title: Online repetitive transcranial magnetic stimulation (TMS) to the parietal operculum disrupts haptic memory for grasping.
abstract: The parietal operculum (OP) contains haptic memory on the geometry of objects that is readily transferrable to the motor cortex but a causal role of OP in memory-guided grasping is only speculative. We explored this issue by using online high-frequency repetitive transcranial magnetic stimulation (rTMS). The experimental task was performed by blindfolded participants acting on objects of variable size. Trials consisted in three phases: haptic exploration of an object, delay, and reach-grasp movement onto the explored object. Motor performance was evaluated by the kinematics of finger aperture. Online rTMS was applied to the left OP region separately in each of the three phases of the task. The results showed that rTMS altered grip aperture only when applied in the delay phase to the OP. In a second experiment a haptic discriminative (match-to-sample) task was carried out on objects similar to those used in the first experiment. Online rTMS was applied to the left OP. No psychophysical effects were induced by rTMS on the detection of explicit haptic object size. We conclude that neural activity in the OP region is necessary for proficient memory-guided haptic grasping. The function of OP seems to be critical while maintaining the haptic memory trace and less so while encoding it or retrieving it.
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Cattaneo
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Maule
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Tabarelli
authors.affiliation: Institut de Neurosciences de la Timone, UMR 7289, 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, Trento, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Barchiesi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012858:Size Perception / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: affordance; dorsal stream; graspable; object; parietal; premotor; reaching; sensorimotor; somatosensory; tactile