Physical determinants of the shape of the psychophysical curve relating tactile roughness to raised-dot spacing: implications for neuronal coding of roughness

2013 ◽  
Vol 109 (5) ◽  
pp. 1403-1415 ◽  
Author(s):  
Adrian Sutu ◽  
El-Mehdi Meftah ◽  
C. Elaine Chapman
Keyword(s):  
Psychometric Function ◽  
Weber Fraction ◽  
Critical Issue ◽  
Linear Increase ◽  
Spatial Period ◽  
Invariant Relation ◽  
Monotonic Increase ◽  
Neuronal Coding ◽  
Tactile Roughness ◽  
Roughness Discrimination

There are conflicting reports as to whether the shape of the psychometric relation between perceived roughness and tactile element spacing [spatial period (SP)] follows an inverted U-shape or a monotonic linear increase. This is a critical issue because the former result has been used to assess neuronal codes for roughness. We tested the hypothesis that the relation's shape is critically dependent on tactile element height (raised dots). Subjects rated the roughness of low (0.36 mm)- and high (1.8 mm)-raised-dot surfaces displaced under their fingertip. Inverted U-shaped curves were obtained as the SP of low-dot surfaces was increased (1.3–6.2 mm, tetragonal arrays); a monotonic increase was observed for high-dot surfaces. We hypothesized that roughness is not a single sensory continuum across the tested SPs of low-dot surfaces, predicting that roughness discrimination would show deviations from the invariant relation between threshold (ΔS) and the value of the standard (S) surface (Weber fraction, ΔS/S) expected for a single continuum. The results showed that Weber fractions were increased for SPs on the descending limb of the inverted U-shaped curve. There was also an increase in the Weber fraction for high-dot surfaces but only at the peak (3 mm), corresponding to the SP at which the slope of the psychometric function showed a modest decline. Together the results indicate that tactile roughness is not a continuum across low-dot SPs of 1.3–6.2 mm. These findings suggest that correlating the inverted U-shaped function with neuronal codes is of questionable validity. A simple intensive code may well contribute to tactile roughness.

Tactile roughness discrimination of the finger pad relies primarily on vibration sensitive afferents not necessarily located in the hand

2012 ◽  
Vol 229 (1) ◽  
pp. 273-279 ◽  
Author(s):  
Xavier Libouton ◽  
Olivier Barbier ◽  
Yorick Berger ◽  
Leon Plaghki ◽  
Jean-Louis Thonnard
Keyword(s):  
Tactile Roughness ◽  
Roughness Discrimination ◽  
Finger Pad

Effects of Sound on the Tactile Perception of Roughness in Peri-Head Space

2011 ◽  
Vol 24 (5) ◽  
pp. 471-483 ◽  
Author(s):  
Jiro Gyoba ◽  
Yuika Suzuki
Keyword(s):  
White Noise ◽  
Sound Source ◽  
Similar Pattern ◽  
Tactile Perception ◽  
Auditory Stimuli ◽  
Auditory Information ◽  
Head Space ◽  
Tactile Stimuli ◽  
Tactile Roughness ◽  
Roughness Discrimination

AbstractThe aim of this study is to investigate whether or not spatial congruency between tactile and auditory stimuli would influence the tactile roughness discrimination of stimuli presented to the fingers or cheeks. In the experiment, when abrasive films were passively presented to the participants, white noise bursts were simultaneously presented from the same or different side, either near or far from the head. The results showed that when white noise was presented from the same side as the tactile stimuli, especially from near the head, the discrimination sensitivity on the cheeks was higher than when sound was absent or presented from a different side. A similar pattern was observed in discrimination by the fingers but it was not significant. The roughness discrimination by the fingers was also influenced by the presentation of sound close to the head, but significant differences between conditions with and without sounds were observed at the decisional level. Thus, the spatial congruency between tactile and auditory information selectively modulated the roughness sensitivity of the skin on the cheek, especially when the sound source was close to the head.

