Publications by authors named "Jackson T Gandour"

41 Publications

Cortical hemisphere preference and brainstem ear asymmetry reflect experience-dependent functional modulation of pitch.

Brain Lang 2021 Jul 21;221:104995. Epub 2021 Jul 21.

Department of Speech Language Hearing Sciences, Purdue University, Lyles Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907, USA. Electronic address:

Temporal attributes of pitch processing at cortical and subcortical levels are differentially weighted and well-coordinated. The question is whether language experience induces functional modulation of hemispheric preference complemented by brainstem ear symmetry for pitch processing. Brainstem frequency-following and cortical pitch responses were recorded concurrently from Mandarin and English participants. A Mandarin syllable with a rising pitch contour was presented to both ears with monaural stimulation. At the cortical level, left ear stimulation in the Chinese group revealed an experience-dependent response for pitch processing in the right hemisphere, consistent with a functionalaccount. The English group revealed a contralateral hemisphere preference consistent with a structuralaccount. At the brainstem level, Chinese participants showed a functional leftward ear asymmetry, whereas English were consistent with a structural account. Overall, language experience modulates both cortical hemispheric preference and brainstem ear asymmetry in a complementary manner to optimize processing of temporal attributes of pitch.
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http://dx.doi.org/10.1016/j.bandl.2021.104995DOI Listing
July 2021

Tone language experience-dependent advantage in pitch representation in brainstem and auditory cortex is maintained under reverberation.

Hear Res 2019 06 15;377:61-71. Epub 2019 Mar 15.

Purdue University, Department of Speech Language Hearing Sciences, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907-2122, USA. Electronic address:

Long-term language and music experience enhances neural representation of temporal attributes of pitch in the brainstem and auditory cortex in favorable listening conditions. Herein we examine whether brainstem and cortical pitch mechanisms-shaped by long-term language experience-maintain this advantage in the presence of reverberation-induced degradation in pitch representation. Brainstem frequency following responses (FFR) and cortical pitch responses (CPR) were recorded concurrently from Chinese and English-speaking natives, using a Mandarin word exhibiting a high rising pitch (/yi/). Stimuli were presented diotically in quiet (Dry), and in the presence of Slight, Mild, and Moderate reverberation conditions. Regardless of language group, the amplitude of both brainstem FFR (F0) and cortical CPR (NaPb) responses decreased with increases in reverberation. Response amplitude for Chinese, however, was larger than English in all reverberant conditions. The Chinese group also exhibited a robust rightward asymmetry at temporal electrode sites (T8 > T7) across stimulus conditions. Regardless of language group, direct comparison of brainstem and cortical responses revealed similar magnitude of change in response amplitude with increasing reverberation. These findings suggest that experience-dependent brainstem and cortical pitch mechanisms provide an enhanced and stable neural representation of pitch-relevant information that is maintained even in the presence of reverberation. Relatively greater degradative effects of reverberation on brainstem (FFR) compared to cortical (NaPb) responses suggest relatively stronger top-down influences on CPRs.
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http://dx.doi.org/10.1016/j.heares.2019.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543830PMC
June 2019

Language experience-dependent advantage in pitch representation in the auditory cortex is limited to favorable signal-to-noise ratios.

Hear Res 2017 11 14;355:42-53. Epub 2017 Sep 14.

Purdue University, Department of Speech Language Hearing Sciences, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN, 47907-2122, USA. Electronic address:

Long-term experience enhances neural representation of temporal attributes of pitch in the brainstem and auditory cortex in favorable listening conditions. Herein we examine whether cortical pitch mechanisms shaped by language experience are more resilient to degradation in background noise, and exhibit greater binaural release from masking (BRM). Cortical pitch responses (CPR) were recorded from Mandarin- and English-speaking natives using a Mandarin word exhibiting a high rising pitch (/yi/). Stimuli were presented diotically in Quiet, and in noise at +5, and 0 dB SNR. CPRs were also recorded in binaural conditions, SONO (where signal and noise were in phase at both ears); or S0Nπ (where signal was in phase and noise 180° out of phase at each ear), using 0 dB SNR. At Fz, both groups showed increase in CPR peak latency and decrease in amplitude with increasing noise level. A language-dependent enhancement of Na-Pb amplitude (Chinese > English) was restricted to Quiet and +5 dB SNR conditions. At T7/T8 electrode sites, Chinese natives exhibited a rightward asymmetry for both CPR components. A language-dependent effect (Chinese > English) was restricted to T8. Regarding BRM, both CPR components showed greater response amplitude for the S0Nπ condition compared to S0N0 across groups. Rightward asymmetry for BRM in the Chinese group indicates experience-dependent recruitment of right auditory cortex. Restriction of the advantage in pitch representation to the quiet and +5 SNR conditions, and the absence of group differences in the binaural release from masking, suggest that language experience affords limited advantage in the neural representation of pitch-relevant information in the auditory cortex under adverse listening conditions.
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http://dx.doi.org/10.1016/j.heares.2017.09.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5675814PMC
November 2017

Language-dependent changes in pitch-relevant neural activity in the auditory cortex reflect differential weighting of temporal attributes of pitch contours.

J Neurolinguistics 2017 Feb 16;41:38-49. Epub 2016 Sep 16.

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN USA.

