarchitectonically defined mask (A1, Pv, V1, pre-SMA; SPM anatomy toolbox, [32]). If a participant did not show significant BOLD responses in a search region, e.g. in case of V1 in sighted controls, group coordinates (resulting from the covariance analysis [10]) were taken. S1 Table lists the coordinates of individual peaks and also indicates whether a subject did not show significant BOLD responses in a region. After identifying these peaks, a sphere around each peak (4 mm radius for Pv, 8 mm radius for A1, V1, pre-SMA) was defined as the respective volume of interest.


Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners.

Dietrich S, Hertrich I, Ackermann H - PLoS ONE (2015)

Volumes of interest used for the model space definition.Location of the domain in which blind subjects showed their individual peak coordinates (yellow) within cytoarchitectonic masks of (A) pulvinar (Pv), (B) supplementary motor area (pre-SMA), (C) primary visual area (V1), and (D) primary auditory area (A1). Note the Pv peaks did neither overlap with MGN (light blue) nor lateral geniculate nucleus (LGN) (dark blue). All selected structures overlaid on a T1 template.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492787&req=5

pone.0132196.g002: Volumes of interest used for the model space definition.Location of the domain in which blind subjects showed their individual peak coordinates (yellow) within cytoarchitectonic masks of (A) pulvinar (Pv), (B) supplementary motor area (pre-SMA), (C) primary visual area (V1), and (D) primary auditory area (A1). Note the Pv peaks did neither overlap with MGN (light blue) nor lateral geniculate nucleus (LGN) (dark blue). All selected structures overlaid on a T1 template.
Mentions: FMRI time series were extracted from activation peaks in the above described four regions (right A1, Pv, V1, and left pre-SMA see Fig 2). Because local maxima of activation differ across subjects, time series extraction relied on individually adjusted coordinates by using a combination of functional and anatomical constraints: (i) an individual significance level of p < 0.05 uncorrected, (ii) maximum distance from group peak (see covariance analysis of [10]) of 4 mm Pv, and 8 mm for A1, V1, pre-SMA), (iii) location within the respective cytoarchitectonically defined mask (A1, Pv, V1, pre-SMA; SPM anatomy toolbox, [32]). If a participant did not show significant BOLD responses in a search region, e.g. in case of V1 in sighted controls, group coordinates (resulting from the covariance analysis [10]) were taken. S1 Table lists the coordinates of individual peaks and also indicates whether a subject did not show significant BOLD responses in a region. After identifying these peaks, a sphere around each peak (4 mm radius for Pv, 8 mm radius for A1, V1, pre-SMA) was defined as the respective volume of interest.

Bottom Line: Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension.By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1.Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

View Article: PubMed Central - PubMed

Affiliation: Department of General Neurology, Hertie Institute for Clinical Brain Research, Center for Neurology, University of Tübingen, Hoppe-Seyler-Str. 3, D-72076 Tübingen, Germany.

ABSTRACT
In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

No MeSH data available.