Phase-locking of gamma and beta in an auditory EEG paradigm and their relationship to self-reported sensory sensitivities
Date
2013
Authors
Phares-Zook, Kelly P., author
Davies, Patricia, advisor
Gavin, William, committee member
Atler, Karen, committee member
Seger, Carol, committee member
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Volume Title
Abstract
Phase-locking factor (PLF), one way to analyze electroencephalography (EEG) data, is the consistency of the brain's response in particular frequency bands to stimuli across multiple trials. Studies in the past have correlated PLF of different brainwave frequencies to behaviors; however, none have looked at the correlation to sensory sensitivities. The objective of the present study was to examine the relationship between PLF and behavioral measures in neurotypical adults. The participants were 38 neurotypical adults aged 18-25. This study involved an auditory paradigm in which three series of eight tones each were presented to the participant while he or she watched a movie. The first series presented eight tones that were identical, the second series presented a deviant tone in the 4th position with the other seven tones identical to the tones presented in the first series, and the third series had a deviant tone presented in the 5th position with the other 7 tones identical to the tones in the first series. These series of tones were presented in pseudorandom fashion while the participants' brainwaves were recorded with an EEG system. To examine the relationship between the consistency of the brain's response to these tones and sensory sensitivities, the participants filled out the Adult/Adolescent Sensory Profile (AASP). It was hypothesized that the PLF value at the onset of the first tone in the series of tones with no deviants would be greater than the subsequent tones in the same series. In the series of tones with no deviants, PLF for gamma (30-50 Hz) for tone 1 was higher than all but one of the PLF responses to subsequent tones. PLF in the beta region (18-30 Hz) in response to tone 1 was higher than the PLF response to all subsequent tones in the series with no deviants. Some, but not all, of these findings reached significance. It was also hypothesized that PLF at the onset of a deviant tone would be greater than PLF at the onset of non-deviant tones 2-8 in the same series. For the series of tones with a deviant in the 4th position, gamma increased from tone 3 to tone 4 for central electrode sites and decreased for frontal electrode sites, although none reached significance. For the series of tones with the deviant in the 5th position, PLF for gamma at tone 5 was greater than at tone 4 for 4/6 electrodes. For the series of tones with a deviant in the 4th position, PLF in the beta region increased from tone 4 to tone 5. For the series of tones with a deviant in the 5th position, PLF in the beta region increased from tone 4 to tone 5 for half of the electrode sites. It was hypothesized that PLF in response to the first tone of a series would not be significantly different from PLF in response to a deviant tone of the same series. PLF in the gamma region did not ever significantly differ from the first tone to the deviant tone. PLF in the beta region did not significantly differ from tone 1 to tone 4 in the series of tones with the deviant in the 4th position, but PLF for tone 1 was significantly higher than PLF for tone 5 for 2/6 electrode sites during the series of tones with the deviant in the 5th position. Lastly, it was hypothesized that individuals who have higher PLF will demonstrate low neurological thresholds as measured by the AASP. Spearman Rho correlations revealed that nearly all significant findings found between PLF and scores on the AASP were positive correlations. Results indicated that better phase-locking in the brain correlates positively with increased sensory sensitivities, as demonstrated by the AASP. Additionally, this study supports prior research indicating that a decrease in PLF does occur from tone 1 to tone 2 when the tones are identical, but questions whether PLF reflects habituation that may occur in response to three or more of the same stimuli.
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Subject
sensory
beta
phase-locking
gamma