Biomedical subjects

Wen-Jui Kuo

Publications and source records attributed to Wen-Jui Kuo.

5 recordsLinked to original sources

PubMed2006

A common coding framework in self-other interaction: evidence from joint action task.

Many of our actions are influenced by the social context. Traditional approach attributes the influence of the social context to arousal state changes in a socially promotive way. The ideomotor approach, which postulates common coding between perceived events and intended actions, uses a conceptual scheme of ideomotor compatibility to explain self-other interaction. In this study, we recorded reaction times (RTs) and event-related potentials in a Go/NoGo task with stimulus-response (S-R) compatibility arrangement to examine how the social context affects self-other interaction. Although the social facilitation theory predicted that RTs would be faster when acting together with audience rather than acting alone, the ideomotor theory predicted S-R compatibility effects only for the joint condition. The results revealed S-R compatibility on the RTs, lateralized readiness potential of the Go trials, and P3 of the NoGo trials in the joint condition, which were in line with the predictions of the ideomotor theory. Owing to the anticipation of other's actions, self and other's actions are internally and unintentionally coded at the representational level and their functional equivalency can be realized through a common coding framework between perception and action systems. Social facilitation theory was not supported, because we found no significant data differences depending on the setting.

Adult↗

PubMed2004

Orthographic and phonological processing of Chinese characters: an fMRI study.

The present study used functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the orthographic and phonological processing of Chinese characters. Four tasks were devised, including one homophone judgment and three physical judgments of characters, pseudo-characters, and Korean-like nonsense figures. While the left occipitotemporal region, left dorsal processing stream, and right middle frontal gyrus constitute a network for orthographic processing, the left premotor gyrus, left middle/inferior frontal gyrus, supplementary motor area (SMA), and the left temporoparietal region work in concert for phonological processing. The ventral part of the left inferior frontal cortex responds specifically to the character stimuli, suggesting a general lexical processing role for this region for linguistic material. The stronger activation of the dorsal visual stream by Chinese homophone judgment pinpoints a tight coupling between phonological representation of Chinese characters and corresponding orthographic percepts. The concomitant engagement of sets of regions for different levels of Chinese orthographic and phonological processing is consistent with the notion of distributed parallel processing.

Adult↗

PubMed2004

Neuronal correlates of consistency and frequency effects on Chinese character naming: an event-related fMRI study.

This event-related functional magnetic resonance imaging (efMRI) study aims to investigate the central representations of Chinese orthography-to-phonology transformation (OPT) by simultaneously manipulating character frequency and consistency. Bilateral inferior frontal cortices (including Broca's area and insula), the left temporoparietal region (superior parietal gyrus and supramarginal gyrus), and the left temporal-occipital junction showed greater activation, especially in low-frequency conditions, when naming inconsistent characters as compared to consistent ones. These findings suggest that these regions are involved in the sublexical conversion of orthographic input into phonological codes in naming Chinese. The similar activation pattern found in these three regions suggests a distributed process, rather than separate neural routes, for lexical and sublexical OPT. In addition, the regions involved in Chinese OPT are congruent with the findings for reading alphabetic scripts and indicate that the neuronal mechanisms for orthography-to-phonology transformation is domain universal across different writing systems.

Adult↗

PubMed2003

Frequency effects of Chinese character processing in the brain: an event-related fMRI study.

Knowing how the brain processes Chinese characters of different frequencies of occurrence may shed light on the extent to which orthographic variations of different languages can influence reading processes in the brain. In the present study, event-related fMRI was used to investigate frequency effects on Chinese character processing. Reading low-frequency characters invoked higher activation in several brain regions including the left premotor/inferior frontal gyrus, supplementary motor area, left anterior insula, left posterior inferior temporal gyrus, left superior parietal cortex, and lingual cortex, while reading high-frequency characters resulted in higher activation in the left supramarginal/angular gyrus and left precuneus. The activation pattern of reading infrequently encountered characters reflects a more demanding processing procedure of retrieving, formulating, and coordinating the phonological output. Access to the lexical route may benefit the reading of high-frequency characters. By uncovering the differential brain responses in reading Chinese characters of different occurrence frequencies, not only has a substantial overlap between functional neuroanatomy of reading Chinese and alphabetical languages been demonstrated, but also features permitting the separation of language-specific content from universal mechanisms.

Adult↗

PubMed2002

Single-trial variability in event-related BOLD signals.

Most current analysis methods for fMRI data assume a priori knowledge of the time course of the hemodynamic response (HR) to experimental stimuli or events in brain areas of interest. In addition, they typically assume homogeneity of both the HR and the non-HR "noise" signals, both across brain regions and across similar experimental events. When HRs vary unpredictably, from area to area or from trial to trial, an alternative approach is needed. Here, we use Infomax independent component analysis (ICA) to detect and visualize variations in single-trial HRs in event-related fMRI data. Six subjects participated in four fMRI sessions each in which ten bursts of 8-Hz flickering-checkerboard stimulation were presented for 0.5-s (short) or 3-s (long) durations at 30-s intervals. Five axial slices were acquired by a Bruker 3-T magnetic resonance imager at interscan intervals of 500 ms (TR). ICA decomposition of the resulting blood oxygenation level-dependent (BOLD) data from each session produced an independent component active in primary visual cortex (V1) and, in several sessions, another active in medial temporal cortex (MT/V5). Visualizing sets of BOLD response epochs with novel BOLD-image plots demonstrated that component HRs varied substantially and often systematically across trials as well as across sessions, subjects, and brain areas. Contrary to expectation, in four of the six subjects the V1 component HR contained two positive peaks in response to short-stimulus bursts, while components with nearly identical regions of activity in long-stimulus sessions from the same subjects were associated with single-peaked HRs. Thus, ICA combined with BOLD-image visualization can reveal dramatic and unforeseen HR variations not apparent to researchers analyzing their data with event-related response averaging and fixed HR templates.

Adult↗