虽然脑力的发挥提高了认知任务的表现,动机因素影响认知的神经机制仍然未知。这里,我们使用功能磁共振成像来测试认知努力的变化,由于任务难度的变化,影响工作记忆的神经表现。参与者(男女)被预先检查工作记忆困难是困难还是容易。我们假设艰苦的试验需要更多的努力,因为以后的决定需要更精细的助记精度。行为上,与简单试验相比,硬试验的瞳孔大小更大,反应时间更慢,这表明我们的努力操作成功.神经上,我们观察到前额叶皮层在延迟期的持续活动,尤其是在艰苦的考验中。然而,备忘录的细节无法从前额叶活动的模式中解码。在视觉皮层的活动模式中,然而,我们发现了对记忆目标的强大解码,在艰苦试验中准确性更高。为了潜在地链接这些跨区域的影响,我们假设这种努力,通过前额叶皮层的持续活动,影响视觉皮层中编码的工作记忆表征的质量。的确,我们发现额叶皮层延迟期活动的幅度在试验基础上预测了视皮层的解码准确性.这些结果表明,努力相关的反馈信号塑造了视觉皮层中的种群活动,提高记忆的保真度。重要性陈述对我们认知能力背后的神经机制的充分理解取决于理解它们与认知努力等因素的相互作用。这里,我们依靠简单的直觉,有些任务比其他任务需要更多的努力,成功取决于我们的努力程度。我们展示了认知努力的发挥-更加努力-如何通过前额叶皮层的反馈来提高视觉皮层中工作记忆表征的质量。这种机制描述了如何分配和战略性地控制支持工作存储器的有限资源。这些结果对精神疾病有影响,比如精神分裂症,动机缺陷可能伪装成认知功能障碍。
While the exertion of mental effort improves performance on cognitive tasks, the neural mechanisms by which motivational factors impact cognition remain unknown. Here, we used fMRI to test how changes in cognitive effort, induced by changes in task difficulty, impact neural representations of working memory (WM). Participants (both sexes) were precued whether WM difficulty would be hard or easy. We hypothesized that hard trials demanded more effort as a later decision required finer mnemonic precision. Behaviorally, pupil size was larger and response times were slower on hard compared with easy trials suggesting our manipulation of effort succeeded. Neurally, we observed robust persistent activity during delay periods in the prefrontal cortex (PFC), especially during hard trials. Yet, details of the memoranda could not be decoded from patterns in prefrontal activity. In the patterns of activity in the visual cortex, however, we found strong decoding of memorized targets, where accuracy was higher on hard trials. To potentially link these across-region effects, we hypothesized that effort, carried by persistent activity in the PFC, impacts the quality of WM representations encoded in the visual cortex. Indeed, we found that the amplitude of delay period activity in the frontal cortex predicted decoded accuracy in the visual cortex on a trial-wise basis. These results indicate that effort-related feedback signals sculpt population activity in the visual cortex, improving mnemonic fidelity.