Guidotti Roberto, Del Gratta Cosimo, Baldassarre Antonello, Romani Gian Luca, Corbetta Maurizio
Department of Neuroscience, Imaging and Clinical Sciences, and Institute for Advanced Biomedical Technologies, "Gabriele D'Annunzio" University Chieti-Pescara, 66100 Chieti, Italy, and
Department of Neuroscience, Imaging and Clinical Sciences, and Institute for Advanced Biomedical Technologies, "Gabriele D'Annunzio" University Chieti-Pescara, 66100 Chieti, Italy, and.
J Neurosci. 2015 Jul 8;35(27):9786-98. doi: 10.1523/JNEUROSCI.3920-14.2015.
When measured with functional magnetic resonance imaging (fMRI) in the resting state (R-fMRI), spontaneous activity is correlated between brain regions that are anatomically and functionally related. Learning and/or task performance can induce modulation of the resting synchronization between brain regions. Moreover, at the neuronal level spontaneous brain activity can replay patterns evoked by a previously presented stimulus. Here we test whether visual learning/task performance can induce a change in the patterns of coded information in R-fMRI signals consistent with a role of spontaneous activity in representing task-relevant information. Human subjects underwent R-fMRI before and after perceptual learning on a novel visual shape orientation discrimination task. Task-evoked fMRI patterns to trained versus novel stimuli were recorded after learning was completed, and before the second R-fMRI session. Using multivariate pattern analysis on task-evoked signals, we found patterns in several cortical regions, as follows: visual cortex, V3/V3A/V7; within the default mode network, precuneus, and inferior parietal lobule; and, within the dorsal attention network, intraparietal sulcus, which discriminated between trained and novel visual stimuli. The accuracy of classification was strongly correlated with behavioral performance. Next, we measured multivariate patterns in R-fMRI signals before and after learning. The frequency and similarity of resting states representing the task/visual stimuli states increased post-learning in the same cortical regions recruited by the task. These findings support a representational role of spontaneous brain activity.
当在静息状态(R-fMRI)下用功能磁共振成像(fMRI)进行测量时,解剖学和功能上相关的脑区之间的自发活动存在相关性。学习和/或任务表现可诱导脑区之间静息同步性的调节。此外,在神经元水平上,大脑自发活动可以重现先前呈现的刺激所诱发的模式。在这里,我们测试视觉学习/任务表现是否能在R-fMRI信号中诱发编码信息模式的变化,这与自发活动在表征与任务相关信息中的作用相一致。人类受试者在对一项新颖的视觉形状方向辨别任务进行知觉学习之前和之后接受了R-fMRI检查。在学习完成后以及第二次R-fMRI检查之前,记录了对训练刺激与新刺激的任务诱发fMRI模式。通过对任务诱发信号进行多变量模式分析,我们在几个皮质区域发现了如下模式:视觉皮质,V3/V3A/V7;在默认模式网络内,楔前叶和顶下小叶;以及在背侧注意网络内,顶内沟,这些区域能够区分训练刺激和新的视觉刺激。分类的准确性与行为表现密切相关。接下来,我们测量了学习前后R-fMRI信号中的多变量模式。在学习后,代表任务/视觉刺激状态的静息状态的频率和相似性在任务所招募的相同皮质区域中增加。这些发现支持了大脑自发活动的表征作用。