Tactile roughness discrimination threshold is unrelated to tactile spatial acuity

2010 ◽  
Vol 208 (2) ◽  
pp. 473-478 ◽  
Author(s):  
Xavier Libouton ◽  
Olivier Barbier ◽  
Leon Plaghki ◽  
Jean-Louis Thonnard
Keyword(s):  
Discrimination Threshold ◽  
Spatial Acuity ◽  
Tactile Roughness ◽  
Roughness Discrimination

scholarly journals The neural code for tactile roughness in the somatosensory nerves

2017 ◽  
Vol 118 (6) ◽  
pp. 3107-3117 ◽  
Author(s):  
Justin D. Lieber ◽  
Xinyue Xia ◽  
Alison I. Weber ◽  
Sliman J. Bensmaia
Keyword(s):  
Fiber Type ◽  
Rhesus Macaques ◽  
Discrimination Performance ◽  
Nerve Fibers ◽  
Neural Code ◽  
Population Response ◽  
Perceptual Dimension ◽  
Tactile Roughness ◽  
Roughness Discrimination ◽  
Sense Of Touch

Roughness is the most salient perceptual dimension of surface texture but has no well-defined physical basis. We seek to determine the neural determinants of tactile roughness in the somatosensory nerves. Specifically, we record the patterns of activation evoked in tactile nerve fibers of anesthetized Rhesus macaques to a large and diverse set of natural textures and assess what aspect of these patterns of activation can account for psychophysical judgments of roughness, obtained from human observers. We show that perceived roughness is determined by the variation in the population response, weighted by fiber type. That is, a surface will feel rough to the extent that the activity varies across nerve fibers and varies across time within nerve fibers. We show that this variation-based neural code can account not only for magnitude estimates of roughness but also for roughness discrimination performance. NEW & NOTEWORTHY Our sense of touch endows us with an exquisite sensitivity to the microstructure of surfaces, the most salient aspect of which is roughness. We analyze the responses evoked in tactile fibers of monkeys by natural textures and compare them to judgments of roughness obtained for the same textures from human observers. We then describe how texture signals from three populations of nerve fibers are integrated to culminate in a percept of roughness.

The Cortisol Response to Normal and Nocturnal Awakening

2000 ◽  
Vol 14 (1) ◽  
pp. 24-28 ◽  
Author(s):  
F. Hucklebridge ◽  
A. Clow ◽  
H. Rahman ◽  
P. Evans
Keyword(s):  
Area Under The Curve ◽  
Secretory Activity ◽  
Linear Increase ◽  
Cortisol Response ◽  
The Awakening ◽  
Basal Cortisol ◽  
Free Cortisol ◽  
Main Effect ◽  
Nocturnal Awakening ◽  
Night Awakening

Abstract Free cortisol as measured in saliva increases markedly following awakening. It is not clear, however, whether this is truly a stress-neuroendocrine response to awakening or a manifestation of the hypothalamic-pituitary-adrenal (HPA) circadian cycle. We investigated whether the awakening cortisol response can be generated in the middle of nocturnal sleep, when secretory activity in the HPA axis is low. In a within subject design, salivary cortisol response was measured under three different awakening conditions: (1) awakening at the normal morning awakening time; (2) awakening four hours prior to normal awakening time, and (3) awakening the following morning after interrupted sleep. The overall main effect was a linear increase in free cortisol following awakening with no significant interaction with awakening condition. Cortisol levels, as determined by area under the cortisol curve calculated with reference to zero, did differ by awakening condition. The two morning awakening conditions were comparable but values were lower for night awakening. Area under the curve change (calculated with reference to the first awakening cortisol base value), however, did not distinguish the three awakening conditions. We conclude from these data that there is a clear free cortisol response to awakening for both nocturnal and morning awakening although the absolute levels produced are lower for nocturnal awakening when basal cortisol is low. Nocturnal interruption of sleep did not affect the subsequent morning response.

