Biomedical subjects

Daisy L Hung

Publications and source records attributed to Daisy L Hung.

10 recordsLinked to original sources

PubMed2006

The temporal signatures of semantic and phonological activations for Chinese sublexical processing: an event-related potential study.

A large number of Chinese characters are made up by pairing a semantic radical and a phonetic radical. The phonetic radical usually gives a phonological clue for the pronunciation of the whole character but does not contribute to its meaning. Using an event-related potential (ERP) measurement, the present study was able to trace the very intricate interplay between phonological and semantic information embedded in the phonetic radical. It was found that, within the first 50 to 100 ms of perceiving the character, the semantic information of the phonetic radical was better preserved when the constituent phonetic radical provided a valid phonological clue (e.g., regular phonogram) than when it contained an invalid phonetic cue (e.g., irregular phonogram). However, no trace of semantic information from the phonetic radical was preserved after 300 ms. These ERP results detail the neuropsychological steps in reading Chinese and support the framework of the lexical constituent model.

Adult↗

PubMed2006

Orthographic neighborhood effects in reading Chinese two-character words.

The present study investigates the effects of neighborhood size and neighborhood frequency in reading Chinese two-character words. The neighborhood size of a word is defined as the summation of neighbors sharing the first constituent (neighborhood size 1) and the second constituent (neighborhood size 2) characters. The first experiment found two opposite neighborhood size effects in lexical decision of high-frequency and low-frequency words. The regression analysis showed that neighborhood size 1 influenced word reading more than the neighborhood size 2. The second experiment confirmed this finding and showed that reading words with higher frequency neighbors took a longer time and elicited greater N400 and LPC than those without higher frequency neighbors. These findings indicate that, when reading Chinese two-character words, all words sharing the first constituent character are activated in the early stage of word recognition and the existence of high-frequency words among neighbors leads to greater competition in the stage of semantic integration and response selection.

Adult↗

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↗

PubMed2006

Neuromagnetic SII responses do not fully reflect pain scale.

To elucidate the role of somatosensory cortices in coding pain magnitude, we recorded the neuromagnetic responses of ten subjects to mild, moderate, and severe pain stimulation by delivering thulium-laser pulses on the dorsum of the left hand. The stimulus intensities for producing different pain levels were determined individually, and the mean values across subjects were 255, 365, and 490 mJ for mild, moderate, and severe pain, respectively. We obtained 40 responses for each intensity condition, and analyzed the averaged cortical signals by multi-dipole modeling. All subjects showed consistent activation over the bilateral secondary somatosensory (SII) cortices for each intensity level, peaking around 150-230 ms, with 15-ms earlier on the contralateral hemisphere. The SII dipole strength was significantly larger for the moderate than for the mild pain stimulation, but lacked further increase as the pain magnitude elevated to the severe level. In contrast, the primary somatosensory cortical response was detected in only half of our subjects, and thus it seemed difficult to evaluate its role in pain intensity coding. Our results suggest that activation strength in human SII cortices reflects the magnitude of peripheral noxious inputs only up to the moderate level, and some other cerebral correlates may get involved in sensing a further increment of pain magnitude.

Adult↗

PubMed2005

Neural correlates of impulsive-violent behavior: an event-related potential study.

Impulsive-violent offenders are often less capable of controlling their behavior. A cued Go/No-go task was used to test the hypothesis that impulsive-violent behavior reflects a deficit in the ability to inhibit prepotent responses and could be reflected in the measurement of event-related potentials. Results showed that the amplitudes of the N2 component at Fz reflected different degrees of inhibition in impulsive-violent offenders compared with matched controls. The N2 amplitude (No-go minus Go) was significantly lower in the impulsive-violent offenders than in matched controls. The amplitude of N2 increased when effort was required to withhold the Go intention. A smaller N2 amplitude was seen in offenders, suggesting difficulties with inhibition of prepotent behavior.

Adult↗

PubMed2005

Processing of disyllabic compound words in Chinese aphasia: evidence for the processing limitations account.

The current study addresses the debate between so-called 'structural' and 'processing limitation' accounts of aphasia, i.e., whether language impairments reflect the 'loss' of linguistic knowledge or its representations, or instead reflect a limitation in processing resources. Confrontation-naming task and category-judgment tasks were used to examine and compare the performance of non-fluent and fluent aphasics on different compound types of nouns and verbs. We demonstrate that aphasic patients' performance is modulated by the canonicity of the particular compound type, a result that holds true even for the category in which patients show a 'selective category deficit.' These findings weigh against the 'loss' of linguistic representations as the underlying cause of noun-verb deficits, instead supporting a 'processing limitations' approach.

Adult↗

PubMed2004

Use of phonological codes for Chinese characters: evidence from processing of parafoveal preview when reading sentences.

The role of phonological coding for character identification was examined with the benefit of processing parafoveal characters in eye fixations while reading Chinese sentences. In Experiment 1, the orthogonal manipulation of phonological and orthographic similarity can separate two types of phonological benefits for homophonic previews, according to whether these previews share the same phonetic radical with the targets or not. The significant phonological benefits indicate that phonological coding is activated early when the character is in the parafovea. Experiment 2 manipulated the character's consistency value and found that the phonological preview benefits are reliable only when the targets are high consistency characters. The results of two experiments suggest that phonological computation is rapid and early at both character and radical levels for Chinese character identification.

Adolescent↗

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↗