Kamitani Yukiyasu, Tong Frank
ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan.
Curr Biol. 2006 Jun 6;16(11):1096-102. doi: 10.1016/j.cub.2006.04.003.
Functional neuroimaging has successfully identified brain areas that show greater responses to visual motion and adapted responses to repeated motion directions. However, such methods have been thought to lack the sensitivity and spatial resolution to isolate direction-selective responses to individual motion stimuli. Here, we used functional magnetic resonance imaging (fMRI) and pattern classification methods to show that ensemble activity patterns in human visual cortex contain robust direction-selective information, from which it is possible to decode seen and attended motion directions. Ensemble activity in areas V1-V4 and MT+/V5 allowed us to decode which of eight possible motion directions the subject was viewing on individual stimulus blocks. Moreover, ensemble activity evoked by single motion directions could effectively predict which of two overlapping motion directions was the focus of the subject's attention and presumably dominant in perception. Our results indicate that feature-based attention can bias direction-selective population activity in multiple visual areas, including MT+/V5 and early visual areas (V1-V4), consistent with gain-modulation models of feature-based attention and theories of early attentional selection. Our approach for measuring ensemble direction selectivity may provide new opportunities to investigate relationships between attentional selection, conscious perception, and direction-selective responses in the human brain.
功能神经成像已成功识别出对视觉运动表现出更强反应以及对重复运动方向表现出适应性反应的脑区。然而，人们一直认为此类方法缺乏分离对单个运动刺激的方向选择性反应所需的灵敏度和空间分辨率。在此，我们使用功能磁共振成像（fMRI）和模式分类方法表明，人类视觉皮层中的整体活动模式包含强大的方向选择性信息，据此可以解码所看到的和所关注的运动方向。V1 - V4区域以及MT + / V5区域的整体活动使我们能够解码受试者在各个刺激块上正在观看的八个可能运动方向中的哪一个。此外，由单个运动方向诱发的整体活动能够有效预测两个重叠运动方向中哪一个是受试者注意力的焦点，并且大概在感知中占主导地位。我们的结果表明，基于特征的注意力可以使包括MT + / V5和早期视觉区域（V1 - V4）在内的多个视觉区域中的方向选择性群体活动产生偏差，这与基于特征的注意力的增益调制模型以及早期注意力选择理论一致。我们测量整体方向选择性的方法可能为研究人类大脑中注意力选择、意识感知和方向选择性反应之间的关系提供新的机会。
