Original Research ARTICLE
Time scales of representation in the human brain: weighing past information to predict future events
- 1 York Neuroimaging Centre, The Biocentre, University of York, York, UK
- 2 Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, UK
- 3 Wellcome Trust Centre for Neuroimaging, University College London, London, UK
The estimates that humans make of statistical dependencies in the environment and therefore their representation of uncertainty crucially depend on the integration of data over time. As such, the extent to which past events are used to represent uncertainty has been postulated to vary over the cortex. For example, primary visual cortex responds to rapid perturbations in the environment, while frontal cortices involved in executive control encode the longer term contexts within which these perturbations occur. Here we tested whether primary and executive regions can be distinguished by the number of past observations they represent. This was based on a decay-dependent model that weights past observations from a Markov process and Bayesian Model Selection to test the prediction that neuronal responses are characterized by different decay half-lives depending on location in the brain. We show distributions of brain responses for short and long term decay functions in primary and secondary visual and frontal cortices, respectively. We found that visual and parietal responses are released from the burden of the past, enabling an agile response to fluctuations in events as they unfold. In contrast, frontal regions are more concerned with average trends over longer time scales within which local variations are embedded. Specifically, we provide evidence for a temporal gradient for representing context within the prefrontal cortex and possibly beyond to include primary sensory and association areas.
Keywords: uncertainty, information theory, surprise, functional MRI, Bayesian spatial models, Bayesian model selection
Citation: Harrison LM, Bestmann S, Rosa MJ, Penny W and Green GGR (2011) Time scales of representation in the human brain: weighing past information to predict future events. Front. Hum. Neurosci. 5:37. doi: 10.3389/fnhum.2011.00037
Received: 14 January 2011; Paper pending published: 04 March 2011;
Accepted: 24 March 2011; Published online: 26 April 2011.
Edited by:Francisco Barcelo, University of Illes Balears, Spain
Reviewed by:Francisco Barcelo, University of Illes Balears, Spain
Stefan J. Kiebel, University College London, UK
Copyright: © 2011 Harrison, Bestmann, Rosa, Penny and Green. This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and other Frontiers conditions are complied with.
*Correspondence: Lee M. Harrison, York Neuroimaging Centre, The Biocentre, York Science Park, University of York, York YO10 5DG. e-mail: firstname.lastname@example.org