The causal involvement of the visual cortex in visual working memory remains unclear: a comment on Phylactou et al., 2023

The role of the early visual cortex in visual working memory is a matter of current debate (Christophel et al., 2017; Xu 2017). Neuroimaging research has consistently shown that early visual areas (V1, V2 and V3) encode the content of VWM (e.g., Harrison and Tong 2009; Serences et al., 2009). However, we are lacking conclusive evidence supporting the causal role of sensory areas in VWM, not at least because previous transcranial magnetic stimulation (TMS) studies provided incongruent results (e.g., van de Ven et al., 2012; van Lamsweerde et al., 2017; Rademaker et al., 2017). In a recent registered report, Phylactou et al., (2023), sought to tackle this controversy via two well powered TMS experiments, designed to correct possible methodological issues of previous attempts. Unfortunately, a key part of their experimental design was based on the wrong anatomical assumption that a given eye projects input from the center of gaze (i.e., from the central retina) primarily to one hemisphere. They hence disregarded two important anatomical facts, namely that early visual areas of each hemisphere represent the contralateral visual hemifield, and that each hemisphere receives equally strong input from each eye. In what follows, we explain the correct anatomy and describe why their main approach failed to address current issues in the literature.