Investigations of alternative kale management: Production, regrowth and quality from different sowing and defoliation dates

2007 ◽  
pp. 29-33 ◽  
Author(s):  
H.E. Brown ◽  
S. Maley ◽  
D.R. Wilson
Keyword(s):  
Sowing Date ◽  
Linear Increase ◽  
Thermal Time ◽  
Total Production

Gruner kale showed a linear increase (8.0 kg DM/ha per °Cd) in biomass with sowings on 1 October, 3 November and 1 December producing 23, 19 and 17 t DM/ha (respectively) by the 29 May. Regrowth following mid season defoliation was slow (5.3 kg DM/ha per °Cd) reducing total production (relative to undefoliated) by 7.5 and 5.5 t DM/ha for treatments defoliated on the 29 January and 14 March, respectively. Keyworks: defoliation, kale, quality, regrowth, sowing date, thermal time, yield

EVALUATION OF PITUITARY-ADRENAL FUNCTION IN CHILDREN

1965 ◽  
Vol 48 (1) ◽  
pp. 81-90 ◽  
Author(s):  
B. van der Wal ◽  
T. Wiegman ◽  
J. F. Janssen ◽  
A. Delver ◽  
D. de Wied
Keyword(s):  
Blood Pressure ◽  
Body Temperature ◽  
Diastolic Blood Pressure ◽  
Linear Increase ◽  
Significant Rise ◽  
Moderate Increase ◽  
Specific Stimulus ◽  
Lysine Vasopressin ◽  
Free Cortisol ◽  
Pituitary Adrenal Axis

ABSTRACT The reactivity of the hypothalamico-pituitary-adrenal axis was determined in 48 children, not suffering from any endocrine disorder. The free cortisol (F)- and corticosterone (B) content of plasma was determined in response to ACTH (clinical corticotrophin; A1 peptide), a corticotrophin releaser (lysine vasopressin) and a non specific stimulus (bacterial polysaccharide) as compared to saline. The two ACTH-preparations infused over one hour in a dose of 5 IU per child elicited a marked increase in both F and B. Lysine vasopressin in a dose of 0.5 IU per year of age similarly infused, exhibited a distinct linear increase in the two circulating cortical steroids, although the effect of this octapeptide was smaller than that of the two ACTH-preparations. Blood pressure was also measured during the infusion with vasopressin or saline. The systolic blood pressure was not significantly affected by vasopressin, but a significant rise in diastolic blood pressure was found. No correlation between the increase in diastolic blood pressure and in blood corticoids in response to vasopressin, was found. The intravenous administration of a relatively small amount of pyrifer caused a moderate increase in circulating F which was significant only at 4 and 6 hours after the injection of the pyrogen. The B content did not increase significantly above that of saline treated control children, presumably because of the relatively weak corticotrophic activity of the pyrogen under these conditions. A positive linear relation between body temperature and time was found. No correlation between increase in body temperature and increase in circulating F could be demonstrated.

THE INFLUENCE OF ETHANOL ON THE CONVERSION OF PREGNENOLONE TO PROGESTERONE BY HUMAN PLACENTAL MICROSOMES

1974 ◽  
Vol 76 (1) ◽  
pp. 178-188 ◽  
Author(s):  
H. Lübbert ◽  
K. Pollow ◽  
R. Wagner ◽  
J. Hammerstein
Keyword(s):  
Kinetic Parameters ◽  
Enzyme Preparation ◽  
Ethanol Concentration ◽  
Hydroxysteroid Dehydrogenase ◽  
Product Formation ◽  
Linear Increase ◽  
Maximal Velocity ◽  
Microsomal Enzyme ◽  
Temperature Optima ◽  
Substrate Concentrations

ABSTRACT The effects of ethanol on kinetic parameters of placental Δ5-3β-hydroxysteroid dehydrogenase were studied. In the presence of high pregnenolone concentrations (50 μm, [S] > Km) the microsomal enzyme preparation exhibited an almost linear increase in activity as the ethanol concentration in the medium was raised from 2.5 to 15 % (v/v). At lower substrate concentrations ([S] << Km) ethanol caused inhibition. Other effects of ethanol were: linearity of product formation with time was prolonged; the maximal velocity was markedly increased; the Km for pregnenolone slightly decreased with increasing ethanol concentrations (2.5 to 10 %, v/v) whereas the Km for NAD remained the same. The pH and temperature optima of the reaction were unaffected by ethanol. Other organic solvents caused similar effects.

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