Hand position-dependent modulation of errors in vibrotactile temporal order judgments: the effects of transcranial magnetic stimulation to the human posterior parietal cortex

Abstract

The ability to decide which of the two stimuli is presented first can be probed using a temporal order judgment (TOJ) task. When the stimuli are delivered to the fingers, TOJ decisions can be confounded by the fact that the hands can be moved to different locations in space. How and where this confounded information is processed in the brain is poorly understood. In the present set of experiments, we addressed this knowledge gap by using single-pulse transcranial magnetic stimulation (TMS) to disrupt processing in the right or left posterior parietal cortex (PPC) during a vibrotactile TOJ task with stimuli applied to the right and left index fingers. In the first experiment, participants held their hands in an uncrossed configuration, and we found that when the index finger contralateral to the site of TMS was stimulated first, there was a significant increase in TOJ errors. This increase did not occur when stimuli were delivered to the ipsilateral finger first. In the second experiment, participants held their hands in a crossed configuration and the pattern of errors was reversed relative to the first experiment. In both the first two experiments, significant increases in TOJ error were present with TMS over either hemisphere, regardless of arm configuration; however, they were larger overall following TMS over the right PPC. Control experiments using sham TMS indicated the systematic modulation in error was not due to nonspecific effects of the stimulation. Additionally, we showed that these TMS-induced changes in TOJ errors were not due to a reduced ability to detect the timing of the vibrotactile stimuli. Taken together, these results demonstrate that both the right and left PPC contribute to the processing underlying vibrotactile TOJs by integrating vibrotactile information and proprioceptive information related to arm position in space.

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

“…Yet, the PRN, particularly the left posterior parietal cortex, would then be invoked for different reasons, such as the sequencing and fine-tuning of movement progression for adequate functional grasp, and later tool use and/or feedback on the effective guidance of such movements, including their timing (Harrington & Haaland, 1991; Harrington et al, 2000; Kimura & Archibald, 1974; Rao et al, 1997; cf. Ritterband-Rosenbaum, Hermosillo, Kroliczak, & van Donkelaar, 2014).…”

Neural dynamics of illusory tactile pulling sensations

“…The tactile P200 is modulated by multisensory integration of bodily processing ( Harjunen et al., 2017 ), and tactile remapping across spatial reference frames ( Bufalari et al., 2014 ; Longo et al., 2012 ). Tactile remapping is a complex process, operating across multiple timescales ( Sambo and Forster, 2009 ; Soto-Faraco and Azañón, 2013 ), a key feature of which may be the transformation of sensory inputs into more amodal, spatial representations in the parietal lobe ( Azañón et al., 2010 ; Heed et al., 2015 ; Ritterband-Rosenbaum et al., 2014 ). A similar re-coding from sensory to amodal representations may occur with the pulling sensation, dependent on, or concurrent with, the extraction of orientation and direction information from the stimulus.…”

Neural dynamics of illusory tactile pulling sensations

“…Of more direct relevance, the temporal characteristics of the pulling sensation are consistent with tactile remapping. Tactile remapping, whereby a force vector is transformed into bodily centered coordinate system, depends on activity in the SPL and IPS (Azañón et al, 2010;Ritterband-Rosenbaum et al, 2014;Heed et al, 2015), takes place after initial somatosensory processing has been completed, and is closely associated with the P200 (Longo et al, 2012;Bufalari et al, 2014). Thus, converging lines of evidence point towards a spatial, parietal cortex account of the pulling sensation.…”