The connectional anatomy of visual mental imagery: evidence from a patient with left occipito-temporal damage

Most of us can use their “mind’s eye” to mentally visualize things that are not in their direct line of sight, an ability known as visual mental imagery. Extensive left temporal damage can impair patients’ visual mental imagery experience, but the critical locus of lesion is unknown. Our recent meta-analysis of 27 fMRI studies of visual mental imagery highlighted a well-delimited region in the left lateral midfusiform gyrus, which was consistently activated during visual mental imagery, and which we called the Fusiform Imagery Node (FIN). Here we describe the connectional anatomy of FIN in neurotypical participants and in RDS, a right-handed patient with an extensive occipitotemporal stroke in the left hemisphere. The stroke provoked right homonymous hemianopia, alexia without agraphia, and color anomia. Despite these deficits, RDS had normal subjective experience of visual mental imagery and reasonably preserved behavioral performance on tests of visual mental imagery of object shape, object color, letters, faces, and spatial relationships. We found that the FIN was spared by the lesion. We then assessed the connectional anatomy of the FIN in the MNI space and in the patient’s native space, by visualizing the fibers of the inferior longitudinal fasciculus (ILF) and of the arcuate fasciculus (AF) passing through the FIN. In both spaces, the ILF connected the FIN with the anterior temporal lobe, and the AF linked it with frontal regions. Our evidence is consistent with the hypothesis that the FIN is a node of a brain network dedicated to voluntary visual mental imagery. The FIN could have a specific role in integrating high-level visual representations in domain-preferring regions in the ventral temporal lobe with elements of semantic knowledge stored in the anterior temporal lobe and in the language circuits. ### Competing Interest Statement The authors have declared no competing interest.