Biology subjects

Bartolomeo, P.

Publications and source records attributed to Bartolomeo, P..

At least 19 recordsLinked to original sources

bioRxiv2026

Classical music in cognitive rehabilitation: Three case studies of spatial neglect

Chronic spatial neglect after right-hemisphere stroke reflects network dysfunction, with recovery influenced by structural connectivity. Music recruits coordinated bi-hemispheric activity and may promote interhemispheric communication after stroke. Following our pilot study in post-stroke aphasia, we asked whether classical music modulates connectivity and behavior in chronic neglect. Three patients completed a crossover protocol comparing two weeks of daily audiovisual classical music with an audiobook control, with neglect, mood, quality-of-life, diffusion MRI, and resting-state high-density EEG measures. All showed right superior longitudinal fasciculus II disconnection with preserved callosal pathways. In N2, line bisection shifted leftward across all five lines after music, together with increased posterior interhemispheric theta-band weighted symbolic mutual information (wSMI), then deteriorated into the pathological range after the audiobook, without mood improvement. N1 showed mixed behavioral effects, with mood and quality of life improving after music. N3 showed no significant spatial improvement and worsened mood after music. These heterogeneous responses motivate larger studies of connectional predictors. The findings support the feasibility of classical music as an adjunct to neglect rehabilitation and suggest that cognitive changes may occur independently of mood, while the audiobook cannot be considered an inert control.

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bioRxiv2026

Within-Trial Noise Accounts for Inhibition of Return

Inhibition of return (IOR) refers to the slowing of response times (RTs) for stimuli presented at previously inspected locations relative to novel locations. However, the exact processing stage(s) at which IOR occurs, and its nature across different response modalities, remain debated. By reanalyzing RT data from a target-target IOR paradigm with a single noisy accumulator model, we tested whether IOR could occur at sensory or attentional stages of processing, or at later stages of decision and action selection. We considered IOR under two conditions: manual and saccadic responses. The within-trial Gaussian noise parameter best explained both manual and saccadic IOR, suggesting that in both modalities, IOR may result from a more fluctuating accumulation of evidence for repeated locations. These results support the hypothesis that target-target IOR may primarily involve attentional-level mechanisms. Significance statementWe respond more slowly to a stimulus that is presented within a short interval in the same location ("inhibition of return"), a bias thought to promote efficient visual exploration. Using evidence-accumulation modeling of manual and eye-movement reaction times from two previous studies, we found that the key change linked to inhibition of return is greater within-trial variability (noise) in evidence accumulation, not a higher decision threshold. Understanding which processing stage is affected can help connect behavioral effects to the brain networks that support attention and orienting.

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bioRxiv2026

Fronto-temporal structural alterations in congenital aphantasia

Congenital aphantasia is characterized by a lifelong self-reported absence of voluntary visual imagery despite preserved visual knowledge, offering a natural model for dissociating sensory representation from conscious imagery. Functional imaging evidence suggests that this dissociation may arise from altered top-down interactions between higher-order control systems and high-level visual cortex, but its structural correlates remain unknown. Here, using diffusion and structural MRI in 18 individuals with congenital aphantasia and 18 matched visualisers, we tested two competing accounts of aphantasia: one predicting structural differences in visual pathways, the other predicting differences in higher-order associative networks. Across multimodal analyses of white-matter tract microstructure, functional-ROI tractography, graph-theoretic network organization, and cortical morphometry, aphantasia was associated with structural differences in frontotemporal and cingulate white-matter tracts, including the uncinate fasciculus, posterior interparietal callosal fibres, and dorsal cingulum, and in frontotemporal cortical regions, including the anterior insula, anterior prefrontal cortex, and medial temporal cortex, together forming a candidate neuroanatomical signature for the broad cognitive-affective profile of aphantasia. By contrast, we found no reliable group differences in early visual cortex, major visual tracts, or the direct structural connections of the core imagery network. Congenital aphantasia therefore exhibits a pattern of structural alterations centered on frontotemporal and cingulate systems, sparing the principal visual pathways. Given the modest sample size, these findings are exploratory and hypothesis-generating and require replication in larger cohorts; they nonetheless suggest that higher-order systems supporting integration and conscious access, rather than visual representations themselves, may contribute to the absence of conscious imagery in congenital aphantasia.

