Motor theory modulated by task load: strategies of phonological processing in frontal aphasia revealed by tDCS over the LIFG

2019 ◽  
Author(s):  
Lílian Rodrigues de Almeida ◽  
Paul A. Pope ◽  
Peter Hansen
Keyword(s):  
Speech Perception ◽  
Speech Production ◽  
Phonological Processing ◽  
Inferior Frontal Gyrus ◽  
Dorsal Stream ◽  
Superior Temporal Gyrus ◽  
Motor Theory ◽  
Task Load ◽  
Cathodal Tdcs ◽  
The Individual

In our previous studies we supported the claim that the motor theory is modulated by task load. Motoric participation in phonological processing increases from speech perception to speech production, with the endpoints of the dorsal stream having changing and complementary weightings for processing: the left inferior frontal gyrus (LIFG) being increasingly relevant and the left superior temporal gyrus (LSTG) being decreasingly relevant. Our previous results for neurostimulation of the LIFG support this model. In this study we investigated whether our claim that the motor theory is modulated by task load holds in (frontal) aphasia. Person(s) with aphasia (PWA) after stroke typically have damage on brain areas responsible for phonological processing. They may present variable patterns of recovery and, consequently, variable strategies of phonological processing. Here these strategies were investigated in two PWA with simultaneous fMRI and tDCS of the LIFG during speech perception and speech production tasks. Anodal tDCS excitation and cathodal tDCS inhibition should increase with the relevance of the target for the task. Cathodal tDCS over a target of low relevance could also induce compensation by the remaining nodes. Responses of PWA to tDCS would further depend on their pattern of recovery. Responses would depend on the responsiveness of the perilesional area, and could be weaker than in controls due to an overall hypoactivation of the cortex. Results suggest that the analysis of motor codes for articulation during phonological processing remains in frontal aphasia and that tDCS is a promising diagnostic tool to investigate the individual processing strategies.

scholarly journals Neural correlates of the effects of tDCS stimulation over the LIFG for phonological processing in dyslexia

2019 ◽  
Author(s):  
Lílian Rodrigues de Almeida ◽  
Peter C. Hansen
Keyword(s):  
Speech Perception ◽  
Speech Production ◽  
Brain Stimulation ◽  
Phonological Processing ◽  
Inferior Frontal Gyrus ◽  
Cognitive Networks ◽  
Speech Sounds ◽  
Anodal Tdcs ◽  
Dorsal Pathway ◽  
Cathodal Tdcs

AbstractFindings of neuroimaging and brain stimulation research suggest that the motor system takes part in phonological processing at least to some extent in healthy speakers. Phonological processing involves a core network of brain regions, the dorsal pathway, where motoric aspects of speech sounds are analysed by the left inferior frontal gyrus (LIFG) and auditory aspects by the left superior temporal gyrus (LSTG). The extent to which each node of the dorsal pathway takes part in phonological processing has been shown to depend on the nature of the task and on the functional integrity of the network. Tasks of speech production rely more on the LIFG, and tasks of speech perception rely more on the LSTG. Persons with dyslexia (PWD) are known to present a deficit in phonological processing. Neuroimaging research has shown that dyslexia typically affects the LSTG, with hypoactivation, and the LIFG, with hyperactivation. Transcranial direct current stimulation (tDCS) has been widely used for cognitive research in humans. It has been recently suggested in the literature that perturbations induced by brain stimulation can cause the weights of nodes in cognitive networks to transiently rearrange. In this study we used tDCS and functional magnetic resonance imaging (fMRI) to investigate the functioning of the dorsal pathway for phonological processing in PWD with tasks of speech production and speech perception. We targeted the LIFG with anodal, cathodal and sham tDCS. For healthy speakers, cathodal tDCS should downregulate performance when the target had high relevance for the task, such as the LIFG for speech production. For targets of smaller relevance, improved performance should be observed due to compensation by the most relevant node(s). Anodal tDCS should improve performance as a function of the relevance of the target for the task. PWD were expected to deviate from this pattern to some extent, especially when compensation by the LSTG was needed during cathodal tDCS of the LIFG for a task of speech perception. Results corroborated the theoretical claim that codes for articulation take part in the processing of speech sounds. However, our findings showed that the PWD pattern of response to tDCS for phonological processing in tasks of speech production and speech perception differed from that expected for healthy speakers. Anodal tDCS of the LIFG induced larger facilitation for the speech perception than for the speech production task, as well as larger compensation for the latter under cathodal tDCS. Findings indicate that tDCS is a promising diagnosis tool for the investigation of alterations in phonological processing caused by dyslexia.

