CAJ | 학술논문

运用事件相关电位技术，采用分支双任务范式，探讨在奖励驱动的双任务加工过程中，第一任务奖励编码和第二任务奖励编码的时间进程及其脑机制。结果发现：双任务的反应时显著大于单任务的反应时；单任务的N2波幅显著大于双任务条件；双任务的P3波幅显著大于单任务条件。双任务加工过程中奖励编码的半球效应主要体现在P3上，且右半球参与第一任务奖励信息的编码，驱动第一任务；两半球协同参与第二任务奖励信息的编码，驱动第二任务。结果表明：双任务所耗费的心理资源更多，同时双任务加工过程中第一任务奖励信息编码的半球优势效应与任务的性质有关。
운용사건상관전위기술，채용분지쌍임무범식，탐토재장려구동적쌍임무가공과정중，제일임무장려편마화제이임무장려편마적시간진정급기뇌궤제。결과발현：쌍임무적반응시현저대우단임무적반응시；단임무적N2파폭현저대우쌍임무조건；쌍임무적P3파폭현저대우단임무조건。쌍임무가공과정중장려편마적반구효응주요체현재P3상，차우반구삼여제일임무장려신식적편마，구동제일임무；량반구협동삼여제이임무장려신식적편마，구동제이임무。결과표명：쌍임무소모비적심리자원경다，동시쌍임무가공과정중제일임무장려신식편마적반구우세효응여임무적성질유관。
The process of integrating working memory with attentional resource is referred to as branching. Branching is observed in everyday life, which enables people to hold a primary goal in mind while exploring and processing a secondary goal. The hemispheric effect of branching has been noted in several dual-task studies using high spatial resolution brain imaging techniques （e. g. functional magnetic resonance imaging）. However, the brain mechanisms underlying the motivational system＇s action on the pursuit of concurrent goals and the associated time course of such an action is less understood. The dissociation mechanism of dual-task processing based on the reward expectation is also not known. The present study attempted to address these issues using high-density event-related potentials （ERPs） and standard tasks. We recorded ERPs in 16 healthy right-handed participants. Each block began with a black fixation cross displayed on a gray background for 1000 ms, followed by a digital item for 500 ms, and a blank interval （ISI） ranged from 1500 to 2000 ms. The test stimuli were digits pseudo-randomly chosen from the series ＂135791＂ and successively presented on a black screen within a square frame. Subjects performed backward digit-matching tasks and pressed ＂F＂ and ＂J＂ buttons for match and non-match responses. They began each block of digits by indicating whether the first digit was ＂1＂ and proceeded by indicating whether two successively presented digits were also in immediate succession in the series ＂135791＂. We referred to this taskas the primary task. Triangle cues appeared at random times which instructed participants to start a secondary backward digit-matching task by either abandoning the primary task （single-task condition） or delaying its execution （dual-task condition）. When the contextual cues disappeared, participants were required to abandon the secondary task, and started the primary task over again （single-task condition） or reverted back to the primary task and finished the execution （dual-task condition）. In both conditions, the digits were accompanied by incentive cues indicating a reward associated with the ongoing task. The reward could be small or large and was earned only when the task was performed with no errors. At the end of the block, a visual feedback was presented indicating the monetary reward obtained from this block. One thousand ms after the offset of the feedback, the next block of digits started. Behavioral results confirmed that under both conditions, the primary and secondary rewards drove primary and secondary task performance, respectively. Furthermore, the reaction time in the secondary task was significantly longer in the dual task compared to the single task condition. ERP waveform analysis revealed that the single-task responses elicited a larger amplitude （N2） than did the dual-task responses in 290-330 ms and the dual-task responses elicited a larger amplitude （P3） than did the single-task responses in 350~800 ms. Moreover, we observed that the right hemispheric dominance drove the single-task performance according to the secondary reward during 500~700 ms in the dual-task condition. The right hemispheric dominance encoded the primary task reward driving primary task while the left and right hemispheric dominance jointly encoded the secondary task reward driving secondary task during 500~800ms. The overall findings suggest that the amount of mental resources consumed in the dual-task condition was much more than that in the single-task condition. This study provided electrophysiological evidence of dynamic hemispheric dominance of the primary task reward effect based on the character of primary task in dual-task processing.