Linking Signal Relevancy and Intensity in Predictive Tactile Suppression

Abstract

Predictable somatosensory feedback leads to a reduction in tactile sensitivity. This phenomenon, called tactile suppression, relies on a mechanism that uses an efference copy of motor commands to help select relevant aspects of incoming sensory signals. We investigated whether tactile suppression is modulated by (a) the task-relevancy of the predicted consequences of movement and (b) the intensity of related somatosensory feedback signals. Participants reached to a target region in the air in front of a screen; visual or tactile feedback indicated the reach was successful. Furthermore, tactile feedback intensity (strong vs. weak) varied across two groups of participants. We measured tactile suppression by comparing detection thresholds for a probing vibration applied to the finger either early or late during reach and at rest. As expected, we found an overall decrease in late-reach suppression, as no touch was involved at the end of the reach. We observed an increase in the degree of tactile suppression when strong tactile feedback was given at the end of the reach, compared to when weak tactile feedback or visual feedback was given. Our results suggest that the extent of tactile suppression can be adapted to different demands of somatosensory processing. Downregulation of this mechanism is invoked only when the consequences of missing a weak movement sequence are severe for the task. The decisive factor for the presence of tactile suppression seems not to be the predicted action effect as such, but the need to detect and process anticipated feedback signals occurring during movement.

Sensorimotor memories influence movement kinematics but not associated tactile processing

“…Thus, no data were available on the basis of which we could have calculated an a priori power analysis. Therefore, our sample size was based on previous studies on tactile suppression 6 , 8 , 11 , 14 , 22 , 26 . Participants were all right-handed as measured by the German translation of the Edinburgh Handedness Inventory 27 ( range = 60–100), free from any known neurological conditions, and had normal or corrected-to-normal visual acuity.…”

“…Despite the importance of somatosensory feedback for motor control and learning, somatosensory afferents, in particular those from the tactile domain, are typically suppressed during movement 8 – 13 . This phenomenon of tactile suppression is primarily explained by an internal feed-forward model that predicts future sensory states of the moving limb and suppresses associated sensory signals 14 , 15 based on efferent signals related to the underlying movement 16 – 18 .…”

Sensorimotor memories influence movement kinematics but not associated tactile processing

“…Twenty-four participants (18 female, 6 male) aged 19-34 years ( mean = 23 ± 3.6) participated in this experiment. The sample size was based on previous studies on tactile suppression (Beyvers et al, 2022a; Fraser & Fiehler, 2018; Fuehrer et al, 2022; Gertz et al, 2018; Manzone et al, 2018; Voudouris et al, 2019). Participants were all right-handed as measured by the German translation of the Edinburgh Handedness Inventory (Oldfield, 1971; range = 600-100), free from any known neurological conditions, and had normal or corrected-to-normal visual acuity.…”

“…Despite the importance of somatosensory feedback for motor control and learning, somatosensory afferents, in particular those from the tactile domain, are typically suppressed during movement (Beyvers et al, 2022a;Buckingham et al, 2010;Colino & Binsted, 2016;Fraser & Fiehler, 2018;Voudouris et al, 2017;Juravle et al, 2017). This phenomenon of tactile suppression is explained by an internal feed-forward model that predicts future sensory states of the moving limb and suppresses associated sensory signals (Fuehrer et al, 2022;Voss et al, 2008) based on efferent signals related to the underlying movement (Voss et al, 2006;Haggard & Whitford, 2014;Arikan et al, 2021).…”