About
142
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Introduction
Gregory Gerling currently works at the School of Engineering and Applied Science at the University of Virginia. His work surrounds the interface of people and machines - focusing in particular on the sense of touch. His research interests are related to the fields of haptics, computational neuroscience, human factors and ergonomics, biomechanics, and human–machine interaction.
Additional affiliations
July 2011 - present
August 2005 - June 2011
January 2001 - July 2005
Education
January 2002 - July 2005
Publications
Publications (142)
Objective
Soft tissue manipulation is used widely to assess myofascial tissue qualitatively but lacks objective measures. To quantify the mobility of myofascial tissue, this effort derives optical biomarkers from the skin surface, as observed in the hands-on workflow of clinicians.
Methods
Digital image correlation using three high-resolution came...
Touch is an essential form of non-verbal communication. While language and its neural basis are widely studied, tactile communication is less well understood. We used fMRI and multivariate pattern analyses in pairs of emotionally close adults to examine the neural basis of human-to-human tactile communication. In each pair, a participant was design...
Classic attachment theory emphasizes the sensitivity of the parent to perceive and appropriately respond to the infant’s cues. However, parent-child attachment is a dyadic interaction that is also dependent upon the sensitivity of the child to the early caregiving environment. Individual differences in infant sensitivity to parental cues is likely...
Interpersonal touch is an important channel of social emotional interaction. How these physical skin-to-skin touch expressions are processed in the peripheral nervous system is not well understood. From microneurography recordings in humans, we evaluated the capacity of six subtypes of cutaneous mechanoreceptive afferents to differentiate human-del...
The PIEZO2 ion channel is critical for transducing light touch into neural signals but is not considered necessary for transducing acute pain in humans. Here, we discovered an exception - a form of mechanical pain evoked by hair pulling. Based on observations in a rare group of individuals with PIEZO2 deficiency syndrome, we demonstrated that hair‐...
Individual differences in tactile acuity have been correlated with age, gender and finger size, whereas the role of the skin's stiffness has been underexplored. Using an approach to image the 3‐D deformation of the skin surface during contact with transparent elastic objects, we evaluate a cohort of 40 young participants, who present a diverse rang...
While often focused on our visual system, adding touch to VR/AR environments can help render more immersive, richer user experiences. One important touch percept to render is compliance, or ‘softness.’ Herein, we evaluate the perceptibility of soft, magnetorheological elastomers (MRE) in bare-finger interactions. Such materials can be reprogrammed...
Interpersonal touch is an important part of our social and emotional interactions. How these physical, skin-to-skin touch expressions are processed in the peripheral nervous system is not well understood. From single-unit microneurography recordings in humans, we evaluated the capacity of six subtypes of cutaneous afferents to differentiate percept...
Individual differences in tactile acuity have been correlated with age, gender, and finger size, while the role of the skin’s stiffness has been underexplored. Using an approach to image the 3- D deformation of the skin surface while in contact with transparent elastic objects, we evaluate a cohort of 40 young participants, who present a diverse ra...
Our daily observations tell us that the delivery of social sentiments and emotions differs between strangers and romantic partners. This work explores how relationship status influences our delivery and perception of social touches and emotions, by evaluating the physics of contact interactions. In a study with human participants, strangers and rom...
To discriminate the compliance of soft objects, we rely upon spatiotemporal cues in the mechanical deformation of the skin. However, we have few direct observations of skin deformation over time, in particular how its response differs with indentation velocities and depths, and thereby helps inform our perceptual judgments. To help fill this gap, w...
Brushed stimuli are perceived as pleasant when stroked lightly on the skin surface of a touch receiver at certain velocities. While the relationship between brush velocity and pleasantness has been widely replicated, we do not understand how resultant skin movements - e.g., lateral stretch, stick-slip, normal indentation - drive us to form such jud...
Brushed stimuli are perceived as pleasant when stroked lightly on the skin surface of a touch receiver at certain velocities. While the relationship between brush velocity and pleasantness has been widely replicated, we do not understand how resultant skin movements - e.g., lateral stretch, stick-slip, normal indentation - drive us to form such jud...
