Department of Psychology, New York University, New York, United States.
Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, United States.
Elife. 2022 Apr 7;11:e73018. doi: 10.7554/eLife.73018.
Early visual cortex exhibits widespread hemodynamic responses in the absence of visual stimulation, which are entrained to the timing of a task and not predicted by local spiking or local field potential. Such task-related responses (TRRs) covary with reward magnitude and physiological signatures of arousal. It is unknown, however, if TRRs change on a trial-to-trial basis according to behavioral performance and task difficulty. If so, this would suggest that TRRs reflect arousal on a trial-to-trial timescale and covary with critical task and behavioral variables. We measured functional magnetic resonance imaging blood-oxygen-level-dependent (fMRI-BOLD) responses in the early visual cortex of human observers performing an orientation discrimination task consisting of separate easy and hard runs of trials. Stimuli were presented in a small portion of one hemifield, but the fMRI response was measured in the ipsilateral hemisphere, far from the stimulus representation and focus of spatial attention. TRRs scaled in amplitude with task difficulty, behavioral accuracy, reaction time, and lapses across trials. These modulations were not explained by the influence of respiration, cardiac activity, or head movement on the fMRI signal. Similar modulations with task difficulty and behavior were observed in pupil size. These results suggest that TRRs reflect arousal and behavior on the timescale of individual trials.
早期视觉皮层在没有视觉刺激的情况下表现出广泛的血流动力学反应，这些反应与任务的时间同步，而不受局部放电或局部场电位的预测。这种与任务相关的反应（TRR）与奖励幅度和觉醒的生理特征相关。然而，目前尚不清楚 TRR 是否会根据行为表现和任务难度在逐次试验的基础上发生变化。如果是这样，这将表明 TRR 反映了在逐次试验的时间尺度上的觉醒，并与关键任务和行为变量相关。我们在执行包含单独简单和困难试验运行的方向辨别任务的人类观察者的早期视觉皮层中测量了功能磁共振成像血氧水平依赖性（fMRI-BOLD）反应。刺激仅在一个半视野的一小部分呈现，但 fMRI 响应在对侧半球中进行测量，远离刺激表示和空间注意力的焦点。TRR 的幅度与任务难度、行为准确性、反应时间以及试验间的失误成正比。这些调制不能用呼吸、心脏活动或头部运动对 fMRI 信号的影响来解释。在瞳孔大小上也观察到了与任务难度和行为相似的调制。这些结果表明，TRR 反映了在单个试验时间尺度上的觉醒和行为。