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bioRxiv2025

Disrupted Integration-Segregation Balance in the Intact Hemisphere in Chronic Spatial Neglect

Spatial neglect is a common and disabling consequence of right hemisphere stroke, characterized by a failure to attend to the contralesional left space, and frequently persists into the chronic stage. There is robust evidence on the role of right-hemisphere frontoparietal dysfunction, interhemispheric structural disconnection and maladaptive activity in the left hemisphere in the persistence of neglect. However, the specific impact of right frontoparietal dysfunction on the functional (re)organization of the left hemisphere remains poorly understood. In this study, we introduce a novel application of functional connectivity gradient analysis to investigate macroscale functional reorganization in the non-lesioned left hemisphere of patients with chronic left spatial neglect. Focusing on resting-state fMRI data, we demonstrate that abnormal segregation patterns in the left frontoparietal and default mode networks are robustly associated with neglect severity and spatial attentional bias. Notably, the principal gradient--typically capturing a global unimodal-to-transmodal hierarchy--was altered in these patients, suggesting a reorganization favoring lateralized unimodal networks. Single-subject analyses confirmed the presence of this pattern in 11 of the 13 patients included in the study. We also show that the structural integrity of the left inferior fronto-occipital fasciculus (IFOF) plays a key role in shaping these functional dynamics. These findings reveal a previously overlooked aspect of neglect pathophysiology: the maladaptive dominance of the non-lesioned hemispheres intrinsic architecture. By combining innovative gradient-based metrics with classical lesion approaches, our study offers a new framework for understanding neglect as an emergent property of large-scale network imbalance, with clinical implications for diagnosis and intervention, and theoretical consequences for models of hemispheric asymmetries and conscious access.

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bioRxiv2025

Face-, color-, and word-specific patches in the human orbitofrontal cortex

The human ventral occipitotemporal cortex (VOTC) contains multiple category-specific areas, organized along posterior-to-anterior and medial-to-lateral axes. However, the role of regions beyond the VOTC in category-specific processing remains less explored. Here, we report the presence of face-, color-and word-specific patches in the human orbitofrontal cortex (OFC) and systematically describe their location, activity amplitude, category selectivity, representational content, and functional connectivity. We compare these features with those of corresponding VOTC category-specific patches. Our findings reveal that these multi-category OFC patches follow a similar medial-lateral organization to those in the VOTC, and face-and color-specific patches form continuous functional gradients with VOTC patches. These results suggest that the OFC contains a topographic organization similar to, but at a higher hierarchical level than, the VOTC object categorization system. One Sentence SummaryFace-, color-, and word-specific patches are present in the human orbitofrontal cortex and form a continuous functional hierarchy with corresponding patches in the ventral occipitotemporal cortex.

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bioRxiv2025

Right-hemisphere frontoparietal oscillations precede conscious report of visual targets.

What neural events precede conscious reports? Hemisphere-asymmetric attentional networks are causally related to conscious perception (Bartolomeo et al., 2025; Kaufmann et al., 2024), but their spectrotemporal dynamics remain unclear. Here, we used magnetoencephalography to examine brain oscillations occurring in human participants (male and female) before a near-threshold target during the cue-target period. In 67% of trials, a supra-threshold visual cue appeared near the target placeholder box, indicating that the target would appear at that location (valid condition). In the remaining 33% of trials, the target appeared at the opposite location (invalid condition). We analyzed brain oscillations, coherence, and theta-gamma phase-amplitude (PAC) coupling in 18 regions of interest involved in attentional and perception (Martin-Signes et al., 2024). Results revealed that: (1) Report of validly cued targets was preceded by early ([~]58 ms post-cue) beta-band activity in the right-hemisphere superior parietal lobule. (2) Report of invalidly cued targets was preceded by late ([~]166 ms post-cue) beta-band activity in the right temporo-occipital (TO) region, PAC in the right lateral visual cortex, and low gamma coherence between this region and the left temporo-parietal junction, (3) Unreported invalidly cued targets were preceded by PAC in the right TO, and by high gamma coherence between this region and the right middle frontal gyrus suggesting a pre-target bias. We show that conscious report is preceded by temporally dissociable, frequency-specific reconfigurations of right-lateralized attentional networks, with an early parietal beta-mediated orienting window and a later ventral beta- and gamma-mediated window that predict conscious reports before target onset. Significance statementConscious perception depends not only on sensory signals, but also on how attentional networks prepare the brain in advance. Using MEG and a spatial cueing task with near-threshold targets, we show distinct right-hemisphere beta- and gamma-band dynamics predicting whether an upcoming stimulus will be reported or missed. Validly cued reports rely on early beta activity in the right superior parietal lobule, whereas invalid reports and omission errors are linked to later beta activity in the right temporo-occipital region, early theta-gamma coupling between this region and the right middle frontal gyrus, and theta-gamma phase-amplitude coupling. These findings reveal hemisphere-asymmetric spectrotemporal signatures by which attention biases predictive processing and shapes the conscious report of future stimuli, informing theories of conscious perception.

