Far Space Remapping by Tool Use: A rTMS Study Over the Right Posterior Parietal Cortex.
BACKGROUND
In previous studies, rTMS has been successfully employed to interfere with the right posterior parietal cortex (rPPC) inducing neglect-like behavior in healthy subjects. Several studies have shown that the use of tools can modulate the boundaries between near and far space: indeed when far space is reached by the stick, far space can be remapped as near.


OBJECTIVE
The aim of the present study was to investigate whether once that rTMS on the rPPC has selectively induced neglect-like bias in the near space (but not in the far space), neglect can appears also in the far space when the subjects used a tool to perform the task.


METHODS
Fifteen right-handed healthy subjects executed a line length judgment task in two different spatial positions (60 cm: near space and 120 cm: far space), with or without rPPC on-line rTMS. In the far space condition, subjects performed the perceptual task while holding or not a tool.


RESULTS
During rTMS, visuospatial performance significantly shifted toward right when the task was performed in the near space and in the far space when the tool was used. No significant effect was found when rTMS was delivered in the far space condition without tool use.


CONCLUSIONS
Our results demonstrate that the application of rTMS on rPPC, specifically affect the representation of near space because it caused neglect both when the subjects acted in the near space and when they acted in a far space that was remapped as near by the use of a tool.
Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands; Hypatia School of Medicine of Caltanissetta - Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
Giuseppe
G
Giglia
SAMBA (SpAtial, Motor & Bodily Awareness) Research Group, Psychology Department, University of Turin, Italy; Neuroscience Institute of Turin (NIT), University of Turin, Italy.
Lorenzo
L
Pia
SAMBA (SpAtial, Motor & Bodily Awareness) Research Group, Psychology Department, University of Turin, Italy; Neuroscience Institute of Turin (NIT), University of Turin, Italy.
Alessia
A
Folegatti
Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
Angela
A
Puma
Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy. Electronic address: brigida.fierro@unipa.it.
Brigida
B
Fierro
Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
Giuseppe
G
Cosentino
SAMBA (SpAtial, Motor & Bodily Awareness) Research Group, Psychology Department, University of Turin, Italy; Neuroscience Institute of Turin (NIT), University of Turin, Italy.
Anna
A
Berti
Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
Filippo
F
Brighina
D000328:Adult; D005260:Female; D064368:Healthy Volunteers / Q000523:psychology; D006801:Humans; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D010468:Perceptual Disorders / Q000209:etiology* / Q000523:psychology*; D013028:Space Perception; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
Far space; Near space; Neglect; Posterior parietal cortex; Tool use; rTMS