Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex

Spontaneous cortical waves have been widely observed, although previous evidence from humans has been indirect, using functional magnetic resonance imaging. This study reports that there are slow modulations in neuronal firing rates and gamma local field potentials in human auditory cortex in the absence of sensory stimuli or task. Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (