Structured Modulations of Ongoing Variability by Task and Development

Patterns of trial-averaged post-stimulus neural activity, e.g. event related potentials (ERPs) are traditionally interpreted as the correlates of cognitive operations. However, single-trial trajectories of neural responses approach these ERP components only in a loose and stochastic manner, questioning legitimacy of these components, proposed roles. Deconstructing the conventional ERP analyses, here we studied patterns of event related variability (ERV) in 2-6 month-old infants and adults using electroencephalography. Our analyses reveal that the ERP components are analogous to the biasing forces on the ongoing dynamics, which instrument the variability quenching and boosting events along neural trajectories. Moreover, the observed ERV possesses a rich temporal structure, modulated by both age and task, rivaling in complexity with that of the classical ERPs. Our findings suggest that since the early infancy, neural trajectories are actively controlled. This is compliant with the hypothesis that neural variability is a resource for cognitive processing, rather than unwanted noise.