Biomedical subjects

Xiaolin Zhou

Publications and source records attributed to Xiaolin Zhou.

17 recordsLinked to original sources

PubMed2006

Brain responses to outcomes of one's own and other's performance in a gambling task.

Previous studies find that the feedback-related negativity in brain potentials is sensitive to the negative outcome of one's own performance. The feedback-related negativity is suggested to reflect the learning processes using feedback about the consequences of recent actions. Learning can also take place when one observes other people's actions and the associated outcomes. We recorded brain potentials while the participant received outcome feedback for their own or for another person's performance in a gambling task. The feedback-related negativity or the feedback-related negativity-like effects were obtained in both situations, suggesting that similar neural mechanisms are involved in evaluating the outcomes of one's own and the other's actions. Thus, the neural processes in learning-by-observation resemble those in learning-by-doing.

Adult↗

PubMed2006

Brain potentials associated with outcome expectation and outcome evaluation.

Feedback-related negativity is a negative deflection in brain potentials associated with feedback indicating monetary losses or response errors. Feedback-related negativity is studied primarily in paradigms in which participants experience negative outcomes that appear to be contingent upon their previous choices. This study investigated whether feedback-related negativity can be elicited by a randomly assigned cue indicating potential monetary loss. The expected loss or win can be materialized or averted depending on participants' performance in a subsequent game. Compared with the win cue, the loss cue elicited a weak but significant feedback-related negativity-like effect. It is suggested that the anterior cingulate cortex, which generates feedback-related negativity, may function as a pre-warning system that alerts the brain to get ready for future events.

Adult↗

PubMed2006

Spatial and nonspatial peripheral auditory processing in congenitally blind people.

Congenitally blind adults' performance in spatial and nonspatial peripheral auditory attention tasks was compared with that of sighted adults in a paradigm manipulating location-based and frequency-based inhibition of return concurrently. Blind study participants responded faster in spatial attention tasks (detection/localization) and slower in the nonspatial frequency discrimination task than sighted participants. Both groups, however, showed the same patterns of interaction between location-based and frequency-based inhibition of return. These results suggest that early vision deprivation enhances the function of the posterior-dorsal auditory 'where' pathway but impairs the function of the anterior-ventral 'what' pathway during peripheral auditory attention. The altered processing speed in the blind, however, is not accompanied by alteration in attentional orienting mechanisms that may be localized to higher cortices.

Acoustic Stimulation↗

PubMed2006

Processing multidimensional objects under different perceptual loads: the priority of bottom-up perceptual saliency.

The role of perceptual load in selective attention to multidimensional objects was investigated by independently manipulating the load along the task-relevant and the task-irrelevant dimensions in the central search array, which was flanked by congruent, incongruent, or neutral peripheral distractors. The relative bottom-up perceptual saliency of these dimensions in capturing attention was manipulated between experiments. When the task-relevant dimension was the color of the letter and the task-irrelevant dimension was the visual shape of the letter (Experiment 1), manipulation of the letter shape perceptual load had no impact upon the pattern of congruency effects in responding to the color, i.e., smaller congruency effects under higher color perceptual loads and larger congruency effects under lower color perceptual loads. When the task-relevant dimension was the shape of the letter and the task-irrelevant dimension was the color of the letter (Experiment 2), there were no congruency effects in responding to the letter shape under high color perceptual loads irrespective of the letter shape loads. When only the target and the flanker were colored whereas the distractors in the central array were not (Experiment 3), the task-irrelevant color information reduced or eliminated the impact of letter shape perceptual load on the congruency effects in responding to the letter shape. These findings suggested that selective attention to multidimensional objects follows the general principles suggested by the perceptual load theory, but the bottom-up perceptual saliency plays a primary role in the distribution of attentional resources over objects and dimensions.

Adolescent↗

PubMed2006

Interaction between location- and frequency-based inhibition of return in human auditory system.

Using a cue-target paradigm, this study investigated the interaction between location and frequency information processing in human auditory inhibition of return (IOR). The cue and the target varied in terms of location and frequency and participants were asked to perform a target detection, localization or frequency discrimination task. Results showed that, when neither location nor frequency of auditory stimuli was particularly relevant to the target detection task, there was a location-based IOR only if the cue and the target were identical in frequency and there was a frequency-based IOR only if the cue and the target were presented at the same location. When a particular feature of auditory stimuli, whether location or frequency, was directly relevant to the current task, the IOR effect was evident for this feature only if the cue and the target differed on the task-irrelevant feature, while the IOR effect was eliminated for the task-relevant feature when the cue and the target had the same task-irrelevant feature. Similarly, the IOR effect based on the task-irrelevant feature was evident when the cue and the target differed on the task-relevant feature, and was eliminated or reversed when the cue and the target shared the task-relevant feature. Theoretical implications of these findings for auditory IOR are discussed.

