scholarly journals Adaptation to mis-pronounced speech: evidence for a prefrontal-cortex repair mechanism

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Esti Blanco-Elorrieta ◽  
Laura Gwilliams ◽  
Alec Marantz ◽  
Liina Pylkkänen
Keyword(s):  
Prefrontal Cortex ◽  
Auditory Cortex ◽  
Acoustic Signal ◽  
Superior Temporal Gyrus ◽  
Matching Task ◽  
Repair Mechanism ◽  
Top Down ◽  
Exchange Of Information ◽  
Auditory Cortices ◽  
Over Time

AbstractSpeech is a complex and ambiguous acoustic signal that varies significantly within and across speakers. Despite the processing challenge that such variability poses, humans adapt to systematic variations in pronunciation rapidly. The goal of this study is to uncover the neurobiological bases of the attunement process that enables such fluent comprehension. Twenty-four native English participants listened to words spoken by a “canonical” American speaker and two non-canonical speakers, and performed a word-picture matching task, while magnetoencephalography was recorded. Non-canonical speech was created by including systematic phonological substitutions within the word (e.g. [s] → [sh]). Activity in the auditory cortex (superior temporal gyrus) was greater in response to substituted phonemes, and, critically, this was not attenuated by exposure. By contrast, prefrontal regions showed an interaction between the presence of a substitution and the amount of exposure: activity decreased for canonical speech over time, whereas responses to non-canonical speech remained consistently elevated. Grainger causality analyses further revealed that prefrontal responses serve to modulate activity in auditory regions, suggesting the recruitment of top-down processing to decode non-canonical pronunciations. In sum, our results suggest that the behavioural deficit in processing mispronounced phonemes may be due to a disruption to the typical exchange of information between the prefrontal and auditory cortices as observed for canonical speech.

scholarly journals Neural adaptation to accented speech: prefrontal cortex aids attunement in auditory cortices

2019 ◽  
Author(s):  
Esti Blanco-Elorrieta ◽  
Laura Gwilliams ◽  
Alec Marantz ◽  
Liina Pylkkänen
Keyword(s):  
Prefrontal Cortex ◽  
Auditory Cortex ◽  
Superior Temporal Gyrus ◽  
Matching Task ◽  
Speech Comprehension ◽  
Accented Speech ◽  
Human Ability ◽  
Auditory Cortices ◽  
Dynamic Exchange ◽  
Over Time

ABSTRACTSpeech is a complex and ambiguous acoustic signal that varies significantly within and across speakers. A prevalent and ubiquitous example of such variation is accented speech, to which humans adapt extremely rapidly. The goal of this study is to uncover the neurobiological bases of the attunement process that enables such fluent comprehension. Twenty-four native English participants listened to words spoken by an unaccented “canonical” American talker and two “accented” talkers, and performed a word-picture matching task, while magnetoencephalography (MEG) was recorded. Accented speech was created by including systematic phonological substitutions within the word (e.g. [s] → [sh]). Activity in the auditory cortex (superior temporal gyrus) was greater for accented speech, but, critically, this was not attenuated by exposure. By contrast, prefrontal regions showed an interaction between the presence of an accent and amount of exposure: while activity decreased for canonical speech over time, responses to accented speech remained consistently elevated. Grainger causality analyses further revealed that prefrontal responses serve to modulate activity in auditory regions, suggesting the recruitment of top-down processing to decode accented signal. In sum, our results show that accented speech does not elicit the same prefrontal reduction in amplitude over time that unaccented speech does, and points to a dynamic exchange of information between the prefrontal and auditory cortices in order to recalculate phonetic classification and subsequent identification of lexical items.Significance statementHuman ability to adapt to different people’s idiosyncratic pronunciations is a hallmark of speech comprehension. This study aims to address whether adaptation to speakers’ accents manifests itself at the perceptual level (i.e. through adaptation of low-level neural responses in the auditory cortex) or at the post-perceptual level (i.e. higher-order regions correcting the sensory signal received from auditory cortex). Our results support the post-perceptual hypothesis: we found that responses in auditory cortex emitted an error-like signal that was invariant to exposure; whereas responses in the prefrontal cortex were modulated by exposure. These findings provide initial insight into accent adaptation, and illuminate the computational stages supporting speech comprehension more generally.