Neural deficits in auditory phonological processing in Chinese children with English reading impairment

2015 ◽  
Vol 19 (2) ◽  
pp. 331-346 ◽  
Author(s):  
XIANGZHI MENG ◽  
HANLIN YOU ◽  
MEIXIA SONG ◽  
AMY S. DESROCHES ◽  
ZHENGKE WANG ◽  
...  
Keyword(s):  
Second Language ◽  
Phonological Processing ◽  
Inferior Frontal Gyrus ◽  
Superior Temporal Gyrus ◽  
Neural Mechanism ◽  
Reading Impairment ◽  
English Reading ◽  
L2 Learners ◽  
L1 And L2 ◽  
Esl Learners

Auditory phonological processing skills are critical for successful reading development in English not only in native (L1) speakers but also in second language (L2) learners. However, the neural deficits of auditory phonological processing remain unknown in English-as-the-second-language (ESL) learners with reading difficulties. Here we investigated neural responses during spoken word rhyme judgments in typical and impaired ESL readers in China. The impaired readers showed comparable activation in the left superior temporal gyrus (LSTG), but reduced activation in the left inferior frontal gyrus (LIFG) and left fusiform and reduced connectivity between the LSTG and left fusiform when compared to typical readers. These findings suggest that impaired ESL readers have relative intact representations but impaired manipulation of phonology and reduced or absent automatic access to orthographic representations. This is consistent with previous findings in native English speakers and suggests a common neural mechanism underlying English impairment across the L1 and L2 learners.

Contemporary model of language organization: an overview for neurosurgeons

2015 ◽  
Vol 122 (2) ◽  
pp. 250-261 ◽  
Author(s):  
Edward F. Chang ◽  
Kunal P. Raygor ◽  
Mitchel S. Berger
Keyword(s):  
Speech Processing ◽  
Phonological Processing ◽  
Semantic Processing ◽  
Functional Organization ◽  
Inferior Frontal Gyrus ◽  
Superior Temporal Gyrus ◽  
Functional Neuroanatomy ◽  
Additional Information ◽  
Dorsal Pathway ◽  
Subcortical Mapping

Classic models of language organization posited that separate motor and sensory language foci existed in the inferior frontal gyrus (Broca's area) and superior temporal gyrus (Wernicke's area), respectively, and that connections between these sites (arcuate fasciculus) allowed for auditory-motor interaction. These theories have predominated for more than a century, but advances in neuroimaging and stimulation mapping have provided a more detailed description of the functional neuroanatomy of language. New insights have shaped modern network-based models of speech processing composed of parallel and interconnected streams involving both cortical and subcortical areas. Recent models emphasize processing in “dorsal” and “ventral” pathways, mediating phonological and semantic processing, respectively. Phonological processing occurs along a dorsal pathway, from the posterosuperior temporal to the inferior frontal cortices. On the other hand, semantic information is carried in a ventral pathway that runs from the temporal pole to the basal occipitotemporal cortex, with anterior connections. Functional MRI has poor positive predictive value in determining critical language sites and should only be used as an adjunct for preoperative planning. Cortical and subcortical mapping should be used to define functional resection boundaries in eloquent areas and remains the clinical gold standard. In tracing the historical advancements in our understanding of speech processing, the authors hope to not only provide practicing neurosurgeons with additional information that will aid in surgical planning and prevent postoperative morbidity, but also underscore the fact that neurosurgeons are in a unique position to further advance our understanding of the anatomy and functional organization of language.

scholarly journals Modality- and Task-specific Brain Regions Involved in Chinese Lexical Processing