Acoustic Stimulation↗

PubMed2006

Spatial coding for the Simon effect in visual search.

Two experiments were conducted to examine the Simon effect (i.e., faster responding when irrelevant stimulus location corresponds with response location than when it does not) in visual search tasks. The search items were arranged in a 4 x 4 grid, and grid locations were coded into sets of four, two involving inner columns and two involving outer columns. In experiment 1, three different types of inefficient search tasks were used. The Simon effects were shown to be larger when the target appeared in one of the outer columns than in one of the inner columns ("laterality effect"). This pattern of results was not observed when distractors were absent, suggesting that the laterality effect depends on the operation of selective attention. In experiment 2, a pop-out search task was used, and no significant effect of target location on the Simon effect was found. Interpretations of the results based on the attention-shift account and referential-coding account were discussed.

Adult↗

PubMed2006

Effects of spatial distribution of attention during inhibition of return (IOR) on flanker interference in hearing and congenitally deaf people.

This study explored the interaction between the spatial distribution of attention during inhibition of return (IOR) and different levels of flanker interference in congenitally deaf subjects as compared with hearing subjects. Color (Experiment 1) and alphanumeric (Experiment 2) flanker interference effects were differentiated into the pre-response and the response levels. The spatial distribution of attention was manipulated through IOR. Subjects were asked to either make color or letter/digit discriminations to the central targets or detect the abrupt-onset peripheral targets. Deaf subjects were significantly faster than hearing subjects at detecting peripheral targets irrespective of the cue validity, while the two groups had comparable sizes of IOR. In the central discrimination tasks, deaf subjects showed significant response level, but not pre-response level, flanker effects irrespective of the type of stimuli and the spatial location of the flanker. For hearing subjects, however, spatial attention interacted with the pre-response and response flanker effects in different ways. While flankers at the cued location caused interference effects at the response level and facilitatory effects at the pre-response level, those at the uncued location caused different effects depending on the type of stimuli. Moreover, increasing the peripheral attention for hearing subjects, by increasing the proportion of peripheral detection trials, made hearing subjects behave like deaf subjects. These results demonstrate that deaf people possess enhanced peripheral attentional resources as compared with hearing people. The spatial distribution of attention modulates mainly the resolution of the pre-response flanker interference in hearing people, but affects neither the pre-response nor the response level interference in deaf people.

Acoustic Stimulation↗

PubMed2006

Center of mass attracts attention.

Using the spatial cueing technique, this study demonstrates that the center of mass (centroid) of a visual scene has a special ability to attract attention even when there is no object presented at this location. Four boxes formed an imaginary square and were presented to the left or right hemifield. After the cueing in one box, a target appeared in one of the four boxes and, in addition, at centroid. Fastest reaction times were observed at centroid, irrespective of whether this centroid was also occupied by a box. Reaction times at the uncued locations varied according to their relative positions to centroid and fixation. No inhibition of return effect was observed when the cue was at centroid.

Adolescent↗

PubMed2006

Semantic and syntactic processing in Chinese sentence comprehension: evidence from event-related potentials.

An ERP experiment was conducted to explore semantic and syntactic processes as well as their interplay in Chinese sentence comprehension. Participants were auditorily presented with Chinese ba sentences, which were either correct, semantically incorrect, syntactically incorrect, or both semantically and syntactically incorrect. The syntactic violation, which was created by eliminating the object-noun phrase from a preposition-object phrase structure, elicited an early starting anterior negativity which merged into a sustained negativity over anterior sites and a temporally limited centro-parietal negativity. The semantic violation elicited an early starting N400 effect. The combined violation in which the syntactic phrase structure violation and the semantic violation were crossed elicited an early staring sustained anterior negativity similar to the pure syntactic effect, and a centro-parietal negativity which was more negative than those of the syntactic condition and the semantic condition. No P600 was obtained neither for the syntactic nor for the combined condition. The results suggest that the syntactic processes (at about 50 ms) appear earlier than the semantic processes (at around 150 ms). They are independent from each other in the early time window (150-250 ms) but interact in a later processing phase (250-400 ms) during Chinese ba sentence comprehension. The broadly distributed negativity, which occurred during the N400 latency range observed in the three violation conditions, is thought to reflect thematic integration processes in the sentence-final position.

Adult↗

PubMed2006

Distinct neural correlates for resolving stroop conflict at inhibited and noninhibited locations in inhibition of return.