There remains a gap in our knowledge base about neural representation of pitch attributes that occur between onset and offset of dynamic, curvilinear pitch contours. The aim is to evaluate how language experience shapes processing of pitch contours as reflected in the amplitude of cortical pitch-specific response components. Responses were elicited from three nonspeech, bidirectional (falling-rising) pitch contours representative of Mandarin Tone 2 varying in location of the turning point with fixed onset and offset. At the frontocentral Fz electrode site, Na-Pb and Pb-Nb amplitude of the Chinese group was larger than the English group for pitch contours exhibiting later location of the turning point relative to the one with the earliest location. Chinese listeners' amplitude was also greater than that of English in response to those same pitch contours with later turning points. At lateral temporal sites (T7/T8), Na-Pb amplitude was larger in Chinese listeners relative to English over the right temporal site. In addition, Pb-Nb amplitude of the Chinese group showed a rightward asymmetry. The pitch contour with its turning point located about halfway of total duration evoked a rightward asymmetry regardless of group. These findings suggest that neural mechanisms processing pitch in the right auditory cortex reflect experience-dependent modulation of sensitivity to weighted integration of changes in acceleration rates of rising and falling sections and the location of the turning point.
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http://dx.doi.org/10.1016/j.jneuroling.2016.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507601PMC
February 2017

Differential sensitivity to changes in pitch acceleration in the auditory brainstem and cortex.

Brain Lang 2017 06 24;169:22-27. Epub 2017 Feb 24.

Department of Speech Language Hearing Sciences, Purdue University, USA. Electronic address:

The cortical pitch-specific response (CPR) is differentially sensitive to pitch contours varying in rate of acceleration-time-variant Mandarin Tone2 (T2) versus constant, linear rising ramp (Linear)-as a function of language experience (Krishnan, Gandour, & Suresh, 2014). CPR and brainstem frequency following response (FFR) data were recorded concurrently from native Mandarin listeners using the same stimuli. Results showed that T2 elicited larger responses than Linear at both cortical and brainstem levels (CPR: Na-Pb, Pb-Nb; FFR). However, Pb-Nb exhibited a larger difference in magnitude between T2 and Linear than either Na-Pb or FFR. This finding highlights differential weighting of brain responses elicited by a specific temporal attribute of pitch. Consistent with the notion of a distributed, integrated hierarchical pitch processing network, temporal attributes of pitch are differentially weighted by subcortical and cortical level processing.
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http://dx.doi.org/10.1016/j.bandl.2017.01.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425296PMC
June 2017

Changes in pitch height elicit both language-universal and language-dependent changes in neural representation of pitch in the brainstem and auditory cortex.

Neuroscience 2017 03 17;346:52-63. Epub 2017 Jan 17.

Purdue University, Department of Speech Language Hearing Sciences, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907-2122, USA. Electronic address:

Language experience shapes encoding of pitch-relevant information at both brainstem and cortical levels of processing. Pitch height is a salient dimension that orders pitch from low to high. Herein we investigate the effects of language experience (Chinese, English) in the brainstem and cortex on (i) neural responses to variations in pitch height, (ii) presence of asymmetry in cortical pitch representation, and (iii) patterns of relative changes in magnitude of pitch height between these two levels of brain structure. Stimuli were three nonspeech homologs of Mandarin Tone 2 varying in pitch height only. The frequency-following response (FFR) and the cortical pitch-specific response (CPR) were recorded concurrently. At the Fz-linked T7/T8 site, peak latency of Na, Pb, and Nb decreased with increasing pitch height for both groups. Peak-to-peak amplitude of Na-Pb and Pb-Nb increased with increasing pitch height across groups. A language-dependent effect was restricted to Na-Pb; the Chinese had larger amplitude than the English group. At temporal sites (T7/T8), the Chinese group had larger amplitude, as compared to English, across stimuli, but also limited to the Na-Pb component and right temporal site. In the brainstem, F0 magnitude decreased with increasing pitch height; Chinese had larger magnitude across stimuli. A comparison of CPR and FFR responses revealed distinct patterns of relative changes in magnitude common to both groups. CPR amplitude increased and FFR amplitude decreased with increasing pitch height. Experience-dependent effects on CPR components vary as a function of neural sensitivity to pitch height within a particular temporal window (Na-Pb). Differences between the auditory brainstem and cortex imply distinct neural mechanisms for pitch extraction at both levels of brain structure.
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http://dx.doi.org/10.1016/j.neuroscience.2017.01.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337167PMC
March 2017

Corrigendum to ''Language-experience plasticity in neural representation of changes in pitch salience'' [Brain Research 1637 (2016) 102-117].

Brain Res 2016 Aug 11;1644:308. Epub 2016 May 11.

Department of Speech Language Hearing Sciences, Purdue University, USA.

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http://dx.doi.org/10.1016/j.brainres.2016.05.004DOI Listing
August 2016

Language-experience plasticity in neural representation of changes in pitch salience.

Brain Res 2016 Apr 20;1637:102-117. Epub 2016 Feb 20.

Department of Speech Language Hearing Sciences, Purdue University, Lyles Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907-2122, USA. Electronic address:

Neural representation of pitch-relevant information at the brainstem and cortical levels of processing is influenced by language experience. A well-known attribute of pitch is its salience. Brainstem frequency following responses and cortical pitch specific responses, recorded concurrently, were elicited by a pitch salience continuum spanning weak to strong pitch of a dynamic, iterated rippled noise pitch contour-homolog of a Mandarin tone. Our aims were to assess how language experience (Chinese, English) affects i) enhancement of neural activity associated with pitch salience at brainstem and cortical levels, ii) the presence of asymmetry in cortical pitch representation, and iii) patterns of relative changes in magnitude along the pitch salience continuum. Peak latency (Fz: Na, Pb, and Nb) was shorter in the Chinese than the English group across the continuum. Peak-to-peak amplitude (Fz: Na-Pb, Pb-Nb) of the Chinese group grew larger with increasing pitch salience, but an experience-dependent advantage was limited to the Na-Pb component. At temporal sites (T7/T8), the larger amplitude of the Chinese group across the continuum was both limited to the Na-Pb component and the right temporal site. At the brainstem level, F0 magnitude gets larger as you increase pitch salience, and it too reveals Chinese superiority. A direct comparison of cortical and brainstem responses for the Chinese group reveals different patterns of relative changes in magnitude along the pitch salience continuum. Such differences may point to a transformation in pitch processing at the cortical level presumably mediated by local sensory and/or extrasensory influence overlaid on the brainstem output.
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http://dx.doi.org/10.1016/j.brainres.2016.02.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4821701PMC
April 2016

Pitch processing of dynamic lexical tones in the auditory cortex is influenced by sensory and extrasensory processes.

