scholarly journals One Way or Another: Cortical Language Areas Flexibly Adapt Processing Strategies to Perceptual And Contextual Properties of Speech

2021 ◽  
Author(s):  
Anastasia Klimovich-Gray ◽  
Ander Barrena ◽  
Eneko Agirre ◽  
Nicola Molinaro
Keyword(s):  
Brain Activity ◽  
Speech Rate ◽  
Semantic Content ◽  
Cortical Circuits ◽  
Top Down ◽  
Temporal Regularity ◽  
Processing Strategies ◽  
Delta Band ◽  
Language Areas ◽  
Normal Speech

Abstract Cortical circuits rely on the temporal regularities of speech to optimize signal parsing for sound-to-meaning mapping. Bottom-up speech analysis is accelerated by top–down predictions about upcoming words. In everyday communications, however, listeners are regularly presented with challenging input—fluctuations of speech rate or semantic content. In this study, we asked how reducing speech temporal regularity affects its processing—parsing, phonological analysis, and ability to generate context-based predictions. To ensure that spoken sentences were natural and approximated semantic constraints of spontaneous speech we built a neural network to select stimuli from large corpora. We analyzed brain activity recorded with magnetoencephalography during sentence listening using evoked responses, speech-to-brain synchronization and representational similarity analysis. For normal speech theta band (6.5–8 Hz) speech-to-brain synchronization was increased and the left fronto-temporal areas generated stronger contextual predictions. The reverse was true for temporally irregular speech—weaker theta synchronization and reduced top–down effects. Interestingly, delta-band (0.5 Hz) speech tracking was greater when contextual/semantic predictions were lower or if speech was temporally jittered. We conclude that speech temporal regularity is relevant for (theta) syllabic tracking and robust semantic predictions while the joint support of temporal and contextual predictability reduces word and phrase-level cortical tracking (delta).

scholarly journals Delta band activity contributes to the identification of command following in disorder of consciousness

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gonzalo Rivera-Lillo ◽  
Emmanuel A. Stamatakis ◽  
Tristan A. Bekinschtein ◽  
David K. Menon ◽  
Srivas Chennu
Keyword(s):  
Functional Neuroimaging ◽  
Brain Activity ◽  
Disorder Of Consciousness ◽  
Fine Grained ◽  
Electrical Brain Activity ◽  
Delta Band ◽  
Delta Modulation ◽  
Command Following ◽  
Band Activity

AbstractThe overt or covert ability to follow commands in patients with disorders of consciousness is considered a sign of awareness and has recently been defined as cortically mediated behaviour. Despite its clinical relevance, the brain signatures of the perceptual processing supporting command following have been elusive. This multimodal study investigates the temporal spectral pattern of electrical brain activity to identify features that differentiated healthy controls from patients both able and unable to follow commands. We combined evidence from behavioural assessment, functional neuroimaging during mental imagery and high-density electroencephalography collected during auditory prediction, from 21 patients and 10 controls. We used a penalised regression model to identify command following using features from electroencephalography. We identified seven well-defined spatiotemporal signatures in the delta, theta and alpha bands that together contribute to identify DoC subjects with and without the ability to follow command, and further distinguished these groups of patients from controls. A fine-grained analysis of these seven signatures enabled us to determine that increased delta modulation at the frontal sensors was the main feature in command following patients. In contrast, higher frequency theta and alpha modulations differentiated controls from both groups of patients. Our findings highlight a key role of spatiotemporally specific delta modulation in supporting cortically mediated behaviour including the ability to follow command. However, patients able to follow commands nevertheless have marked differences in brain activity in comparison with healthy volunteers.

Evidence motivating consideration of an alternative approach

Speech Timing ◽  
2020 ◽  
pp. 49-63
Author(s):  
Alice Turk ◽  
Stefanie Shattuck-Hufnagel
Keyword(s):  
Motor Control ◽  
Speech Rate ◽  
Speech Motor Control ◽  
Articulatory Phonology ◽  
Fitts Law ◽  
Alternative Approach ◽  
Principled Explanation ◽  
Spatial Interference ◽  
Normal Speech ◽  
Speech Motor

