Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Av Arlindo Bétio, 1000, Ermelino Matarazzo, São Paulo-SP, CEP 03828-000, Brazil.
Behav Brain Res. 2009 Dec 14;205(1):10-8. doi: 10.1016/j.bbr.2009.07.019. Epub 2009 Jul 23.
Performing two tasks simultaneously often degrades performance of one or both tasks. While this dual-task interference is classically interpreted in terms of shared attentional resources, where two motor tasks are performed simultaneously interactions within primary motor cortex (i.e., activity-dependent coupling) may also be a contributing factor. In the present study TMS (transcranial magnetic stimulation) was used to examine the contribution of activity-dependent coupling to dual-task interference during concurrent performance of a bimanual coordination task and a discrete probe reaction time (RT) task involving the foot. Experiments 1 and 2 revealed that activity-dependent coupling within the leg corticomotor pathway was greater during dual-task performance than single-task performance, and this was associated with interference on the probe RT task (i.e., increased RT). Experiment 3 revealed that dual-task interference occurred regardless of whether the dual-task involved two motor tasks or a motor and cognitive task, however activity-dependent coupling was present only when a dual motor task was performed. This suggests that activity-dependent coupling is less detrimental to performance than attentional processes operating upstream of the corticomotor system. Finally, while prioritising the RT task reduced, but did not eliminate, dual-task interference the contribution of activity-dependent coupling to dual-task interference was not affected by task prioritisation. This suggests that although activity-dependent coupling may contribute to dual motor-task interference, attentional processes appear to be more important. It also suggests that activity-dependent coupling may not be subject to modulation by attentional processes.
同时执行两个任务通常会降低一个或两个任务的性能。虽然这种双重任务干扰通常被解释为共享注意力资源，但两个运动任务同时进行时，初级运动皮层内的相互作用（即活动依赖性耦合）也可能是一个促成因素。在本研究中，TMS（经颅磁刺激）被用于检查活动依赖性耦合对同时执行双手协调任务和涉及脚部的离散探针反应时间 (RT) 任务时的双重任务干扰的贡献。实验 1 和 2 表明，在双任务执行期间，腿部运动皮质通路内的活动依赖性耦合大于单任务执行期间，这与探针 RT 任务的干扰有关（即 RT 增加）。实验 3 表明，无论双任务是否涉及两个运动任务还是运动和认知任务，都会发生双任务干扰，但只有在执行双运动任务时才会出现活动依赖性耦合。这表明，与运动皮质系统上游的注意过程相比，活动依赖性耦合对性能的影响较小。最后，尽管优先处理 RT 任务会减少但不会消除双重任务干扰，但任务优先级对活动依赖性耦合对双重任务干扰的贡献没有影响。这表明，尽管活动依赖性耦合可能会导致双重运动任务干扰，但注意过程似乎更为重要。这也表明，活动依赖性耦合可能不受注意过程的调节。