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bioRxiv2023

Listening to classical music influences brain connectivity in post-stroke aphasia: a pilot study

Stroke-induced aphasia is a leading cause of cognitive disability. The healthy right hemisphere may play a role in aphasia compensation. Music-based therapy, known to enhance cognitive functions after stroke, offers a potential intervention due to its impact on brain connectivity, engaging both hemispheres. In this proof-of-concept study, we aimed to assess the feasibility and effectiveness of music-assisted therapy for language disorders following left hemisphere strokes. We also sought preliminary insights into the impact of music on post-stroke brain connectivity. We enrolled four right-handed patients (one female and three males, mean age 57.75 years, SD 7.63) who experienced their first left-hemisphere stroke inducing chronic aphasia symptoms three months post-stroke. Patients were randomly assigned to receive either two weeks of music therapy, involving daily 2-hour sessions of listening to instrumental music by Haydn, Mozart, and Beethoven, in addition to standard rehabilitation, or two weeks of standard care, using a crossover design. Patients underwent cognitive and neuroimaging assessments at baseline, crossover, and study end, with preliminary evaluation one week before the study to confirm stable deficits. All patients listened to the same curated playlist, accompanied by narrations situating the music in its with historical context. Cognitive assessments included the Core Assessment of Language Processing (CALAP) and a French aphasia battery (Bilan Informatise dAphasie, BIA). EEG and MRI data were analyzed, focusing on functional connectivity metrics (weighted symbolic mutual information, permutation entropy) and white matter tractography. Preliminary findings indicate that music therapy may be a feasible and promising approach to aphasia rehabilitation, with improvements observed in language tests and brain connectivity metrics. Despite limitations such as a small sample size and patient heterogeneity, these preliminary results suggest that intensive classical music listening may enhance language abilities in post-stroke aphasia patients. Additionally, using EEG connectivity metrics originally designed for non-communicative patients provides a novel avenue for monitoring brain plasticity during rehabilitation.

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bioRxiv2023

Ultra-high field fMRI of visual mental imagery in typical imagers and aphantasic individuals

Most of us effortlessly describe visual objects, whether seen or remembered. Yet, around 4% of people report congenital aphantasia: they struggle to visualize objects despite being able to describe their visual appearance. What neural mechanisms create this disparity between subjective experience and objective performance? Aphantasia can provide novel insights into conscious processing and awareness. We used ultra-high field 7T fMRI to establish the neural circuits involved in visual mental imagery and perception, and to elucidate the neural mechanisms associated with the processing of internally generated visual information in the absence of imagery experience in congenital aphantasia. Ten typical imagers and 10 aphantasic individuals performed imagery and perceptual tasks in five domains: object shape, object color, written words, faces, and spatial relationships. In typical imagers, imagery tasks activated left-hemisphere frontoparietal areas, the relevant domain-preferring areas in the ventral temporal cortex partly overlapping with the perceptual domain-preferring areas, and a domain-general area in the left fusiform gyrus (the Fusiform Imagery Node). The results were valid for each individual participant. In aphantasic individuals, imagery activated similar visual areas, but there was reduced functional connectivity between the Fusiform Imagery Node and frontoparietal areas. Our results unveil the domain-general and domain-specific circuits of visual mental imagery, their functional disorganization in aphantasia, and support the general hypothesis that conscious visual experience - whether perceived or imagined - depends on the integrated activity of high-level visual cortex and frontoparietal networks.

