Biology subjects

Ackerley, R.

Publications and source records attributed to Ackerley, R..

8 recordsLinked to original sources

bioRxiv2026

A psychophysical characterization of tactile and temperature perception on the human torso

Numerous studies have been conducted to investigate touch on the hand and forearm, but less is known about the rest of the body, particularly the torso and breasts, which play an important role in affective touch. We conducted psychophysical tests on three skin sites on the torso: upper breast, nipple-areola complex (NAC), and under the breast, as well as on two control sites: palm and forearm. We studied touch pleasantness and intensity by applying gentle caress-like strokes using a soft brush, and measured temperature and tactile detection thresholds. The results show an inverted U-shaped relationship for pleasantness over increasing stroking velocity for all skin sites, although we found some differences between sites, particularly at 30 cm.s-1, where participants found stroking on the NAC to be more intense and women additionally found it to be less pleasant. For temperature detection, we found that the NAC was more sensitive in men. For tactile detection, we mainly observed that the areola was far less sensitive than the other areas. Together, these results provide insights into tactile perception in the torso on a fundamental level, which can be applied to understanding how to regain sensations after mastectomy.

neuroscience↗

bioRxiv2026

Perceptual integration of multisensory haptic, visual, and auditory feedback for roughness discrimination in augmented reality

Understanding how our different senses interact to shape our perception is essential to design realistic and immersive virtual and augmented reality (VR/AR) experiences. The present study investigated how roughness perception can be modulated through haptic, visual, and auditory cues in AR using a vibrotactile wristband. Participants compared virtual textures varying in vibration frequency/amplitude, visual grain size, and friction sound. Results revealed strong linear relationships between stimulus parameters and perceived roughness, with haptic frequency and visual cues driving the highest discrimination performance. Adding non-informative sensory feedback reduced perceptual sensitivity, acting as noise. Individual differences emerged: participants who rated haptic as the easiest modality showed greater sensitivity to haptic variations, while visual-reliant participants performed better with visual cues. We conclude that roughness in AR can be systematically manipulated, but is vulnerable to perceptual interference from irrelevant inputs, where our work provides actionable insights for implementing optimized and adaptive AR/VR interfaces.

neuroscience↗

bioRxiv2026

Roughness or sliminess: What makes a haptic material unpleasant

The current study aims to identify materials that most people experience as being unpleasant to touch and to uncover the perceptual attributes that link to unpleasantness. We sampled 79 everyday materials covering a wide range of sensory properties such as fluidity, granularity, roughness, and softness, e.g., cooking oil, sand, coconut, and silk. We asked participants to freely explore these materials with their dominant hand and subsequently rate their unpleasantness and 23 sensory attributes (e.g., elasticity, stickiness) in the absence of visual and auditory feedback. We collected data on material unpleasantness from two populations: Germany and the UK. Our wide array of materials showed different unpleasantness levels that correlated with specific perceptual material attributes. In general, viscous and deformable materials (e.g., hair gel, play-doh) felt more unpleasant to touch than surface-soft and smooth materials. Results were comparable for the German and UK samples. Overall, our results revealed a relationship between specific sensory attributes of materials and their unpleasantness, which seems to be consistent across German and UK samples. Our findings contribute to the understanding of how various sensory attributes are related to haptic unpleasantness. These insights advance our understanding of haptic perception with various implications, such as product design and affective computing systems, as both seek to integrate touch for detecting and modulating human affective states.

neuroscience↗

bioRxiv2026

Changes of sensory and emotional tactile dimensions with age in self-touch via the application of creams

Touch moderates how we interact with objects, others, and ourselves, where self-touch is particularly important in self-care, although fewer studies have investigated its perception, especially with age. Here, women aged 20-28 and 65-75 years rated how self-applied creams felt on the cheek and forearm, using sensory and emotional descriptors in the Touch Perception Task. Factor analyses uncovered higher tactile dimensions, including Texture, Moisture, Positive Affect, and Negative Affect. Sensory dimensions were more intense in the young group, whereas Positive Affect was stronger in the older group. We then used network and clustering analyses to map how the descriptors interacted. Young participants showed significantly higher connectivity between descriptors, whereas older participants displayed fewer connections, but many became mixed sensory-emotional pairings. Clustering analyses revealed further changes in the tactile groupings with age. We conclude that aging reshapes touch into an emotionally-rich experience, which impacts how interact with ourselves and others.