This chapter begins to motivate the development of an alternative approach to speech production by pointing out three potential difficulties with the highly-successful Articulatory Phonology/Task Dynamics approach. First, it discusses the extensive nature of modifications to AP/TD default specifications required to account for the wide variety of surface phonetic forms. The need for a large number of adjustments in AP/TD raises questions about the appropriateness of the AP/TD default-adjustment approach, which would have been more appropriate if the default, non-prominent, phrase-medial, normal-speech-rate specifications could be used most of the time. Second, it discusses the lack of a principled explanation for behaviors described by Fitts’ law. While the theory can accommodate some aspects of Fitts’ law, others are not explained or accommodated. Finally, it suggests that AP/TD’s gestural score architecture raises the risk of spatial interference among overlapping, independent gestures. These three challenges taken together set the stage for the discussion of additional challenges in Chapter 4, which further motivate consideration of phonology-extrinsic-timing-based approaches to speech motor control.

scholarly journals The rhythmic nature of visual perception

2018 ◽  
Vol 119 (4) ◽  
pp. 1251-1253 ◽  
Author(s):  
Randolph F. Helfrich
Keyword(s):  
Neural Network ◽  
Visual Perception ◽  
Brain Activity ◽  
Oculomotor System ◽  
Top Down ◽  
Discrete Sampling ◽  
The Neural Network ◽  
The World ◽  
Oscillatory Brain Activity

Our continuous perception of the world could be the result of discrete sampling, where individual snapshots are seamlessly fused into a coherent stream. It has been argued that endogenous oscillatory brain activity could provide the functional substrate of cortical rhythmic sampling. A new study demonstrates that cortical rhythmic sampling is tightly linked to the oculomotor system, thus providing a novel perspective on the neural network underlying top-down guided visual perception.

scholarly journals Top–Down Inhibitory Mechanisms Underlying Auditory–Motor Integration for Voice Control: Evidence by TMS

2020 ◽  
Vol 30 (8) ◽  
pp. 4515-4527 ◽  
Author(s):  
Dongxu Liu ◽  
Guangyan Dai ◽  
Churong Liu ◽  
Zhiqiang Guo ◽  
Zhiqin Xu ◽  
...  
Keyword(s):  
Auditory Feedback ◽  
Brain Activity ◽  
Event Related Potential ◽  
Control Mechanisms ◽  
Top Down ◽  
Vocal Production ◽  
Left Dlpfc ◽  
Dorsolateral Prefrontal ◽  
Pitch Regulation ◽  
Condition C

Abstract The dorsolateral prefrontal cortex (DLPFC) has been implicated in auditory–motor integration for accurate control of vocal production, but its precise role in this feedback-based process remains largely unknown. To this end, the present event-related potential study applied a transcranial magnetic stimulation (TMS) protocol, continuous theta-burst stimulation (c-TBS), to disrupt cortical activity in the left DLPFC as young adults vocalized vowel sounds while hearing their voice unexpectedly shifted upwards in pitch. The results showed that, as compared to the sham condition, c-TBS over left DLPFC led to significantly larger vocal compensations for pitch perturbations that were accompanied by significantly smaller cortical P2 responses. Source localization analyses revealed that this brain activity pattern was the result of reduced activation in the left superior frontal gyrus and right inferior parietal lobule (supramarginal gyrus). These findings demonstrate c-TBS-induced modulatory effects of DLPFC on the neurobehavioral processing of vocal pitch regulation, suggesting that disrupting prefrontal function may impair top–down inhibitory control mechanisms that prevent speech production from being excessively influenced by auditory feedback, resulting in enhanced vocal compensations for feedback perturbations. This is the first study that provides direct evidence for a causal role of the left DLPFC in auditory feedback control of vocal production.

scholarly journals Between Thought and Expression, a Magnetoencephalography Study of the “Tip-of-the-Tongue” Phenomenon

2014 ◽  
Vol 26 (10) ◽  
pp. 2210-2223 ◽  
Author(s):  
Karmen Resnik ◽  
David Bradbury ◽  
Gareth R. Barnes ◽  
Alex P. Leff
Keyword(s):  
Brain Activity ◽  
Brain Regions ◽  
Temporal Region ◽  
Speech Output ◽  
Proper Nouns ◽  
Confrontation Naming ◽  
Beta Power ◽  
Oscillatory Brain Activity ◽  
Language Areas ◽  
Tip Of The Tongue