Eur J Neurosci 2015 May 6;41(11):1496-504. Epub 2015 May 6.

Department of Speech Language Hearing Sciences, Purdue University, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN, 47907, USA.

The aim is to evaluate how language experience (Chinese, English) shapes processing of pitch contours as reflected in the amplitude of cortical pitch response components. Responses were elicited from three dynamic curvilinear nonspeech stimuli varying in pitch direction and location of peak acceleration: Mandarin lexical Tone 2 (rising) and Tone 4 (falling), and a flipped variant of Tone 2, Tone 2' (nonnative). At temporal sites (T7/T8), Chinese listeners' Na-Pb response amplitudes to Tones 2 and 4 were greater than those of English listeners in the right hemisphere only; a rightward asymmetry for Tones 2 and 4 was restricted to the Chinese group. In common to both Fz-to-linked T7/T8 and T7/T8 electrode sites, the stimulus pattern (Tones 2 and 4 > Tone 2') was found in the Chinese group only. As reflected by Pb-Nb at Fz, Chinese subjects' amplitudes were larger than those of English subjects in response to Tones 2 and 4, and Tones 2 and 4 were larger than Tone 2', whereas for English subjects, Tone 2 was larger than Tone 2' and Tone 4. At frontal electrode sites (F3/F4), regardless of component or hemisphere, Chinese subjects' responses were larger in amplitude than those of English subjects across stimuli. For either group, responses to Tones 2 and 4 were larger than Tone 2'. No hemispheric asymmetry was observed at the frontal electrode sites. These findings demonstrate that cortical pitch response components are differentially modulated by experience-dependent, temporally distinct but functionally overlapping, weighting of sensory and extrasensory effects on pitch processing of lexical tones in the right temporal lobe and, more broadly, are consistent with a distributed hierarchical predictive coding process.
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http://dx.doi.org/10.1111/ejn.12903DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4461533PMC
May 2015

LANGUAGE EXPERIENCE SHAPES PROCESSING OF PITCH RELEVANT INFORMATION IN THE HUMAN BRAINSTEM AND AUDITORY CORTEX: ELECTROPHYSIOLOGICAL EVIDENCE.

Acoust Aust 2014 Dec;42(3):166-178

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN 47907, USA.

Pitch is a robust perceptual attribute that plays an important role in speech, language, and music. As such, it provides an analytic window to evaluate how neural activity relevant to pitch undergo transformation from early sensory to later cognitive stages of processing in a well coordinated hierarchical network that is subject to experience-dependent plasticity. We review recent evidence of language experience-dependent effects in pitch processing based on comparisons of native vs. nonnative speakers of a tonal language from electrophysiological recordings in the auditory brainstem and auditory cortex. We present evidence that shows enhanced representation of linguistically-relevant pitch dimensions or features at both the brainstem and cortical levels with a stimulus-dependent preferential activation of the right hemisphere in native speakers of a tone language. We argue that neural representation of pitch-relevant information in the brainstem and early sensory level processing in the auditory cortex is shaped by the perceptual salience of domain-specific features. While both stages of processing are shaped by language experience, neural representations are transformed and fundamentally different at each biological level of abstraction. The representation of pitch relevant information in the brainstem is more fine-grained spectrotemporally as it reflects sustained neural phase-locking to pitch relevant periodicities contained in the stimulus. In contrast, the cortical pitch relevant neural activity reflects primarily a series of transient temporal neural events synchronized to certain temporal attributes of the pitch contour. We argue that experience-dependent enhancement of pitch representation for Chinese listeners most likely reflects an interaction between higher-level cognitive processes and early sensory-level processing to improve representations of behaviorally-relevant features that contribute optimally to perception. It is our view that long-term experience shapes this adaptive process wherein the top-down connections provide selective gating of inputs to both cortical and subcortical structures to enhance neural responses to specific behaviorally-relevant attributes of the stimulus. A theoretical framework for a neural network is proposed involving coordination between local, feedforward, and feedback components that can account for experience-dependent enhancement of pitch representations at multiple levels of the auditory pathway. The ability to record brainstem and cortical pitch relevant responses concurrently may provide a new window to evaluate the online interplay between feedback, feedforward, and local intrinsic components in the hierarchical processing of pitch relevant information.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380086PMC
December 2014

Language experience enhances early cortical pitch-dependent responses.

J Neurolinguistics 2015 Feb;33:128-148

School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA.

