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1.
Nat Commun ; 12(1): 1120, 2021 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602925

RESUMO

The integration and interaction of vision, touch, hearing, smell, and taste in the human multisensory neural network facilitate high-level cognitive functionalities, such as crossmodal integration, recognition, and imagination for accurate evaluation and comprehensive understanding of the multimodal world. Here, we report a bioinspired multisensory neural network that integrates artificial optic, afferent, auditory, and simulated olfactory and gustatory sensory nerves. With distributed multiple sensors and biomimetic hierarchical architectures, our system can not only sense, process, and memorize multimodal information, but also fuse multisensory data at hardware and software level. Using crossmodal learning, the system is capable of crossmodally recognizing and imagining multimodal information, such as visualizing alphabet letters upon handwritten input, recognizing multimodal visual/smell/taste information or imagining a never-seen picture when hearing its description. Our multisensory neural network provides a promising approach towards robotic sensing and perception.


Assuntos
Biomimética , Redes Neurais de Computação , Reconhecimento Psicológico , Humanos , Imaginação , Aprendizagem , Neurônios/fisiologia , Olfato/fisiologia , Paladar/fisiologia , Tato/fisiologia , Visão Ocular/fisiologia
2.
Nat Commun ; 12(1): 221, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33431883

RESUMO

Dedicated maps for cognitive quantities such as timing, size and numerosity support the view that topography is a general principle of brain organization. To date, however, all of these maps were driven by the visual system. Here, we ask whether there are supramodal topographic maps representing cognitive dimensions irrespective of the stimulated sensory modality. We measured haptically and visually driven numerosity-selective neural responses using model-based analyses and ultra-high field (7T) fMRI. We found topographically organized neural populations tuned to haptic numerosity. The responses to visual or haptic numerosity shared a similar cortical network. However, the maps of the two modalities only partially overlap. Thus, although both visual and haptic numerosities are processed in a similar supramodal functional network, the underlying neural populations may be related, but distinct. Therefore, we hypothesize that overlap between modality-specific maps facilitates cross-modal interactions and supramodal representation of cognitive quantities.


Assuntos
Rede Nervosa/fisiologia , Tato/fisiologia , Adulto , Feminino , Dedos/fisiologia , Mãos/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Movimento (Física) , Atividade Motora/fisiologia , Estimulação Luminosa , Percepção Visual/fisiologia
3.
Neuron ; 109(5): 778-787.e3, 2021 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-33472037

RESUMO

Fast synaptic transmission relies upon the activation of ionotropic receptors by neurotransmitter release to evoke postsynaptic potentials. Glutamate and GABA play dominant roles in driving highly dynamic activity in synaptically connected neuronal circuits, but ionotropic receptors for other neurotransmitters are also expressed in the neocortex, including nicotinic receptors, which are non-selective cation channels gated by acetylcholine. To study the function of non-glutamatergic excitation in neocortex, we used two-photon microscopy to target whole-cell membrane potential recordings to different types of genetically defined neurons in layer 2/3 of primary somatosensory barrel cortex in awake head-restrained mice combined with pharmacological and optogenetic manipulations. Here, we report a prominent nicotinic input, which selectively depolarizes a subtype of GABAergic neuron expressing vasoactive intestinal peptide leading to disinhibition during active sensorimotor processing. Nicotinic disinhibition of somatosensory cortex during active sensing might contribute importantly to integration of top-down and motor-related signals necessary for tactile perception and learning.


