title: Human ventral parietal cortex plays a functional role on visuospatial attention and primary consciousness. A repetitive transcranial magnetic stimulation study.
abstract: In this paper, we used repetitive transcranial magnetic stimulation (rTMS) in 18 normal subjects to investigate whether the ventral posterior parietal cortex (PPC) plays a causal role on visuospatial attention and primary consciousness and whether these 2 functions are linearly correlated with each other. Two distinct experimental conditions involved a similar visual stimuli recognition paradigm. In "Consciousness" experiment, number of consciously perceived visual stimuli was lower by about 10% after rTMS (300 ms, 20 Hz, motor threshold intensity) on left or right PPC than after sham (pseudo) rTMS. In "Attentional" Posner's experiment, these stimuli were always consciously perceived. Compared with sham condition, parietal rTMS slowed of about 25 ms reaction time to go stimuli, thus disclosing effects on endogenous covert spatial attention. No linear correlation was observed between the rTMS-induced impairment on attention and conscious perception. Results suggest that PPC plays a slight but significant causal role in both visuospatial attention and primary consciousness. Furthermore, these high-level cognitive functions, as modulated by parietal rTMS, do not seem to share either linear or simple relationships.
authors.affiliation: Dipartimento Fisiologia Umana e Farmacologia, Università degli Studi di Roma La Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy. claudio.babiloni@uniroma1.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Babiloni
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vecchio
authors.forename: Simone
authors.initials: S
authors.lastname: Rossi
authors.forename: Alberto
authors.initials: A
authors.lastname: De Capua
authors.forename: Sabina
authors.initials: S
authors.lastname: Bartalini
authors.forename: Monica
authors.initials: M
authors.lastname: Ulivelli
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D003243:Consciousness / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation; D014796:Visual Perception / Q000502:physiology*