CONICET | Buscador de Institutos y Recursos Humanos

Brain function can be conceived as a hierarchy of generative models that optimize predictions of sensory inputs, and minimize ?surprise?. Each level of the hierarchy makes predictions of neural events at a lower level in the hierarchy, which returns a prediction error when these expectations are violated. We tested the generalisation of this hypothesis to multiple sequential deviations, and the identified the most likely organisation of the network that accommodates deviations in temporal structure of stimuli. Magnetoencephalography of healthy human participants during an auditory paradigm identified prediction error responses in bilateral primary auditory cortex, superior temporal gyrus and lateral prefrontal cortex, for deviation by frequency, intensity, location, duration and silent gap. We examined the connectivity between cortical sources using a set of 21 generative models that embedded alternate hypotheses of frontotemporal network dynamics. Bayesian model selection provided evidence for two new features of functional network organisation. First, an expectancy signal provided input to the prefrontal cortex bilaterally, related to the temporal structure of stimuli. Second, there are functionally significant lateral connections between superior temporal and/or prefrontal cortex. The results support a predictive coding hypothesis, but go beyond previous work in demonstrating the generalisation to multiple concurrent stimulus dimensions, and the evidence for a temporal-expectancy input at the higher level of the frontotemporal hierarchy. We propose that this framework for studying the brain?s response to unexpected events is not limited to simple sensory tasks but may also apply to the neurocognitive mechanisms of higher cognitive functions and their disorders.