Mechanism of Temporal Perceptual Learning

Xu, Rannie

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Year:: 2021
Contributor:: Xu, Rannie (creator); Watanabe, Takeo (Advisor); Sasaki, Yuka (Reader); Freestone, David (Reader); Brown University. Department of Cognitive, Linguistic, and Psychological Sciences (sponsor)
Genre:: theses
Subject:: Perceptual learning; Proton magnetic resonance spectroscopy; Time perception
Extent:: x, 94 p.

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Abstract:: Abstract of “Mechanisms of Temporal Perceptual Learning” by Ran Xu, Ph.D., Brown University, February 2021 Our ability to estimate and discriminate short temporal intervals can be improved with practice. This type of learning is known as temporal perceptual learning (TPL) and constitutes one of the most unique and profound demonstrations of neural plasticity in the brain. Despite its ubiquity in our daily lives, the underlying mechanisms of TPL are poorly understood. In the present dissertation, we investigated whether TPL is primarily governed by low-level changes in a temporal stimulus, or high-level task-specific mechanisms. In our first set of studies, we trained two groups of participants using a single-interval auditory discrimination task. Training intervals were either one of eight predetermined values (fixed group), or random from trial to trial (random group). Before and after training, we also measured discrimination performance using an untrained two-interval temporal comparison task. Our results revealed a selective improvement in performance for the fixed group, however, this learning did not generalize between the trained and untrained tasks. These results highlight the sensitivity of TPL to high-level stimulus and task structure, indicating that learning mechanisms reflect processes beyond changes in interval representation. Next, we used proton magnetic resonance spectroscopy (MRS) in conjunction with psychophysical measures to provide the first empirical evidence of neurochemical changes in association with TPL. During the first and last day of training, we obtained concentrations of glutamate and γ-aminobutyric acid (GABA) using MRS. On the first day of training, learning was significantly associated with an increase in the (E)xcitation-to-(I)nhibition ratio of the right inferior parietal cortex (IPC), but not the left primary auditory cortex (A1). This finding is consistent with the hypothesis that TPL acts to immediately consolidate a learning state through shifts in excitatory and inhibitory neurochemical processing. Our findings demonstrate for the first time, the relationship between temporal learning and neural plasticity as indexed by the E/I ratio, which provide an important avenue into the mechanisms underlying TPL. Taken together, these results highlight the involvement of high-level mechanisms in temporal discrimination learning.
Notes:: Thesis (Ph. D.)--Brown University, 2021

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Xu, Rannie, "Mechanism of Temporal Perceptual Learning" (2021). Cognitive, Linguistic, and Psychological Sciences Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:f442rssy/

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Cognitive, Linguistic, and Psychological Sciences Theses and Dissertations

Theses and Dissertations for the Cognitive, Linguistic, and Psychological Sciences department.
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