Mechanosensory neurons that innervate the tongue provide essential information to guide feeding, speech, and social grooming. We use in vivo calcium imaging of mouse trigeminal ganglion neurons to identify functional groups of mechanosensory neurons innervating the anterior tongue. These sensory neurons respond to thermal and mechanical stimulation...
Background:
Without meaningful, intuitive sensory feedback, even the most advanced myoelectric devices require significant cognitive demand to control. The Dermal Sensory Regenerative Peripheral Nerve Interface (DS-RPNI) is a biologic interface designed to establish high-fidelity sensory feedback from prosthetic limbs.
Methods:
DS-RPNIs are cons...
Touch is a powerful communication tool, but we have a limited understanding of the role played by particular physical features of interpersonal touch communication. In this study, adults living in Sweden performed a task in which messages (attention, love, happiness, calming, sadness, and gratitude) were conveyed by a sender touching the forearm of...
Across a plethora of social situations, we touch others in natural and intuitive ways to share thoughts and emotions, such as tapping to get one’s attention or caressing to soothe one’s anxiety. A deeper understanding of these human-to-human interactions will require, in part, the precise measurement of skin-to-skin physical contact. Among prior ef...
Background and aims:
In humans, all cutaneous A-beta afferents are considered to exclusively signal discriminative touch, whereas A-delta and C afferents signal pain. We recently identified A-beta high-threshold mechanoreceptors that encoded painful skin indentations and when selectively activated evoked painful percepts. We termed them “ultrafast...
Across a plethora of social situations, we touch others in natural and intuitive ways to share thoughts and emotions, such as tapping to get one's attention or caressing to soothe one's anxiety. A deeper understanding of these human-to-human interactions will require, in part, the precise measurement of skin-to-skin physical contact. Among prior ef...
Mechanosensory neurons in the mouth provide essential information to guide feeding and speech. How classes of oral mechanoreceptors contribute to oral behaviors is not well understood; in particular, the functional properties of lingual mechanoreceptors remain elusive. Previous work identified putative mechanosensory endings in the tongue with nove...
We routinely communicate distinct social and emotional sentiments through nuanced touch. For example, we might gently hold another's arm to offer a sense of calm, yet intensively hold another's arm to express excitement or anxiety. As this example indicates, distinct sentiments may be shaped by the subtlety in one's touch delivery. This work invest...
Thin von Frey monofilaments are a clinical tool used worldwide to assess touch deficits. Ones ability to perceive touch with low-force monofilaments (0.008 0.07 g) establishes an absolute threshold and thereby the extent of impairment. While individual monofilaments bend at defined forces, there are no empirical measurements of the skin surfaces re...
We routinely communicate distinct social and emotional sentiments through nuanced touch. For example, we might gently hold anothers arm to offer a sense of calm, yet intensively hold anothers arm to express excitement or anxiety. As this example indicates, distinct sentiments may be shaped by the subtlety in ones touch delivery. This work investiga...
Touch is a powerful communication tool, but we have a limited understanding of the role played by particular physical features of interpersonal touch communication. In this study, adults living in Sweden performed a task in which messages (attention, love, happiness, calming, sadness and gratitude) were conveyed by a sender touching the forearm of...
Search and rescue missions are time-sensitive, with their duration impacting survivability. Unmanned aerial vehicles (UAVs) are increasingly shortening response time, accelerating area coverage, and informing resource allocation. However, interactions of UAVs and human operators pose challenges, for example, related to understandability and trust i...
Brushed stimuli are perceived as pleasant when stroked lightly on the skin surface of a touch receiver at certain velocities. While the relationship between brush velocity and pleasantness has been widely replicated, we do not understand how resultant skin movements - e.g., lateral stretch, stick-slip, normal indentation - drive us to form such jud...
Tactile acuity differs between individuals, likely a function of several interrelated factors. The extent of the impact of skin mechanics on individual differences is unclear. Herein, we investigate if differences in skin elasticity between individuals impact their ability to distinguish compliant spheres near limits of discriminability. After char...
