Decoding tactile afferent activity to obtain an estimate of instantaneous force and torque applied to the fingerpad

Heba Khamis, Ingvars Birznieks, Stephen J. Redmond

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)

    Abstract

    Dexterous manipulation is not possible without sensory information about object properties and manipulative forces. Fundamental neuroscience has been unable to demonstrate how information about multiple stimulus parameters may be continuously extracted, concurrently, from a population of tactile afferents. This is the first study to demonstrate this, using spike trains recorded from tactile afferents innervating the monkey fingerpad. A multiple-regression model, requiring no a priori knowledge of stimulus-onset times or stimulus combination, was developed to obtain continuous estimates of instantaneous force and torque. The stimuli consisted of a normal-force ramp (to a plateau of 1.8, 2.2, or 2.5 N), on top of which -3.5, -2.0, 0, +2.0, or 3.5 mNm torque was applied about the normal to the skin surface. The model inputs were sliding windows of binned spike counts recorded from each afferent. Models were trained and tested by 15-fold crossvalidation to estimate instantaneous normal force and torque over the entire stimulation period. With the use of the spike trains from 58 slow-adapting type I and 25 fast-adapting type I afferents, the instantaneous normal force and torque could be estimated with small error. This study demonstrated that instantaneous force and torque parameters could be reliably extracted from a small number of tactile afferent responses in a real-time fashion with stimulus combinations that the model had not been exposed to during training. Analysis of the model weights may reveal how interactions between stimulus parameters could be disentangled for complex population responses and could be used to test neurophysiologically relevant hypotheses about encoding mechanisms.
    Original languageEnglish
    Pages (from-to)474-484
    Number of pages11
    JournalJournal of Neurophysiology
    Volume114
    Issue number1
    DOIs
    Publication statusPublished - 2015

    Keywords

    • fingertip force
    • fingertips
    • mechanoreceptors
    • tactile afferents
    • torque

    Fingerprint

    Dive into the research topics of 'Decoding tactile afferent activity to obtain an estimate of instantaneous force and torque applied to the fingerpad'. Together they form a unique fingerprint.

    Cite this