Studies Into Touch in Healthy Humans to Provide Sensory Feedback in Prostheses (TACTHUM)

Our sense of touch is essential to explore our environment and experience life and is based on signals from receptors in the body that are sensitive to different types of stimulation. The TACTHUM projects aims to investigate the fundamental firing of mechanoreceptors in the body to various external stimuli, with an end-aim to better understand the human somatosensory system and to apply this knowledge to provide comprehensive sensory feedback in prosthetics. We have a vast system of peripheral receptors in the skin and muscles that provide us with exquisitely detailed information about our everyday interactions. When there is injury to a body part, such as in amputation, there is a significant loss of somatosensory input. Prosthetic devices have greatly developmed in the past few years, especially with the introduction of useful sensory feedback. However, there is a lot to discover both about the workings of the somatosensory system and how to recreate this to give feedback in a prosthetic device.

The main objective of the TACTHUM project is to understand how to recover and apply useful somatosensory feedback in prostheses for amputees. There are a number of other sub-objectives, to:

1. Determine how tactile mechanoreceptors encode the texture of natural surfaces during passive and active exploration.
2. Investigate how our sense of touch varies with emotional state.
3. Explore what happens to our sense of touch when we explore surfaces at different temperatures.
4. Understand the origin of our perception of humidity.
5. Investigate differences in the encoding of tactile information with age.
6. Determine the perceptions generated by the stimulation of single tactile afferents.
7. Study changes in spontaneous activity and responses to tactile stimulation on the residual limb of amputees.

To accomplish these objectives, we will primarily use the technique of microneurography, in vivo recordings from peripheral nerves, to gain direct information about the firing of peripheral neurons in humans. In conjunction with this, we will use a variety of mechanical and thermal stimuli to excite somatosensory fibers and register the activity of other physiological and perceptual measures. This will allow us to gain a fuller understanding of how the incoming somatosensory signals are interpreted and processed. Overall, we aim to explore how more naturalistic tactile interactions are encoded and how these can be translated to provide realistic prosthetic feedback.

Study Overview

• Status: Recruiting
• Conditions: Amputation; Aging; Prosthesis User; Somatosensory Disorders; Tactile Disorders
• Intervention / Treatment: Device: Different surfaces to be touched; Behavioral: Emotional state change; Device: Electrical stimulation

• Study Type: Interventional
• Enrollment (Estimated): 210
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rochelle Ackerley, PhD; Phone Number: 0033413550888; Email: rochelle.ackerley@univ-amu.fr
• Study Contact Backup: Name: Jean-Marc Aimonetti, PhD; Phone Number: 0033413550833; Email: jean-marc.aimonetti@univ-amu.fr

Study Locations

• France
  • Marseille, France, 13003
    • Recruiting
    • CNRS - Aix-Marseille University UMR7291
    • Contact: Rochelle Ackerley, PhD; Email: rochelle.ackerley@univ-amu.fr
    • Contact: Jean-Marc Aimonetti, PhD; Email: jean-marc.aimonetti@univ-amu.fr
    • Principal Investigator: Rochelle Ackerley, PhD
    • Sub-Investigator: Jean-Marc Aimonetti, PhD
  • Marseille, France, 13013
    • Not yet recruiting
    • Hôpital HIA Lavéran
    • Contact: Rochelle Ackerley, PhD; Email: rochelle.ackerley@univ-amu.fr
    • Contact: Laurent Théfenne, MD; Email: laurentthefenne@orange.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Men and women aged between 20 and 70.
• Be a member of a social security scheme, or a beneficiary of such a scheme
• Be calm enough to sit still for four hours.
• Specific for people participating in Arm 7 on amputees: People with an upper or lower limb amputation (unilateral) of more than 2 years.

Exclusion Criteria:

• Have peripheral neuropathy (diabetes, Raynaud's disease) or chronic muscle and/or sensory pain.
• Have a neurological or psychiatric history.
• Be subject to epilepsy.
• Be pregnant (declared) or breastfeeding, having given birth within the last year.
• Be afraid of injections.
• Being under dermatological treatment.
• Have a pacemaker.
• Not being able to understand the information leaflet and the consent form or sign it.
• Be subject to a legal protection measure (declarative)
• Be a protected adult (curatorship or guardianship)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

