title: Perceptual pseudoneglect in schizophrenia: candidate endophenotype and the role of the right parietal cortex.
abstract: Several contributions have reported an altered expression of pseudoneglect in psychiatric disorders, highlighting the existence of an anomalous brain lateralization in affected subjects. Surprisingly, no studies have yet investigated pseudoneglect in first-degree relatives (FdR) of psychiatric patients. We investigated performance on "paper and pencil" line bisection (LB) tasks in 68 schizophrenic patients (SCZ), 42 unaffected FdR, 41 unipolar depressive patients (UP), and 103 healthy subjects (HS). A subgroup of 20 SCZ and 16 HS underwent computerized LB and mental number line bisection (MNL) tasks requiring judgment of prebisected lines and numerical intervals. Moreover, we evaluated, in a subgroup of 15 SCZ, performance on LB and MNL before and after parietal transcranial direct current stimulation (tDCS). In comparison to HS and UP, SCZ showed a systematic rightward bias on LB, partially corrected by selective right posterior parietal tDCS. Interestingly, even FdR showed a lack of pseudoneglect on LB, expressing a mean error lying in the middle between those of HS and SCZ. On the other hand, our results showed no significant difference between the performance of SCZ and HS on MNL. Both groups showed a comparable leftward bias that could not be significantly altered after left or right parietal tDCS. These findings confirm the existence of reduced lateralization in SCZ, suggesting specific impaired functioning of the right parietal lobule. Notably, we report a lack of pseudoneglect not only in SCZ but also in FdR, raising the hypothesis that an inverted laterality pattern may be considered a concrete marker of schizotypal traits.
authors.affiliation: Clinica Psichiatrica, Dipartimento di Neuroscienze, Universita` degli Studi di Roma Tor Vergata, Via Nomentana 1362, 00137 Rome, Italy. michele.81@live.it
authors.forename: Michele
authors.initials: M
authors.lastname: Ribolsi
authors.forename: Giulia
authors.initials: G
authors.lastname: Lisi
authors.forename: Giorgio
authors.initials: G
authors.lastname: Di Lorenzo
authors.forename: Giacomo
authors.initials: G
authors.lastname: Koch
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Oliveri
authors.forename: Valentina
authors.initials: V
authors.lastname: Magni
authors.forename: Bianca
authors.initials: B
authors.lastname: Pezzarossa
authors.forename: Anna
authors.initials: A
authors.lastname: Saya
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rociola
authors.forename: Ivo A
authors.initials: IA
authors.lastname: Rubino
authors.forename: Cinzia
authors.initials: C
authors.lastname: Niolu
authors.forename: Alberto
authors.initials: A
authors.lastname: Siracusano
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003866:Depressive Disorder / Q000503:physiopathology; D058068:Endophenotypes; D005190:Family / Q000523:psychology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000503:physiopathology*; D010468:Perceptual Disorders / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D013028:Space Perception; D055815:Young Adult