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.

Sensorimotor experience and verb-category mapping in human sensory, motor and parietal neurons

“…This is consistent with our hypothesis that parietal neurons will play a critical role in more abstract verb-semantic processing (Aziz-Zadeh & Damasio, 2008; Cattaneo et al, 2015; Jirak, Menz, Buccino, Borghi, & Binkofski, 2010). Some of the verb-category features (e.g.…”

“…Rather, these sensorimotor mappings may in fact be a fundamental neural mechanism of verb-semantic processing. Some aspects of sensorimotor mapping have also been found to be connected to associative cortices such as the inferior frontal (Barrós-Loscertales et al, 2012; Kemmerer & Gonzalez-Castillo, 2010; Moody & Gennari, 2010), temporal (Papeo et al, 2014; Romagno, Rota, Ricciardi, & Pietrini, 2012) and parietal areas (Buccino et al, 2001; Cattaneo, Maule, Tabarelli, Brochier, & Barchiesi, 2015; Fogassi et al, 2005). …”

“…We anticipate that some of these modulated units will also be modulated by attempted motor movements, exhibiting “bimodal” properties. Hypothesis II : the spike activities of parietal units will be modulated by both sensorimotor features and verb-category features of presented verbs (Aziz-Zadeh & Damasio, 2008; Cattaneo et al, 2015; Jirak, Menz, Buccino, Borghi, & Binkofski, 2010). This would be evidence that two mapping mechanisms (sensorimotor and verb-category) overlap in their cortical distribution, recruiting different neuronal populations within the same macroscopic region.…”

Transcranial Direct Current Stimulation on Parietal Operculum Contralateral to the Moving Limb Does Not Affect the Programming of Intra-Limb Anticipatory Postural Adjustments

“…Recent studies highlighted the parietal operculum (PO) as a “hub,” in which converge several sensory-motor streams originating from different cerebral areas. The PO is “the cortical flap that covers the dorsocaudal part of the Sylvian fissure,” which may be divided into four cytoarchitectonical areas (OP1–OP4) (Eickhoff et al, 2006b; Cattaneo et al, 2015). Several studies focused on the role of PO in secondary sensory processes, highlighting its involvement in the integration of proprioceptive and tactile information within the framework of motor control (Milner et al, 2007; Sepulcre, 2014).…”

Gaze direction influences grasping actions towards unseen, haptically explored, objects

“…The canonical model of haptic information processing for object manipulation depicts a circuit involving the ventral caudal nucleus of the thalamus, the anterior parietal cortex and two parallel streams through the secondary somatosensory cortex and the insula on one side and through the superior parietal lobule on the other 1 . Such robust model has been repeatedly confirmed in non-human and human primates on the basis of physiological, imaging and neuropsychological data [2][3][4][5] . In the recent years, however, a growing body of evidence points to a role of the early visual cortex (EVC) in processing haptic information.…”