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bioRxiv2022

The Interplay of Attention and Conscious Perception: Evidence from Human Intracerebral Recordings and Computational Modeling

How do attention and consciousness interact in the human brain? Rival theories of consciousness disagree on the role of fronto-parietal attentional networks in conscious perception. We recorded neural activity from 727 intracerebral contacts in 13 epileptic patients, while they detected near-threshold targets preceded by attentional cues. Unsupervised clustering revealed three patterns: (1) Attention-enhanced conscious report accompanied sustained right-hemisphere fronto-temporal activity, in networks connected by the superior longitudinal fasciculus (SLF) II-III, and late accumulation in bilateral dorso-prefrontal and right-hemisphere orbitofrontal cortex (SLF I-III). (2) Attentional reorienting affected conscious report through early, sustained activity in a right-hemisphere network (SLF III). (3) Conscious report accompanied left-hemisphere dorsolateral-prefrontal activity. Task modeling with recurrent neural networks identified specific excitatory and inhibitory interactions between attention and consciousness, and their causal contribution to conscious perception of near-threshold targets. Thus, distinct, hemisphere-asymmetric fronto-parietal networks support attentional gain and reorienting in shaping human conscious experience. One-Sentence SummaryIntracerebral recordings, tractography and modeling reveal the interaction of attention and consciousness in the human brain.

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bioRxiv2022

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

Most of us can use our "minds 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 patients 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.

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bioRxiv2021

Spatiotemporal dynamics of human attention revealed byintracerebral recording

Exogenous attention, the process that makes external salient stimuli pop-out of a visual scene, is essential for survival. How attention-capturing events modulate human brain processing remains unclear. Here we show how the psychological construct of exogenous attention gradually emerges over large-scale gradients in the human cortex, by analyzing activity from 1,403 intracortical contacts implanted in 28 individuals, while they performed an exogenous attention task. The timing, location and task-relevance of attentional events defined a spatiotemporal gradient of three neural clusters, which mapped onto cortical gradients and presented a hierarchy of timescales. Visual attributes modulated neural activity at one end of the gradient, while at the other end it reflected the upcoming response timing, with attentional effects occurring at the intersection of visual and response signals. These findings challenge multi-step models of attention, and suggest that frontoparietal networks, which process sequential stimuli as separate events sharing the same location, drive exogenous attention phenomena such as inhibition of return.

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bioRxiv2020

Distinct Contributions of Nonpredictive and Predictive Peripheral Cues to Visual Conscious Perception: an MEG study

How do attentional networks influence conscious perception? To answer this question, we used magnetoencephalography (MEG) in human participants, and assessed the effects of spatially nonpredictive or predictive supra-threshold peripheral cues on the conscious perception of near-threshold Gabors. Three main results emerged. (1) As compared with invalid cues, both nonpredictive and predictive valid cues increased conscious detection. Yet, only predictive cues shifted the response criterion towards a more liberal decision (i.e., willingness to report the presence of a target under conditions of greater perceptual uncertainty) and affected target contrast leading to 50% detections. (2) Conscious perception following valid predictive cues was associated to enhanced activity in frontoparietal networks. These responses were lateralized to the left hemisphere during attentional orienting, and to the right hemisphere during target processing. The involvement of frontoparietal networks occurred earlier in valid than in invalid trials, a possible neural marker of the cost of re-orienting attention. (3) When detected targets were preceded by invalid predictive cues, and thus reorienting to the target was required, neural responses occurred in left hemisphere temporo-occipital regions during attentional orienting, and in right hemisphere anterior insular and temporo-occipital regions during target processing. These results confirm and specify the role of frontoparietal networks in modulating conscious processing, and detail how invalid orienting of spatial attention disrupts conscious processing. Significance StatementDo we need to pay attention to external objects in order to become aware of them? Characterizing the spatiotemporal dynamics of attentional effects on visual perception is critical to understand how humans process and select relevant information. Participants detected near-threshold visual targets preceded by supra-threshold spatial cues with varying degrees of predictivity, while their brain activity was recorded using magnetoencephalography. Results demonstrated that valid predictive cues biased participants conscious perception through an early recruitment of frontoparietal regions, and that attentional costs associated to invalid predictive cues were related to activation of the right hemisphere ventral network. This work characterizes the neural dynamics associated with the cost of attentional reorienting on conscious processing.

