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Examine visual lateralization of Chinese characters using a bilateral visual
presentation protocol and fMRI
Chun-Yu, Chen
The goal of this study is to examine neural and psychological basis of visual
lateralization of Chinese single-character and two-character word using a bilateral
visual presentation protocol and fMRI. Chinese characters were simultaneously,
bilaterally presented to the participants, one in the LVF and one in the RVF. On the
same (visual) presentation frame, there was a central cue (< or >) accompanying the
two characters to indicate which character (the LVF one or the RVF one) to attend
and process for lexical decision. For robustness checking, frequency of the characters
was included as a variable and varied (low, medium, and high). Results of
single-character and two-character word conditions show opposite processing
profiles in the left and right visual target assignment. That is, while a LVF/RH
advantage was revealed in the single-character condition, a RVF/LH advantage was
found for the two-character word condition. Our findings are consistent with the
behavioral data previously reported (Tzeng et al., 1979).
Keywords: left visual field (LVF) superiority, Chinese character, fmri
Analysis of Speech Perception and Cortical Auditory Evoked Potentials in
Mandarin Sensorineural Hearing Loss with Cochlear Dead Region
Sung-Yue Lin1, Guo-She Lee2, 3, Wen-Jui Kuo1
1Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan.
2Faculty of Medicine and Institute of Brain Science, School of Medicine
National
Yang-Ming University
3Department of Otorhinolaryngology, Ren-Ai Branch, Taipei City Hospital
Abstract
In a tonal language, the identity of a word depends largely on the tonal
identification of the contour of vocal fundamental frequency energy of which usually
centers in a low frequency of less than 600 Hz. However, cochlear dead region (DR)
is present mostly in the frequency range of 2000 Hz to 4000 Hz, and the effect of DR
on a tonal language is worth investigating. Thirty-two native Mandarin speakers with
moderate-to-severe degree of sensorineural hearing loss were included in this study.
The pure-tone audiometry, speech recognition threshold (SRT) and word recognition
score (WRS) were used to evaluate the degree of hearing loss and word recognition.
On the other hand this study is the first to take advantage of cortical auditory evoked
potential system ( CAEP), can detect the cerebral cortex to detect changes in
clinical speech perception examination ,and reaching an objective verification of
complex hearing aids hearing impairment is. The threshold equalizing noise (TEN)
tests were used to identify the presence of DR. The results showed that most DRs
were present in high frequencies. The hearing thresholds of the ears with a DR were
not significantly different from those without DR. However, the WRS was
significantly worse for the DR ears, especially for those whose DR included three or
more audiometric frequencies. A DR caused a significantly worse word recognition
for the tonal language speakers of Mandarin in Taiwan, although the DR frequency
occurred in the high frequency of 2000 Hz to 4000 Hz.
Key Words: cochlear dead region, Mandarin Chinese in Taiwan, sensorineural
hearing loss, threshold equalizing noise, tonal language, word recognition, cortical
auditory evoked potential system ( CAEP)
Integrating prior knowledge and data: The neural basis of judgment under
ambiguity.
Chih-Chung, Ting
Advisor: Shih-Wei, Wu
Abstract
We examine how neural systems compute the probabilities of possible outcomes
given prior information about probability as well as immediate sensory evidence in the
form of a likelihood function. Bayesian decision theory provides a normative model for
integrating prior and likelihood to arrive at the posterior probability of each outcome.
We designed a novel lottery decision task to investigate how the brain represents
priors, likelihood functions based on immediate sensory evidence, and their
integration as a posterior. Using functional magnetic resonance imaging (fMRI) we
found evidence for representation of priors and integration computations in the medial
prefrontal cortex (mPFC), while the inferior parietal lobule (IPL) encodes the level of
uncertainty about reward probability conveyed through immediate sensory evidence.
Connectivity analysis revealed that during valuation there was an increase in
functional connectivity between mPFC and IPL, indicating that information about
likelihood is communicated through this frontal-parietal network for integration.
Together, these results demonstrate distinct neural systems for representing prior
knowledge and sensory evidence about reward statistics, and highlight a candidate
neural mechanism that integrates the two during valuation.