Two-point tactile discrimination ability is influenced by temporal features of stimulation

Abstract

Two-point discrimination threshold is commonly used for assessing tactile spatial resolution. Since the effect of temporal features of cutaneous test stimulation on spatial discrimination ability is not yet well known, we determined whether the ability to discriminate between two stimulus locations varies with the interstimulus interval (ISI) of sequentially presented tactile stimuli or the length of the stimulus train. Electrotactile stimuli were applied to one or two locations on the skin of the thenar eminence of the hand in healthy human subjects. Tactile discrimination ability was determined using methods based on the signal detection theory allowing the assessment of sensory performance, independent of the subject's response criterion. With stimulus pairs, the ability to discriminate spatial features of stimulation (one location vs. two stimulus locations 4 cm apart) was improved when the ISI was equal to or longer than that required for tactile temporal discrimination. With stimulus trains, the ability to discriminate spatial features of stimulation was significantly improved with an increase in the stimulus train (from 3 to 11 pulses corresponding to train lengths from 40 to 200 ms). These results indicate that temporal features of tactile stimulation significantly influence sensory performance in a tactile spatial discrimination task. Precise control of temporal stimulus parameters should help to reduce variations in results on the two-point discrimination threshold.

Temporal Asynchrony but Not Total Energy Nor Duration Improves the Judgment of Numerosity in Electrotactile Stimulation

“…This result extends what is already known about the comparison between simultaneous and sequential stimulation in tactile discrimination tasks (Wentink et al, 2011;Boldt et al, 2014). Wentink and co-authors applied up to three simultaneous or sequential vibrotactile stimuli on the leg and asked participants to estimate number and location of stimuli.…”

“…However, the authors used longer durations in intermittent compared to simultaneous stimulation which makes it difficult to understand the nature of the advantage of the intermittent stimulation. The comparison between simultaneous and sequential presentation of the stimuli was investigated in two recent studies (i.e., Wentink et al, 2011;Boldt et al, 2014). The results showed an advantage of sequential stimulation when estimating the number of active channels.…”

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“…Additionally, the two-point tactile discrimination test, which measures fine sensory abilities, was used to assess tactile spatial resolution. 28 All the clinical measures were assessed before magnetic resonance scanning.…”

Vibrotactile Spatial Acuity and Intensity Discrimination on the Lower Back Using Coin Motors

“…The TPD threshold is defined as the minimal distance necessary for a subject to recognize a stimulus pair as two separate stimuli. Static TPD thresholds using simultaneous two-point stimulation have been charac on vib are no using ties (i.e voltage cificall ically i (SOA) ing ele tion of ty [15] …”