Publications by authors named "Pascal Fortier-Poisson"

5 Publications

  • Page 1 of 1

A Novel Wearable Device for Continuous Ambulatory ECG Recording: Proof of Concept and Assessment of Signal Quality.

Biosensors (Basel) 2019 Jan 21;9(1). Epub 2019 Jan 21.

Electrophysiology Division, Institut Universitaire de cardiologie et de pneumologie de Québec, Québec, G1V 4G5, QC, Canada.

Diagnosis of arrhythmic disorders is challenging because of their short-lasting, intermittent character. Conventional technologies of noninvasive ambulatory rhythm monitoring are limited by modest sensitivity. We present a novel form of wearable electrocardiogram (ECG) sensors providing an alternative tool for long-term rhythm monitoring with the potential of increased sensitivity to detect intermittent or subclinical arrhythmia. The objective was to assess the signal quality and R-R coverage of a wearable ECG sensor system compared to a standard 3-lead Holter. In this phase-1 trial, healthy individuals underwent 24-h simultaneous rhythm monitoring using the OMsignal system together with a 3-lead Holter recording. The OMsignal system consists of a garment (bra or shirt) with integrated sensors recording a single-lead ECG and an acquisition module for data storage and processing. Head-to-head signal quality was assessed regarding adequate P-QRS-T distinction and was performed by three electrophysiologists blinded to the recording technology. The accuracy of signal coverage was assessed using Bland-Altman analysis. Fifteen individuals underwent simultaneous 24-h recording. Signal quality and accuracy of the OMgaments was equivalent to Holter-monitoring (84% vs 93% electrophysiologists rating, = 0.06). Signal coverage of R-R intervals showed a very close overlay between the OMsignal system and Holter signals, mean difference in heart rate of 2 5 bpm. The noise level of OMgarments was comparable to Holter recording. OMgarments provide high signal quality for adequate rhythm analysis, representing a promising novel technology for long-term non-invasive ECG monitoring.
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http://dx.doi.org/10.3390/bios9010017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468449PMC
January 2019

Correlation of fingertip shear force direction with somatosensory cortical activity in monkey.

J Neurophysiol 2016 Jan 14;115(1):100-11. Epub 2015 Oct 14.

Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, Québec, Canada

To examine the activity of somatosensory cortex (S1) neurons to self-generated shear forces on the index and thumb, two monkeys were trained to grasp a stationary metal tab with a key grip and exert forces without the fingers slipping in one of four orthogonal directions for 1 s. A majority (∼85%) of slowly adapting and rapidly adapting (RA) S1 neurons had activity modulated with shear force direction. The cells were recorded mainly in areas 1 and 2 of the S1, although some area 3b neurons also responded to shear direction or magnitude. The preferred shear vectors were distributed in every direction, with tuning arcs varying from 50° to 170°. Some RA neurons sensitive to dynamic shear force direction also responded to static shear force but within a narrower range, suggesting that the direction of the shear force may influence the adaptation rate. Other neurons were modulated with shear forces in diametrically opposite directions. The directional sensitivity of S1 cortical neurons is consistent with recordings from cutaneous afferents showing that shear direction, even without slip, is a powerful stimulus to S1 neurons.
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http://dx.doi.org/10.1152/jn.00749.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4760468PMC
January 2016

Neuronal activity in somatosensory cortex related to tactile exploration.

J Neurophysiol 2016 Jan 14;115(1):112-26. Epub 2015 Oct 14.

Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, Québec, Canada

The very light contact forces (∼0.60 N) applied by the fingertips during tactile exploration reveal a clearly optimized sensorimotor strategy. To investigate the cortical mechanisms involved with this behavior, we recorded 230 neurons in the somatosensory cortex (S1), as two monkeys scanned different surfaces with the fingertips in search of a tactile target without visual feedback. During the exploration, the monkeys, like humans, carefully controlled the finger forces. High-friction surfaces offering greater tangential shear force resistance to the skin were associated with decreased normal contact forces. The activity of one group of neurons was modulated with either the normal or tangential force, with little or no influence from the orthogonal force component. A second group responded to kinetic friction or the ratio of tangential to normal forces rather than responding to a specific parameter, such as force magnitude or direction. A third group of S1 neurons appeared to respond to particular vectors of normal and tangential force on the skin. Although 45 neurons correlated with scanning speed, 32 were also modulated by finger forces, suggesting that forces on the finger should be considered as the primary parameter encoding the skin compliance and that finger speed is a secondary parameter that co-varies with finger forces. Neurons (102) were also tested with different textures, and the activity of 62 of these increased or decreased in relation to the surface friction.
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http://dx.doi.org/10.1152/jn.00747.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4760505PMC
January 2016

