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

Abstract

Most of us can use our "mind's eye" to mentally visualize things that are not in our 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 act as a bridge between visual information and semantic knowledge processed in the anterior temporal lobe and in the language circuits.

Longitudinal prediction of motor dysfunction after stroke: a disconnectome study

“…When comparing those methods, the disconnection analysis often explains more variance in data than lesion load analysis (Corbetta et al 2015 ; Hope et al 2016 ). The disconnection analysis (Conrad et al 2022 ; Hajhajate et al 2022 ; Forkel et al 2022 ; Souter et al 2022 ; Silvestri et al 2022 ; Sperber et al 2022 ) is different from the lesion network symptom mapping methods that estimate from a normative dataset the functional connectivity impaired by a lesion (Boes et al 2015 ; Bowren et al 2022 ; Cotovio et al 2022 ). Thus, prediction studies may benefit from the redirection of the focus in clinical research from lesion localisation analysis to the analysis of the disconnections where remote alterations of a focal damage to distant regions can also be considered as a contributor to a network of structures and functions.…”

Visual mental imagery in typical imagers and in aphantasia: A millimeter-scale 7-T fMRI study

“…Left temporal activity at a location close to the FIN (Talarach coordinates: -54, -52, -2) was shown to correlate with reported imageability during the solution of advanced mathematical problems (Amalric & Dehaene, 2016). Moreover, functional connectivity between FIN and dlPFC / OFC dovetails nicely with the anatomical connectivity of the FIN (Hajhajate et al, 2022), and support its role as a domain-general node at the confluence of top-down influences from the FP networks and horizontal connections with the VTC domain-preferring regions.…”

“…The separation between domain-general and domain-specific functions in the VTC is likely to minimize the cost of long-distance wiring (Sporns & Betzel, 2016) thanks to locally dense connections between domain-preferring regions and the FIN, and sparser connections with more remote areas. The FIN, equipped with long-range connections with the perisylvian language network and the anterior temporal lobe (Hajhajate et al, 2022), may thus act as a central hub for global back-and-forth communication between visual areas and language-related regions. Thus, the FIN may act as a bridge between semantic and visual information, enabling the generation of mental images with a visual content.…”

Tracking the mind’s eyes: Spatiotemporal Dynamics of Domain-General and Domain-Specific Visual Mental Imagery

“…For example, neurological patients typically do not show such deficits after damage to the early visual cortex (Bartolomeo, 2002;Bridge et al, 2012Bridge et al, , 2012Chatterjee & Southwood, 1995;De Gelder et al, 2015;Goldenberg et al, 1995;Spagna, 2022). Similarly, Hajhajate et al, (2022) discussed the case of a stroke patient with an extensive occipito-temporal damage in the left hemisphere who retained the ability to conjure visual mental images despite experiencing right homonymous hemianopia, alexia without agraphia, and color anomia (Hajhajate et al, 2022).…”