It is well documented that the anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC) are intensively involved in conflict control. However, it remains unclear how these "executive" brain regions will act when the conflict control process interacts with spatial attentional orienting. In the classical spatial cueing paradigm [Posner, M. I., & Cohen, Y. (1984). Components of visual orienting. In H. Bouma & D. G. Bouwhuis (Eds.), Attention and performance X (pp. 531-556). Hillsdale, NJ: Erlbaum], response to a target is delayed when it appears at the cued location compared with at the uncued location, if the time interval between the cue and the target is greater than 300 msec. This effect of inhibition of return (IOR) can alter the resolution of Stroop conflict such that the Stroop interference effect disappears at the cued (inhibited) location [Vivas, A. B., & Fuentes, L. J. Stroop interference is affected in inhibition of return. Psychonomic Bulletin and Review, 8, 315-323, 2001]. In this event-related functional magnetic resonance study, we investigate the differential neural mechanisms underlying interactions between pre-response interference, response interference, and spatial orienting. Two types of Stroop words [incongruent response-eligible words (IE), incongruent response-ineligible words (II)] and neutral words were presented either at the cued or uncued location. The significant pre-response interference at the uncued location activated the left rostral ACC as compared with at the cued location. Moreover, although the IE words which have conflicts at both pre-response and response levels did not cause significant behavioral interference at the cued location, they activated the left DLPFC as compared with at the uncued location. Furthermore, neutral words showed significant IOR effects behaviorally, and they activated the left frontal eye field (FEF) at the uncued location relative to the cued location. These results suggest that the left rostral ACC is involved in the interaction between pre-response conflict and IOR, whereas the left DLPFC is involved in the interaction between response conflict and IOR. Moreover, the FEF is involved in shifting attentional focus to novel locations during spatial search.

Adult↗

PubMed2005

Tissue-engineered vessel strengthens quickly under physiological deformation: application of a new perfusion bioreactor with machine vision.

In order to develop a patent tissue-engineered blood vessel that grossly resembles native tissue, required culture times in most studies exceed 8 weeks. For the sake of shortening the maturation period of the constructs, we have used deformation as the basic index for mechanical environment control. A new bioreactor with a machine vision identifier was developed to accurately control the deformation of the construct during the perfusion process. Two groups of seeded constructs (n = 4 per group) were investigated in this study, with one group stimulated by a cyclic deformation of 10% and the other by a pulsatile pressure that gradually increased to 120 mm Hg (the control group). After 21 days of culture, the mechanical properties of the constructs were examined. The average burst strength and suture retention strength in the two groups were significantly different (t test, p < 0.05). For the experimental group, the average burst strength and suture retention strength were higher than those of the control group, by 31.6 and 23.4%, respectively. Specifically, the average burst strength of the constructs reached 1,402 mm Hg (close to that of the native vessel, i.e. 1,680 mm Hg) within a relatively short period of 21 days. In conclusion, deformation is an observable, controllable and very valuable index for mechanical environment control in vascular tissue engineering. It makes the control of mechanical stimuli more essential and experiments more comparable.

Animals↗

PubMed2005

Visual attention deficits in Alzheimer's disease: an fMRI study.

Cognitive and neuroscience studies indicate that attentional operations are impaired in Alzheimer's disease (AD). Our goal was to define the anatomical areas of activation associated with visual attention processing and to define deficits or changes that may occur in AD patients compared with control group. Thirteen AD patients and 13 age- and education-matched normal controls were tested in two visual search tasks (one was a conjunction task, where feature binding is required. The other was a subset task, where group stimuli is needed without feature binding) using fMRI techniques. After stereotactical normalization, voxel-by-voxel t statistics was used to compare activated brain areas between patients and control subjects. Our findings suggest that both search tasks are controlled by partially overlapping cerebral networks, including parietal, frontal and occipital-temporal cortical regions and primary visual cortex. The AD patient group showed less activation in both parietal lobes and the left frontal regions, while increased activation was found in the right frontal lobes and the right occipito-temporal cortical regions with the conjunction task. In the subset task, decreased activation in AD patients was seen in the left parietal lobe and bilateral frontal lobes, while increased activation was seen in both medial temporal lobes. In addition, for the comparison between tasks, The difference is very small for AD patients. Control group showed a higher amplitude in the right prefrontal region, temporal cortical regions and parietal lobe. These results indicate that attention deficits in AD patients may be attributed to both binding problem and grouping inefficiency.

Aged↗

PubMed2005

Prediction of vascular tissue engineering results with artificial neural networks.

Tissue engineers are often confused on finding the most successful strategy for specific patient. In this study, we used artificial neural networks to predict the outcomes of different vascular tissue engineering strategies, thus providing advisory information for experimental designers. Over 30 variables were used as features of the tissue engineering strategies. Different architectures of artificial neural networks with back propagation algorithm were tested to obtain the best model configuration for the prediction of the tissue engineering strategies. In the computational experiments, the artificial neural networks with one and two hidden layers could, respectively, detect unsuccessful strategies with the highest predictive accuracy of 91.45 and 94.24%. In conclusion, artificial intelligence has great potential in tissue engineering decision support. It can provide accurate advisory information for tissue engineers, thus reducing failures and improving therapeutic effects.