Pitch processing at cortical and subcortical stages of processing is shaped by language experience. We recently demonstrated that specific components of the cortical pitch response (CPR) index the more rapidly-changing portions of the high rising Tone 2 of Mandarin Chinese, in addition to marking pitch onset and sound offset. In this study, we examine how language experience (Mandarin vs. English) shapes the processing of different temporal attributes of pitch reflected in the CPR components using stimuli representative of within-category variants of Tone 2. Results showed that the magnitude of CPR components (Na-Pb and Pb-Nb) and the correlation between these two components and pitch acceleration were stronger for the Chinese listeners compared to English listeners for stimuli that fell within the range of Tone 2 citation forms. Discriminant function analysis revealed that the Na-Pb component was more than twice as important as Pb-Nb in grouping listeners by language affiliation. In addition, a stronger stimulus-dependent, rightward asymmetry was observed for the Chinese group at the temporal, but not frontal, electrode sites. This finding may reflect selective recruitment of experience-dependent, pitch-specific mechanisms in right auditory cortex to extract more complex, time-varying pitch patterns. Taken together, these findings suggest that long-term language experience shapes early sensory level processing of pitch in the auditory cortex, and that the sensitivity of the CPR may vary depending on the relative linguistic importance of specific temporal attributes of dynamic pitch.
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http://dx.doi.org/10.1016/j.jneuroling.2014.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261237PMC
February 2015

Cortical pitch response components show differential sensitivity to native and nonnative pitch contours.

Brain Lang 2014 Nov 10;138:51-60. Epub 2014 Oct 10.

Department of Speech Language Hearing Sciences, Purdue University, USA. Electronic address:

The aim of this study is to evaluate how nonspeech pitch contours of varying shape influence latency and amplitude of cortical pitch-specific response (CPR) components differentially as a function of language experience. Stimuli included time-varying, high rising Mandarin Tone 2 (T2) and linear rising ramp (Linear), and steady-state (Flat). Both the latency and magnitude of CPR components were differentially modulated by (i) the overall trajectory of pitch contours (time-varying vs. steady-state), (ii) their pitch acceleration rates (changing vs. constant), and (iii) their linguistic status (lexical vs. non-lexical). T2 elicited larger amplitude than Linear in both language groups, but size of the effect was larger in Chinese than English. The magnitude of CPR components elicited by T2 were larger for Chinese than English at the right temporal electrode site. Using the CPR, we provide evidence in support of experience-dependent modulation of dynamic pitch contours at an early stage of sensory processing.
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http://dx.doi.org/10.1016/j.bandl.2014.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4335674PMC
November 2014

Cortical pitch response components index stimulus onset/offset and dynamic features of pitch contours.

Neuropsychologia 2014 Jul 18;59:1-12. Epub 2014 Apr 18.

School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA. Electronic address:

Voice pitch is an important information-bearing component of language that is subject to experience dependent plasticity at both early cortical and subcortical stages of processing. We have already demonstrated that pitch onset component (Na) of the cortical pitch response (CPR) is sensitive to flat pitch and its salience … CPR responses from Chinese listeners were elicited by three citation forms varying in pitch acceleration and duration. Results showed that the pitch onset component (Na) was invariant to changes in acceleration. In contrast, Na–Pb and Pb–Nb showed a systematic decrease in the interpeak latency and decrease in amplitude with increase in pitch acceleration that followed the time course of pitch change across the three stimuli. A strong correlation with pitch acceleration was observed for these two components only – a putative index of pitch-relevant neural activity associated with the more rapidly-changing portions of the pitch contour. Pc–Nc marks unambiguously the stimulus offset … and their functional roles as related to sensory and cognitive properties of the stimulus. [Corrected]
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http://dx.doi.org/10.1016/j.neuropsychologia.2014.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169671PMC
July 2014

A functional deficit in the sensorimotor interface component as revealed by oral reading in Thai conduction aphasia.

J Neurolinguistics 2013 May;26(3):337-347

Department of Speech Language Hearing Sciences, Purdue University, 1353 Heavilon Hall, 500 Oval Drive, West Lafayette, IN 47907-2038, USA.

The contemporary view is that a disruption in phonological encoding underlies the speech production deficit in conduction aphasia. We therefore expect to observe a commonality in phonological errors regardless of task - speaking, reading, or writing. A case report is presented of an oral reading task performed by a Thai conduction aphasic with evidence of localized damage in the left temporoparietal zone. He was instructed to read aloud selections from elementary school materials printed in Thai script at his own pace. A phonological analysis of substitution errors revealed that syllable-initial consonants were more vulnerable to disruption than vowels or tones. Tonal errors were seen to be a secondary consequence of a substitution error involving the syllable-initial consonant. His impaired performance is interpreted as evidence in support of a sensorimotor interface system that converts phonological representations derived from visual orthographic input into articulatory motor representations for speech output.
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http://dx.doi.org/10.1016/j.jneuroling.2012.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633224PMC
May 2013

Relationship between brainstem, cortical and behavioral measures relevant to pitch salience in humans.

Neuropsychologia 2012 Oct 23;50(12):2849-2859. Epub 2012 Aug 23.

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN 47907-2038, USA. Electronic address:

Neural representation of pitch-relevant information at both the brainstem and cortical levels of processing is influenced by language or music experience. However, the functional roles of brainstem and cortical neural mechanisms in the hierarchical network for language processing, and how they drive and maintain experience-dependent reorganization are not known. In an effort to evaluate the possible interplay between these two levels of pitch processing, we introduce a novel electrophysiological approach to evaluate pitch-relevant neural activity at the brainstem and auditory cortex concurrently. Brainstem frequency-following responses and cortical pitch responses were recorded from participants in response to iterated rippled noise stimuli that varied in stimulus periodicity (pitch salience). A control condition using iterated rippled noise devoid of pitch was employed to ensure pitch specificity of the cortical pitch response. Neural data were compared with behavioral pitch discrimination thresholds. Results showed that magnitudes of neural responses increase systematically and that behavioral pitch discrimination improves with increasing stimulus periodicity, indicating more robust encoding for salient pitch. Absence of cortical pitch response in the control condition confirms that the cortical pitch response is specific to pitch. Behavioral pitch discrimination was better predicted by brainstem and cortical responses together as compared to each separately. The close correspondence between neural and behavioral data suggest that neural correlates of pitch salience that emerge in early, preattentive stages of processing in the brainstem may drive and maintain with high fidelity the early cortical representations of pitch. These neural representations together contain adequate information for the development of perceptual pitch salience.
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http://dx.doi.org/10.1016/j.neuropsychologia.2012.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483071PMC
October 2012

Distortion products and their influence on representation of pitch-relevant information in the human brainstem for unresolved harmonic complex tones.

