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Yoon Han (Computer Science Major)
“Influences of Early Acoustic Experience on Sensory Perception”
Sponsor: Professor Shaowen Bao, Helen Wills Neuroscience Institute
Project Description
As part of Professor Shaowen Bao’s lab, Yoon will expand our understanding of the influence of sensory input on information processing during an epoch of early development known as the “critical period”. At the behavioral level, he will investigate how early experience of single-frequency tone pips influences frequency discrimination ability in rats. At the physiological level, he will examine the auditory cortex (A1) of tone-exposed rats to extract response properties of the cortical neurons, such as the characteristic frequency, spontaneous firing rate, maximum firing rate, and tuning bandwidth. At the systems level, he will simulate the auditory cortex with a population of model neurons using computational methods with previously extracted properties. By creating a model of the perceptual discrimination process, Yoon will investigate how repeated exposures to a sound influence perception discrimination of acoustically similar sounds.
Scholar's Photo
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Yoon stands next to the rack of recording equipments.
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Scholar's Journal
It is said that one cannot fully understand something until you experience it first hand. Scientific knowledge, something that I used to take it for granted, consists of a gradual accumulation of discoveries. Some of them were carefully planned research projects that aim to address an open question. My summer research sponsored by Haas Scholars Program constantly reminded me of the value in finding new knowledge.
My project involved two steps that were followed by a combining step. I previously studied the plasticity of the rat auditory cortex—how perceptual learning changes the firing rate, bandwidth, and other neuronal properties. However, computational modeling has been a new experience. It is the interdisciplinary study of math, programming, and neuroscience. To bridge the gap between perception of sound and raw stimulation, I had to gather the data from both ends—the neurons in the auditory cortex and the behavioral data of rats. For these steps, the lab in Northwest Animal Facility was my quiet, secure (guarded 24/7), and fully air-conditioned second home. The first part, electrophysiological mapping of the rat’s auditory cortex took long hours, sometimes continuous work that spans more than a day! The second part involved training of rats everyday, teaching them to discriminate between two different tones of sound. Some laboratory rats were extremely smart—they easily scored more than 90% of the time. Some weren’t—they did not show much improvement. As I am on the last step, I use methods that I learned from statistics and mathematics, implementing the model through programming. The results from the last step will show a mechanism of how the neuronal properties of the auditory cortex that has been shaped by early acoustic experience influence the perception characterized by the animal’s behavior.
I am very grateful for the Haas Scholars Program’s generosity to offer me this valuable opportunity. After spending a summer and continuing to expand on my current research work, I came to more appreciate the previous knowledge in textbooks. Moreover, I will always remember that obtaining new knowledge requires ambition to pioneer new areas and persistence to finish the work.
Read the paper based on Yoon's Haas Scholars Project, published in Nature Neuroscience in 2007.
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