Assuntos
Neurônios GABAérgicos/fisiologia , Receptores Nicotínicos/fisiologia , Córtex Somatossensorial/fisiologia , Percepção do Tato/fisiologia , Animais , Comportamento Animal , Feminino , Masculino , Potenciais da Membrana , Neurônios/fisiologia , Optogenética , Tato/fisiologia , Peptídeo Intestinal Vasoativo/análise , Vibrissas/fisiologia
4.
Nat Commun ; 12(1): 657, 2021 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-33510158

RESUMO

The sensation of pressure allows us to feel sustained compression and body strain. While our understanding of cutaneous touch has grown significantly in recent years, how deep tissue sensations are detected remains less clear. Here, we use quantitative sensory evaluations of patients with rare sensory disorders, as well as nerve blocks in typical individuals, to probe the neural and genetic mechanisms for detecting non-painful pressure. We show that the ability to perceive innocuous pressures is lost when myelinated fiber function is experimentally blocked in healthy volunteers and that two patients lacking Aß fibers are strikingly unable to feel innocuous pressures at all. We find that seven individuals with inherited mutations in the mechanoreceptor PIEZO2 gene, who have major deficits in touch and proprioception, are nearly as good at sensing pressure as healthy control subjects. Together, these data support a role for Aß afferents in pressure sensation and suggest the existence of an unknown molecular pathway for its detection.


Assuntos
Canais Iônicos/fisiologia , Mecanorreceptores/fisiologia , Sensação/fisiologia , Tato/fisiologia , Adulto , Idoso , Feminino , Humanos , Canais Iônicos/genética , Masculino , Mecanorreceptores/metabolismo , Pessoa de Meia-Idade , Mutação , Bloqueio Nervoso/métodos , Pressão , Propriocepção/genética , Propriocepção/fisiologia , Transtornos das Sensações/diagnóstico , Transtornos das Sensações/genética , Transtornos das Sensações/fisiopatologia , Pele/inervação , Pele/fisiopatologia , Adulto Jovem
5.
Neurosci Lett ; 743: 135566, 2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33352289

RESUMO

Smokers have a higher incidence of chronic pain than non-smokers, but the neural mechanism is not yet fully understood. Nicotine is the main component of tobacco and acts as an agonist for nicotinic cholinergic receptors (nAChRs) in the nervous system. This study was approved by the IACUC of UM. The effects of chronic nicotine administration on mechanical sensitivity were studied using a rat model. The changes in the expression levels of the α7 isoform of nAChR (α7-nAChR), inflammatory cytokines TNFα and COX-2, as well as the density of neuro-immune cells (astrocytes and microglia) were measured concurrently. The results indicate that long-term nicotine administration induces hypersensitivity to mechanical stimuli, as demonstrated by a significant reduction in the pain perception threshold. In response to nicotine, the expression levels of α7-nAChR increased in the periaqueductal gray matter (PAG) and decreased in the spinal cord. Acute administration of the selective α7-nAChR agonist CDP-Choline reversed this hypersensitivity. Chronic nicotine administration led to an increase of microglial cells in the dorsal horn of the spinal cord and increased expression levels of the cytokines TNFα and COX-2. This study suggests that decreased α7-nAChR expression in the spinal cord, as a result of long-term exposure to nicotine, may be causatively linked to chronic pain. Simultaneously, the increase of neuro-immune factors in the spinal cord is also a potential factor leading to chronic pain.


Assuntos
Modelos Animais de Doenças , Hiperalgesia/metabolismo , Nicotina/toxicidade , Medula Espinal/metabolismo , Tato/fisiologia , Receptor Nicotínico de Acetilcolina alfa7/biossíntese , Animais , Dor Crônica/induzido quimicamente , Dor Crônica/tratamento farmacológico , Dor Crônica/metabolismo , Citidina Difosfato Colina/farmacologia , Citidina Difosfato Colina/uso terapêutico , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Masculino , Nicotina/administração & dosagem , Nicotina/agonistas , Nootrópicos/farmacologia , Nootrópicos/uso terapêutico , Ratos , Ratos Sprague-Dawley , Medula Espinal/efeitos dos fármacos , Receptor Nicotínico de Acetilcolina alfa7/genética
6.
Neurosci Lett ; 744: 135592, 2021 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-33359925