Hear Res 2012 Oct 14;292(1-2):26-34. Epub 2012 Aug 14.

School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907-2038, USA.

Pitch experiments aimed at evaluating temporal pitch mechanism(s) often utilize complex sounds with only unresolved harmonic components, and a low-pass noise masker to eliminate the potential contribution of audible distortion products to the pitch percept. Herein we examine how: (i) masker induced reduction of neural distortion products (difference tone: DT; and cubic difference tone: CDT) alters the representation of pitch relevant information in the brainstem; and (ii) the pitch salience is altered when distortion products are reduced and/or eliminated. Scalp recorded brainstem frequency following responses (FFR) were recorded in normal hearing individuals using a complex tone with only unresolved harmonics presented in quiet, and in the presence of a low-pass masker at SNRs of +15, +5, and -5 dB. Difference limen for F0 discrimination (F0 DL) was obtained in quiet and in the presence of low-pass noise. Magnitude of DT components (with the exception of components at F0 and 2F0), and the CDT components decreased with increasing masker level. Neural pitch strength decreased with increasing masker level for both the envelope-related (FFR(ENV)) and spectral-related (FFR(SPEC)) phase-locked activity. Finally, F0 DLs increased with decreasing SNRs suggesting poorer F0 discrimination with reduction of the distortion products. Collectively, these findings support the notion that both DT and CDT, as reflected in the FFR(ENV) and FFR(SPEC), respectively, influence both the brainstem representation of pitch relevant information and the pitch salience of the complex sounds.
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http://dx.doi.org/10.1016/j.heares.2012.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483078PMC
October 2012

Linguistic status of timbre influences pitch encoding in the brainstem.

Neuroreport 2011 Nov;22(16):801-3

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, Indiana 47907-2038, USA.

The aim of this experiment is to assess the effects of the linguistic status of timbre on pitch processing in the brainstem. Brainstem frequency following responses were evoked by the Mandarin high-rising lexical tone superimposed on a native vowel quality ([i]), nonnative vowel quality ([œ]), and iterated rippled noise (nonspeech). Results revealed that voice fundamental frequency magnitudes were larger when concomitant with a native vowel quality compared with either nonnative vowel quality or nonspeech timbre. Such experience-dependent effects suggest that subcortical sensory encoding of pitch interacts with timbre in the human brainstem. As a consequence, responses of the perceptual system can be differentially shaped to pitch patterns in relation to the linguistic status of their concomitant timbre.
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http://dx.doi.org/10.1097/WNR.0b013e32834b2996DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3188353PMC
November 2011

Musicians demonstrate experience-dependent brainstem enhancement of musical scale features within continuously gliding pitch.

Neurosci Lett 2011 Oct 30;503(3):203-7. Epub 2011 Aug 30.

Department of Speech, Language, and Hearing Sciences, Purdue University, W. Lafayette, IN 47907, USA.

In contrast to language, where pitch patterns consist of continuous and curvilinear contours, musical pitch consists of relatively discrete, stair-stepped sequences of notes. Behavioral and neurophysiological studies suggest that both tone-language and music experience enhance the representation of pitch cues associated with a listener's domain of expertise, e.g., curvilinear pitch in language, discrete scale steps in music. We compared brainstem frequency-following responses (FFRs) of English-speaking musicians (musical pitch experience) and native speakers of Mandarin Chinese (linguistic pitch experience) elicited by rising and falling tonal sweeps that are exemplary of Mandarin tonal contours but uncharacteristic of the pitch patterns typically found in music. In spite of musicians' unfamiliarity with such glides, we find that their brainstem FFRs show enhancement of the stimulus where the curvilinear sweep traverses discrete notes along the diatonic musical scale. This enhancement was note specific in that it was not observed immediately preceding or following the scale tone of interest (passing note). No such enhancements were observed in Chinese listeners. These findings suggest that the musician's brainstem may be differentially tuned by long-term exposure to the pitch patterns inherent to music, extracting pitch in relation to a fixed, hierarchical scale.
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http://dx.doi.org/10.1016/j.neulet.2011.08.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3196385PMC
October 2011

Musicians and tone-language speakers share enhanced brainstem encoding but not perceptual benefits for musical pitch.

Brain Cogn 2011 Oct 10;77(1):1-10. Epub 2011 Aug 10.

Department of Speech, Language, and Hearing Sciences, Purdue University, W. Lafayette, IN 47907, USA.

Behavioral and neurophysiological transfer effects from music experience to language processing are well-established but it is currently unclear whether or not linguistic expertise (e.g., speaking a tone language) benefits music-related processing and its perception. Here, we compare brainstem responses of English-speaking musicians/non-musicians and native speakers of Mandarin Chinese elicited by tuned and detuned musical chords, to determine if enhancements in subcortical processing translate to improvements in the perceptual discrimination of musical pitch. Relative to non-musicians, both musicians and Chinese had stronger brainstem representation of the defining pitches of musical sequences. In contrast, two behavioral pitch discrimination tasks revealed that neither Chinese nor non-musicians were able to discriminate subtle changes in musical pitch with the same accuracy as musicians. Pooled across all listeners, brainstem magnitudes predicted behavioral pitch discrimination performance but considering each group individually, only musicians showed connections between neural and behavioral measures. No brain-behavior correlations were found for tone language speakers or non-musicians. These findings point to a dissociation between subcortical neurophysiological processing and behavioral measures of pitch perception in Chinese listeners. We infer that sensory-level enhancement of musical pitch information yields cognitive-level perceptual benefits only when that information is behaviorally relevant to the listener.
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http://dx.doi.org/10.1016/j.bandc.2011.07.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159732PMC
October 2011

Functional ear (a)symmetry in brainstem neural activity relevant to encoding of voice pitch: a precursor for hemispheric specialization?

