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- All Subjects: EEG
- Creators: Daliri, Ayoub
- Creators: Brewer, Gene
- Member of: Theses and Dissertations
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.
stimuli played prior to the onset of speech production. In this experiment, we are examining the
specificity of the auditory stimulus by implementing congruent and incongruent speech sounds in
addition to non-speech sound. Electroencephalography (EEG) data was recorded for eleven adult
subjects in both speaking (speech planning) and silent reading (no speech planning) conditions.
Data analysis was accomplished manually as well as via generation of a MATLAB code to
combine data sets and calculate auditory modulation (suppression). Results of the P200
modulation showed that modulation was larger for incongruent stimuli than congruent stimuli.
However, this was not the case for the N100 modulation. The data for pure tone could not be
analyzed because the intensity of this stimulus was substantially lower than that of the speech
stimuli. Overall, the results indicated that the P200 component plays a significant role in
processing stimuli and determining the relevance of stimuli; this result is consistent with role of
P200 component in high-level analysis of speech and perceptual processing. This experiment is
ongoing, and we hope to obtain data from more subjects to support the current findings.
This thesis is a tutorial for a MATLAB user-interface, known as EEGLAB. Cognitive and neural correlates of analytical and insight processes were evaluated and analyzed in the CRAT using EEG. It was hypothesized that different EEG signals will be measured for analytical versus insight problem solving, primarily observed in the gamma wave production. The data was interpreted using EEGLAB, which allows psychological processes to be quantified based on physiological response. I have written a tutorial showing how to process the EEG signal through filtering, extracting epochs, artifact detection, independent component analysis, and the production of a time – frequency plot. This project has combined my interest in psychology with my knowledge of engineering and expand my knowledge of bioinstrumentation.
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.