ABSTRACT
Objective To investigate neural correlates of the generation,execution and inhibition of motor intention. Methods Behavioral performance and event-related potentials (ERP) of 14 participants were recorded when they performed a two-staged Go-Nogo task. At the stage of intention preparation,three kinds of the "what" cues were presented separately to the participants : (1) to press a response key by the left or the right hand (the instructed) ,(2) to decide freely which hand will be used (the free) ,(3) to wait for the second cue (the control). At the stage of intention execution,the "whether" cue suggested the participants execute (Go) or withdraw (Nogo) the previous intention either voluntarily or forcedly. Results The interaction effect between the "what" and the "whether" was significant(F(2,26) = 8.262, P=0.002). The forced responses were faster than those of voluntary action under both the instructed condition ((468.52 ±105.87)ms vs (546.67 ±146.33)ms) and the control condition ((536.78 ± 83.28) ms vs (589.75 ± 140.80) ms). No significant difference was found for the free condition((538.71 ± 127. 39) ms vs (561. 44 ± 146. 51) ms). At the stage of intention preparation,significant ERP effects between the instructed intention and the freely intention were revealed in bilateral frontal regions (150～200 ms) , frontoparietal area (300～700 ms)and right temporal area. At the stage of intention execution,ERP effects between voluntary inhibition and voluntary action were observed in left prefrontal area (160～220 ms) ,fro-nto-cento-parietal area and right frontoparietal area. (300～550 ms). Conclusion The motor intention may be generated in the prefrontal area and maintained in the frontoparietal network. The left prefrontal and fronto-centro-parietal areas inhibit intention in the early stage and the right frontoparietal area involves response inhibition lately.
ABSTRACT
Objective To investigate neural correlates of the retrieval of temporal order.Methods ERP of 19 channels was recorded from 17 healthy young students while they performed a recency judgment task,a recognition task and a visual discrimination task separately,which were based on Sternberg paradigm.One-way ANOVA of repeated-measurement and post-hoc paired comparisons were carried out for both the task factor(temporal order,recognition and control)and the temporal distance factor correspondingly.The latter contains 3 intervals (1,2 and 3)between the targets.Results The temporal distance effect was significant:the closer targets correspond to longer reaction time((745.5±106.1)ms,(711.7±102.2)ms,(653.7±81.5)ms;F_((1.28,20.48))=43.37,P=0.00]and higher error rate((62.8±7.0)%,(72.5±5.4)%,(84.5±6.4)%;F_((1.32,21.11))=135.99,P=0.00].Significant behavioral effect of the task factor was also found for both reaction time(F_((1.32,21.11))=135.99,P=0.00)and error rate(F_((2,32))=200.31,P=0.00).No significant behavioral difference was found between the temporal order group and the recognition group.The spatiotemporal pattern of statistical parametric mapping(SPM)suggested the ERP effects of temporal order were presented in left temporal region (260～270 ms),bilateral parietal-occipital areas(280～290 ms),and bilateral parietal lobes(300～400 ms)prominently.No ERP effect was found between the temporal order task and the recognition task.Conclusions The neural correlates of the temporal distance effect exist in bilateral parietal regions.Temporal order as well as object information processing involves similar cerebral regions during the retrieval period.