RESUMO

Attention-Deficit Hyperactivity Disorder (ADHD) is a predominant neurobehavioral disorder of childhood with motor and sensory symptoms often persisting into adulthood. Motor control theories highlight the importance of the bidirectional relationship between sensation and movement for maintaining skilled behaviors like speech. The impact of ADHD on speech in adults has not been well established. The purpose of this study is to assess group differences in quantitative speech and oral somatosensory measures in adults with and without ADHD and to describe the relationship between ADHD symptomology and speech production. A total of 50 adults (18-26 years) were recruited and divided in two groups based on diagnosis: those with (n = 28) and those without (n = 22) ADHD. All participants provided a speech sample to measure articulatory accuracy and speech rate and completed quantitative point-pressure testing using tactile detection and discrimination on bilateral sites on the lower lip and lateral edge of the tongue tip. Independent t-tests corrected for multiple comparisons identified significant group differences using FDR corrected q values in speech production for correct syllables per second and overall speech rate (q<.05). Additionally, there were significant group differences (q<.05) for detection and discrimination threshold estimates at one testing location. Bivariate correlations identified a relationship between several speech measures and self-reported ADHD symptoms such that as symptom severity increased, speech accuracy for correct syllables per second decreased. Young adults with ADHD have subtle differences in speech production compared to non-ADHD control participants. Speech scientists might consider screening for ADHD when collecting normative data samples.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Músculos Faciais/fisiologia , Destreza Motora/fisiologia , Fala/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Adolescente , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Feminino , Humanos , Masculino , Pressão , Adulto Jovem
7.
Expert Rev Med Devices ; 18(1): 63-74, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33372550

RESUMO

INTRODUCTION: Hearing-assistive devices, such as hearing aids and cochlear implants, transform the lives of hearing-impaired people. However, users often struggle to locate and segregate sounds. This leads to impaired threat detection and an inability to understand speech in noisy environments. Recent evidence suggests that segregation and localization can be improved by providing missing sound-information through haptic stimulation. AREAS COVERED: This article reviews the evidence that haptic stimulation can effectively provide sound information. It then discusses the research and development required for this approach to be implemented in a clinically viable device. This includes discussion of what sound information should be provided and how that information can be extracted and delivered. EXPERT OPINION: Although this research area has only recently emerged, it builds on a significant body of work showing that sound information can be effectively transferred through haptic stimulation. Current evidence suggests that haptic stimulation is highly effective at providing missing sound-information to cochlear implant users. However, a great deal of work remains to implement this approach in an effective wearable device. If successful, such a device could offer an inexpensive, noninvasive means of improving educational, work, and social experiences for hearing-impaired individuals, including those without access to hearing-assistive devices.


Assuntos
Percepção Auditiva/fisiologia , Audição , Pessoas com Deficiência Auditiva/reabilitação , Tato/fisiologia , Humanos , Ruído , Estimulação Física , Desenho de Prótese
8.
Sci Rep ; 10(1): 22342, 2020 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-33339874

RESUMO

Humans have the ability to use a diverse range of handheld tools. Owing to its versatility, a virtual environment with haptic feedback of the force is ideally suited to investigating motor learning during tool use. However, few simulators exist to recreate the dynamic interactions during real tool use, and no study has compared the correlates of motor learning between a real and virtual tooling task. To this end, we compared two groups of participants who either learned to insert a real or virtual tool into a fixture. The trial duration, the movement speed, the force impulse after insertion and the endpoint stiffness magnitude decreased as a function of trials, but they changed at comparable rates in both environments. A ballistic insertion strategy observed in both environments suggests some interdependence when controlling motion and controlling interaction, contradicting a prominent theory of these two control modalities being independent of one another. Our results suggest that the brain learns real and virtual insertion in a comparable manner, thereby supporting the use of a virtual tooling task with haptic feedback to investigate motor learning during tool use.


