title: A DCM study of spectral asymmetries in feedforward and feedback connections between visual areas V1 and V4 in the monkey.
abstract: This paper reports a dynamic causal modeling study of electrocorticographic (ECoG) data that addresses functional asymmetries between forward and backward connections in the visual cortical hierarchy. Specifically, we ask whether forward connections employ gamma-band frequencies, while backward connections preferentially use lower (beta-band) frequencies. We addressed this question by modeling empirical cross spectra using a neural mass model equipped with superficial and deep pyramidal cell populations-that model the source of forward and backward connections, respectively. This enabled us to reconstruct the transfer functions and associated spectra of specific subpopulations within cortical sources. We first established that Bayesian model comparison was able to discriminate between forward and backward connections, defined in terms of their cells of origin. We then confirmed that model selection was able to identify extrastriate (V4) sources as being hierarchically higher than early visual (V1) sources. Finally, an examination of the auto spectra and transfer functions associated with superficial and deep pyramidal cells confirmed that forward connections employed predominantly higher (gamma) frequencies, while backward connections were mediated by lower (alpha/beta) frequencies. We discuss these findings in relation to current views about alpha, beta, and gamma oscillations and predictive coding in the brain.
authors.affiliation: Ernst Strüngmann Institute (ESI) in Cooperation with Max Planck Society, Deutschordenstraße 46, Frankfurt 60528, Germany; Center for Neuroscience and Center for Mind and Brain, University of California, Davis, Davis, CA 95618, USA. Electronic address: andrembastos@gmail.com.
authors.forename: A M
authors.initials: AM
authors.lastname: Bastos
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: V
authors.initials: V
authors.lastname: Litvak
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: R
authors.initials: R
authors.lastname: Moran
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Kapittelweg 29, Nijmegen 6535 EN, Netherlands; Cognitive and Systems Neuroscience Group, Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam 1098 XH, Netherlands.
authors.forename: C A
authors.initials: CA
authors.lastname: Bosman
authors.affiliation: Ernst Strüngmann Institute (ESI) in Cooperation with Max Planck Society, Deutschordenstraße 46, Frankfurt 60528, Germany; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Kapittelweg 29, Nijmegen 6535 EN, Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Fries
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: K J
authors.initials: KJ
authors.lastname: Friston
mesh_terms: D000818:Animals; D025461:Feedback, Physiological; D000882:Haplorhini / Q000502:physiology*; D008962:Models, Theoretical; D009415:Nerve Net / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*
keywords: Beta oscillations; Computation; Connectivity; Dynamic causal modeling; Gamma oscillations; Neuronal; Synchronization coherence; Transfer functions