Effect of time of day on reward circuitry. A discussion of Byrne et al. 2017

TL;DR

This paper critically discusses Byrne et al. 2017's study on how time of day affects reward circuitry, highlighting methodological issues that limit the validity and generalizability of its findings.

Contribution

The paper provides a critical review of Byrne et al.'s methodology and analysis, emphasizing the need for clearer reporting and better control of confounding factors.

Findings

Highlights issues in small volume correction reporting

Points out circularity in multilevel modeling analysis

Notes lack of behavioral correlation with neural results

Abstract

Byrne and colleagues present a paper on a timely topic with potentially important results. However, we think that issues in the design and analysis complicate the interpretation and limit the generalizability of the findings. Specifically, the details of the small volume correction used in the primary analysis are not adequately described and, moreover, the results do not appear to be corroborated by the whole-brain analysis. In addition, the follow-up multilevel modeling, which is fundamental to the conclusions of the paper, is inherently circular thereby guaranteeing discovery of the reported effect. Finally, the study does not control for other factors that vary over the course of the day and are known to impact MRI measurements, and fails to link the neural results directly to any relevant behavior.