Matching Items (4)

Filtering by

Clear all filters

133028-Thumbnail Image.png

Somatosensory Modulation during Speech Planning

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

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.

Contributors

Agent

Created

Date Created
2019-05

148383-Thumbnail Image.png

Utilizing functional MRI to Analyze Differences in the Brain in Response to Speech and Music Stimuli in Persons with Aphasia

Description

The distinctions between the neural resources supporting speech and music comprehension have long been studied using contexts like aphasia and amusia, and neuroimaging in control subjects. While many models have emerged to describe the different networks uniquely recruited in response

The distinctions between the neural resources supporting speech and music comprehension have long been studied using contexts like aphasia and amusia, and neuroimaging in control subjects. While many models have emerged to describe the different networks uniquely recruited in response to speech and music stimuli, there are still many questions, especially regarding left-hemispheric strokes that disrupt typical speech-processing brain networks, and how musical training might affect the brain networks recruited for speech after a stroke. Thus, our study aims to explore some questions related to the above topics. We collected task-based functional MRI data from 12 subjects who previously experienced a left-hemispheric stroke. Subjects listened to blocks of spoken sentences and novel piano melodies during scanning to examine the differences in brain activations in response to speech and music. We hypothesized that speech stimuli would activate right frontal regions, and music stimuli would activate the right superior temporal regions more than speech (both findings not seen in previous studies of control subjects), as a result of functional changes in the brain, following the left-hemispheric stroke and particularly the loss of functionality in the left temporal lobe. We also hypothesized that the music stimuli would cause a stronger activation in right temporal cortex for participants who have had musical training than those who have not. Our results indicate that speech stimuli compared to rest activated the anterior superior temporal gyrus bilaterally and activated the right inferior frontal lobe. Music stimuli compared to rest did not activate the brain bilaterally, but rather only activated the right middle temporal gyrus. When the group analysis was performed with music experience as a covariate, we found that musical training did not affect activations to music stimuli specifically, but there was greater right hemisphere activation in several regions in response to speech stimuli as a function of more years of musical training. The results of the study agree with our hypotheses regarding the functional changes in the brain, but they conflict with our hypothesis about musical expertise. Overall, the study has generated interesting starting points for further explorations of how musical neural resources may be recruited for speech processing after damage to typical language networks.

Contributors

Agent

Created

Date Created
2021-05

134804-Thumbnail Image.png

Startle-evoked movement in multi-jointed, two-dimensional reaching tasks

Description

Previous research has shown that a loud acoustic stimulus can trigger an individual's prepared movement plan. This movement response is referred to as a startle-evoked movement (SEM). SEM has been observed in the stroke survivor population where results have shown

Previous research has shown that a loud acoustic stimulus can trigger an individual's prepared movement plan. This movement response is referred to as a startle-evoked movement (SEM). SEM has been observed in the stroke survivor population where results have shown that SEM enhances single joint movements that are usually performed with difficulty. While the presence of SEM in the stroke survivor population advances scientific understanding of movement capabilities following a stroke, published studies using the SEM phenomenon only examined one joint. The ability of SEM to generate multi-jointed movements is understudied and consequently limits SEM as a potential therapy tool. In order to apply SEM as a therapy tool however, the biomechanics of the arm in multi-jointed movement planning and execution must be better understood. Thus, the objective of our study was to evaluate if SEM could elicit multi-joint reaching movements that were accurate in an unrestrained, two-dimensional workspace. Data was collected from ten subjects with no previous neck, arm, or brain injury. Each subject performed a reaching task to five Targets that were equally spaced in a semi-circle to create a two-dimensional workspace. The subject reached to each Target following a sequence of two non-startling acoustic stimuli cues: "Get Ready" and "Go". A loud acoustic stimuli was randomly substituted for the "Go" cue. We hypothesized that SEM is accessible and accurate for unrestricted multi-jointed reaching tasks in a functional workspace and is therefore independent of movement direction. Our results found that SEM is possible in all five Target directions. The probability of evoking SEM and the movement kinematics (i.e. total movement time, linear deviation, average velocity) to each Target are not statistically different. Thus, we conclude that SEM is possible in a functional workspace and is not dependent on where arm stability is maximized. Moreover, coordinated preparation and storage of a multi-jointed movement is indeed possible.

Contributors

Agent

Created

Date Created
2016-12

165768-Thumbnail Image.png

Investigation of Sensorimotor Abilities in Stroke Survivors With Aphasia: A Delayed Auditory Feedback Study

Description

Aphasia is an acquired speech-language disorder that is brought upon because of post-stroke damage to the left hemisphere of the brain. Treatment for individuals with these speech production impairments can be challenging for clinicians because there is high variability in

Aphasia is an acquired speech-language disorder that is brought upon because of post-stroke damage to the left hemisphere of the brain. Treatment for individuals with these speech production impairments can be challenging for clinicians because there is high variability in language recovery after stroke and lesion size does not predict language outcome (Lazar et al, 2008). It is also important to note that adequate integration between the sensory and motor systems is critical for many aspects of fluent speech and correcting speech errors. The present study seeks to investigate how delayed auditory-feedback paradigms, which alter the time scale of sensorimotor interactions in speech, might be useful in characterizing the speech production impairments in individuals with aphasia. To this end, six individuals with aphasia and nine age-matched control subjects were introduced to delayed auditory feedback at 4 different intervals during a sentence reading task. Our study found that the aphasia group generated more errors in 3 out of the 4 linguistic categories measured across all delay lengths, but that there was no significant main effect delay or interaction between group and delay. Acoustic analyses revealed variability among scores within the control and aphasia groups on all phoneme types. For example, acoustic analyses highlighted how the individual with conduction aphasia showed significantly longer amplitudes at all delays, and significantly larger duration at no delay, but that significance diminished as delay periods increased. Overall, this study suggests that delayed auditory feedback’s effects vary across individuals with aphasia and provides a base of research to be further built on by future testing of individuals with varying aphasia types and levels of severity.

Contributors

Agent

Created

Date Created
2022-05