“Tip-of-the-tongue” (TOT) is the phenomenon associated with the inaccessibility of a known word from memory. It is universally experienced, increases in frequency with age, and is most common for proper nouns. It is a good model for the symptom of anomia experienced much more frequently by some aphasic patients following brain injury. Here, we induced the TOT state in older participants while they underwent brain scanning with magnetoencephalography to investigate the changes in oscillatory brain activity associated with failed retrieval of known words. Using confrontation naming of pictures of celebrities, we successfully induced the TOT state in 29% of trials and contrasted it with two other states: “Know” where the participants both correctly recognized the celebrity's face and retrieved their name and “Don't Know” when the participants did not recognize the celebrity. We wished to test Levelt's influential model of speech output by carrying out two analyses, one epoching the data to the point in time when the picture was displayed and the other looking back in time from when the participants first articulated their responses. Our main findings supported the components of Levelt's model, but not their serial activation over time as both semantic and motor areas were identified in both analyses. We also found enduring decreases in the alpha frequency band in the left ventral temporal region during the TOT state, suggesting ongoing semantic search. Finally, we identified reduced beta power in classical peri-sylvian language areas for the TOT condition, suggesting that brain regions that encode linguistic memories are also involved in their attempted retrieval.

scholarly journals Comparison of Controlled and Uncontrolled Normal Speech Rate

1971 ◽  
Vol 50 (1A) ◽  
pp. 116-117
Author(s):  
R. Gregorski ◽  
L. Shockey ◽  
I. Lehiste
Keyword(s):  
Speech Rate ◽  
Normal Speech

scholarly journals Paradoxical response reversal of top-down modulation in cortical circuits with three interneuron types

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Luis Carlos Garcia del Molino ◽  
Guangyu Robert Yang ◽  
Jorge F Mejias ◽  
Xiao-Jing Wang
Keyword(s):  
Complex Dynamics ◽  
Pyramidal Cells ◽  
Cortical Circuits ◽  
Top Down ◽  
Paradoxical Response ◽  
Neural Populations ◽  
Connectivity Patterns ◽  
Response Reversal ◽  
Cell Type Specific ◽  
Cortical Circuit

Pyramidal cells and interneurons expressing parvalbumin (PV), somatostatin (SST), and vasoactive intestinal peptide (VIP) show cell-type-specific connectivity patterns leading to a canonical microcircuit across cortex. Experiments recording from this circuit often report counterintuitive and seemingly contradictory findings. For example, the response of SST cells in mouse V1 to top-down behavioral modulation can change its sign when the visual input changes, a phenomenon that we call response reversal. We developed a theoretical framework to explain these seemingly contradictory effects as emerging phenomena in circuits with two key features: interactions between multiple neural populations and a nonlinear neuronal input-output relationship. Furthermore, we built a cortical circuit model which reproduces counterintuitive dynamics observed in mouse V1. Our analytical calculations pinpoint connection properties critical to response reversal, and predict additional novel types of complex dynamics that could be tested in future experiments.

The Effects of Syllable Structure on Diadochokinetic and Reading Rates

1980 ◽  
Vol 23 (4) ◽  
pp. 894-908 ◽  
Author(s):  
William R. Tiffany
Keyword(s):  
Repetition Rate ◽  
Speech Rate ◽  
Reading Rate ◽  
Syllable Structure ◽  
The Other ◽  
Rate Performance ◽  
Valid Measurement ◽  
Normal Reading ◽  
Structural Variables ◽  
Normal Speech

Paragraphs with controlled phonetic structures were matched to similarly structured diadochokinetic (Maximum Repetition Rate) tasks in an effort to devise a more valid measurement for (1) assessing possible relationships between diadochokinesis and speech rate, and (2) evaluating the effects on articulation rates of such structural variables as number of consonants in a syllable, and alternating versus simple syllable repetitions. Highly stable results were obtained, suggesting the possibility of a sharp neurophysiological or biomechanical barrier which varies markedly among presumably normal speakers. Maximum repetition rates were poor predictors of normal reading rate performance. On the other hand, normal reading rates were found to be approximately the same as the maximum repetition rates—about 13.5 phones per second. The inference is that normal speech is not, as commonly supposed, obviously slower than maximum rates of syllable articulation, for equivalent syllables. The major source of variation in syllable rate measures was simply the number of phones in a syllable. The effects of articulatory place and manner appeared relatively trivial by comparison.

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