Animals↗

PubMed2005

Auditory and speech processing and reading development in Chinese school children: behavioural and ERP evidence.

By measuring behavioural performance and event-related potentials (ERPs) this study investigated the extent to which Chinese school children's reading development is influenced by their skills in auditory, speech, and temporal processing. In Experiment 1, 102 normal school children's performance in pure tone temporal order judgment, tone frequency discrimination, temporal interval discrimination and composite tone pattern discrimination was measured. Results showed that children's auditory processing skills correlated significantly with their reading fluency, phonological awareness, word naming latency, and the number of Chinese characters learned. Regression analyses found that tone temporal order judgment, temporal interval discrimination and composite tone pattern discrimination could account for 32% of variance in phonological awareness. Controlling for the effect of phonological awareness, auditory processing measures still contributed significantly to variance in reading fluency and character naming. In Experiment 2, mismatch negativities (MMN) in event-related brain potentials were recorded from dyslexic children and the matched normal children, while these children listened passively to Chinese syllables and auditory stimuli composed of pure tones. The two groups of children did not differ in MMN to stimuli deviated in pure tone frequency and Chinese lexical tones. But dyslexic children showed smaller MMN to stimuli deviated in initial consonants or vowels of Chinese syllables and to stimuli deviated in temporal information of composite tone patterns. These results suggested that Chinese dyslexic children have deficits in auditory temporal processing as well as in linguistic processing and that auditory and temporal processing is possibly as important to reading development of children in a logographic writing system as in an alphabetic system.

Asian People↗

PubMed2005

Applying informatics in tissue engineering.

OBJECTIVE: To facilitate tissue engineering strategies determination with informatics tools. METHODS: Firstly, tissue engineering experimental data were standardized and integrated into a centralized database; secondly, we used data mining tools (e.g. artificial neural networks and decision trees) to predict the outcomes of tissue engineering strategies; thirdly, a strategy design algorithm was developed, and its efficacy was validated with animal experiments; lastly, we constructed an online database and a decision support system for tissue engineering. RESULTS: The artificial neural networks and the decision trees respectively predicted the outcomes of tissue engineering strategies with the predictive accuracy of 95.14% and 85.26%. Following the strategies generated by computer, we cured 18 of the 20 experimental animals with a significantly lower cost than usual. CONCLUSION: Informatics is beneficial for realizing safe, effective and economical tissue engineering.

Artificial Intelligence↗

PubMed2003

Perception of English intonation by English, Spanish, and Chinese listeners.

Native language affects the perception of segmental phonetic structure, of stress, and of semantic and pragmatic effects of intonation. Similarly, native language might influence the perception of similarities and differences among intonation contours. To test this hypothesis, a cross-language experiment was conducted. An English utterance was resynthesized with seven falling and four rising intonation contours. English, Iberian Spanish, and Chinese listeners then rated each pair of nonidentical stimuli for degree of difference. Multidimensional scaling of the results supported the hypothesis. The three groups of listeners produced statistically different perceptual configurations for the falling contours. All groups, however, perceptually separated the falling from the rising contours. This result suggested that the perception of intonation begins with the activation of universal auditory mechanisms that process the direction of relatively slow frequency modulations. A second experiment therefore employed frequency-modulated sine waves that duplicated the fundamental frequency contours of the speech stimuli. New groups of English, Spanish, and Chinese subjects yielded no cross-language differences between the perceptual configurations for these nonspeech stimuli. The perception of similarities and differences among intonation contours calls upon universal auditory mechanisms whose output is molded by experience with one's native language.

Adolescent↗

PubMed2002

[Adhesive deformity from the upper eyelid fold formation and its treatment].

OBJECTIVE: On the basis of the concept of adhesive deformity from upper eyelid fold formation, the clinical results after using various methods to correct the adhesive deformities are summarized. METHODS: A total of 33 cases of adhesive deformity from upper eyelid fold formation have been treated using various corrective methods including taking off the sutures, shifting of the septal fat or the pre-septal orbicularis muscle, transferring of pretarsal orbicularis muscle, grafting of autogenous fat tissue, and repairing or/and shortening of the palpebral levator. Postoperative follow-up ranged from 3 months to 2 years. RESULTS: The effective results have been got with the used methods except shifting of the pre-septal orbicularis muscle or transferring of pretarsal orbicularis muscle. CONCLUSIONS: The suitable methods to correct the adhesive deformity from upper eyelid fold formation must be chosen according to the causes and the local situations.

Adult↗