2009 ◽  
Vol 21 (8) ◽  
pp. 1473-1487 ◽  
Author(s):  
Li Liu ◽  
Xiaoxiang Deng ◽  
Danling Peng ◽  
Fan Cao ◽  
Guosheng Ding ◽  
...  
Keyword(s):  
Phonological Processing ◽  
Lexical Processing ◽  
Inferior Frontal Gyrus ◽  
Superior Temporal Gyrus ◽  
Brain Regions ◽  
Middle Temporal Gyrus ◽  
Chinese Speakers ◽  
Specific Effects ◽  
Left Middle ◽  
And Task

fMRI was used to examine lexical processing in native adult Chinese speakers. A 2 task (semantics and phonology) × 2 modality (visual and auditory) within-subject design was adopted. The semantic task involved a meaning association judgment and the phonological task involved a rhyming judgment to two sequentially presented words. The overall effect across tasks and modalities was used to identify seven ROIs, including the left fusiform gyrus (FG), the left superior temporal gyrus (STG), the left ventral inferior frontal gyrus (VIFG), the left middle temporal gyrus (MTG), the left dorsal inferior frontal gyrus (DIFG), the left inferior parietal lobule (IPL), and the left middle frontal gyrus (MFG). ROI analyses revealed two modality-specific areas, FG for visual and STG for auditory, and three task-specific areas, IPL and DIFG for phonology and VIFG for semantics. Greater DIFG activation was associated with conflicting tonal information between words for the auditory rhyming task, suggesting this region's role in strategic phonological processing, and greater VIFG activation was correlated with lower association between words for both the auditory and the visual meaning task, suggesting this region's role in retrieval and selection of semantic representations. The modality- and task-specific effects in Chinese revealed by this study are similar to those found in alphabetical languages. Unlike English, we found that MFG was both modality- and task-specific, suggesting that MFG may be responsible for the visuospatial analysis of Chinese characters and orthography-to-phonology integration at a syllabic level.

scholarly journals Nonword Repetition by Children With Cochlear Implants

2004 ◽  
Vol 47 (5) ◽  
pp. 1103-1116 ◽  
Author(s):  
Caitlin M. Dillon ◽  
Rose A. Burkholder ◽  
Miranda Cleary ◽  
David B. Pisoni
Keyword(s):  
Working Memory ◽  
Speech Perception ◽  
Speech Production ◽  
Cochlear Implants ◽  
Phonological Processing ◽  
Oral Communication ◽  
Speaking Rate ◽  
Nonword Repetition ◽  
Phonological Working Memory ◽  
Verbal Rehearsal

Seventy-six children with cochlear implants completed a nonword repetition task. The children were presented with 20 nonword auditory patterns over a loud-speaker and were asked to repeat them aloud to the experimenter. The children's responses were recorded on digital audiotape and then played back to normal-hearing adult listeners to obtain accuracy ratings on a 7-point scale. The children's nonword repetition performance, as measured by these perceptual accuracy ratings, could be predicted in large part by their performance on independently collected measures of speech perception, verbal rehearsal speed, and speech production. The strongest contributing variable was speaking rate, which is widely argued to reflect verbal rehearsal speed in phonological working memory. Children who had become deaf at older ages received higher perceptual ratings. Children whose early linguistic experience and educational environments emphasized oral communication methods received higher perceptual ratings than children enrolled in total communication programs. The present findings suggest that individual differences in performance on nonword repetition are strongly related to variability observed in the component processes involved in language imitation tasks, including measures of speech perception, speech production, and especially verbal rehearsal speed in phonological working memory. In addition, onset of deafness at a later age and an educational environment emphasizing oral communication may be beneficial to the children's ability to develop the robust phonological processing skills necessary to accurately repeat novel, nonword sound patterns.

scholarly journals A causal test of the motor theory of speech perception: a case of impaired speech production and spared speech perception

2015 ◽  
Vol 32 (2) ◽  
pp. 38-57 ◽  
Author(s):  
Alena Stasenko ◽  
Cory Bonn ◽  
Alex Teghipco ◽  
Frank E. Garcea ◽  
Catherine Sweet ◽  
...  
Keyword(s):  
Speech Perception ◽  
Speech Production ◽  
Motor Theory ◽  
Impaired Speech
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