Violated predictions alter neural encoding within and between sensory modalities

Speaker: Professor Jason Mattingley
Queensland Brain Institute
University of Queensland

Title: Violated predictions alter neural encoding within and between sensory modalities

Abstract: 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 can reduce its sensory processing load is to use stored knowledge to predict likely future states of the world and update this information only when new stimuli violate expectations. In this talk I will present findings from experiments in humans and animal models in which we asked whether the encoding of elementary visual features, such as edge orientation, is modulated when otherwise identical stimuli are expected or unexpected based on the history of stimulus presentation. In human participants we used brain imaging to measure neural activity evoked by grating stimuli of different orientations, and used multivariate forward modelling to determine how orientation selectivity is affected for expected versus unexpected stimuli. In rodents and non-human primates, we used two-photon calcium imaging and micro-electrode array recordings to quantify the effects of expectation on orientation tuning in single neurons and multi-unit activity patterns. Across species and imaging modalities, we consistently find that visual selectivity is modulated by stimulus expectancy, even when predictions are generated within the auditory modality. I will discuss the implications of these findings for predictive coding theories of sensory processing.