Repetition Probability Does Not Affect fMRI Repetition Suppression for Objects
Repetition Probability Does Not Affect fMRI Repetition Suppression for Objects
复制标题
DOI：
10.1523/jneurosci.3423-12.2013
复制
发表时间：
2013-06-05
影响因子：
5.3
通讯作者：
Vogels, Rufin
中科院分区：
文献类型：
--
作者：
Kovacs, Gyula;Kaiser, Daniel;Vogels, Rufin
此前，几项功能磁共振成像(FMRI)研究指出知觉期望在决定人类适应或重复抑制(RS)中的作用。这些研究表明，一个区块内人脸重复的概率会影响人类大脑中与人脸相关的区域的适应程度(Summerfield等人，2008年)。然而，目前一项使用物体作为刺激的猕猴单细胞/局部场电位(LFP)记录研究发现，没有证据表明颞叶下部皮质的重复概率对神经反应的调制(Kaliukhovich和Vogels，2010)。在这里，我们研究了刺激重复概率是否影响人脑中对非人脸对象刺激的fMRI重复抑制。受试者被暴露在两个相同的[重复试验(RTS)]或两个不同的[交替试验(ATS)]对象刺激下。这两种类型的试验都是由75%[重复块(RBS)]或25%[交替块(ABS)]组成的块。我们发现，在物体敏感的枕外侧皮质以及面部敏感的枕叶和梭形面部区域，强RS，即RTS的信号低于ATS。然而，更重要的是，RBS和ABS在每个区域的RS的大小没有显著差异。这与之前猴子单单位/LFP的发现是一致的，并表明在非面部视觉对象的情况下，RS不受人类重复概率的调节。我们的结果表明，不同的视觉刺激类别的知觉预期效应是不同的。
Previously several functional magnetic resonance imaging (fMRI) studies point toward the role of perceptual expectations in determining adaptation or repetition suppression (RS) in humans. These studies showed that the probability of repetitions of faces within a block influences the magnitude of adaptation in face-related areas of the human brain (Summerfield et al., 2008). However, a current macaque single-cell/local field potential (LFP) recording study using objects as stimuli found no evidence for the modulation of the neural response by the repetition probability in the inferior temporal cortex (Kaliukhovich and Vogels, 2010). Here we examined whether stimulus repetition probability affects fMRI repetition suppression for nonface object stimuli in the human brain. Subjects were exposed to either two identical [repetition trials (RTs)] or two different [alternation trials (ATs)] object stimuli. Both types of trials were presented blocks consisting of either 75% [repetition blocks (RBs)] or 25% [alternation blocks (ABs)] of RTs. We found strong RS, i.e., a lower signal for RTs compared to ATs, in the object sensitive lateral occipital cortex as well as in the face-sensitive occipital and fusiform face areas. More importantly, however, there was no significant difference in the magnitude of RS between RBs and ABs in each of the areas. This is in agreement with the previous monkey single-unit/LFP findings and suggests that RS in the case of nonface visual objects is not modulated by the repetition probability in humans. Our results imply that perceptual expectation effects vary for different visual stimulus categories.