C9orf72 and Hallucinations: Atrophy analysis in this study showed decreased grey matter density in the superior parietal lobule,2 which is known to be involved in top-down processes including internal representation of space and attentional orientation and manipulation of spatial information in working memory—suggesting this region along with the thalamus may be critical for hallucination generation in C9orf72 (Fig. 3).61,62 A similar profile emerged for patients with visual hallucinations that included deficits in attention.