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bioRxiv2020

LATER but FORTIOR: diffusion modelling of inhibition of return

Inhibition of return (IOR) refers to the slowing of response times (RTs) for stimuli repeated at previously inspected locations, as compared with novel ones. However, the exact processing stage(s) at which IOR occurs, and its nature across different response modalities, remain debated. We tested predictions on these issues originating from the FORTIOR model (fronto-parietal organization of response times in IOR; Seidel Malkinson & Bartolomeo, 2018), and from evidence accumulation models. We reanalysed RT data from a target-target IOR paradigm (Bourgeois et al.,2013a, 2013b) by using a LATER-like evidence accumulation model (Carpenter & Williams, 1995), to test the predictions of FORTIOR, and specifically whether IOR could occur at sensory/attentional stages of processing, or at stages of decision and action selection. We considered the following conditions: manual or saccadic response modality, before or after TMS perturbation over four cortical regions. Results showed that the Gaussian noise parameter best explained both manual and saccadic IOR, suggesting that in both response modalities IOR may result from slower accumulation of evidence for repeated locations. Additionally, across stimulated regions, TMS affected only manual RTs, lowering them equally in the conditions with repeated targets (Return) and non-repeated targets (Non-return). Accordingly, the modelling results show that TMS stimulation did not significantly alter the pattern between model parameters, with the Gaussian noise parameter remaining the parameter best explaining the Return - Non-return RT difference. Moreover, TMS over the right intra-parietal sulcus (IPS) perturbed IOR by shortening the Return RT. When directly testing this effect by modelling the TMS impact in the Return condition, the Bayesian information criterion of the Gaussian noise parameter was the smallest, but this effect did not reach significance. These results support the hypothesis that target-target IOR is a predominantly sensory/attentional phenomenon, and may be modulated by activity in fronto-parietal networks.

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bioRxiv2020

Color naming and categorization depend on distinct functional brain networks

Naming a color can be understood as an act of categorization, i.e. identifying it as a member of category of colors that are referred to by the same name. But are naming and categorization equivalent cognitive processes, and consequently rely on same neural substrates? Here, we used task and resting-state fMRI, as well as behavioral measures to identify functional brain networks that modulated naming and categorization of colors. Color naming and categorization response times were modulated by different resting state connectivity networks spanning from the color-sensitive regions in the ventro-occipital cortex. Color naming correlated with the connectivity between the left posterior color region, the left medial temporal gyrus, and the left angular gyrus; whereas color categorization involved the connectivity between the bilateral posterior color regions, the left frontal, right temporal and bilateral parietal areas. The networks supporting naming and categorization did not overlap, suggesting that the two processes rely on different neural mechanisms. SignificanceWhen we name a color, we also identify it as a member of a color category, e.g. blue or yellow. Are neural processes underlying color categorization equivalent to those of color naming? Here, we address this question by measuring how individual differences in color categorization and naming response times relate to the strength of functional connections in the brain. Color naming speed correlated with left-hemispheric connectivity between the color-sensitive visual regions and the anterior temporal lobe. Color categorization speed was modulated by a different brain network, encompassing bilateral color-sensitive visual areas, and high-level executive and semantic regions. Thus, color categorization and naming performance involved distinct, non-overlapping brain networks, suggesting that the two processes depend on different neural mechanisms.

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bioRxiv2020

Visual mental imagery engages the left fusiform gyrus, but not the early visual cortex: a meta-analysis of neuroimaging evidence

The dominant neural model of visual mental imagery (VMI) stipulates that memories from the medial temporal lobe acquire sensory features in early visual areas. However, neurological patients with damage restricted to the occipital cortex typically show perfectly vivid VMI, while more anterior damages extending into the temporal lobe, especially in the left hemisphere, often cause VMI impairments. Here we present two major results reconciling neuroimaging findings in neurotypical subjects with the performance of brain-damaged patients: (1) a large-scale metaanalysis of 46 fMRI studies, of which 27 investigated specifically visual mental imagery, revealed that VMI engages fronto-parietal networks and a well-delimited region in the left fusiform gyrus. (2) A Bayesian analysis showing no evidence for imagery-related activity in early visual cortices. We propose a revised neural model of VMI that draws inspiration from recent cytoarchitectonic and lesion studies, whereby fronto-parietal networks initiate, modulate, and maintain activity in a core temporal network centered on the fusiform imagery node, a high-level visual region in the left fusiform gyrus.

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bioRxiv2019

Detecting behavioral patterns for diagnosis and rehabilitation of visual neglect: a technology-enhanced version of the Baking Tray Task

AO_SCPLOWBSTRACTC_SCPLOWVisual neglect is a frequent and disabling consequence of right brain damage. Traditional paper-and- pencil tests of neglect have limitations in sensitivity and ecological validity. The Baking Tray Task (BTT), instead, approaches real-life situations, because it requires participants to place 16 physical objects on a board. The number of objects placed on the left and right portions of the board provides a clinical index of visual neglect. Here we present E-TAN, a technology-enhanced platform which allows patients to perform an enhanced version of the BTT (E-BTT). This platform automatically determines the object locations on the board, and also records the sequence and timing of their placement. We used E-BTT to test 9 patients with right hemisphere damage, and compared their performance with that obtained by 115 healthy participants. To this end, we developed a new method of analysis of participants performance, based on the use of the convex hull described by the objects on the board. This measure provides an estimate of the portion of space processed by each participant, and can effectively discriminate neglect patients from patients without neglect. E-TAN allows clinicians to assess visuospatial performance by using a convenient, fast, and relatively automatized procedure, that patients can even perform at home to follow-up the effects of rehabilitation.

