Feedback to V1: a reverse hierarchy in vision
Feedback to V1: a reverse hierarchy in vision
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DOI：
10.1007/s00221-003-1478-5
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发表时间：
2003-05-01
影响因子：
2
通讯作者：
Walsh, V
中科院分区：
文献类型：
--
作者：
Juan, CH;Walsh, V
我们研究了视觉区V1在视觉检测中的参与，以评估反向层次理论（Ahissar和Hochstein 2000）中提出的V1反馈连接的作用。在实验1中，信号检测功能和连接检测任务的重复脉冲经颅磁刺激（rTMS）超过VI刺激发作后500英寸。在实验2中，rTMS被延迟，以允许不间断的信号处理100英寸后，视觉刺激发作。随后500 ms的TMS现在中断了会合目标的检测，但没有中断特征目标的检测。在实验3中，我们应用双脉冲TMS在不同的时间间隔，以评估V1参与这些任务的时间。单一功能检测涉及V1只在40和100毫秒之间的某个点后，视觉阵列发病;检测的目标所定义的连接功能涉及V1在整个第一个100英寸，也在200和240毫秒之间的视觉刺激发病后。我们认为，在连接任务的早期效应是由于“重复采样的视觉阵列，以提取信号从外部噪音。联合搜索中的后效应归因于从次级视觉区返回V1的返回投射，与反向层次理论相一致。这两项任务的效果与最近的神经生理学实验中假设的前馈和反馈回路的早期和重复迭代一致（参见Foxe和Simpson 2002）。
We examined the involvement of visual area V1 in visual detection to assess the role of feedback connections to V1 as proposed in reverse hierarchy theory (Ahissar and Hochstein 2000). In Experiment 1, signal detection was decreased in feature and conjunction detection tasks by repetitive pulse TMS (rTMS) over VI for 500 ins after stimulus onset. In Experiment 2, rTMS was delayed to allow uninterrupted signal processing for 100 ins after visual stimulus onset. TMS for the subsequent 500 ms now disrupted detection of conjunction but not feature targets. In Experiment 3 we applied double pulse TMS at varying intervals to assess the timing of V1 involvement in these tasks. Single feature detection involved V1 only at some point between 40 and 100 ms after visual array onset; detection of targets defined by conjunctions of features involved V1 throughout the first 100 ins and also between 200 and 240 ms after visual stimulus onset. We suggest that the early effects in the conjunction task are due to 'repeated sampling of the visual array to extract the signal from external noise. The later effects in conjunction search are attributed to the return projections from secondary visual areas back to V1, consistent with the reverse hierarchy theory. The effects in both tasks are consistent with early and repeated iterations of feed forward and feedback loops as hypothesised in recent neurophysiological experiments (see Foxe and Simpson 2002).