Biomedical subjects

Sliman Bensmaïa

Publications and source records attributed to Sliman Bensmaïa.

3 recordsLinked to original sources

PubMed2005

Vibrotactile intensity and frequency information in the pacinian system: a psychophysical model.

The objective of the study was to characterize the Pacinian representation of stimulus waveform. Subjects were presented with pairs of high-frequency vibrotactile stimuli that varied in intensity and/or frequency content and made same-different judgments under conditions of low-frequency adaptation designed to minimize the contribution of the RA system. We wished to infer the nature of the information conveyed by the Pacinian system about the stimuli from measured sensitivity (d') to stimulus differences. We first tested the hypothesis that the Pacinian system conveys only intensive information about vibratory stimuli and found that intensive cues could not account for much of the variance in the discrimination data. We then proposed a model characterizing the Pacinian-mediated representation of an arbitrary stimulus as a pattern of activation in a set of frequency-tuned minichannels. The model was shown to predict the discriminability of the stimulus pairs presented in the psychophysical experiments. Furthermore, the model parameters, optimized to fit the discrimination data, were compatible with analogous values obtained in other experimental contexts. One of the assumptions underlying the model is that information about individual spectral components is conveyed in parallel and quasi-independently. By simulating the response of a population of Pacinian afferents to a polyharmonic stimulus, we demonstrated that such a population can simultaneously convey information about multiple frequency components, despite having a homogeneous spectral profile.

Adult↗

PubMed2005

Pacinian representations of fine surface texture.

Subjects were presented with pairs of finely textured stimuli and were instructed to rate their dissimilarity, using free magnitude estimation. The subjects also rated the stimuli along each of four textural continua: roughness, hardness, stickiness, and warmth. In subsequent experimental sessions, we used a Hall effect transducer to measure the vibrations produced in the subjects' fingertip skin as the stimuli were scanned across it. We wished to assess the extent to which the perceptual dissimilarity of the textures could be explained in terms of the perceptual dissimilarity of the vibrations they elicited in the skin. To that end, we invoked a model characterizing the Pacinian representation of a vibratory stimulus. From the model, we computed the difference in the vibratory representations of the two stimuli in each pair. We found that the bulk of the variance in perceived dissimilarity of the textures was accounted for by differences in the Pacinian representations of the vibrations they produced. Our results further suggested that the textural information conveyed by the Pacinian system concerns surface roughness and, possibly, stickiness.

Adult↗

PubMed2002

A transduction model of the Meissner corpuscle.

I propose a transduction model of the Meissner corpuscle that integrates ideas put forth by Freeman and Johnson and results obtained by Looft. The principal development in the present model is its specification that RA receptor potentials are updated as a linear function of stimulus velocity above baseline; the model thus readily accommodates non-sinusoidal input. It also incorporates modifications to Freeman and Johnson's model proposed by Slavík and Bell, namely a period of refractoriness lasting 1 ms followed by a period of hyperexcitability lasting 13.5 ms. The model is applied to various psychophysical and physiological situations: psychophysical threshold vs. frequency, RA afferent impulse rates vs. intensity, impulse regularity vs. frequency, phase retardation vs. frequency, and responses to non-repeating noise and to complex stimuli. Model output closely matches psychophysical and neurophysiological data. The proposed model thus reliably predicts RA afferent responses to arbitrary stimuli and may facilitate the development of theories relating psychophysical phenomena to their underlying neural representations.

Animals↗