title: The Response of the Left Ventral Attentional System to Invalid Targets and its Implication for the Spatial Neglect Syndrome: a Multivariate fMRI Investigation.
abstract: In humans, invalid visual targets that mismatch spatial expectations induced by attentional cues are considered to selectively engage a right hemispheric "reorienting" network that includes the temporal parietal junction (TPJ), the inferior frontal gyrus (IFG), and the medial frontal gyrus (MFG). However, recent findings suggest that this hemispheric dominance is not absolute and that it is rather observed because the TPJ and IFG areas in the left hemisphere are engaged both by invalid and valid cued targets. Because of this, the BOLD response of the left hemisphere to invalid targets is usually cancelled out by the standard "invalid versus valid" contrast used in functional magnetic resonance imaging investigations of spatial attention. Here, we used multivariate pattern recognition analysis (MVPA) to gain finer insight into the role played by the left TPJ and IFG in reorienting to invalid targets. We found that in left TPJ and IFG blood oxygen level-dependent (BOLD) responses to invalid and valid targets were associated to different patterns of neural activity, possibly reflecting the presence of functionally distinct neuronal populations. Pattern segregation was significant at group level, it was present in almost all of the participants to the study and was observed both for targets in the left and right side of space. A control whole-brain MVPA ("Searchlight" analysis) confirmed the results obtained in predefined regions of interest and highlighted that also other areas, that is, superior parietal and frontal-polar cortex, show different patterns of BOLD response to valid and invalid targets. These results confirm and expand previous evidence highlighting the involvement of the left hemisphere in reorienting of visual attention (Doricchi et al. 2010; Dragone et al. 2015). These findings suggest that asymmetrical reorienting deficits suffered by right brain damaged patients with left spatial neglect, who have severe impairments in contralesional reorienting and less severe impairments in ipsilesional reorienting, are due to preserved reorienting abilities in the intact left hemisphere.
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy.|Department of Experimental Psychology, Ghent University, Ghent, Belgium.
authors.forename: Massimo
authors.initials: M
authors.lastname: Silvetti
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy.|Dipartimento di Psicologia 39, Università degli Studi di Roma "La Sapienza", Roma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Lasaponara
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy.|Dipartimento di Psicologia 39, Università degli Studi di Roma "La Sapienza", Roma, Italy.|Institute of Cognitive Neuroscience, University College London, London, UK.
authors.forename: Francesca
authors.initials: F
authors.lastname: Lecce
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy.|Dipartimento di Psicologia 39, Università degli Studi di Roma "La Sapienza", Roma, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Dragone
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Macaluso
authors.affiliation: Fondazione Santa Lucia IRCCS, Roma, Italy fabrizio.doricchi@uniroma1.it.|Dipartimento di Psicologia 39, Università degli Studi di Roma "La Sapienza", Roma, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Doricchi
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D053483:Eye Movement Measurements; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000502:physiology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010363:Pattern Recognition, Automated; D010468:Perceptual Disorders / Q000503:physiopathology; D011930:Reaction Time; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: TPJ; attention; multivariate fMRI; reorienting; spatial neglect