Brain Lang 2011 Dec 11;119(3):226-31. Epub 2011 Jun 11.

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN, USA 47907-2038, USA.

Pitch processing is lateralized to the right hemisphere; linguistic pitch is further mediated by left cortical areas. This experiment investigates whether ear asymmetries vary in brainstem representation of pitch depending on linguistic status. Brainstem frequency-following responses (FFRs) were elicited by monaural stimulation of the left and right ear of 15 native speakers of Mandarin Chinese using two synthetic speech stimuli that differ in linguistic status of tone. One represented a native lexical tone (Tone 2: T2); the other, T2', a nonnative variant in which the pitch contour was a mirror image of T2 with the same starting and ending frequencies. Two 40-ms portions of f(0) contours were selected in order to compare two regions (R1, early; R2 late) differing in pitch acceleration rate and perceptual saliency. In R2, linguistic status effects revealed that T2 exhibited a larger degree of FFR rightward ear asymmetry as reflected in f(0) amplitude relative to T2'. Relative to midline (ear asymmetry=0), the only ear asymmetry reaching significance was that favoring left ear stimulation elicited by T2'. By left- and right-ear stimulation separately, FFRs elicited by T2 were larger than T2' in the right ear only. Within T2', FFRs elicited by the earlier region were larger than the later in both ears. Within T2, no significant differences in FFRS were observed between regions in either ear. Collectively, these findings support the idea that origins of cortical processing preferences for perceptually-salient portions of pitch are rooted in early, preattentive stages of processing in the brainstem.
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http://dx.doi.org/10.1016/j.bandl.2011.05.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3193894PMC
December 2011

Enhanced brainstem encoding predicts musicians' perceptual advantages with pitch.

Eur J Neurosci 2011 Feb 29;33(3):530-8. Epub 2010 Dec 29.

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN, USA.

Important to Western tonal music is the relationship between pitches both within and between musical chords; melody and harmony are generated by combining pitches selected from the fixed hierarchical scales of music. It is of critical importance that musicians have the ability to detect and discriminate minute deviations in pitch in order to remain in tune with other members of their ensemble. Event-related potentials indicate that cortical mechanisms responsible for detecting mistuning and violations in pitch are more sensitive and accurate in musicians as compared with non-musicians. The aim of the present study was to address whether this superiority is also present at a subcortical stage of pitch processing. Brainstem frequency-following responses were recorded from musicians and non-musicians in response to tuned (i.e. major and minor) and detuned (± 4% difference in frequency) chordal arpeggios differing only in the pitch of their third. Results showed that musicians had faster neural synchronization and stronger brainstem encoding for defining characteristics of musical sequences regardless of whether they were in or out of tune. In contrast, non-musicians had relatively strong representation for major/minor chords but showed diminished responses for detuned chords. The close correspondence between the magnitude of brainstem responses and performance on two behavioral pitch discrimination tasks supports the idea that musicians' enhanced detection of chordal mistuning may be rooted at pre-attentive, sensory stages of processing. Findings suggest that perceptually salient aspects of musical pitch are not only represented at subcortical levels but that these representations are also enhanced by musical experience.
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http://dx.doi.org/10.1111/j.1460-9568.2010.07527.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3059719PMC
February 2011

Language-dependent pitch encoding advantage in the brainstem is not limited to acceleration rates that occur in natural speech.

Brain Lang 2010 Sep 8;114(3):193-8. Epub 2010 Jun 8.

Department of Speech Language Hearing Sciences, Purdue University, USA.

Experience-dependent enhancement of neural encoding of pitch in the auditory brainstem has been observed for only specific portions of native pitch contours exhibiting high rates of pitch acceleration, irrespective of speech or nonspeech contexts. This experiment allows us to determine whether this language-dependent advantage transfers to acceleration rates that extend beyond the pitch range of natural speech. Brainstem frequency-following responses (FFRs) were recorded from Chinese and English participants in response to four, 250-ms dynamic click-train stimuli with different rates of pitch acceleration. The maximum pitch acceleration rates in a given stimulus ranged from low (0.3Hz/ms; Mandarin Tone 2) to high (2.7Hz/ms; 2 octaves). Pitch strength measurements were computed from the FFRs using autocorrelation algorithms with an analysis window centered at the point of maximum pitch acceleration in each stimulus. Between-group comparisons of pitch strength revealed that Chinese exhibit more robust pitch representation than English across all four acceleration rates. Regardless of language group, pitch strength was greater in response to acceleration rates within or proximal to natural speech relative to those beyond its range. Though both groups showed decreasing pitch strength with increasing acceleration rates, pitch representations of the Chinese group were more resistant to degradation. FFR spectral data were complementary across acceleration rates. These findings demonstrate that perceptually salient pitch cues associated with lexical tone influence brainstem pitch extraction not only in the speech domain, but also in auditory signals that clearly fall outside the range of dynamic pitch that a native listener is exposed to.
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http://dx.doi.org/10.1016/j.bandl.2010.05.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913296PMC
September 2010

Hemispheric asymmetries in phonological processing of tones versus segmental units.

Neuroreport 2010 Jul;21(10):690-4

Research Center for Psychological Application, South China Normal University, Guangzhou, PR China.