Individual differences in tactile acuity are observed within and between age cohorts. Such differences in acuity may be attributed to various sources, including aspects of nervous system, skin mechanics, finger size, cognitive and behavioral factors, etc. This work considers individual differences, within a younger cohort of participants, in discri...
Our sense of touch helps us encounter the richness of our natural world. Across a myriad of contexts and repetitions, we have learned to deploy certain exploratory movements in order to elicit perceptual cues that are salient and efficient. The task of identifying optimal exploration strategies and somatosensory cues that underlie our softness perc...
Our sense of touch helps us encounter the richness of our natural world. Across a myriad of contexts and repetitions, we have learned to deploy certain exploratory movements in order to elicit perceptual cues that are optimal and efficient. Such cues help us assess an object's roughness, or stickiness, or as in this case, its softness. Leveraging e...
We regularly touch soft, compliant fruits and tissues. To help us discriminate them, we rely upon cues embedded in spatial and temporal deformation of finger pad skin. However, we do not yet understand, in touching objects of various compliance, how such patterns evolve over time, and drive perception. Using a 3-D stereo imaging technique in passiv...
Our perception of compliance is informed by multi-dimensional tactile cues. Compared with stationary cues at terminal contact, time-dependent cues may afford optimal efficiency, speed, and fidelity. In this work, we investigate strategies by which temporal cues may encode compliances by modulating our exploration time. Two potential perceptual stra...
Touch interaction cues help inform our sense of compliance. Efforts to ascertain the most relevant cues are mostly done with materials such as silicone-elastomers, foams, and robotic devices. It is unclear how well these engineered substances approximate the intrinsic material properties of ecologically compliant objects. Herein we study human tact...
We employ distinct exploratory procedures to improve our perceptual judgments of an object’s properties. For instance, with respect to compliance, we exert pressure against a resisting force. The present work investigates ties between strategies for active control of the finger and resultant cues by which compliances may be discriminated. In partic...
Human-to-human touch conveys rich, meaningful social and emotional sentiment. At present, however, we understand neither the physical attributes that underlie such touch, nor how the attributes evoke responses in unique types of peripheral afferents. Indeed, nearly all electrophysiological studies use well-controlled but non-ecological stimuli. Her...
Couples often communicate their emotions, e.g., love or sadness, through physical expressions of touch. Prior efforts have used visual observation to distinguish emotional touch communications by certain gestures tied to one's hand contact, velocity and position. The work herein describes an automated approach to eliciting the essential features of...
Differentiation between self-produced tactile stimuli and touch by others is necessary for social interactions and for a coherent concept of “self.” The mechanisms underlying this distinction are unknown. Here, we investigated the distinction between self- and other-produced light touch in healthy volunteers using three different approaches: fMRI,...
In our ability to discriminate compliant, or ‘soft,’ objects, we rely upon information acquired from interactions at the finger pad. We have yet to resolve the most pertinent perceptual cues. However, doing so is vital for building effective, dynamic displays. By introducing psychophysical illusions through spheres of various size and elasticity, w...
Distinct firing properties among touch receptors are influenced by multiple, interworking anatomical structures. Our understanding of the functions and crosstalk of Merkel cells and their associated neurites—the end organs of slowly adapting type I (SAI) afferents—remains incomplete. Piezo2 mechanically activated channels are required both in Merke...
Model produced instantaneous firing frequencies under a parameter sweep with computational model, low magnitude of stimulation, wildtype case.
Panels A—C show IFFs when the generator function is run in the context of the entire end organ model. These correspond to the parameter modifications to generate the currents in Fig 3, panels D—F. The tau va...
The parameters τSI and τRI, respectively, of the generator function are fitted from recording data.
In particular, panel (A) shows a characteristic trace of in vitro Merkel cell membrane potential over time under a current clamped prep, delivered a step mechanical stimulus at about 88% of the saturation threshold, and panel (B) shows a characterist...
To accompany the low magnitude stimulus example in Fig 3C, shown here is the high magnitude stimulus case, likewise showing the need for the USI component.