7

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Study of tactile afferent responses to natural surfaces	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.
Experimental: Modulation of touch according to the emotional state	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.; Behavioral: Emotional state change; The emotional state of the participant will be modulated by listening to music.
Experimental: Effect of temperature on tactile sensitivity	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.
Experimental: Origin of wetness perception	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.
Experimental: Aging and tactile sensitivity	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.; Behavioral: Emotional state change; The emotional state of the participant will be modulated by listening to music.; Device: Electrical stimulation; The participant will receive electrical stimulation of single nerve fibers (a few microamps) to artificially excite an individual afferent.
Experimental: Tactile perceptions induced by the stimulation of single sensory fibers	Device: Electrical stimulation; The participant will receive electrical stimulation of single nerve fibers (a few microamps) to artificially excite an individual afferent.
Experimental: Study of tactile feedback after amputation	Device: Different surfaces to be touched; The participant will touch various different surfaces and textures, including ones of different temperature and including solids and liquids.; Device: Electrical stimulation; The participant will receive electrical stimulation of single nerve fibers (a few microamps) to artificially excite an individual afferent.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microneurography recording	The discharge of a peripheral nerve fiber will be recorded during the stimulation conditions. From this recording, measures of the total number of impulses evoked, the instantaneous and average frequencies, firing variability, and frequency composition will be extracted.	Measured during the experiment (single event, max. 6 hours), during stimulation intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Electrodermal response	Electrodermal response will be recorded from electrodes attached to the glabrous skin, to register further effects of the stimulation on the body.	Measured during the experiment (single event, max. 6 hours), during stimulation intervention
Heart rate	Heart rate will be recorded via three electrodes on the skin, to register further effects of the stimulation on the body.	Measured during the experiment (single event, max. 6 hours), during stimulation intervention
Electromyography	Electromyography (EMG) will be recorded from surface skin electrodes over the muscle, to register further effects of the stimulation on the body. From this recording, measures of the total activity (area under the curve) during a stimulation period and the frequency composition will be extracted.	Measured during the experiment (single event, max. 6 hours), during stimulation intervention
Electroencephalography	Electroencephalography (EEG) will be recorded from surface scalp skin using a 64 electrodes setup, to register further effects of the stimulation on brain responses. From this recording, measures of the event-related potentials to stimulation will be analyzed and the frequency composition (theta, alpha, beta, gamma) of the response will be extracted.	Measured during the experiment (single event, max. 6 hours), during stimulation intervention
Perceptual ratings of pleasantness	The perceptual rating of the perceived pleasantness of different applied stimuli will be gained to determine the overt sensations induced by the stimulation. The scale is a visual analog scale with the anchors 'pleasant' and 'unpleasant' that outputs a scale of 0 (unpleasant) to 100 (pleasant).	Measured during the experiment (single event, max. 6 hours), directly after the stimulation intervention
Perceptual ratings of roughness	The perceptual rating of the perceived roughness of different applied stimuli will be gained to determine the overt sensations induced by the stimulation. The scale is a visual analog scale with the anchors 'smooth' and 'rough' that outputs a scale of 0 (smooth) to 100 (rough).	Measured during the experiment (single event, max. 6 hours), directly after the stimulation intervention
Perceptual ratings of intensity	The perceptual rating of the perceived intensity of different applied stimuli will be gained to determine the overt sensations induced by the stimulation. The scale is a visual analog scale with the anchors 'not al all intense' and 'intense' that outputs a scale of 0 (not at all intense) to 100 (intense).	Measured during the experiment (single event, max. 6 hours), directly after the stimulation intervention

Collaborators and Investigators

• Sponsor: Institut National de la Santé Et de la Recherche Médicale, France
• Investigators: Principal Investigator: Maya Elzeiere, MD, CNRS - Aix-Marseille University; Study Director: Rochelle Ackerley, PhD, CNRS - Aix-Marseille University

Study record dates

Study Major Dates

• Study Start (Actual): April 15, 2024
• Primary Completion (Estimated): October 2, 2034
• Study Completion (Estimated): November 2, 2034

Study Registration Dates

• First Submitted: September 2, 2022
• First Submitted That Met QC Criteria: September 16, 2022
• First Posted (Actual): September 21, 2022

Study Record Updates

• Last Update Posted (Actual): March 4, 2026
• Last Update Submitted That Met QC Criteria: March 3, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Temperature; Microneurography; Prosthetics; Touch; Tactile; Somarosensation; Mechanoreceptor
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Sensation Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Somatosensory Disorders; Investigative Techniques; Physical Stimulation; Electric Stimulation
• Other Study ID Numbers: C21-19; 2021-A01604-37 (Registry Identifier: IDRCB)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No