The aim of this functional magnetic resonance imaging study is to identify neuroanatomical substrates underlying phonological processing of segmental (consonant, rhyme) and suprasegmental (tone) units. An auditory verbal recognition paradigm was used in which native speakers of Mandarin Chinese were required to match a phonological unit that occurs in a list of three syllables to the corresponding unit of a following probe. The results show that hemispheric asymmetries arise depending on the type of phonological unit. In direct contrasts between phonological units, tones, relative to consonants and rhymes, yield increased activation in frontoparietal areas of the right hemisphere. This finding indicates that the cortical circuitry subserving lexical tones differs from that of consonants or rhymes.
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http://dx.doi.org/10.1097/WNR.0b013e32833b0a10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890240PMC
July 2010

Neural representation of pitch salience in the human brainstem revealed by psychophysical and electrophysiological indices.

Hear Res 2010 Sep 10;268(1-2):60-6. Epub 2010 May 10.

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, IN 47907-2038, USA.

Acoustically, pitch is related to the temporal regularity or periodicity of a sound. Perceptual and electrophysiologic studies have revealed that pitch salience grows systematically with increasing stimulus periodicity. The aim of this study is to show that information relevant to pitch salience is already encoded in the phase-locked neural activity of brainstem neurons in order to demonstrate that the neural manifestation of pitch salience emerges well before cortical involvement. Brainstem frequency following responses (FFRs) were recorded from participants in response to linguistic tones, which varied only in their degree of pitch salience. Neural pitch strength was computed from FFRs using autocorrelation algorithms. In addition, behavioral frequency difference limens (F0 DLs) were measured from each participant to obtain a perceptual estimate related to pitch salience. Brainstem neural pitch strength increased systematically with increasing temporal regularity in stimulus periodicity, indicating more robust encoding for salient pitch. F0 DLs decreased with increasing stimulus periodicity revealing better pitch change detection for more salient stimuli. FFR neural pitch strength and behavioral F0 DLs were negatively correlated suggesting that subcortical processing can, in part, predict an individual's behavioral judgments of pitch salience. These data imply that changes to the acoustic periodicity of a stimulus directly influence brainstem encoding and the corresponding behavioral responses to pitch. We infer that information related to pitch salience may emerge early along the auditory pathway and is likely rooted in pre-attentive, sensory-level processing.
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http://dx.doi.org/10.1016/j.heares.2010.04.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171186PMC
September 2010

The effects of tone language experience on pitch processing in the brainstem.

J Neurolinguistics 2010 Jan;23(1):81-95

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, Indiana, USA.

Neural encoding of pitch in the auditory brainstem is shaped by long-term experience with language. The aim herein was to determine to what extent this experience-dependent effect is specific to a particular language. Analysis of variance of brainstem responses to Mandarin and Thai tones revealed that regardless of language identity, pitch-tracking accuracy of whole tones was higher in the two tone language groups (Chinese, Thai) compared to the non-tone language group (English), and that pitch strength of 40-ms tonal sections was generally more robust in tone relative to non-tone languages. Discriminant analysis of tonal sections, as defined by variation in direction and degree of slope, showed that moderate rising pitch was the most important variable for classifying English, Chinese, and Thai participants into their respective groups. We conclude that language-dependent enhancement of pitch representation transfers to other languages with similar phonological systems. From a neurobiological perspective, these findings suggest that neural mechanisms local to the brainstem are tuned for processing pitch dimensions that are perceptually salient depending upon the melodic patterns of a language.
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http://dx.doi.org/10.1016/j.jneuroling.2009.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805250PMC
January 2010

Brainstem pitch representation in native speakers of Mandarin is less susceptible to degradation of stimulus temporal regularity.

Brain Res 2010 Feb 2;1313:124-33. Epub 2009 Dec 2.

Department of Speech Language Hearing Sciences, Purdue University, 1353 Heavilon Hall, 500 Oval Drive, West Lafayette, IN 47907-2038, USA.

It has been demonstrated that neural encoding of pitch in the auditory brainstem is shaped by long-term experience with language. To date, however, all stimuli have exhibited a high degree of pitch saliency. The experimental design herein permits us to determine whether experience-dependent pitch representation in the brainstem is less susceptible to progressive degradation of the temporal regularity of iterated rippled noise (IRN). Brainstem responses were recorded from Chinese and English participants in response to IRN homologues of Mandarin Tone 2 (T2(IRN)). Six different iterations steps were utilized to systematically vary the degree of temporal regularity in the fine structure of the IRN stimuli to produce a pitch salience continuum ranging from low to high. Pitch-tracking accuracy and pitch strength were computed from the brainstem responses using autocorrelation algorithms. Analysis of variance of brainstem responses to T2(IRN) revealed that pitch-tracking accuracy is higher in the native tone language group (Chinese) relative to the non-tone language group (English) except for the three lowest steps along the continuum, and moreover, that pitch strength is greater in the Chinese group even in severely degraded stimuli for two of the six 40-ms sections of T2(IRN) that exhibit rapid changes in pitch. For these same two sections, exponential time constants for the stimulus continuum revealed that pitch strength emerges 2-3 times faster in the tone language than in the non-tone language group as a function of increasing pitch salience. These findings altogether suggest that experience-dependent brainstem mechanisms for pitch are especially sensitive to those dimensions of tonal contours that provide cues of high perceptual saliency in degraded as well as normal listening conditions.
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http://dx.doi.org/10.1016/j.brainres.2009.11.061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2838171PMC
February 2010

Cross-domain effects of music and language experience on the representation of pitch in the human auditory brainstem.

J Cogn Neurosci 2011 Feb 19;23(2):425-34. Epub 2009 Nov 19.

Purdue University, West Lafayette, IN 47907-2038, USA.

