Helen Wills Neuroscience Institute, University of California (UC), Berkeley, California 94720-3370,
Division of Science and Mathematics, New York University Abu Dhabi, New York 10011.
J Neurosci. 2018 Jun 6;38(23):5267-5276. doi: 10.1523/JNEUROSCI.3061-17.2018. Epub 2018 May 8.
Visual working memory (VWM) recruits a broad network of brain regions, including prefrontal, parietal, and visual cortices. Recent evidence supports a "sensory recruitment" model of VWM, whereby precise visual details are maintained in the same stimulus-selective regions responsible for perception. A key question in evaluating the sensory recruitment model is how VWM representations persist through distracting visual input, given that the early visual areas that putatively represent VWM content are susceptible to interference from visual stimulation.To address this question, we used a functional magnetic resonance imaging inverted encoding model approach to quantitatively assess the effect of distractors on VWM representations in early visual cortex and the intraparietal sulcus (IPS), another region previously implicated in the storage of VWM information. This approach allowed us to reconstruct VWM representations for orientation, both before and after visual interference, and to examine whether oriented distractors systematically biased these representations. In our human participants (both male and female), we found that orientation information was maintained simultaneously in early visual areas and IPS in anticipation of possible distraction, and these representations persisted in the absence of distraction. Importantly, early visual representations were susceptible to interference; VWM orientations reconstructed from visual cortex were significantly biased toward distractors, corresponding to a small attractive bias in behavior. In contrast, IPS representations did not show such a bias. These results provide quantitative insight into the effect of interference on VWM representations, and they suggest a dynamic tradeoff between visual and parietal regions that allows flexible adaptation to task demands in service of VWM. Despite considerable evidence that stimulus-selective visual regions maintain precise visual information in working memory, it remains unclear how these representations persist through subsequent input. Here, we used quantitative model-based fMRI analyses to reconstruct the contents of working memory and examine the effects of distracting input. Although representations in the early visual areas were systematically biased by distractors, those in the intraparietal sulcus appeared distractor-resistant. In contrast, early visual representations were most reliable in the absence of distraction. These results demonstrate the dynamic, adaptive nature of visual working memory processes, and provide quantitative insight into the ways in which representations can be affected by interference. Further, they suggest that current models of working memory should be revised to incorporate this flexibility.
视觉工作记忆（VWM）招募了广泛的大脑区域网络，包括前额叶、顶叶和视觉皮层。最近的证据支持 VWM 的“感觉招募”模型，即精确的视觉细节在负责感知的相同刺激选择性区域中得到保持。评估感觉招募模型的一个关键问题是，鉴于假定代表 VWM 内容的早期视觉区域容易受到视觉刺激的干扰，VWM 表示如何在分散的视觉输入中持续存在。为了解决这个问题，我们使用功能磁共振成像反转编码模型方法来定量评估分心物对早期视觉皮层和顶内沟（IPS）中 VWM 表示的影响，IPS 是另一个先前涉及 VWM 信息存储的区域。这种方法使我们能够重建 VWM 对方向的表示，无论是在视觉干扰之前还是之后，并检查定向分心物是否系统地偏向这些表示。在我们的人类参与者（男性和女性）中，我们发现，在预期可能出现分心的情况下，方向信息同时在早期视觉区域和 IPS 中保持，并且这些表示在没有分心的情况下持续存在。重要的是，早期视觉表示容易受到干扰；从视觉皮层重建的 VWM 方向明显偏向分心物，对应于行为中的小吸引力偏差。相比之下，IPS 表示没有表现出这种偏差。这些结果提供了对干扰对 VWM 表示影响的定量见解，并表明视觉和顶叶区域之间存在动态权衡，这使得能够灵活地适应 VWM 的任务需求。尽管有大量证据表明，刺激选择性视觉区域在工作记忆中保持精确的视觉信息，但尚不清楚这些表示如何在后续输入中持续存在。在这里，我们使用基于定量模型的 fMRI 分析来重建工作记忆的内容并检查分心输入的影响。尽管早期视觉区域的表示受到分心物的系统偏差，但顶内沟中的表示似乎不受干扰物的影响。相比之下，在没有分心的情况下，早期视觉表示最可靠。这些结果表明视觉工作记忆过程具有动态适应性，并提供了对表示如何受到干扰影响的定量见解。此外，它们表明，工作记忆的当前模型应该进行修订，以纳入这种灵活性。
