title: Reflections on agranular architecture: predictive coding in the motor cortex.
abstract: The agranular architecture of motor cortex lacks a functional interpretation. Here, we consider a 'predictive coding' account of this unique feature based on asymmetries in hierarchical cortical connections. In sensory cortex, layer 4 (the granular layer) is the target of ascending pathways. We theorise that the operation of predictive coding in the motor system (a process termed 'active inference') provides a principled rationale for the apparent recession of the ascending pathway in motor cortex. The extension of this theory to interlaminar circuitry also accounts for a sub-class of 'mirror neuron' in motor cortex--whose activity is suppressed when observing an action--explaining how predictive coding can gate hierarchical processing to switch between perception and action.
authors.affiliation: Department of Visual Neuroscience, UCL Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK. Electronic address: s.shipp@ucl.ac.uk.
authors.forename: Stewart
authors.initials: S
authors.lastname: Shipp
authors.forename: Rick A
authors.initials: RA
authors.lastname: Adams
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Friston
mesh_terms: D000818:Animals; D006801:Humans; D008959:Models, Neurological; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010465:Perception / Q000502:physiology*