Assuntos
Encéfalo/fisiologia , Aprendizagem/fisiologia , Atividade Motora/fisiologia , Desempenho Psicomotor/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Simulação por Computador , Retroalimentação , Humanos , Laparoscopia , Masculino , Neurociências/tendências , Tato/fisiologia , Interface Usuário-Computador , Adulto Jovem
9.
PLoS One ; 15(12): e0244321, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33338075

RESUMO

BACKGROUND: Women involved in repetitive, fatiguing, jobs develop more neck and/or shoulder musculoskeletal disorders than men. Sex differences in the pain response to exercise could contribute to the higher prevalence of neck/shoulder musculoskeletal disorders in women. The objective of this study was to assess sex differences in pain sensitivity following a fatiguing upper limb task. Relationships between measures of fatigue and of the sensitivity to nociceptive and to non-nociceptive stimulations were also explored. METHODS: Thirty healthy adults (15 women) performed a fatiguing repetitive pointing task with their dominant arm. Upper limb electromyography was recorded from the dominant upper trapezius, anterior deltoid and bicep brachii and from the contralateral tibialis anterior. Before and immediately after the repetitive pointing task, pressure pain and light touch sensitivity thresholds were measured over the same muscles. RESULTS: Electromyographic signs of fatigue were observed only in the anterior deltoid and biceps brachii muscles. Pressure pain thresholds over both muscles increased slightly (effect size ≤ 0.34), but no changes occurred over the upper trapezius and the tibialis anterior. Light touch thresholds increased moderately to importantly after the repetitive pointing task over all four muscles (effect sizes = 0.58 to 0.87). No sex differences were observed in any sensory variable. Moreover, no or weak correlations (r = -0.27 to 0.39) were observed between electromyographical signs of fatigue, light touch threshold and pressure pain threshold variables. CONCLUSIONS: We observed sex-independent effects of a repetitive upper limb task on the sensitivity to painful and to nonpainful stimuli. Moreover, the hypoalgesia induced by the repetitive pointing task was weak and localized, and did not directly correlate with the induced muscle fatigue. Results suggest that fatigue-related changes in the sensitivity to noxious and innocuous stimuli could not explain women's greater prevalence of neck/shoulder musculoskeletal disorders.


Assuntos
Transtornos Traumáticos Cumulativos/fisiopatologia , Percepção da Dor/fisiologia , Limiar da Dor/fisiologia , Adulto , Braço/fisiologia , Transtornos Traumáticos Cumulativos/metabolismo , Eletromiografia/métodos , Fadiga/fisiopatologia , Feminino , Humanos , Masculino , Movimento/fisiologia , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Pescoço/fisiologia , Caracteres Sexuais , Fatores Sexuais , Ombro/fisiologia , Tato/fisiologia , Extremidade Superior/fisiologia
10.
PLoS One ; 15(12): e0244594, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33378385

RESUMO

Sense of body ownership is an immediate and distinct experience of one's body as belonging to oneself. While it is well-recognized that ownership feelings emerge from the integration of visual and somatosensory signals, the principles upon which they are integrated are still intensely debated. Here, we used the rubber hand illusion (RHI) to examine how the interplay of visual, tactile, and proprioceptive signals is governed depending on their spatiotemporal properties. For this purpose, the RHI was elicited in different conditions varying with respect to the extent of visuo-proprioceptive divergence (i.e., the distance between the real and fake hands) and differing in terms of the availability and spatiotemporal complexity of tactile stimulation (none, simple, or complex). We expected that the attenuating effect of distance on illusion strength will be more pronounced in the absence of touch (when proprioception gains relatively higher importance) and absent in the presence of complex tactile signals. Additionally, we hypothesized that participants with greater proprioceptive acuity-assessed using an elbow joint position discrimination task-will be less susceptible to the illusion, but only under the conditions of limited tactile stimulation. In line with our prediction, RHI was attenuated at the farthest distance only when tactile information was absent or simplified, but the attenuation was effectively prevented by the use of complex tactile stimulation-in this case, RHI was comparably vivid at both distances. However, passive proprioceptive acuity was not related to RHI strength in either of the conditions. The results indicate that complex-structured tactile signals can override the influence of proprioceptive signals in body attribution processes. These findings extend our understanding of body ownership by showing that it is primarily determined by informative cues from the most relevant sensory domains, rather than mere accumulation of multisensory evidence.


