Abstract
AbstractA dorsal fronto-parietal network, including regions in intra-parietal sulcus (IPS) and frontal eye field (FEF), has been hypothesized to control the allocation of spatial attention to environmental stimuli. One putative mechanism of control is the de-synchronization of electroencephalography (EEG) alpha rhythms (~8-12 Hz) in parieto-occipital cortex in anticipation of a visual target. We show that brief interference by transcranial magnetic stimulation (rTMS) with preparatory activity in right IPS or right FEF while subjects attend to a spatial location impairs identification of target stimuli ~2 seconds later. Moreover, the visual deficit relates to the disruption of anticipatory (pre-stimulus) alpha desynchronization and its topography in parieto-occipital cortex. After right IPS stimulation, the degree to which alpha desynchronization is suppressed predicts the speed of visual identification. These results demonstrate the causal role of posterior parietal cortex in the control of visuo-spatial attention exerted through the synchronization of visual neurons.
Highlights
IntroductionObservers develop expectations about visual scenes that can guide and enhance perception.For example, we can voluntarily attend to a location in the visual field, and subsequent stimuli at that location will be recognized more accurately and rapidly [1, 2]
Observers develop expectations about visual scenes that can guide and enhance perception.For example, we can voluntarily attend to a location in the visual field, and subsequent stimuli at that location will be recognized more accurately and rapidly [1, 2]
The behavioral interference caused by repetititive transcranial magnetic stimulation (rTMS) was measured on the accuracy and reaction times (RTs) of target identification ~1.5 seconds later (Figure 1A)
Summary
Observers develop expectations about visual scenes that can guide and enhance perception.For example, we can voluntarily attend to a location in the visual field, and subsequent stimuli at that location will be recognized more accurately and rapidly [1, 2]. We test the hypothesis that dorsal prefrontal and parietal regions control spatial attention in visual cortex through the anticipatory de-synchronization (or power modulation) of ongoing alpha rhythms. We predict that disruption of neural activity in prefrontal and parietal cortices while observers attend to a target location will interfere both with visual perception and the anticipatory de-synchronization of alpha rhythms in parieto-occipital cortex. To interfere with neural activity we employed repetititive transcranial magnetic stimulation (rTMS), a method already successfully utilized for studying the role of prefrontal and parietal cortices in target detection and reorienting of attention to sensory stimuli [25,26,27,28,29,30,31,32], while we monitored activity in visual cortex by simultaneous recordings of EEG rhythms
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