LAUSR

of visual mental imagery proposing a reverse visual hierarchy starting from prefrontal areas back to sensory areas. I would like to thank Paolo Bartolomeo, Dounia Hajhajate, Jianghao Liu and Alfredo Spagna for their correspondence on our Review (The human imagination: the cogni tive neuro science of visual mental imagery. Nat. Rev. Neurosci. 20, 624–634 (2019))1, which raises some important issues (Assessing the causal role of early visual areas in visual mental imagery. Nat. Rev. Neurosci. https:// doi.org/10.1038/10.1038/s41583-020-0348-5 (2020))2. Neuropsychological work reports that individuals with visual cortex damage can show some imagery-like processes without perception3,4, while damage to the temporal lobe can correspond to a lack of imagery/ memory abilities5,6. Further, individuals with aphantasia (no imagery vividness or sensory imagery)7,8 show normal sensory perception (although this is yet to be tested in detail), suggesting a general dissociation, and has been linked to areas outside of early visual cortex9. Based on these reports Bartolomeo et. al., suggest a revision to the reverse visual hierarchy model I described, without a causal role of early visual cortex. Here I outline three reasons why this is not required. Much of the neuropsychological work on imagery is actually correlational, often documented brain injury is correlated with subjective descriptions of imagery loss. Hence, we do not know an individual’s imagery abilities prior to the injury. For it to be causal, visual imagery would need to be accurately assessed before and after predefined or ‘planned’ and controlled damage or interruption to a particular brain region of places, faces, spatial imagery or imagery vividness. To put this another way, visual imagery, like visual perception, is not a unitary process. Different features, colour, form and motion, and their levels of precision are processed across different brain areas and most likely use a range of mechanisms. Further complicating this hierarchical spread is the extreme range of individual differences that naturally exist with imagery, together making cross-methodological comparisons and meta-analyses difficult.