Limits...
Functional maps of human auditory cortex: effects of acoustic features and attention.

Woods DL, Stecker GC, Rinne T, Herron TJ, Cate AD, Yund EW, Liao I, Kang X - PLoS ONE (2009)

Bottom Line: Sensory responses in both medial and lateral auditory cortex decreased in magnitude throughout stimulus blocks.The results are consistent with the view that medial regions of human auditory cortex contain tonotopically organized core and belt fields that map the basic acoustic features of sounds while surrounding higher-order parabelt regions are tuned to more abstract stimulus attributes.Intermodal selective attention enhances processing in neuronal populations that are partially distinct from those activated by unattended stimuli.

View Article: PubMed Central - PubMed

Affiliation: Human Cognitive Neurophysiology Laboratory, VANCHCS, Martinez, California, United States of America. dlwoods@ucdavis.edu

ABSTRACT

Background: While human auditory cortex is known to contain tonotopically organized auditory cortical fields (ACFs), little is known about how processing in these fields is modulated by other acoustic features or by attention.

Methodology/principal findings: We used functional magnetic resonance imaging (fMRI) and population-based cortical surface analysis to characterize the tonotopic organization of human auditory cortex and analyze the influence of tone intensity, ear of delivery, scanner background noise, and intermodal selective attention on auditory cortex activations. Medial auditory cortex surrounding Heschl's gyrus showed large sensory (unattended) activations with two mirror-symmetric tonotopic fields similar to those observed in non-human primates. Sensory responses in medial regions had symmetrical distributions with respect to the left and right hemispheres, were enlarged for tones of increased intensity, and were enhanced when sparse image acquisition reduced scanner acoustic noise. Spatial distribution analysis suggested that changes in tone intensity shifted activation within isofrequency bands. Activations to monaural tones were enhanced over the hemisphere contralateral to stimulation, where they produced activations similar to those produced by binaural sounds. Lateral regions of auditory cortex showed small sensory responses that were larger in the right than left hemisphere, lacked tonotopic organization, and were uninfluenced by acoustic parameters. Sensory responses in both medial and lateral auditory cortex decreased in magnitude throughout stimulus blocks. Attention-related modulations (ARMs) were larger in lateral than medial regions of auditory cortex and appeared to arise primarily in belt and parabelt auditory fields. ARMs lacked tonotopic organization, were unaffected by acoustic parameters, and had distributions that were distinct from those of sensory responses. Unlike the gradual adaptation seen for sensory responses, ARMs increased in amplitude throughout stimulus blocks.

Conclusions/significance: The results are consistent with the view that medial regions of human auditory cortex contain tonotopically organized core and belt fields that map the basic acoustic features of sounds while surrounding higher-order parabelt regions are tuned to more abstract stimulus attributes. Intermodal selective attention enhances processing in neuronal populations that are partially distinct from those activated by unattended stimuli.

Show MeSH

Related in: MedlinePlus

Grid measurement.Activations in auditory cortex were quantified using medial (yellow) and lateral (white) grids. Each grid contained individual grid elements of identical size (approximately 5×5 mm) on the inflated cortical surface. Average cortical surface curvature is shown (gyri = green, sulci = red). LGI = long gyri of the insula; HG = Heschl's Gyrus, IPL = inferior parietal lobe, PT = Planum Temporale, STG = superior temporal gyrus. Approximate anterior-posterior and medial-lateral directions on the inflated surface are shown.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2664477&req=5

pone-0005183-g004: Grid measurement.Activations in auditory cortex were quantified using medial (yellow) and lateral (white) grids. Each grid contained individual grid elements of identical size (approximately 5×5 mm) on the inflated cortical surface. Average cortical surface curvature is shown (gyri = green, sulci = red). LGI = long gyri of the insula; HG = Heschl's Gyrus, IPL = inferior parietal lobe, PT = Planum Temporale, STG = superior temporal gyrus. Approximate anterior-posterior and medial-lateral directions on the inflated surface are shown.

Mentions: The data were quantified in adjacent medial and lateral grids that covered auditory cortex and the adjacent superior temporal gyrus (Figure 4). SDAs and ARMs were analyzed in each grid with a 9-way ANOVA for repeated measures incorporating the following factors: subjects (treated as a random factor), tone frequency, tone intensity, ear of delivery, sparse vs. continuous imaging, hemisphere, type and/or presence of concurrent visual stimuli, and anterior-posterior (A-P) and medial-lateral (M-L) location on the grid. All-ASAs were analyzed with a 10-way ANOVA that included auditory stimulation conditions (BA, BV, and UA) as an additional attention factor along with the factors included in SDA and ARM analyses. Main effects and first order interactions were evaluated at the p<0.05 level with third- and higher-order interactions evaluated using a stricter p<0.01 criterion. F-ratios and probabilities are reported for significant results and results approaching significance, whereas F-ratios alone are presented for other comparisons. Preliminary analysis showed that neither SDAs nor ARMs changed significantly across the successive experiment sessions (F(2,16) = 1.82 and 0.49, respectively). Therefore, data were pooled across experimental sessions during the analysis of both sparse and continuous data.