Without the USI component, the output IFF reaches a plateau and does not adapt as is typically observed for SAI afferents.
(TIF)
Time course of IFF decay observed in neural recordings cannot be achieved by skin viscoelasticity alone in absence of USI current.
In Panel A, three computational simulations were run where the skin’s viscoelasticity was varied by changing G∞ from 0.81, 0.35, and 0.10 for a 418 micron thick skin in the finite element model. The range of relaxation...
Understanding how we perceive differences in material compliance, or ‘softness,’ is a central topic in the field of haptics. The intrinsic elasticity of an object is the primary factor thought to influence our perceptual estimates. Therefore, most studies test and report the elasticity of their stimuli, typically as stiffness or modulus. However, m...
We need to understand the physics of how the skin of the finger pad deforms, and their tie to perception, to accurately reproduce a sense of compliance, or 'softness,' in tactile displays. Contact interactions with compliant materials are distinct from those with rigid surfaces where the skin flattens completely. To capture unique patterns in skin...
In mammals, touch is encoded by sensory receptors embedded in the skin. For one class of receptors in the mouse, the architecture of its Merkel cells, unmyelinated neurites, and heminodes follow particular renewal and remodeling trends over hair cycle stages from ages 4 to 10 weeks. As it is currently impossible to observe such trends across a sing...
Grasping and manipulating an object requires us to perceive its material compliance. Compliance is thought to be encoded by relationships of force, displacement and contact area at the finger pad. Prior work suggests that objects must be sufficiently deformed to become discriminable, but the utility of time-dependent cues has not been fully explore...
Sensory tissues exposed to the environment, such as skin, olfactory epithelia, and taste buds, continuously renew; therefore, peripheral neurons must have mechanisms to maintain appropriate innervation patterns. Although somatosensory neurons regenerate after injury, little is known about how these neurons cope with normal target organ changes. To...
The papers in this special section is to focus on the deployment of haptics in the field of neuroscience. The neuroscience of haptics has made many breakthroughs over the last six or so decades and these scientific advances are now being leveraged to develop new therapies for patients suffering from sensorimotor disorders and new technologies to im...
In order to accelerate implementation of hyperelastic materials for finite element analysis, we developed an automatic numerical algorithm that only requires the strain energy function. This saves the effort on analytical derivation and coding of stress and tangent modulus, which is time-consuming and prone to human errors. Using the one-sided Newt...
Distinct patterns in neuronal firing are observed between classes of cutaneous afferents. Such differences may be attributed to end organ morphology, distinct ion-channel complements, and skin microstructure, among other factors. Even for just the slowly adapting type I afferent, the skin’s mechanics for a particular specimen might impact the affer...
Distinct patterns in neuronal firing are observed between classes of cutaneous afferents. Similarly, differences in sensitivity are observed within a class of afferents, e.g., slowly adapting type I afferents. Given the dramatic changes in skin thickness and elasticity that are observed in the mouse due to normal skin remodeling, one could speculat...
Distinguishing an object's compliance, into percepts of "softness" and "hardness," is crucial to our ability to grasp and manipulate it. Biomechanical cues at the skin's surface such as contact area and force rate have been thought to help encode compliance. However, no one has directly measured contact area with compliant materials, and few studie...
The information that emergency medical technicians (EMTs) collect at the incident site is typically communicated verbally to the emergency department (ED) prior to arrival. However, communication by verbal channels can introduce lags, is limited by human recall and attention, is repetitious, and often lacks consistent and sufficient detail. To fill...
To combat the risk of hyperglycemia while in the hospital, a patient's insulin delivery should be correlated with blood glucose levels and meal consumption. At present, there is a particularly acute disconnect between insulin delivery and meal consumption. There are simply no formal processes for communicating the status of meal delivery, and there...
Each year, approximately 185,000 Americans suffer the devastating loss of a limb. The effects of upper limb amputations are profound because a person's hands are tools for everyday functioning, expressive communication, and other uniquely human attributes. Despite the advancements in prosthetic technology, current upper limb prostheses are still li...