Roughness of simulated surfaces examined with a haptic tool: effects of spatial period, friction, and resistance amplitude.

Exp Brain Res 2010 Apr 11;202(1):33-43. Epub 2009 Dec 11.

Département de Physiologie, Centre de Recherche en Sciences Neurologiques, Université de Montréal, C.P. 6128 Succursale Centre ville, Montreal, QC, H3C 3T8, Canada.

A specifically designed force-feedback device accurately simulated textures consisting of lateral forces opposing motion, simulating friction. The textures were either periodic trapezoidal forces, or sinusoidal forces spaced at various intervals from 1.5 mm to 8.5 mm. In each of two experiments, 10 subjects interacted with the virtual surfaces using the index finger placed on a mobile plate that produced the forces. The subjects selected their own speed and contact force for exploring the test surface. The apparatus returned force fields as a function of both the finger position and the force normal to the skin allowing full control over the tangential interaction force. In Experiment #1, subjects used an integer, numerical scale of their own choosing to rate the roughness of eight identical, varyingly spaced force ramps superimposed on a background resistance. The results indicated that subjective roughness was significantly, but negatively, correlated (mean r = -0.84) with the spatial period of the resistances for all subjects. In a second experiment, subjects evaluated the roughness of 80 different sinusoidal modulated force fields, which included 4 levels of resistance amplitude, 4 levels of baseline friction, and 5 spatial periods. Multiple regression was used to determine the relationship between friction, tangential force amplitude, and spatial period to roughness. Together, friction and tangential force amplitude produced a combined correlation of 0.70 with subjective roughness. The addition of spatial period only increased the multiple regression correlation to 0.71. The correlation between roughness estimates and the rate of change in tangential force was 0.72 in Experiment #1 and 0.57 in Experiment #2. The results suggest that the sensation of roughness is strongly influenced by friction and tangential force amplitude, whereas the spatial period of simulated texture alone makes a negligible contribution to the sensation of roughness.
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http://dx.doi.org/10.1007/s00221-009-2105-xDOI Listing
April 2010

Perception of simulated local shapes using active and passive touch.

J Neurophysiol 2009 Dec 14;102(6):3519-29. Epub 2009 Oct 14.

Département de Physiologie, Université de Montréal, Montreal, Quebec, Canada.

This study reexamined the perceptual equivalence of active and passive touch using a computer-controlled force-feedback device. Nine subjects explored a 6 x 10-cm workspace, with the index finger resting on a mobile flat plate, and experienced simulated Gaussian ridges and troughs (width, 15 mm; amplitude, 0.5 to 4.5 mm). The device simulated shapes by modulating either lateral resistance with no vertical movement or by vertical movement with no lateral forces, as a function of the digit position in the horizontal workspace. The force profiles and displacements recorded during active touch were played back to the stationary finger in the passive condition, ensuring that stimulation conditions were identical. For the passive condition, shapes simulated by vertical displacements of the finger had lower categorization thresholds and higher magnitude estimates compared with those of active touch. In contrast, the results with the lateral force fields showed that with passive touch, subjects recognized that a stimulus was present but were unable to correctly categorize its shape as convex or concave. This result suggests that feedback from the motor command can play an important role in processing sensory inputs during tactile exploration. Finally, subjects were administered a ring-block anesthesia of the digital nerves of the index finger and subsequently retested. Removing skin sensation significantly increased the categorization threshold for the perception of shapes generated by lateral force fields, but not for those generated by displacement fields.
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http://dx.doi.org/10.1152/jn.00043.2009DOI Listing
December 2009