Space and time interact with each other in the cognitive system. Recent studies indicate the posteriorparietal cortex (PPC) as the neural correlate of spatial–temporal interactions. We studied whether thecontribution of the PPC becomes critical in tasks requiring the performance of spatial computations ontime intervals. We adopted an integrated neuropsychological and transcranial magnetic stimulation (rTMS)approach, presenting behavioural timing tasks to both healthy subjects and right-brain-damaged patientswith and without evidence of spatial neglect. rTMS of the right PPC of healthy subjects induced alateralised bias during a task requiring setting the midpoint of a time interval. This bias mimicked therightward bias observed in tasks requiring setting the midpoint of line intervals. These effects wereselectively encountered when rTMS was applied during the retrieval phase of the task, while no effectswere observed during the initial encoding phase of the time interval. Similar effects were also observedduring bisection of time intervals by right-brain-damaged patients with spatial neglect. The specific role ofthe right PPC in bisection of physical intervals was confirmed by an experiment in which line segmentswere used.
Representation of time intervals in the right posterior parietal cortex: Implications for a mental time line
Koch GSecondo
;
2009
Abstract
Space and time interact with each other in the cognitive system. Recent studies indicate the posteriorparietal cortex (PPC) as the neural correlate of spatial–temporal interactions. We studied whether thecontribution of the PPC becomes critical in tasks requiring the performance of spatial computations ontime intervals. We adopted an integrated neuropsychological and transcranial magnetic stimulation (rTMS)approach, presenting behavioural timing tasks to both healthy subjects and right-brain-damaged patientswith and without evidence of spatial neglect. rTMS of the right PPC of healthy subjects induced alateralised bias during a task requiring setting the midpoint of a time interval. This bias mimicked therightward bias observed in tasks requiring setting the midpoint of line intervals. These effects wereselectively encountered when rTMS was applied during the retrieval phase of the task, while no effectswere observed during the initial encoding phase of the time interval. Similar effects were also observedduring bisection of time intervals by right-brain-damaged patients with spatial neglect. The specific role ofthe right PPC in bisection of physical intervals was confirmed by an experiment in which line segmentswere used.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