Assuntos
Ilusões/fisiologia , Propriocepção/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Borracha , Adulto Jovem
11.
PLoS One ; 15(12): e0227462, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33382701

RESUMO

An age-old hypothesis proposes that object motion across the receptor surface organizes sensory maps (Lotze, 19th century). Skin patches learn their relative positions from the order in which they are stimulated during motion events. We propose that reversing the local motion within a global motion sequence ('motion scrambling') provides a good test for this idea, and present results of the first experiment implementing the paradigm. We used 6-point apparent motion along the forearm. In the Scrambled sequence, two middle locations were touched in reversed order (1-2-4-3-5-6, followed by 6-5-3-4-2-1, in a continuous loop). This created a double U-turn within an otherwise constant-velocity motion, as if skin patches 3 and 4 physically swapped locations. The control condition, Orderly, proceeded at constant velocity at inter-stimulus onset interval of 120 ms. The 26.4-minute conditioning (delivered in twenty-four 66-s bouts) was interspersed with testing of perceived motion direction between the two middle tactors presented on their own (sequence 3-4 or 4-3). Our twenty participants reported motion direction. Direction discrimination was degraded following exposure to Scrambled pattern and was 0.31 d' weaker than following Orderly conditioning (p = .007). Consistent with the proposed role of motion, this could be the beginning of re-learning of relative positions. An alternative explanation is that greater speed adaptation occurred in the Scrambled pattern, raising direction threshold. In future studies, longer conditioning should tease apart the two explanations: our re-mapping hypothesis predicts an overall reversal in perceived motion direction between critical locations (for either motion direction), whereas the speed adaptation alternative predicts chance-level performance at worst, without reversing.


Assuntos
Adaptação Fisiológica , Condicionamento Psicológico , Percepção de Movimento/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos/fisiologia , Feminino , Antebraço/inervação , Antebraço/fisiologia , Humanos , Masculino , Movimento (Física) , Psicofísica/métodos , Pele/inervação , Fenômenos Fisiológicos da Pele
12.
Nat Commun ; 11(1): 5074, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033265

RESUMO

Touch and itch sensations are crucial for evoking defensive and emotional responses, and light tactile touch may induce unpleasant itch sensations (mechanical itch or alloknesis). The neural substrate for touch-to-itch conversion in the spinal cord remains elusive. We report that spinal interneurons expressing Tachykinin 2-Cre (Tac2Cre) receive direct Aß low threshold mechanoreceptor (LTMR) input and form monosynaptic connections with GRPR neurons. Ablation or inhibition markedly reduces mechanical but not acute chemical itch nor noxious touch information. Chemogenetic inhibition of Tac2Cre neurons also displays pronounced deficit in chronic dry skin itch, a type of chemical itch in mice. Consistently, ablation of gastrin-releasing peptide receptor (GRPR) neurons, which are essential for transmitting chemical itch, also abolishes mechanical itch. Together, these results suggest that innocuous touch and chemical itch information converge on GRPR neurons and thus map an exquisite spinal circuitry hard-wired for converting innocuous touch to irritating itch.


Assuntos
Rede Nervosa/fisiopatologia , Prurido/fisiopatologia , Tato/fisiologia , Animais , Comportamento Animal , Injeções Espinhais , Luz , Potenciais da Membrana , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Precursores de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Receptores da Bombesina/metabolismo , Pele/patologia , Medula Espinal/fisiopatologia , Sinapses/metabolismo , Taquicininas/metabolismo
13.
Nat Commun ; 11(1): 4602, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32929071

RESUMO

Human behaviors are extremely sophisticated, relying on the adaptive, plastic and event-driven network of sensory neurons. Such neuronal system analyzes multiple sensory cues efficiently to establish accurate depiction of the environment. Here, we develop a bimodal artificial sensory neuron to implement the sensory fusion processes. Such a bimodal artificial sensory neuron collects optic and pressure information from the photodetector and pressure sensors respectively, transmits the bimodal information through an ionic cable, and integrates them into post-synaptic currents by a synaptic transistor. The sensory neuron can be excited in multiple levels by synchronizing the two sensory cues, which enables the manipulating of skeletal myotubes and a robotic hand. Furthermore, enhanced recognition capability achieved on fused visual/haptic cues is confirmed by simulation of a multi-transparency pattern recognition task. Our biomimetic design has the potential to advance technologies in cyborg and neuromorphic systems by endowing them with supramodal perceptual capabilities.