Auditory-Somatosensory Multisensory Processing in Auditory Association Cortex: An fMRI Study

2002 ◽  
Vol 88 (1) ◽  
pp. 540-543 ◽  
Author(s):  
John J. Foxe ◽  
Glenn R. Wylie ◽  
Antigona Martinez ◽  
Charles E. Schroeder ◽  
Daniel C. Javitt ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Multisensory Integration ◽  
Multisensory Processing ◽  
Primary Auditory Cortex ◽  
Superior Temporal Gyrus ◽  
Brain Regions ◽  
Association Cortex ◽  
Convergence Region ◽  
Auditory Cortices ◽  
Auditory Association Cortex

Using high-field (3 Tesla) functional magnetic resonance imaging (fMRI), we demonstrate that auditory and somatosensory inputs converge in a subregion of human auditory cortex along the superior temporal gyrus. Further, simultaneous stimulation in both sensory modalities resulted in activity exceeding that predicted by summing the responses to the unisensory inputs, thereby showing multisensory integration in this convergence region. Recently, intracranial recordings in macaque monkeys have shown similar auditory-somatosensory convergence in a subregion of auditory cortex directly caudomedial to primary auditory cortex (area CM). The multisensory region identified in the present investigation may be the human homologue of CM. Our finding of auditory-somatosensory convergence in early auditory cortices contributes to mounting evidence for multisensory integration early in the cortical processing hierarchy, in brain regions that were previously assumed to be unisensory.

scholarly journals All in thirty milliseconds: EEG evidence of hierarchical and asymmetric phonological encoding of vowels

2018 ◽  
Author(s):  
Anna Dora Manca ◽  
Francesco Di Russo ◽  
Francesco Sigona ◽  
Mirko Grimaldi
Keyword(s):  
Auditory Cortex ◽  
Speech Processing ◽  
Late Phase ◽  
Primary Auditory Cortex ◽  
Superior Temporal Gyrus ◽  
Phonological Representations ◽  
Distinctive Features ◽  
Feature Representations ◽  
Auditory Cortices ◽  
Anterior Posterior

How the brain encodes the speech acoustic signal into phonological representations (distinctive features) is a fundamental question for the neurobiology of language. Whether this process is characterized by tonotopic maps in primary or secondary auditory areas, with bilateral or leftward activity, remains a long-standing challenge. Magnetoencephalographic and ECoG studies have previously failed to show hierarchical and asymmetric hints for speech processing. We employed high-density electroencephalography to map the Salento Italian vowel system onto cortical sources using the N1 auditory evoked component. We found evidence that the N1 is characterized by hierarchical and asymmetric indexes structuring vowels representation. We identified them with two N1 subcomponents: the typical N1 (N1a) peaking at 125-135 ms and localized in the primary auditory cortex bilaterally with a tangential distribution and a late phase of the N1 (N1b) peaking at 145-155 ms and localized in the left superior temporal gyrus with a radial distribution. Notably, we showed that the processing of distinctive feature representations begins early in the primary auditory cortex and carries on in the superior temporal gyrus along lateral-medial, anterior-posterior and inferior-superior gradients. It is the dynamical interface of both auditory cortices and the interaction effects between different distinctive features that generate the categorical representations of vowels.

Tracking the Effects of Top–Down Attention on Word Discrimination Using Frequency-tagged Neuromagnetic Responses

2020 ◽  
Vol 32 (5) ◽  
pp. 877-888
Author(s):  
Maxime Niesen ◽  
Marc Vander Ghinst ◽  
Mathieu Bourguignon ◽  
Vincent Wens ◽  
Julie Bertels ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Speech Processing ◽  
Brain Activity ◽  
Inferior Frontal Gyrus ◽  
Superior Temporal Gyrus ◽  
Middle Temporal Gyrus ◽  
Attention Condition ◽  
Top Down ◽  
Early Step ◽  
Word Discrimination

Discrimination of words from nonspeech sounds is essential in communication. Still, how selective attention can influence this early step of speech processing remains elusive. To answer that question, brain activity was recorded with magnetoencephalography in 12 healthy adults while they listened to two sequences of auditory stimuli presented at 2.17 Hz, consisting of successions of one randomized word (tagging frequency = 0.54 Hz) and three acoustically matched nonverbal stimuli. Participants were instructed to focus their attention on the occurrence of a predefined word in the verbal attention condition and on a nonverbal stimulus in the nonverbal attention condition. Steady-state neuromagnetic responses were identified with spectral analysis at sensor and source levels. Significant sensor responses peaked at 0.54 and 2.17 Hz in both conditions. Sources at 0.54 Hz were reconstructed in supratemporal auditory cortex, left superior temporal gyrus (STG), left middle temporal gyrus, and left inferior frontal gyrus. Sources at 2.17 Hz were reconstructed in supratemporal auditory cortex and STG. Crucially, source strength in the left STG at 0.54 Hz was significantly higher in verbal attention than in nonverbal attention condition. This study demonstrates speech-sensitive responses at primary auditory and speech-related neocortical areas. Critically, it highlights that, during word discrimination, top–down attention modulates activity within the left STG. This area therefore appears to play a crucial role in selective verbal attentional processes for this early step of speech processing.

scholarly journals Topography of speech-related acoustic and phonological feature encoding throughout the human core and parabelt auditory cortex

