Vetter Petra, Edwards Grace, Muckli Lars
Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow Glasgow, UK.
Front Psychol. 2012 Jun 8;3:176. doi: 10.3389/fpsyg.2012.00176. eCollection 2012.
Predicting visual information facilitates efficient processing of visual signals. Higher visual areas can support the processing of incoming visual information by generating predictive models that are fed back to lower visual areas. Functional brain imaging has previously shown that predictions interact with visual input already at the level of the primary visual cortex (V1; Harrison et al., 2007; Alink et al., 2010). Given that fixation changes up to four times a second in natural viewing conditions, cortical predictions are effective in V1 only if they are fed back in time for the processing of the next stimulus and at the corresponding new retinotopic position. Here, we tested whether spatio-temporal predictions are updated before, during, or shortly after an inter-hemifield saccade is executed, and thus, whether the predictive signal is transferred swiftly across hemifields. Using an apparent motion illusion, we induced an internal motion model that is known to produce a spatio-temporal prediction signal along the apparent motion trace in V1 (Muckli et al., 2005; Alink et al., 2010). We presented participants with both visually predictable and unpredictable targets on the apparent motion trace. During the task, participants saccaded across the illusion whilst detecting the target. As found previously, predictable stimuli were detected more frequently than unpredictable stimuli. Furthermore, we found that the detection advantage of predictable targets is detectable as early as 50-100 ms after saccade offset. This result demonstrates the rapid nature of the transfer of a spatio-temporally precise predictive signal across hemifields, in a paradigm previously shown to modulate V1.
预测视觉信息有助于视觉信号的高效处理。更高层次的视觉区域可以通过生成反馈到较低视觉区域的预测模型来支持对传入视觉信息的处理。功能性脑成像先前已表明,预测在初级视觉皮层(V1)水平就已经与视觉输入相互作用(哈里森等人,2007年;阿林克等人,2010年)。鉴于在自然观看条件下注视每秒最多变化四次,只有当皮层预测及时反馈以处理下一个刺激并处于相应的新视网膜拓扑位置时,它们在V1中才有效。在这里,我们测试了时空预测是在执行半视野间扫视之前、期间还是之后不久更新的,因此,预测信号是否能迅速跨半视野传递。使用一种表观运动错觉,我们诱导了一个内部运动模型,已知该模型会沿着V1中的表观运动轨迹产生时空预测信号(穆克利等人,2005年;阿林克等人,2010年)。我们在表观运动轨迹上向参与者呈现视觉上可预测和不可预测的目标。在任务过程中,参与者在检测目标的同时跨错觉进行扫视。如先前发现的那样,可预测刺激比不可预测刺激被检测到的频率更高。此外,我们发现可预测目标的检测优势在扫视偏移后早至50 - 100毫秒就可检测到。这一结果表明,在先前已证明可调节V1的范式中,时空精确预测信号跨半视野传递的快速性。