Assuntos
Células Receptoras Sensoriais/fisiologia , Tato/fisiologia , Visão Ocular/fisiologia , Animais , Linhagem Celular , Eletrodos , Humanos , Camundongos , Movimento (Física) , Nanotubos de Carbono/química , Reconhecimento Automatizado de Padrão
14.
Plast Reconstr Surg ; 146(2): 156e-164e, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32740578

RESUMO

BACKGROUND: Scarpa fascia preservation during abdominoplasty has been shown to reduce complications associated with the traditional technique. As an extension of a previously published randomized controlled trial, this study aims to clarify whether preservation of Scarpa fascia during abdominoplasty has an influence on scar quality or sensibility recovery. METHODS: This was a single-center clinical trial, involving 160 patients randomly assigned to one of two surgical procedures: classic full abdominoplasty (group A) and abdominoplasty with preservation of Scarpa fascia (group B). Patients were later convoked to assess scar quality and abdominal cutaneous sensibility. Scar quality was evaluated through the Patient and Observer Scar Assessment Scale. Cutaneous sensibility was measured on the upper and lower abdomen, using light touch, Semmes-Weinstein testing (5.07/10-g monofilament), and a 25-gauge needle. RESULTS: A total of 99 patients (group A, 54 patients; group B, 45 patients) responded to contact, with a mean follow-up time of 44 months. Concerning scar quality, Patient and Observer Scar Assessment Scale scores were similar between groups. On the upper abdomen, there was a statistically significant difference between groups on cutaneous sensibility, on the examination with the Semmes-Weinstein 5.07/10-g monofilament (group A, 79.6 percent; group B, 93.3 percent; p = 0.046) and pain (group A, 90.7 percent; group B, 100 percent; p = 0.044). No statistically significant differences were found between groups on the lower abdomen. A considerable proportion of patients (two-thirds) still presented sensibility alterations in the subumbilical area 3½ years after abdominoplasty. CONCLUSION: Scarpa fascia preservation during abdominoplasty does not influence scar quality, but it improves sensibility recovery in the supraumbilical area. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.


Assuntos
Abdominoplastia/métodos , Cicatriz/diagnóstico , Tratamentos com Preservação do Órgão/métodos , Complicações Pós-Operatórias/diagnóstico , Tato/fisiologia , Parede Abdominal , Abdominoplastia/efeitos adversos , Adulto , Cicatriz/etiologia , Fáscia/inervação , Fasciotomia/efeitos adversos , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Índice de Gravidade de Doença , Pele/inervação , Resultado do Tratamento , Adulto Jovem
15.
PLoS One ; 15(7): e0233988, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32615583

RESUMO

Light touch with an earth-fixed reference point improves balance during quite standing. In our current study, we implemented a paradigm to assess the effects of disrupting the right posterior parietal cortex on dynamic stabilization of body sway with and without Light Touch after a graded, unpredictable mechanical perturbation. We hypothesized that the benefit of Light Touch would be amplified in the more dynamic context of an external perturbation, reducing body sway and muscle activations before, at and after a perturbation. Furthermore, we expected sway stabilization would be impaired following disruption of the right Posterior Parietal Cortex as a result of increased postural stiffness. Thirteen young adults stood blindfolded in Tandem-Romberg stance on a force plate and were required either to keep light fingertip contact to an earth-fixed reference point or to stand without fingertip contact. During every trial, a robotic arm pushed a participant's right shoulder in medio-lateral direction. The testing consisted of 4 blocks before TMS stimulation and 8 blocks after, which alternated between Light Touch and No Touch conditions. In summary, we found a strong effect of Light Touch, which resulted in improved stability following a perturbation. Light Touch decreased the immediate sway response, steady state sway following re-stabilization, as well as muscle activity of the Tibialis Anterior. Furthermore, we saw gradual decrease of muscle activity over time, which indicates an adaptive process following exposure to repetitive trials of perturbations. We were not able to confirm our hypothesis that disruption of the rPPC leads to increased postural stiffness. However, after disruption of the rPPC, muscle activity of the Tibialis Anterior is decreased more compared to sham. We conclude that rPPC disruption enhanced the intra-session adaptation to the disturbing effects of the perturbation.


