Haptically Guided Grasping. fMRI Shows Right-Hemisphere Parietal Stimulus Encoding, and Bilateral Dorso-Ventral Parietal Gradients of Object- and Action-Related Processing during Grasp Execution

Abstract

The neural bases of haptically-guided grasp planning and execution are largely unknown, especially for stimuli having no visual representations. Therefore, we used functional magnetic resonance imaging (fMRI) to monitor brain activity during haptic exploration of novel 3D complex objects, subsequent grasp planning, and the execution of the pre-planned grasps. Haptic object exploration, involving extraction of shape, orientation, and length of the to-be-grasped targets, was associated with the fronto-parietal, temporo-occipital, and insular cortex activity. Yet, only the anterior divisions of the posterior parietal cortex (PPC) of the right hemisphere were significantly more engaged in exploration of complex objects (vs. simple control disks). None of these regions were re-recruited during the planning phase. Even more surprisingly, the left-hemisphere intraparietal, temporal, and occipital areas that were significantly invoked for grasp planning did not show sensitivity to object features. Finally, grasp execution, involving the re-recruitment of the critical right-hemisphere PPC clusters, was also significantly associated with two kinds of bilateral parieto-frontal processes. The first represents transformations of grasp-relevant target features and is linked to the dorso-dorsal (lateral and medial) parieto-frontal networks. The second monitors grasp kinematics and belongs to the ventro-dorsal networks. Indeed, signal modulations associated with these distinct functions follow dorso-ventral gradients, with left aIPS showing significant sensitivity to both target features and the characteristics of the required grasp. Thus, our results from the haptic domain are consistent with the notion that the parietal processing for action guidance reflects primarily transformations from object-related to effector-related coding, and these mechanisms are rather independent of sensory input modality.

Planning Functional Grasps of Simple Tools Invokes the Hand-independent Praxis Representation Network: An fMRI Study

“…Consistent with our earlier study (Marangon, Kubiak, & Kroliczak, 2016), signal modulations in the angular gyri (AG), bilateral ventral PreCun, and mid-to-posterior middle and superior temporal gyri (mpMTG/STG) were revealed. The pattern, illustrated in Supplementary Figure 1A, results from greater inhibition of these areas for the more difficult task of planning grasps of tools.…”

“…The inverse contrast between pantomimed tool use and planning functional grasp revealed bilateral modulations in AG, vPreCun, mpMTG/STG, SI-MI, and dorsal lateral/medial prefrontal cortices. In our earlier study (Marangon et al, 2016), such a network was revealed for an easier manual task. Figure 4B also demonstrates that pantomime tool use invokes left aSMG/aIPS, right SI and Fig.…”

Haptic exploration attenuates and alters somatosensory cortical oscillations

“…Briefly, compared with the passive condition, cortical oscillations in the 6-24 Hz range were more synchronized from 0-175 ms within the somatosensory and parietal cortices during haptic exploration. These outcomes are aligned with prior functional MRI and EEG studies that have connected activity in these cortical regions with object localization during a haptic task (Reed et al 2005;Neuper et al 2006;Marangon et al 2015). Conversely, the sharp decreases seen in alpha (8-16 Hz) and beta (18-26 Hz) activity were notably stronger and centralized to the somatosensory cortices during the passive stimulation condition.…”

“…; Marangon et al . ). Conversely, the sharp decreases seen in alpha (8–16 Hz) and beta (18–26 Hz) activity were notably stronger and centralized to the somatosensory cortices during the passive stimulation condition.…”

Functional and Structural Neuroplasticity Induced by Short-Term Tactile Training Based on Braille Reading

“…Besides somatosensory areas, we expected to observe training-induced changes within multisensory cortical regions known to be involved in tactile recognition: the fusiform gyrus/lateral occipital cortex and associative parietal areas (Amedi et al, 2001 , 2002 ; Sadato et al, 2002 ; Kassuba et al, 2011 ; Kim and Zatorre, 2011 ; Marangon et al, 2016 ).…”