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.
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).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
26
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.
University of Connecticut
Storrs, Connecticut, United States
Categorization accuracy
Participants categorize items which vary along a perceptual continuum. Steepness of the categorization curve is extracted to estimate categorization accuracy.
Time frame: Immediately following the stimulation pulses (within one second of the final pulse).
Two-alternative forced choice accuracy
Participants are given two options and asked to indicate which item they heard in the previous signal. Accuracy in making this decision is a primary outcome measure.
Time frame: Immediately following the stimulation pulses (within one second of the final pulse).
Two-alternative forced choice reaction time
Participants are given two options and asked to indicate which item they heard in the previous signal. Reaction time to make this decision is a primary outcome measure.
Time frame: Immediately following the stimulation pulses (within one second of the final pulse).
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