In haptic exploration, when running a fingertip along a surface, the control system may attempt to anticipate upcoming changes in curvature in order to maintain a consistent level of contact force. Such predictive mechanisms are well known in the visual system, but have yet to be studied in the somatosensory system. Thus, the present experiment was designed to reveal human capabilities for different types of haptic prediction. A robot arm with a large 3D workspace was attached to the index fingertip and was programmed to produce virtual surfaces with curvatures that varied within and across trials. With eyes closed, subjects moved the fingertip around elliptical hoops with flattened regions or Limaçon shapes, where the curvature varied continuously. Subjects anticipated the corner of the flattened region rather poorly, but for the Limaçon shapes, they varied finger speed with upcoming curvature according to the two-thirds power law. Furthermore, although the Limaçon shapes were randomly presented in various 3D orientations, modulation of contact force also indicated good anticipation of upcoming changes in curvature. The results demonstrate that it is difficult to haptically anticipate the spatial location of an abrupt change in curvature, but smooth changes in curvature may be facilitated by anticipatory predictions.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3691064 | PMC |
| http://dx.doi.org/10.1007/s00221-013-3529-x | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A lever hypothesis for Synaptotagmin-1 action in neurotransmitter release.
Proc Natl Acad Sci U S A
January 2025
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.
Neurotransmitter release is triggered in microseconds by Ca-binding to the Synaptotagmin-1 C-domains and by SNARE complexes that form four-helix bundles between synaptic vesicles and plasma membranes, but the coupling mechanism between Ca-sensing and membrane fusion is unknown. Release requires extension of SNARE helices into juxtamembrane linkers that precede transmembrane regions (linker zippering) and binding of the Synaptotagmin-1 CB domain to SNARE complexes through a "primary interface" comprising two regions (I and II). The Synaptotagmin-1 Ca-binding loops were believed to accelerate membrane fusion by inducing membrane curvature, perturbing lipid bilayers, or helping bridge the membranes, but SNARE complex binding through the primary interface orients the Ca-binding loops away from the fusion site, hindering these putative activities.
View Article and Find Full Text PDFAbscission is a tightly regulated process in which plants shed unnecessary, infected, damaged, or aging organs, as well as ripe fruits, through predetermined abscission zones in response to developmental, hormonal, and environmental signals. Despite its importance, the underlying mechanisms remain incompletely understood. This study highlights the deleterious effects of abscission on chloroplast ultrastructure in the cells of the tomato flower pedicel abscission zone, revealing spatiotemporal differential gene expression and key transcriptional networks involved in chloroplast vesiculation during abscission.
View Article and Find Full Text PDFInternal structural changes in age-related curved hair due to cyclical extension: An IR spectroscopy study.
Int J Cosmet Sci
January 2025
Department of Engineering Science, Osaka Electro-Communication University, Neyagawa, Japan.
Objective: This study aimed to identify structural changes in age-related curved hair (referred to as "YUGAMI" hair in Japanese) induced by cyclical extension using infrared (IR) spectroscopy coupled with chemometrics, such as multivariate curve resolution (MCR) and two-dimensional correlation spectroscopy (2DCOS).
Methods: The hair fibres were stretched at a strain level of 0.3-N, and this operation was counted as one cycle and was repeated 500 cycles.
Pseudo-Phosphorylated Tau Forms Paired Helical Filaments in the Presence of High-Curvature Cholesterol-Containing Lipid Membranes.
J Am Chem Soc
January 2025
Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States.
The tau protein misfolds in neurodegenerative diseases such as Alzheimer's disease (AD). These pathological tau aggregates are associated with neuronal membranes, but molecular structural information about how disease-like tau fibrils interact with the lipid membrane is scarce. Here, we use solid-state NMR to investigate the structure of a tau construct bearing four AD-relevant phospho-mimetic mutations (4E tau) with cholesterol-containing high-curvature lipid membranes, which mimic the membrane of synaptic vesicles in neurons.
View Article and Find Full Text PDFInfluence of lens thickness on the accommodative range in healthy eyes.
J Optom
January 2025
Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium; Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, Antwerp University, Wilrijk, Belgium. Electronic address:
Background: The maximum accommodative range is a useful indication of visual function. It decreases with age, but the exact cause of this decrease is not fully understood. It is associated with the increasing rigidity of the lens and changes to the lens shape, as well as the geometry of the zonular attachments.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!