Functional maps of human auditory cortex: effects of acoustic features and attention.

Woods DL, Stecker GC, Rinne T, Herron TJ, Cate AD, Yund EW, Liao I, Kang X - PLoS ONE (2009)

Grid measurement.Activations in auditory cortex were quantified using medial (yellow) and lateral (white) grids. Each grid contained individual grid elements of identical size (approximately 5×5 mm) on the inflated cortical surface. Average cortical surface curvature is shown (gyri = green, sulci = red). LGI = long gyri of the insula; HG = Heschl's Gyrus, IPL = inferior parietal lobe, PT = Planum Temporale, STG = superior temporal gyrus. Approximate anterior-posterior and medial-lateral directions on the inflated surface are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2664477&req=5

pone-0005183-g004: Grid measurement.Activations in auditory cortex were quantified using medial (yellow) and lateral (white) grids. Each grid contained individual grid elements of identical size (approximately 5×5 mm) on the inflated cortical surface. Average cortical surface curvature is shown (gyri = green, sulci = red). LGI = long gyri of the insula; HG = Heschl's Gyrus, IPL = inferior parietal lobe, PT = Planum Temporale, STG = superior temporal gyrus. Approximate anterior-posterior and medial-lateral directions on the inflated surface are shown.
Mentions: The data were quantified in adjacent medial and lateral grids that covered auditory cortex and the adjacent superior temporal gyrus (Figure 4). SDAs and ARMs were analyzed in each grid with a 9-way ANOVA for repeated measures incorporating the following factors: subjects (treated as a random factor), tone frequency, tone intensity, ear of delivery, sparse vs. continuous imaging, hemisphere, type and/or presence of concurrent visual stimuli, and anterior-posterior (A-P) and medial-lateral (M-L) location on the grid. All-ASAs were analyzed with a 10-way ANOVA that included auditory stimulation conditions (BA, BV, and UA) as an additional attention factor along with the factors included in SDA and ARM analyses. Main effects and first order interactions were evaluated at the p<0.05 level with third- and higher-order interactions evaluated using a stricter p<0.01 criterion. F-ratios and probabilities are reported for significant results and results approaching significance, whereas F-ratios alone are presented for other comparisons. Preliminary analysis showed that neither SDAs nor ARMs changed significantly across the successive experiment sessions (F(2,16) = 1.82 and 0.49, respectively). Therefore, data were pooled across experimental sessions during the analysis of both sparse and continuous data.

Bottom Line: Sensory responses in both medial and lateral auditory cortex decreased in magnitude throughout stimulus blocks.The results are consistent with the view that medial regions of human auditory cortex contain tonotopically organized core and belt fields that map the basic acoustic features of sounds while surrounding higher-order parabelt regions are tuned to more abstract stimulus attributes.Intermodal selective attention enhances processing in neuronal populations that are partially distinct from those activated by unattended stimuli.

View Article: PubMed Central - PubMed

Affiliation: Human Cognitive Neurophysiology Laboratory, VANCHCS, Martinez, California, United States of America. dlwoods@ucdavis.edu

ABSTRACT

Background: While human auditory cortex is known to contain tonotopically organized auditory cortical fields (ACFs), little is known about how processing in these fields is modulated by other acoustic features or by attention.

Methodology/principal findings: We used functional magnetic resonance imaging (fMRI) and population-based cortical surface analysis to characterize the tonotopic organization of human auditory cortex and analyze the influence of tone intensity, ear of delivery, scanner background noise, and intermodal selective attention on auditory cortex activations. Medial auditory cortex surrounding Heschl's gyrus showed large sensory (unattended) activations with two mirror-symmetric tonotopic fields similar to those observed in non-human primates. Sensory responses in medial regions had symmetrical distributions with respect to the left and right hemispheres, were enlarged for tones of increased intensity, and were enhanced when sparse image acquisition reduced scanner acoustic noise. Spatial distribution analysis suggested that changes in tone intensity shifted activation within isofrequency bands. Activations to monaural tones were enhanced over the hemisphere contralateral to stimulation, where they produced activations similar to those produced by binaural sounds. Lateral regions of auditory cortex showed small sensory responses that were larger in the right than left hemisphere, lacked tonotopic organization, and were uninfluenced by acoustic parameters. Sensory responses in both medial and lateral auditory cortex decreased in magnitude throughout stimulus blocks. Attention-related modulations (ARMs) were larger in lateral than medial regions of auditory cortex and appeared to arise primarily in belt and parabelt auditory fields. ARMs lacked tonotopic organization, were unaffected by acoustic parameters, and had distributions that were distinct from those of sensory responses. Unlike the gradual adaptation seen for sensory responses, ARMs increased in amplitude throughout stimulus blocks.

Conclusions/significance: The results are consistent with the view that medial regions of human auditory cortex contain tonotopically organized core and belt fields that map the basic acoustic features of sounds while surrounding higher-order parabelt regions are tuned to more abstract stimulus attributes. Intermodal selective attention enhances processing in neuronal populations that are partially distinct from those activated by unattended stimuli.

Show MeSH
Related in: MedlinePlus