ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of task probability on context processing using AX-type continuous performance test (AX-CPT) and event-related potential (ERP).</p><p><b>METHODS</b>We set 3 groups of complementary probabilities (AX/AY: 0.55/0.15, 0.35/0.35, and 0.15/0.55) for AX task and AY task and kept the probability 0.15 for both BX and BY tasks. Eighteen subjects were asked to press the button only when the go-probe (X: green "<" or ">") followed the go-cue (A: blue "ooo") and withdraw response when the go-probe or a nogo-probe (Y: red "<" or ">") followed the nogo-cue (B: blue "xxx").</p><p><b>RESULTS</b>As the task probability increased, the reaction time of AX task was shortened and the rate of false alarm of BX task increased significantly. The probability effects of ERP revealed by statistical parametric mapping occurred in many regions during both cue and probe stages: cue A in the parietal central (300-350 ms) and the left occipital area (450-500 ms); cue B in the right frontal pole (350-500 ms) and the left frontal pole (750-950 ms); AX probe in the right frontoparietal area (200-250 ms), the left frontal pole, the right dorsal prefrontal and bilateral parietal region (300-400 ms), and the bilateral occipital area and parietal region (400-650 ms); AY probe in the fronto-central area (350-500 ms) - the P3 effect; BX probe in the right temporal and the left occipital areas (300-350 ms); BY probe in the left temporal area (150-250 ms).</p><p><b>CONCLUSION</b>The task probability not only influences both the encoding of go-cue and expectancy of nogo-cue but also modulates the neural assemblies of probe processing differentially.</p>
Subject(s)
Adult , Female , Humans , Young Adult , Cues , Evoked Potentials , Physiology , Spatio-Temporal AnalysisABSTRACT
ObjectiveTo investigate the neural mechanism of processing the salient target during the visual search task with spatiotemporal patterns of event-related potential(ERP).MethodsSixteen subjects were asked to judge the existence of a low or high salient target from 4 items,in which one distractor might be also salient or not.A two-way repeated-measure ANOVA was carried out for behavioral performance and ERP data( distractor saliency:YES,NO)*( target:none,low salient,high salient).ResultsSignificant interaction was found between target and distractor for the reaction time (F( 1.99,29.79) =21.56,P=0.00).For the low salient target,significant difference of reaction time was found between the YES (552.57 ± 82.32 ms) and NO (540.47 ± 75.68 ms)of distractor saliency( t (15) =- 2.489,P =0.025 ).However,such difference of reaction time was not significant for the high salient target.The statistical parametric mapping of F-value of ERP suggested the effect of the distractor saliency revealed in the right fronto-parietal-temporal areas related to stimulus novelty and the effect of the target saliency appeared in the parietal-occipital regions related to visual processing during the same stage ( 350 ～ 450ms ).The significant interaction occurred in the left temporal regions (450 ～ 600 ms ) related to stimulus familiarity and its classification.ConclusionDue to both mechanisms of the parallel processing for the target and the distractor during the perceptual stage and the effective classification of the familiar network within left hemisphere during the stage of pattern classification,the salient target can be processed quickly in spite of the interference from the salient distractor.
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Objective To evaluate and report the performance of PL-11 platelet analyzer.Methods Intravenous blood samples anticoagulated with EDTA-K2 and sodium citrate were tested by the PL-11 platelet analyzer to evaluate the intra-assay and inter-assay coefficient of variation (CV),carry-over rate,accuracy,linearity of the PL-11 platelet analyzer.Platelet aggregation rate of sodium citrate-anticoagulated fasting venous blood collected from 30 physical examinees in outpatient department of The First Affiliated Hospital of Soochow University between February and July,2012 was detected by the PL-11 platelet analyzer and MPG-3E multifunctional double channel blood coagulation analyzer,respectively.The correlation was detected between the PL-11 platelet analyzer and MPG-3E multifunctional double channel blood coagulation analyzer.Results All the parameters were conformed to the standard of Clinical Laboratory Improvement Amendment 88.Both of the intra-assay and inter-assay CV values were less than 5％ ; carry-over rate was less than 1％ ; the accuracy and the linearity was excellent correlated to the result of photoelectric turbidimetry (R2 =0.9439).Conclusions PL-11 platelet analyzer can directly use whole blood dynamics to analyze platelet aggregation process and quantitatively analyze the various components of blood cells (including platelets and red blood cells),the result reports are accurate and reliable.
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Objective To investigate the neural mechanism of the reduction of switch cost induced by short presentation of the task cue.Methods The event-related potentials (ERP) was recorded from 19 subjects while they performed a Chinese Stroop switching task.The factorial design of repeated-measures was adopted with the cue presentation time (100/1000 ms) and the type of succeeding task (repeat/switch).Results For the switch cost of reaction time (the switch subtracts the repeat),the difference between the long cue group (15.0 ± 33.3 ms) and the short group (0.80 -±40.7 ms) had the significantly tendency( t (18) =- 1.77,P=0.09).During the stage of cue processing,the ERP effects of cue reveal in the frontal-occipital areas ( 100 ～ 200 ms),frontoparietal and tempo-occipital regions (200 ～500 ms),frontoparietal network and centro-occipital regions (500 ～900ms).During the stage of task execution,the ERP effects of the cue were observed from the left fronto-occipital areas ( 300 ～ 400 ms) to parieto-occipital areas (400 ～ 900 ms).The ERP effects of the task started from the right hemisphere (500 ～600 ms ) and extended to bilateral prefrontal and centro-parietal area (600 ～900 ms ).Conclusion The short cue presentation can not only start up the preparation of frontoparietal network earlier during cue processing stage but also enhance its retrieval in the left dorsal lateral frontal cortex during task executive stage.