Cortical candidates for self-other distinction based on visual and action cues: where do we stand?

TL;DR

This paper reviews brain regions involved in distinguishing self-generated actions from external sensations, focusing on how visual and action cues are compared.

Contribution

The paper highlights experimental biases and proposes ways to improve designs for studying visuomotor comparisons in the brain.

Findings

Three candidate brain regions (EBA, STS, AG) are involved in comparing sensory and action cues.

Differences in experimental design affect the interpretation of visuomotor comparisons.

Adaptation and factorial conflict designs offer new approaches but come with challenges.

Abstract

Distinguishing sensations that were generated by one’s actions (reafference) from those that were not may be grounded in the comparison of sensory and action cues; i.e., in evaluating sensory movement feedback against motor predictions by “comparator” modules in the brain. For the evaluation of visual movement feedback, brain imaging studies have converged on three candidate brain regions for such comparisons: the EBA, the STS, and the AG. Yet, the question whether the “action cues” received by those regions are motor or non-motor signals cannot conclusively be answered, partly due to the heterogeneity of the imaging results and differences in experimental methodology. Thus, there is an ongoing debate which of these regions implement visuomotor comparisons, rather than merely intersensory (e.g., visuoproprioceptive) comparisons blind to the cause of movement. In this mini review, I revisit the assumptions of classical (visuomotor) comparator models; discuss potential experimental biases resulting from non-motoric cues; highlight how differences in kinematic predictability result from different kinds of experimental visual feedback distortion—and how this could be capitalized on; and I discuss the potential promises and pitfalls of recent experimental approaches using adaptation designs and factorial visuomotor conflict designs with additional control over the locus of movement generation.

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