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Poster De Conférence Année : 2012

Breaking the boundaries of somatosensory plasticity: improved touch at the fingers transfers to the lips

Résumé

It is now well established that cortical plasticity occurs in the adult brain and that plastic phenomena are involved in many brain functions. Understanding the rules governing plasticity and its functional consequences is extremely challenging. A cutaneous coactivation (CA) protocol has been successfully used to study somatosensory plasticity (see Godde et al, 2003). CA relies on the Hebbian postulate and consists of synchronous and passive coactivation of several non-overlapping receptive fields which produces transient somatosensory changes. The aim of this study was to evaluate whether pure somatosensory plasticity, experimentally induced at a specific cutaneous location (i.e., right index fingertip) can cross somatotopically defined boundaries and functionally affect physically distant, but cortically adjacent body-part regions (i.e., the perioral lip region). A two-point discrimination (2PD) task was used to determine the spatial discrimination thresholds at the right and left index finger (RD2 & LD2), and at the right and left sides of the upper lip area. This test was performed during 4 sessions on 2 consecutive days. Between the third and fourth session, a vibrotactile CA was applied for three hours at the RD2 fingertip. Thirty participants were randomly attributed to either of two groups: a test group (n=15, mean age = 20.53 ± 2.26 years), in which subjects received a true CA at the RD2 fingertip; and a control group (n=15, mean age = 23.5 ± 3.25 years), in which the CA was replaced by a sham CA (stimulator fixed at the fingertip but turned off). Results showed that in the test group three hours of CA led to a significant decrease of the 2PD threshold at RD2 fingertip, from 1.77 ± 0.28 mm to 1.52 ± 0.43 mm (mean decrease of 15.26%), thus replicating previous results. Critically, a significant 2PD threshold decrease was also found at both sides of the upper lip area (from 6.02 ± 0.88 mm to 5.44 ± 1.24 mm, mean decrease of 10.29%). No effects were found at either the LD2 fingertip or at any body-part region of the control group. These results demonstrate that experimentally-induced plasticity following RD2 coactivation improves participants’ tactile discrimination performance not only at the coactivated body site, but also at cortically adjacent body sites. Thus, CA-induced somatosensory plasticity appears to cross somatotopically defined boundaries between cortical body-parts representations, spreading its functional consequences to cortically adjacent, but peripherally unstimulated body parts.

Domaines

Neurosciences
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Dates et versions

hal-03237595 , version 1 (26-05-2021)

Identifiants

  • HAL Id : hal-03237595 , version 1

Citer

Dollyane Muret, Hubert R. Dinse, Christian Urquizar, Olivier Sillan, Karen T. Reilly, et al.. Breaking the boundaries of somatosensory plasticity: improved touch at the fingers transfers to the lips. Society for Neuroscience meeting, Oct 2012, New Orleans, United States. . ⟨hal-03237595⟩
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