Matching Items (3)
Filtering by
- Creators: Liss, Julie
Description
The activation of the primary motor cortex (M1) is common in speech perception tasks that involve difficult listening conditions. Although the challenge of recognizing and discriminating non-native speech sounds appears to be an instantiation of listening under difficult circumstances, it is still unknown if M1 recruitment is facilitatory of second language speech perception. The purpose of this study was to investigate the role of M1 associated with speech motor centers in processing acoustic inputs in the native (L1) and second language (L2), using repetitive Transcranial Magnetic Stimulation (rTMS) to selectively alter neural activity in M1. Thirty-six healthy English/Spanish bilingual subjects participated in the experiment. The performance on a listening word-to-picture matching task was measured before and after real- and sham-rTMS to the orbicularis oris (lip muscle) associated M1. Vowel Space Area (VSA) obtained from recordings of participants reading a passage in L2 before and after real-rTMS, was calculated to determine its utility as an rTMS aftereffect measure. There was high variability in the aftereffect of the rTMS protocol to the lip muscle among the participants. Approximately 50% of participants showed an inhibitory effect of rTMS, evidenced by smaller motor evoked potentials (MEPs) area, whereas the other 50% had a facilitatory effect, with larger MEPs. This suggests that rTMS has a complex influence on M1 excitability, and relying on grand-average results can obscure important individual differences in rTMS physiological and functional outcomes. Evidence of motor support to word recognition in the L2 was found. Participants showing an inhibitory aftereffect of rTMS on M1 produced slower and less accurate responses in the L2 task, whereas those showing a facilitatory aftereffect of rTMS on M1 produced more accurate responses in L2. In contrast, no effect of rTMS was found on the L1, where accuracy and speed were very similar after sham- and real-rTMS. The L2 VSA measure was indicative of the aftereffect of rTMS to M1 associated with speech production, supporting its utility as an rTMS aftereffect measure. This result revealed an interesting and novel relation between cerebral motor cortex activation and speech measures.
ContributorsBarragan, Beatriz (Author) / Liss, Julie (Thesis advisor) / Berisha, Visar (Committee member) / Rogalsky, Corianne (Committee member) / Restrepo, Adelaida (Committee member) / Arizona State University (Publisher)
Created2018
Description
Previous studies have found that the detection of near-threshold stimuli is decreased immediately before movement and throughout movement production. This has been suggested to occur through the use of the internal forward model processing an efferent copy of the motor command and creating a prediction that is used to cancel out the resulting sensory feedback. Currently, there are no published accounts of the perception of tactile signals for motor tasks and contexts related to the lips during both speech planning and production. In this study, we measured the responsiveness of the somatosensory system during speech planning using light electrical stimulation below the lower lip by comparing perception during mixed speaking and silent reading conditions. Participants were asked to judge whether a constant near-threshold electrical stimulation (subject-specific intensity, 85% detected at rest) was present during different time points relative to an initial visual cue. In the speaking condition, participants overtly produced target words shown on a computer monitor. In the reading condition, participants read the same target words silently to themselves without any movement or sound. We found that detection of the stimulus was attenuated during speaking conditions while remaining at a constant level close to the perceptual threshold throughout the silent reading condition. Perceptual modulation was most intense during speech production and showed some attenuation just prior to speech production during the planning period of speech. This demonstrates that there is a significant decrease in the responsiveness of the somatosensory system during speech production as well as milliseconds before speech is even produced which has implications for speech disorders such as stuttering and schizophrenia with pronounced deficits in the somatosensory system.
ContributorsMcguffin, Brianna Jean (Author) / Daliri, Ayoub (Thesis director) / Liss, Julie (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Studies in Second Language Acquisition and Neurolinguistics have argued that adult learners when dealing with certain phonological features of L2, such as segmental and suprasegmental ones, face problems of articulatory placement (Esling, 2006; Abercrombie, 1967) and somatosensory stimulation (Guenther, Ghosh, & Tourville, 2006; Waldron, 2010). These studies have argued that adult phonological acquisition is a complex matter that needs to be informed by a specialized sensorimotor theory of speech acquisition. They further suggested that traditional pronunciation pedagogy needs to be enhanced by an approach to learning offering learners fundamental and practical sensorimotor tools to advance the quality of L2 speech acquisition.
This foundational study designs a sensorimotor approach to pronunciation pedagogy and tests its effect on the L2 speech of five adult (late) learners of American English. Throughout an eight week classroom experiment, participants from different first language backgrounds received instruction on Articulatory Settings (Honickman, 1964) and the sensorimotor mechanism of speech acquisition (Waldron 2010; Guenther et al., 2006). In addition, they attended five adapted lessons of the Feldenkrais technique (Feldenkrais, 1972) designed to develop sensorimotor awareness of the vocal apparatus and improve the quality of L2 speech movement. I hypothesize that such sensorimotor learning triggers overall positive changes in the way L2 learners deal with speech articulators for L2 and that over time they develop better pronunciation.
After approximately eight hours of intervention, analysis of results shows participants’ improvement in speech rate, degree of accentedness, and speaking confidence, but mixed changes in word intelligibility and vowel space area. Albeit not statistically significant (p >.05), these results suggest that such a sensorimotor approach to L2 phonological acquisition warrants further consideration and investigation for use in the L2 classroom.
This foundational study designs a sensorimotor approach to pronunciation pedagogy and tests its effect on the L2 speech of five adult (late) learners of American English. Throughout an eight week classroom experiment, participants from different first language backgrounds received instruction on Articulatory Settings (Honickman, 1964) and the sensorimotor mechanism of speech acquisition (Waldron 2010; Guenther et al., 2006). In addition, they attended five adapted lessons of the Feldenkrais technique (Feldenkrais, 1972) designed to develop sensorimotor awareness of the vocal apparatus and improve the quality of L2 speech movement. I hypothesize that such sensorimotor learning triggers overall positive changes in the way L2 learners deal with speech articulators for L2 and that over time they develop better pronunciation.
After approximately eight hours of intervention, analysis of results shows participants’ improvement in speech rate, degree of accentedness, and speaking confidence, but mixed changes in word intelligibility and vowel space area. Albeit not statistically significant (p >.05), these results suggest that such a sensorimotor approach to L2 phonological acquisition warrants further consideration and investigation for use in the L2 classroom.
ContributorsLima, J. Alberto S., Jr (Author) / Pruitt, Kathryn (Thesis advisor) / Gelderen, Elly van (Thesis advisor) / Liss, Julie (Committee member) / James, Mark (Committee member) / Arizona State University (Publisher)
Created2015