neuroscience↗

bioRxiv2026

The influence of force on the encoding and perception of affective touch

Stroking touch has been shown to be most pleasant at intermediate velocities of 1-10 cm.s-1, which relates well to the activity of C-low threshold mechanoreceptors (C-LTMRs), also called C-tactile afferents in humans, that have been implicated in encoding positive affective touch. This well-established finding has been demonstrated at gentle stroking forces (typically 0.4 N peak normal force), yet few studies have investigated the effect of force on the perception of stroking touch or on the activity of C-LTMRs. Presently, we investigated the pleasantness and intensity of stroking touch (0.3, 1, 3, 10, 30 cm.s-1) at different forces (0.2, 0.4, 0.8, 1.2, 1.6, 2.0 N) on hairy forearm skin and compared this to responses from C-LTMRs during stroking touch at the same velocities, but over fewer forces (0.05, 0.4, 1.5 N). We found significant effects of stroking velocity and force for both tactile pleasantness and intensity ratings. Pleasantness showed the typical inverted-U shaped relationship over stroking velocities, but this was modified by force: higher forces significantly decreased pleasantness at faster velocities. Conversely, tactile intensity increased linearly with both increasing velocity and force. Recordings from seven C-LTMRs showed that their firing frequency changed with stroking velocity, but that they were strongly modulated by force. Overall, we demonstrate the profound effect that force has on the perception of stroking touch, where tactile pleasantness and intensity appear to be a multi-faceted construct that are related to C-LTMR and A{beta}-LTMR activity, respectively, but that the firing in individual mechanoreceptor populations cannot fully account for percepts.

neuroscience↗

bioRxiv2025

Physical determinants of perceived vibration intensity: Insights from haptic feedback given at the wrist

Understanding how mechanical vibrations applied to the skin translate into touch sensations is key to advancing tactile interfaces, from non-invasive neuroprosthetics to effective haptic tools. We investigate how modulating vibration waveform, frequency, and amplitude of a wrist-worn vibrotactile device influence perceived touch intensity, while simultaneously measuring accelerations at the actuator and skin surface. Thirty participants provided free-magnitude estimates of perceived intensity, showing that perceived intensity is significantly influenced by all parameters, while being strongly correlated with actuator and skin accelerations. Modulating the waveform shape showed that square waves are consistently rated as more intense. Vibration frequency exerted a non-linear influence, with perceived intensity peaking ~150 Hz and secondary acceleration and perceptual peaks were found at low frequencies for square and sawtooth waveforms. Thus, the skin faithfully preserves the mechanical signature of vibrations, which are clearly differentiated perceptually. These findings demonstrate that precise tactile characterization, both physically and perceptually, is essential, where device vibrations delivered to the skin determine what is perceived to a very high degree. As vibrations are relatively easy to control and apply, this opens up opportunities to convey a multitude of sensations, from brief taps to pressure, as well as more complex percepts like roughness and texture.

neuroscience↗

bioRxiv2025

Single human fingertip mechanoreceptive afferents simultaneously encode multidimensional aspects of touch

Touch using the hands is essential for recognizing surface features and manipulating objects, where different aspects are encoded by four main types of low-threshold mechanoreceptors (LTMs) in glabrous skin. Although factors such as movement, vibration, and pressure are often studied individually, touch requires their integration to produce complex sensations. We investigated these processes jointly by recording single-unit activity via microneurography from human LTM afferents in the median nerve as periodic gratings slid across their receptive fields, varying the normal force and sliding velocity per trial. Mixed-effects models revealed that fast-adapting type 1 (FA-1) afferent firing was influenced by all three parameters--force, velocity, and spatial period. Slowly-adapting type 1 (SA-1) afferent firing was primarily driven by force, and to a lesser extent, velocity. These findings support the view that FA-1 afferents encode stimulus intensity in an approximately linear manner, while SA-1 afferents function mainly as force detectors, demonstrating that mechanoreceptive afferents provide a complementary and multidimensional representation of texture during sliding contact. This distributed encoding challenges the notion that LTMs are dedicated to single stimulus features, suggesting that tactile information is represented across LTM populations where each class contributes differently-weighted inputs to capture skin-object interactions.

physiology↗

bioRxiv2018

Imaging human cortical responses to intraneural microstimulation using magnetoencephalography

The sensation of touch in the glabrous skin of the human hand is conveyed by thousands of fast-conducting mechanoreceptive afferents, which can be categorised into four distinct types. The spiking properties of these afferents in the periphery in response to varied tactile stimuli are well-characterised, but relatively little is known about the spatiotemporal properties of the neural representations of these different receptor types in the human cortex. Here, we use the novel methodological combination of single-unit intraneural microstimulation (INMS) with magnetoencephalography (MEG) to localise cortical representations of individual touch afferents in humans, by measuring the extracranial magnetic fields from neural currents. We found that by assessing the modulation of the beta (13-30 Hz) rhythm during single-unit INMS, significant changes in oscillatory amplitude occur in the contralateral primary somatosensory cortex within and across a group of fast adapting type I mechanoreceptive 20 afferents, which corresponded well to the induced response from matched vibrotactile stimulation. Combining the spatiotemporal specificity of MEG with the selective single-unit stimulation of INMS enables the interrogation of the central representations of different aspects of tactile afferent signalling within the human cortices. The fundamental finding that single-unit INMS ERD responses are robust and consistent with natural somatosensory stimuli will permit us to more dynamically probe the central nervous system responses in humans, to address questions about the processing of touch from the different classes of mechanoreceptive afferents and the effects of varying the stimulus frequency and patterning.

neuroscience↗