title: Haptic working memory for grasping: the role of the parietal operculum.
abstract: We investigated how haptic information on object geometry is encoded in the parietal operculum (OP) and is used for guiding object-directed motor acts in humans. We tested the effects of conditioning single-pulse transcranial magnetic stimulation (spTMS) applied to the left OP on corticospinal excitability assessed by a test spTMS applied to the ipsilateral motor cortex (M1) 5 ms after conditioning spTMS. Participants explored the size of a graspable object visually or haptically and waited for a go-signal to grasp it in the dark. They received TMS during the delay phase. In a separate group of participants performing the same task, conditioning spTMS was applied to the ventral premotor cortex (vPM) 7 ms before test spTMS. Results showed that conditioning TMS over OP modulated M1 output according to the information on object size that had been acquired haptically but not visually. Vice versa, conditioning TMS over vPM modulated M1 output according to information on object size acquired by vision but not haptically. Moreover spTMS over OP produced a significant modulation of the upcoming reaching behavior only when the object had been explored haptically. We show that OP contains a haptic memory of objects' macrogeometry and the appropriate motor plan for grasping them.
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Maule
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Barchiesi
authors.affiliation: INT, CNRS-Aix-Marseille Université, Marseille, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brochier
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Cattaneo
mesh_terms: D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006225:Hand / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D014796:Visual Perception / Q000502:physiology
keywords: premotor cortex; sensorimotor transformation; tactile memory; transcranial magnetic stimulation; working memory