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Making sense of white noise in terms of temporal segmentation pattern in human auditory cortex.(4月1日,周一,下午2点)
Published:2013-04-01 Hits:879

Title: Making sense of white noise in terms of temporal segmentation pattern in human auditory cortex.

Speaker: Dr. Huan Luo(罗欢)

She is a professor at Institute of Biophysics, Chinese Academy of Sciences. She obtained B.E. in Electrical Engineering at Wuhan University in 1999, and Ph.D. in Cognitive and Neuroscience at the University of Maryland College Park in 2007. She joined Institute of Biophysics in 2007 as an associate professor and became professor since 2012. Her research seeks to understand the temporal organization process in auditory and visual perception and the underlying brain oscillatory phase modulation neural mechanism, by combining neuroimaging, psychophysical and computational techniques.

Time: 2-3 pm, April 1, 2013

Place: Room 2201, East Guanghua Tower


Natural stream such as speech, music and movie contains information at concurrent multiple temporal scales, implying that the brain needs to rely on a temporal segmentation process to adaptively entrain to and dynamically represent external continuous information input. Our previous studies have shown that an ongoing phase modulation of intrinsic neuronal oscillation mechanism serves as crucial instrument of temporal segmentation of incoming natural sensory stream, for both natural spoken sentences (Luo&Poeppel, 2007) and audio-visual natural movie clips (Luo et al., 2010). However, it remains unknown whether such temporal organization process can be intrinsically built up instead of relying on explicit cues contained in external stimulus. In other words, does the temporal segmentation merely reflect an exogenous entrainment or is indeed an endogenous fundamental process? In a recent experiment, we used white noise stimulus, which contains neither semantic labels nor prominent acoustic features, to examine the issue. We demonstrate that as an original novel noise reoccurred and became differentiated from other noise sounds, as reflected in behavior, it gradually initiated a specific robust phase pattern in low-frequency (3-8 Hz) auditory cortical responses. Moreover, different memorized noises elicit distinguishable phase responses, suggesting their specificity to noise structure. The results thus indicate that the gradual establishment of temporal segmentation pattern, as reflected in phase response, mediates the implicit learning process by which originally undifferentiated noises become new auditory objects. We propose a population-level neural representation for newly learned auditory objects, based on phase-mediated organization pattern in time, by analogy with spatial organization in vision.

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