Neural encoding of pitch in the auditory brainstem is known to be shaped by long-term experience with language or music, implying that early sensory processing is subject to experience-dependent neural plasticity. In language, pitch patterns consist of sequences of continuous, curvilinear contours; in music, pitch patterns consist of relatively discrete, stair-stepped sequences of notes. The primary aim was to determine the influence of domain-specific experience (language vs. music) on the encoding of pitch in the brainstem. Frequency-following responses were recorded from the brainstem in native Chinese, English amateur musicians, and English nonmusicians in response to iterated rippled noise homologues of a musical pitch interval (major third; M3) and a lexical tone (Mandarin tone 2; T2) from the music and language domains, respectively. Pitch-tracking accuracy (whole contour) and pitch strength (50 msec sections) were computed from the brainstem responses using autocorrelation algorithms. Pitch-tracking accuracy was higher in the Chinese and musicians than in the nonmusicians across domains. Pitch strength was more robust across sections in musicians than in nonmusicians regardless of domain. In contrast, the Chinese showed larger pitch strength, relative to nonmusicians, only in those sections of T2 with rapid changes in pitch. Interestingly, musicians exhibited greater pitch strength than the Chinese in one section of M3, corresponding to the onset of the second musical note, and two sections within T2, corresponding to a note along the diatonic musical scale. We infer that experience-dependent plasticity of brainstem responses is shaped by the relative saliency of acoustic dimensions underlying the pitch patterns associated with a particular domain.
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http://dx.doi.org/10.1162/jocn.2009.21362DOI Listing
February 2011

Sensory processing of linguistic pitch as reflected by the mismatch negativity.

Ear Hear 2009 Oct;30(5):552-8

Department of Speech Language Hearing Sciences, Purdue University, West Lafayette, Indiana 47907-2038, USA.

Objective: To assess the extent to which acoustic and phonetic change-detection processes contribute to the mismatch negativity (MMN) to linguistic pitch contours.

Design: MMN was elicited from Mandarin and English speakers using a passive oddball paradigm. Two oddball conditions were constructed. In one condition (T1/T2i), the Mandarin high-level tone (T1) was compared with a convex high-rising tone (inverted T2, henceforth referred to as T2i) that occurs as a contextual variant of T1 in running speech. In the other (T2/T2i), the concave high-rising tone (T2) was compared with T2i. Phonetically, T1/T2i represents a within-category contrast for native speakers, whereas T2/T2i represents a between-category contrast. The between-category pair (T2/T2i), however, is more similar acoustically than the within-category pair (T1/T2i). In an attention-demanding behavioral paradigm, the same speakers also performed an auditory discrimination task to determine the perceptual distinctiveness of the two tonal pairs.

Results: Results revealed that the Chinese group, relative to the English, showed larger MMN responses and earlier peak latencies for both conditions, indicating experience-dependent enhancement in representing linguistically relevant pitch contours. At attentive stages of processing, however, the Chinese group was less accurate than the English in discriminating the within-category contrast (T1-T2i).

Conclusions: These findings demonstrate that experience-dependent neural effects at early preattentive stages of processing may be driven primarily by acoustic features of pitch contours that occur in natural speech. At attentive stages of processing, perception is strongly influenced by tonal categories and their relations to one another. The MMN is a useful index for examining long-term plasticity to linguistically relevant acoustic features.
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http://dx.doi.org/10.1097/AUD.0b013e3181a7e1c2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2804883PMC
October 2009

The role of the auditory brainstem in processing linguistically-relevant pitch patterns.

Brain Lang 2009 Sep 14;110(3):135-48. Epub 2009 Apr 14.

Department of Speech Language Hearing Sciences, Purdue University, 1353 Heavilon Hall, 500 Oval Drive, West Lafayette, IN 47907-2038, USA.

Historically, the brainstem has been neglected as a part of the brain involved in language processing. We review recent evidence of language-dependent effects in pitch processing based on comparisons of native vs. nonnative speakers of a tonal language from electrophysiological recordings in the auditory brainstem. We argue that there is enhancing of linguistically-relevant pitch dimensions or features well before the auditory signal reaches the cerebral cortex. We propose that long-term experience with a tone language sharpens the tuning characteristics of neurons along the pitch axis with enhanced sensitivity to linguistically-relevant, rapidly changing sections of pitch contours. Though not specific to a speech context, experience-dependent brainstem mechanisms for pitch representation are clearly sensitive to particular aspects of pitch contours that native speakers of a tone language have been exposed to. Such experience-dependent effects on lower-level sensory processing are compatible with more integrated, hierarchically organized pathways to language and the brain.
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http://dx.doi.org/10.1016/j.bandl.2009.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2731823PMC
September 2009

Experience-dependent neural representation of dynamic pitch in the brainstem.

Neuroreport 2009 Mar;20(4):408-13

Department of Speech Language Hearing Sciences, Purdue University, Indiana 47907-2038, USA.

Brainstem frequency-following responses were recorded from Chinese and English participants in response to an iterated rippled noise homologue of Mandarin Tone 2 (T2) and linear and inverted curvilinear variants. Pitch-tracking accuracy and pitch strength analyses showed advantages for the Chinese group over the English in response to T2 only. Pitch strength was larger for the Chinese group in rapidly changing sections of T2 compared with corresponding sections of a linear ramp. We conclude that experience-dependent neural plasticity at subcortical levels of representation is highly sensitive to specific features of pitch patterns in one's native language. Such experience-dependent effects suggest that subcortical sensory encoding interacts with cognitive processing in the cerebral cortex to shape the perceptual system's response to pitch patterns.
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http://dx.doi.org/10.1097/WNR.0b013e3283263000DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2692950PMC
March 2009
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