Abstract
The brain is not a silent, complex input/output system waiting to be driven by external stimuli; instead, it is a closed, self-referential system operating on its own with sensory information modulating rather than determining its activity. Ongoing spontaneous brain activity costs the majority of the brain's energy budget, maintains the brain's functional architecture, and makes predictions about the environment and the future. I will discuss some recent research on the functional significance and the organization of spontaneous brain activity, with implications for perception research. The past decade has seen rapid development in the field of resting-state fMRI networks. In one of the first studies that established the functional significance of these networks, we showed that strokes disrupted large-scale networks in the spontaneous fMRI signals, and that the degree of such disruption predicted the patients' behavioral impairment (spatial neglect). Next, we identified the neurophysiological signal underlying the coherent patterns in the spontaneous fMRI signal, the slow cortical potential (SCP). The SCP is a novel neural correlate of the fMRI signal; existing evidence suggests that it most likely underlies both spontaneous fMRI signals and task-evoked fMRI responses. I further discuss some existing data suggesting a potential involvement of the SCP in conscious awareness, including the influence of spontaneous SCP fluctuations on visual perception. Lastly, given that both the SCP and the fMRI signal display a power-law distribution in their temporal power spectra, I argue that the role of scale-free brain activity in perception and consciousness warrants future investigation.