Left and Right Hemisphere Contributions to Speech Perception

NCT ID: NCT04989309

Last Updated: 2025-06-15

Basic Information

• Recruitment Status: ENROLLING_BY_INVITATION
• Clinical Phase: NA
• Total Enrollment: 26 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-12-19
• Study Completion Date: 2026-06-30

Brief Summary

Left and right temporal brain areas are thought to contribute to speech perception, but the division of labor between left and right hemisphere regions is still unclear. Here we use transcranial magnetic stimulation (TMS) to stimulate left and right temporal foci and a vertex control site to temporarily disrupt activation at the stimulation site, using a "virtual lesion" approach to test the effect of stimulation site on a series of speech perception tasks.

This portion of the project is basic research. However, since TMS is viewed as an intervention, studies involving TMS in this grant are considered clinical trials.

Detailed Description

This study uses TMS to temporarily disrupt neural activity in the left and right temporal cortex and examine the effect of this disruption on speech perception tasks. Vertex stimulation is included as a control condition against which left and right superior temporal stimulation effects are compared. Adult participants first undergo structural MRI and a speech localizer using functional MRI to identify speech-sensitive voxels in the left and right temporal cortex. These regions are set by-participant as the foci for stimulation. Stimulation site is blocked, and typically distributed across sessions. 10 Hz pulse trains of 2.5 sec each are delivered to the stimulation site, with an auditory stimulus arriving either immediately after the last pulse (Exps 2 and 6) or, for longer sentence level stimuli (Exp 3), during the pulse train. Behavioral measures include accuracy and reaction times to rate phonetic stimuli (Exp 2), detect the presence of a probe word in the preceding sentence (Exp 3), or categorize stimuli by phonetic contrast and talker (Exp 6).

Conditions

Neural Bases of Speech Perception

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Experiment 3. Phonetic ambiguity in continuous speech

Experiment 3 is designed to test whether left vs. right temporal lobe stimulation selectively disrupts processing of naturally-occurring phonetic ambiguity as compared to vertex stimulation (control). Participants will receive stimulation at all three sites (left temporal, right temporal, vertex, with order of stimulation counterbalanced across participants). Stimuli will be nonsense sentences produced clearly or in a casual register. By-sentence phonetic ambiguity is estimated by the proximity of each token to other vowels belonging to different categories. Sentences will be embedded in speech-shaped noise to increase difficulty. Participants will listen to each sentence, then respond whether a visually-presented probe word appeared in the sentence ("BRASS?"). Dependent variables are accuracy and reaction time on this probe verification task.

Group Type: EXPERIMENTAL

Transcranial Magnetic Stimulation

Intervention Type: DEVICE

TMS will be delivered in 10 Hz pulses for 2.5 seconds, with behavioral measures of speech perception and object categorization immediately following each pulse. TMS at this schedule is thought to temporarily disrupt activity at the stimulation site.

Experiment 2. Phonetic precision disrupted by TMS

Experiment 2 tests the influence of temporary disruption of activity within the left or right temporal cortex on the speed and precision of phonetic decisions compared to vertex stimulation. Participants will receive stimulation at all three sites (left temporal, right temporal, vertex, with order of stimulation counterbalanced across participants). Immediately following stimulation pulses, participants will perform a visual analog scale (VAS) phonetic rating task on tokens from the four continua, embedded in speech-shaped noise. To control for the possibility that TMS leads to a generalized deficit in categorization, a control task will involve categorization of visual objects on a morphed "dog" to "cat" object continuum. (We expect this task to be unaffected by TMS). The variables of interest are the steepness of the categorization curve, mean reaction time to all items on the continuum, and the difference in reaction time for boundary vs. endpoint tokens.

Group Type: EXPERIMENTAL

Transcranial Magnetic Stimulation

Intervention Type: DEVICE

TMS will be delivered in 10 Hz pulses for 2.5 seconds, with behavioral measures of speech perception and object categorization immediately following each pulse. TMS at this schedule is thought to temporarily disrupt activity at the stimulation site.

Experiment 6: Disruption of talker-specific phonetic learning using TMS.

Experiment 6 is designed to test whether disruption of activity in left or right temporal regions (vs. vertex control) using TMS interferes with talker-specific learning. Participants will receive stimulation at all three sites (left temporal, right temporal, vertex, with order of stimulation counterbalanced across participants). The study uses a training paradigm where one talker's speech is manipulated to always have relatively short voice onset times (VOTs) for voiceless stops (e.g., /k/ in "coal") and another to have relatively long VOTs. Immediately after stimulation, listeners will undergo a training trial where they identify sounds as mapping to Talker 1 or Talker 2's voice, and to the word (e.g. "gain" vs. "cane"). At test, listeners hear two VOT variants and are asked which is more typical of that talker's speech. The dependent variable is the accuracy of reporting which variant is typical of the talker.

Group Type: EXPERIMENTAL

Transcranial Magnetic Stimulation

Intervention Type: DEVICE

TMS will be delivered in 10 Hz pulses for 2.5 seconds, with behavioral measures of speech perception and object categorization immediately following each pulse. TMS at this schedule is thought to temporarily disrupt activity at the stimulation site.

Interventions

Transcranial Magnetic Stimulation

TMS will be delivered in 10 Hz pulses for 2.5 seconds, with behavioral measures of speech perception and object categorization immediately following each pulse. TMS at this schedule is thought to temporarily disrupt activity at the stimulation site.

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

• Monolingual native speaker of English
• No history of neurological impairments or disease
• Free of speech and language disorders (per self-report, and confirmed by short language battery described by Fidler, Vance, & Plante, 2011)
• Pure-tone thresholds of 30 decibels or better in both ears (no worse than mild hearing loss), with no more than 15 dB between-ear difference.
• Right-handed, as confirmed by Oldfield Handedness Inventory

Exclusion Criteria

• Any condition where TMS would be contraindicated according to the most recent guidelines, including, but not limited to:

• History of seizure or epilepsy
• Metal in the skull
• Use of legal or illicit drugs that can potentially reduce the threshold for seizure. As examples, we list some exclusionary drugs in each of the following categories. This is not an exhaustive list of the exclusionary drugs. We consult with faculty in the University of Connecticut College of Pharmacy to check for seizure risk with other drugs that participants report.

• Antidepressants including Imipramine, amitriptyline, sertraline, venlafaxine, buproprion
• Antipsychotics including Chlorpromazine, clozapine, haloperidol, aripiprazole
• Antivirals including foscarnet, ganciclovir
• Antiparasitics including chloroquine, mefloquine (antiparasitics)
• Antibiotics including penicillin, ampicillin
• Immunosuppressants including cyclosporin
• Anticholinergenics
• Antihistimines (including over-the-counter drugs like Claritin & Benadryl)
• Sympathomimetics (including Sudafed, Ritalin).
• Illegal drugs such as methamphetamines, cocaine, MDMA, ketamine.
• Diagnosis of a psychiatric disorder (per self-report)
• Pregnancy

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

National Institute on Deafness and Other Communication Disorders (NIDCD)

NIH

Sponsor Role: collaborator

University of Connecticut

OTHER

Sponsor Role: lead

Responsible Party

Emily Myers

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

University of Connecticut

Storrs, Connecticut, United States

Countries

United States

References

Kennedy-Higgins D, Devlin JT, Nuttall HE, Adank P. The Causal Role of Left and Right Superior Temporal Gyri in Speech Perception in Noise: A Transcranial Magnetic Stimulation Study. J Cogn Neurosci. 2020 Jun;32(6):1092-1103. doi: 10.1162/jocn_a_01521. Epub 2020 Jan 14.

Reference Type: BACKGROUND

PMID: 31933438 (View on PubMed)

Rossi S, Antal A, Bestmann S, Bikson M, Brewer C, Brockmoller J, Carpenter LL, Cincotta M, Chen R, Daskalakis JD, Di Lazzaro V, Fox MD, George MS, Gilbert D, Kimiskidis VK, Koch G, Ilmoniemi RJ, Lefaucheur JP, Leocani L, Lisanby SH, Miniussi C, Padberg F, Pascual-Leone A, Paulus W, Peterchev AV, Quartarone A, Rotenberg A, Rothwell J, Rossini PM, Santarnecchi E, Shafi MM, Siebner HR, Ugawa Y, Wassermann EM, Zangen A, Ziemann U, Hallett M; basis of this article began with a Consensus Statement from the IFCN Workshop on "Present, Future of TMS: Safety, Ethical Guidelines", Siena, October 17-20, 2018, updating through April 2020. Safety and recommendations for TMS use in healthy subjects and patient populations, with updates on training, ethical and regulatory issues: Expert Guidelines. Clin Neurophysiol. 2021 Jan;132(1):269-306. doi: 10.1016/j.clinph.2020.10.003. Epub 2020 Oct 24.

Reference Type: BACKGROUND

PMID: 33243615 (View on PubMed)

Other Identifiers

R01DC013064

Identifier Type: NIH

Identifier Source: secondary_id

View Link

H21-0046

Identifier Type: -

Identifier Source: org_study_id