Biomedical subjects

Shujuan Tian

Publications and source records attributed to Shujuan Tian.

6 recordsLinked to original sources

PubMed2005

Distinctive conflict processes associated with different stimulus presentation patterns: an event-related potential study.

Twelve subjects were asked to perform visual stimulus presentation tasks. Two figures were presented either simultaneously or sequentially. They were either in congruity (same shapes) or in conflict (different shapes) with each other. Conflicting stimulus pairs presented sequentially evoked a negative event-related component with a fronto-central and bilateral posterior scalp distribution, referred to as N270. In contrast, stimuli displayed simultaneously elicited a N220 with fronto-central prominence, irrespective of whether they were in conflict or in congruity. The results suggest that the N270 may be associated with the processing of a conflict with working memory information whereas the N220 might reflect the detection and evaluation of attention to visual information in the human brain.

Adult↗

PubMed2004

The sequential processing of visual feature conjunction mismatches in the human brain.

To clarify the brain mechanism for multifeature stimulus comparison, subjects matched the features of two serial visual stimuli in pairs. Stimulus pairs were of four categories: C-S-, color same, shape same (match); C-S+, color same, shape different (shape mismatch); C+S-, color different, shape same (color mismatch); C+S+, color different, shape different (conjunction mismatches). Subjects matched the stimuli in three different sessions according to different attention tasks: attending to color (Ac), attending to shape (As), or attending to both color and shape (Acs). A negative one-peak brain potential, N270, was elicited in all the mismatch conditions with amplitude enhanced in the task-relevant mismatch. Negative potential with two peaks, N270 and N400, appeared when attending to the conjunction mismatches concurrently. The two serial negativities in response to attended feature conjunctions might reflect the temporal different stages for processing conjunction mismatches or conflicts.

Adult↗

PubMed2003

Brain potentials elicited by matching global and occluded 3-dimensional contours.

Subjects were instructed to match 3-dimensional forms while event-related potentials (ERPs) were recorded to explore the relationship between visual completion and conflict processing. Sequentially presented paired stimuli (S1 and S2) were identical in condition I, while in condition II the images were of the same contour, but S2 contained an invisible portion, and in condition III S1 and S2 were of different contours. Subjects indicated if stimuli were physically identical or contour similar in two separate sessions. Following the onset of S2, ERP components P100, N150, and LPC were recorded in all conditions. N150 was enhanced in condition II in both sessions, and N270 was elicited in conditions II and III. N150 is related to visual completion, while N270 is related to the evaluation of information discrepancy, belonging to independent systems.

Adult↗

PubMed2003

Event-related potential N270 and its distribution in adults and school-age children.

To compare the pattern and distribution of event-related potential (ERP) N270 in adults and school-age children and to explore the development of conflict processing systems in the human brain, pairs of colored numbers were sequentially presented on a screen to subjects. The subjects were instructed to discriminate whether the color or magnitude of the pairs of numbers were identical (match) or different (conflict), and ERPs were recorded at the same time. In adults, a negative potential peaking at 270ms (N270) was elicited when the second stimulus (S2) conflicted with the first stimulus (S1) in either task relevant or irrelevant conditions. N270 was distributed widely on the scalp in adults. In children, N270 was only elicited by a task-relevant conflict. N270 in the color conflict was distributed bilaterally on the scalp and N270 elicited by the magnitude conflict was found to be on the left central-frontal areas. In school-age children, ERP N270 is elicited under the control of attention. Its distribution on the scalp depends on the attributes of stimulus pairs.

Adult↗

PubMed2002

Event-related potentials evoked by multi-feature conflict under different attentive conditions.

Event-related potentials (ERPs) were recorded in subjects while they were performing a matching task. The focus of the present study was on the contributions made by ERP recording to revealing the time-course of multi-conflict information processing in the brain during visual attention. Participants were instructed to discriminate whether the attributes of the first stimulus (S1) were the same as those of the second one (S2) of a pair. Stimuli were defined by three features: color, global shape, and local shape. In condition 1, all attributes of the two stimuli of the pair were constant (no conflict); in condition 2, S2 was different from S1 in all attributes (conflict). The experiment comprised three tasks. In task 1, subjects attended to the color of the stimuli and ignored the other attributes. In task 2, they were asked to attend to both color and global shape of stimuli and disregard the local shape. In task 3, all attributes were attended to. An ERP component N270 was elicited by attending to the color conflict in session one. In task 2, attending to color and global shape induced two ERP effects in the conflict condition: N270 and N400. The results suggest that the attended different conflicts of the two visual attributes of the stimuli were processed in series. However, in task 3, only one apparent negative component, N270, was observed in the conflict condition. The difference between data from task 2 and 3 showed that more than one processing model exists in the human brain for processing multiple visual attribute conflicts.

Adult↗

PubMed2002

The N270 component of the event-related potential reflects supramodal conflict processing in humans.

It is unclear whether crossmodal information conflict can initiate the conflict processing system indexed by a component of the event-related potential (ERP) called the N270, which previously has been observed only for visual conflict. ERPs were recorded in ten subjects, while they were engaged in a visual-auditory discrimination task. A visual stimulus of a facial photograph was followed by an auditory stimulus of Chinese syllable [a] or [i], which might be sounded by the same gender of its preceding photograph (gender match) or by different gender (gender conflict). Subjects pressed a button for gender match and another for gender conflict. A prominent N270, similar to that evoked by visual conflicts, was elicited by the auditory stimuli in gender conflict condition. It is likely that N270 reflects the brain activity of a supra-modal conflict processing system.

Acoustic Stimulation↗