15:25 - 16:00 - Coffee break

17:40 -  Discussion and closing

Grip force adaptation relies on cutaneous feedback from human fingertips at slip onset

Jean-Louis Thonnard (Université Catholique de Louvain, Belgium)

Human tactile afferents provide essential feedback for grasp stability during dexterous object manipulation. Interacting forces between an object and the fingers induce slip events that are thought to provide information about grasp stability. Using microneurography we describe how afferents respond to partial slip events particularly FA-I who are encoding compressive strain rates resulting from those slips.

How moisture and contact conditions shape finger friction at initial slip

Seakwang Nam (Kyungpook National University, Korea)

Understanding how the human finger begins to slip on a surface is crucial for grasp stability in both humans and robots. This study investigates how finger moisture, pressing time, and surface temperature influence friction during initial slip on glass. The findings reveal how subtle changes in contact conditions affect friction dynamics and offer valuable insights for designing tactile-responsive robotic systems.

Tactile perception of microscale surfaces

David Gueorguiev (Université Catholique de Louvain, Belgium)

Touch has the astonishing ability to perceive surface properties that are orders of magnitude smaller than skin cells, mechanosensitive structures, or afferents' density. The mechanisms that enable this extraordinary capacity are still largely unknown but seem to rely on an acute sensitivity to material properties such as the friction, hydrophobicity, microstructure. This sensitivity is probably mediated by population coding involving all afferent types. This talk explores several cases of tactile hypersensitivity and the potential tactile mechanisms mediating it.

Neurophysiology of active touch: from surface perception to tactile discrimination

Mariama Dione (Aix-Marseille Université, France)

Humans often slide their finger pads over surfaces to explore their properties. This typical movement deforms the skin in a way that optimally stimulates the skin mechanoreceptors. Tactile information then travels through the nervous system, to finally reach the brain and produce a touch percept. In the first part of this talk, I will present ongoing results on how mechanoreceptors encode touch during naturalistic exploration of everyday surfaces in humans in relation to skin deformation (force, vibration) and verbal evaluations. In the second part, I will present perspectives, considering more complex discrimination tasks, performed using one to several fingers.

What research about hands tells us about feet

Ingvars Birznieks (University of New South Wales Sydney, Australia)

Sensing friction (slipperiness) between the skin and surface is important for informing our interaction with the environment. It shapes our perception of surface material properties and, most importantly, controls our movements. It has been well established that frictional information is crucial achieving fine grip force control during object manipulation tasks precluding objects or tools to slip out of our hands. However, only lately significant advances have been made in understanding the sensory processes by which tactile receptors in the fingertip skin signal this information. Furthermore, recent studies have determined the role of skin divergence pattern and small submillimeter range lateral displacements which are inherently present in reach-and-grip movement kinematics. Nonetheless, the use of frictional information for motor control and feeling slipperiness is not limited to hands. For balance and to avoid slips and falls, our feet evaluate slipperiness of the surface we move on. Although sensory principles in two body locations might be similar given that the glabrous skin shares the same types of tactile receptors, hands and feet differ biomechanically and functionally, thus requiring different solutions to implement them. In this presentation, I will discuss discoveries of sophisticated sensory mechanisms enabling friction sensing with the evidence comprising psychophysics experiments, biomechanical analyses and observations of movement control strategies. I will provide insight into unique friction sensing mechanisms employed by feet and discuss how knowledge gained from studying friction sensing approaches in hands relates to these mechanisms in feet. The implications that footwear has on the perception of slipperiness will be also addressed.

From texture perception to tactile interface design

Frederic Giraud (Université de Lille, France)

Tactile surface perception is a multimodal process that relies on both spatial encoding of macroscopic features and vibratory cues generated during active exploration. The dynamic interaction between the finger pulp and objects is therefore at the origin of texture perception. Depending whether the texture, is fine or coarse, tactile interfaces should reproduce spatial and/or vibratory stimuli which activate the mechanoreceptors. This talk will draw connections between perception of textures and the design of haptic surfaces, including vibration-based and friction-modulating systems. An example of multimodal tactile interfaces will be presented. 

Tactile illusion on Hands

Gunhyuk Park (Gwangju Institute of Science and Technology, Korea)

Multimodal feedback can elicit illusory sensations on diverse body sites including hands. This talk introduces the recent two practices of the speaker that validate phantom sensations in matching with visual motions and estimate thermal masking/referral effects for the thermal and vibration feedback combined with a slip feedback device.