Professor Jason Mattingley, UQ : "Understanding the role of prediction in sensory encoding"

Speaker:

Professor Jason Mattingley
Queensland Brain Institute & School of Psychology
The University of Queensland

Title: Understanding the role of prediction in sensory encoding"

Abstract: 

At any given moment the brain receives more sensory information than it can use to guide adaptive behaviour, creating the need for mechanisms that promote efficient processing of incoming sensory signals. One way in which the brain might reduce its sensory processing load is to encode successive presentations of the same stimulus in a more efficient form, a process known as neural adaptation. Conversely, when a stimulus violates an expected pattern, it should evoke an enhanced neural response. Such a scheme for sensory encoding has been formalised in predictive coding theories, which propose that recent experience establishes expectations in the brain that generate prediction errors when violated. In this talk I will present findings from experiments in humans and mice in which we asked whether the encoding of elementary visual features is modulated when otherwise identical stimuli are expected or unexpected based upon the history of stimulus presentation. In human participants we employed electroencephalography to measure neural activity evoked by gratings of different orientations, and used multivariate forward modelling to determine how orientation selectivity is affected for expected versus unexpected stimuli. Using an analogous visual paradigm in awake head-fixed mice, we used two-photon calcium imaging to quantify orientation tuning of individual neurons in the primary visual cortex to expected and unexpected gratings. Results revealed enhanced orientation tuning to unexpected visual stimuli, both at the level of whole-brain responses and for individual visual cortex neurons. I will discuss the implications of these findings for predictive coding theories of sensory encoding.