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bioRxiv2017

Anatomical Predictors Of Recovery From Visual Neglect After Prism Adaptation Therapy

Visual neglect is a frequent and disabling consequence of right hemisphere damage. Previous work demonstrated a probable role of posterior callosal dysfunction in the chronic persistence of neglect signs. Prism adaptation is a non-invasive and convenient technique to rehabilitate chronic visual neglect, but it is not effective in all patients. Here we aimed to assess the hypothesis that prism adaptation improves left neglect by facilitating compensation through the contribution of the left, undamaged hemisphere. We assessed the relationship between prism adaptation effects, cortical thickness and white matter integrity in a group of 14 patients with unilateral right-hemisphere strokes and chronic visual neglect. Results showed that patients who benefitted from prism adaptation had thicker cortex in temporo-parietal, prefrontal and cingulate areas of the left, undamaged hemisphere. Additionally, these patients had a higher fractional anisotropy value in the body and genu of the corpus callosum. Results from normal controls show that these callosal regions connect temporo-parietal, sensorimotor and prefrontal areas. Finally, shorter time intervals from the stroke tended to improve patients response to prism adaptation. We concluded that prism adaptation may improve left visual neglect by promoting the contribution of the left hemisphere to neglect compensation. These results support current hypotheses on the role of the healthy hemisphere in the compensation for stroke-induced, chronic neuropsychological deficits, and suggest that prism adaptation can foster this role by exploiting sensorimotor/prefrontal circuits, especially when applied at early stages post-stroke.

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bioRxiv2017

Fronto-parietal Organization for Response Times in Inhibition of Return: The FORTIOR Model

Inhibition of Return (IOR) refers to a slowing of response times (RTs) for visual stimuli repeated at the same spatial location, as compared to stimuli occurring at novel locations. The functional mechanisms and the neural bases of this phenomenon remain debated. Here we present FORTIOR, a model of the cortical control of visual IOR in the human brain. The model is based on known facts about the anatomical and functional organization of fronto-parietal attention networks, and accounts for a broad range of behavioral findings in healthy participants and brain-damaged patients. FORTIOR does that by combining four principles of asymmetry: O_LIAsymmetry in the networks topography, whereby the temporoparietal junction (TPJ) and ventrolateral prefrontal cortex (vlPFC) nodes are lateralized to the right hemisphere, causing higher activation levels in the right intraparietal sulcus (IPS) and frontal eye field (FEF) nodes.\nC_LIO_LIAsymmetry in inter-hemispheric connectivity, in which inter-hemispheric connections from left hemisphere IPS to right hemisphere IPS and from left hemisphere FEF to right hemisphere FEF are weaker than in the opposite direction.\nC_LIO_LIAsymmetry of visual inputs, stipulating that the FEF receives direct visual input coming from the ipsilateral visual cortex, while the right TPJ and vlPFC and IPS nodes receive input from both the contralateral and the ipsilateral visual fields.\nC_LIO_LIAsymmetry in the response modality, with a higher response threshold for the manual response system than that required to trigger a saccadic response. This asymmetry results in saccadic IOR being more robust to interference than manual IOR.\nC_LI\n\nFORTIOR accounts for spatial asymmetries in the occurrence of IOR after brain damage and after non-invasive transcranial magnetic stimulation on parietal and frontal regions. It also provides a framework to understand dissociations between manual and saccadic IOR, and makes testable predictions for future experiments to assess its validity.\n\nResearch highlightsO_LIFORTIOR is a model of cortical control of visual IOR in the human brain\nC_LIO_LIFORTIOR is based on the architecture of fronto-parietal networks\nC_LIO_LIFORTIOR presents asymmetries favoring the right hemisphere\nC_LIO_LIFORTIOR explains complex patterns of IOR-related results\nC_LIO_LIFORTIOR provides testable predictions\nC_LI

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