title: Dynamic causal modelling of eye movements during pursuit: Confirming precision-encoding in V1 using MEG.
abstract: This paper shows that it is possible to estimate the subjective precision (inverse variance) of Bayesian beliefs during oculomotor pursuit. Subjects viewed a sinusoidal target, with or without random fluctuations in its motion. Eye trajectories and magnetoencephalographic (MEG) data were recorded concurrently. The target was periodically occluded, such that its reappearance caused a visual evoked response field (ERF). Dynamic causal modelling (DCM) was used to fit models of eye trajectories and the ERFs. The DCM for pursuit was based on predictive coding and active inference, and predicts subjects' eye movements based on their (subjective) Bayesian beliefs about target (and eye) motion. The precisions of these hierarchical beliefs can be inferred from behavioural (pursuit) data. The DCM for MEG data used an established biophysical model of neuronal activity that includes parameters for the gain of superficial pyramidal cells, which is thought to encode precision at the neuronal level. Previous studies (using DCM of pursuit data) suggest that noisy target motion increases subjective precision at the sensory level: i.e., subjects attend more to the target's sensory attributes. We compared (noisy motion-induced) changes in the synaptic gain based on the modelling of MEG data to changes in subjective precision estimated using the pursuit data. We demonstrate that imprecise target motion increases the gain of superficial pyramidal cells in V1 (across subjects). Furthermore, increases in sensory precision - inferred by our behavioural DCM - correlate with the increase in gain in V1, across subjects. This is a step towards a fully integrated model of brain computations, cortical responses and behaviour that may provide a useful clinical tool in conditions like schizophrenia.
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK. Electronic address: rick.adams@ucl.ac.uk.
authors.forename: Rick A
authors.initials: RA
authors.lastname: Adams
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK; School of Psychology, University Park, Nottingham University, Nottingham, NG7 2RD, UK. Electronic address: Markus.Bauer@nottingham.ac.uk.
authors.forename: Markus
authors.initials: M
authors.lastname: Bauer
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK. Electronic address: d.pinotsis@ucl.ac.uk.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Pinotsis
authors.affiliation: The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK. Electronic address: k.friston@ucl.ac.uk.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Friston
mesh_terms: D000293:Adolescent; D000328:Adult; D001499:Bayes Theorem; D001931:Brain Mapping / Q000379:methods*; D053483:Eye Movement Measurements; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011698:Pursuit, Smooth; D012815:Signal Processing, Computer-Assisted; D013597:Systems Analysis; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult
keywords: Active inference; Dynamic causal modelling; Magnetoencephalography; Oculomotor control; Precision; Smooth pursuit; Visual occlusion