Attentional Enhancement of Auditory Mismatch Responses: a DCM/MEG Study.

Ryszard Auksztulewicz,Karl Friston

doi:10.1093/cercor/bhu323

Abstract

Despite similar behavioral effects, attention and expectation influence evoked responses differently: Attention typically enhances event-related responses, whereas expectation reduces them. This dissociation has been reconciled under predictive coding, where prediction errors are weighted by precision associated with attentional modulation. Here, we tested the predictive coding account of attention and expectation using magnetoencephalography and modeling. Temporal attention and sensory expectation were orthogonally manipulated in an auditory mismatch paradigm, revealing opposing effects on evoked response amplitude. Mismatch negativity (MMN) was enhanced by attention, speaking against its supposedly pre-attentive nature. This interaction effect was modeled in a canonical microcircuit using dynamic causal modeling, comparing models with modulation of extrinsic and intrinsic connectivity at different levels of the auditory hierarchy. While MMN was explained by recursive interplay of sensory predictions and prediction errors, attention was linked to the gain of inhibitory interneurons, consistent with its modulation of sensory precision.

Highlights

The predictive coding account of perceptual inference (Rao and Ballard 1999) entailed by the free-energy principle (Friston and Kiebel 2009; Friston 2010) has been increasingly influential in explaining how the brain uses generative models to process sensory inputs
We modeled MEG data acquired in a task combining temporal attention and an auditory roving oddball paradigm to disentangle the neural mechanisms of attention and expectation
Mismatch responses to frequency deviants were strongly modulated by temporal attention, speaking against the common interpretation of the Mismatch negativity (MMN) response as being pre-attentive (Näätänen et al 2001; Garrido, Kilner, Kiebel et al 2009)

Summary

Introduction

The predictive coding account of perceptual inference (Rao and Ballard 1999) entailed by the free-energy principle (Friston and Kiebel 2009; Friston 2010) has been increasingly influential in explaining how the brain uses generative models to process sensory inputs. Previous work on the mismatch negativity (MMN)—a typical neural response to unpredicted stimuli—has suggested an underlying modulation of feedforward and feedback connectivity, implementing the propagation of sensory prediction errors and predictions, respectively (Garrido, Kilner, Kiebel, Stephan et al 2007, 2008, Garrido, Kilner, Stephan et al 2009; Wacongne et al 2012). Despite recent research, it is unclear how mismatch responses interact with top-down factors such as attention (Summerfield and Egner 2009; Lange 2013). One goal of this study was to revisit the dominant pre-attentive view of mismatch responses by replicating a few previous experiments showing a clear attentional modulation of the MMN (Woldorff et al 1991; Sussman et al 2013) and extending their findings to temporal attention

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Conclusion