2020 ◽  
Author(s):  
Liberty S. Hamilton ◽  
Yulia Oganian ◽  
Edward F. Chang
Keyword(s):  
Auditory Cortex ◽  
Functional Organization ◽  
Functional Characterization ◽  
Spectral Feature ◽  
Superior Temporal Gyrus ◽  
Relative Pitch ◽  
Phonological Features ◽  
Superior Surface ◽  
Human Auditory Cortex ◽  
Auditory Cortices

AbstractSpeech perception involves the extraction of acoustic and phonological features from the speech signal. How those features map out across the human auditory cortex is unknown. Complementary to noninvasive imaging, the high spatial and temporal resolution of intracranial recordings has greatly contributed to recent advances in our understanding. However, these approaches are typically limited by piecemeal sampling of the expansive human temporal lobe auditory cortex. Here, we present a functional characterization of local cortical encoding throughout all major regions of the primary and non-primary human auditory cortex. We overcame previous limitations by using rare direct recordings from the surface of the temporal plane after surgical microdissection of the deep Sylvian fissure between the frontal and temporal lobes. We recorded neural responses using simultaneous high-density direct recordings over the left temporal plane and the lateral superior temporal gyrus, while participants listened to natural speech sentences and pure tone stimuli. We found an anatomical separation of simple spectral feature tuning, including tuning for pure tones and absolute pitch, on the superior surface of the temporal plane, and complex tuning for phonological features, relative pitch and speech amplitude modulations on lateral STG. Broadband onset responses are unique to posterior STG and not found elsewhere in auditory cortices. This onset region is functionally distinct from the rest of STG, with latencies similar to primary auditory areas. These findings reveal a new, detailed functional organization of response selectivity to acoustic and phonological features in speech throughout the human auditory cortex.

scholarly journals Representation of speech categories in the primate auditory cortex

2011 ◽  
Vol 105 (6) ◽  
pp. 2634-2646 ◽  
Author(s):  
Joji Tsunada ◽  
Jung Hoon Lee ◽  
Yale E. Cohen
Keyword(s):  
Prefrontal Cortex ◽  
Auditory Cortex ◽  
Auditory Processing ◽  
Nonhuman Primates ◽  
Superior Temporal Gyrus ◽  
Auditory Pathway ◽  
Auditory Stimuli ◽  
The Core ◽  
Ventral Pathway

A “ventral” auditory pathway in nonhuman primates that originates in the core auditory cortex and ends in the prefrontal cortex is thought to be involved in components of nonspatial auditory processing. Previous work from our laboratory has indicated that neurons in the prefrontal cortex reflect monkeys' decisions during categorical judgments. Here, we tested the role of the superior temporal gyrus (STG), a region of the secondary auditory cortex that is part of this ventral pathway, during similar categorical judgments. While monkeys participated in a match-to-category task and reported whether two consecutive auditory stimuli belonged to the same category or to different categories, we recorded spiking activity from STG neurons. The auditory stimuli were morphs of two human-speech sounds ( bad and dad). We found that STG neurons represented auditory categories. However, unlike activity in the prefrontal cortex, STG activity was not modulated by the monkeys' behavioral reports (choices). This finding is consistent with the anterolateral STG's role as a part of functional circuit involved in the coding, representation, and perception of the nonspatial features of an auditory stimulus.

scholarly journals Ordering global governance complexes: The evolution of the governance complex for international civil aviation

2021 ◽  
Author(s):  
Mette Eilstrup-Sangiovanni
Keyword(s):  
Global Governance ◽  
International Institutions ◽  
Historical Data ◽  
Civil Aviation ◽  
Top Down ◽  
Bottom Up ◽  
Governance Systems ◽  
Governance Effectiveness ◽  
Political Agents ◽  
Over Time

AbstractMany observers worry that growing numbers of international institutions with overlapping functions undermine governance effectiveness via duplication, inconsistency and conflict. Such pessimistic assessments may undervalue the mechanisms available to states and other political agents to reduce conflictual overlap and enhance inter-institutional synergy. Drawing on historical data I examine how states can mitigate conflict within Global Governance Complexes (GGCs) by dissolving or merging existing institutions or by re-configuring their mandates. I further explore how “order in complexity” can emerge through bottom-up processes of adaptation in lieu of state-led reform. My analysis supports three theoretical claims: (1) states frequently refashion governance complexes “top-down” in order to reduce conflictual overlap; (2) “top-down” restructuring and “bottom-up” adaptation present alternative mechanisms for ordering relations among component institutions of GGCs; (3) these twin mechanisms ensure that GGCs tend to (re)produce elements of order over time–albeit often temporarily. Rather than evolving towards ever-greater fragmentation and disorder, complex governance systems thus tend to fluctuate between greater or lesser integration and (dis)order.

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