Assuntos
Lobo Parietal/fisiologia , Equilíbrio Postural/fisiologia , Tato/fisiologia , Adulto , Mapeamento Encefálico , Retroalimentação Sensorial , Feminino , Humanos , Masculino , Contração Muscular , Neuronavegação , Pressão , Estresse Mecânico , Estimulação Magnética Transcraniana , Adulto Jovem
16.
PLoS One ; 15(7): e0234969, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32640003

RESUMO

Existing haptic feedback devices are limited in their capabilities and are often cumbersome and heavy. In addition, these devices are generic and do not adapt to the users' grasping behavior. Potentially, a human-oriented design process could generate an improved design. While current research done on human grasping was aimed at finding common properties within the research population, we investigated the dynamic patterns that make human grasping behavior distinct rather than generalized, i.e. subject specific. Experiments were conducted on 31 subjects who performed grasping tasks on five different objects. The kinematics and kinetics parameters were measured using a motion capture system and force sensors. The collected data was processed through a pipeline of dimensionality reduction and clustering algorithms. Using finger joint angles and reaction forces as our features, we were able to classify these tasks with over 95% success. In addition, we examined the effects of the objects' mechanical properties on those patterns and the significance of the different features for the differentiation. Our results suggest that grasping patterns are, indeed, subject-specific; this, in turn, could suggest that a device capable of providing personalized feedback can improve the user experience and, in turn, increase the usability in different applications. This paper explores an undiscussed aspect of human dynamic patterns. Furthermore, the collected data offer a valuable dataset of human grasping behavior, containing 1083 grasp instances with both kinetics and kinematics data.


Assuntos
Fenômenos Biomecânicos/fisiologia , Força da Mão/fisiologia , Tato/fisiologia , Adulto , Feminino , Mãos/fisiologia , Humanos , Individualidade , Masculino , Realidade Virtual
17.
PLoS One ; 15(7): e0235314, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645051

RESUMO

OBJECTIVES: 1) Determine the effects of old age on sensorimotor responses to a fatiguing work-like task. 2) Explore how old age influences the relationships between task fatigability, everyday perceptions of fatigability, and sensorimotor function. METHODS: Healthy young (N = 17, 9W) and older (N = 13, 10W) adults completed the Pittsburgh Fatigability Scale to assess everyday perceptions of physical (PF) and mental fatigability and performed a repetitive tapping task to fatigue. Before and after the task, grip strength was assessed using a hand-grip dynamometer and touch-pressure sensitivity was measured (shoulder, hand) using Semmes-Weinstein monofilaments. RESULTS: Older, but not young adults, had increased touch-pressure sensitivity at the shoulder after fatigue (interaction, p = 0.007). No changes in grip strength were observed (p>0.05). Task fatigability was not different between young and old adults (p>0.05). Having less task fatigability was associated with lower PF, higher grip strength, and higher touch-pressure sensitivity at the hand (ρ = 0.37-0.58, p<0.05), with the hand sensation association also observed in the old adult subgroup (ρ = 0.56, p = 0.046). CONCLUSIONS: With old age, there were fatigue-related alterations to sensory but not physical function. While task fatigability was associated with perceptual, physical, and sensory features, sensory features appear to have a more important role with old age.


Assuntos
Envelhecimento/fisiologia , Fadiga/fisiopatologia , Atividade Motora/fisiologia , Extremidade Superior/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Fadiga Mental/fisiopatologia , Pessoa de Meia-Idade , Percepção , Pressão , Estatísticas não Paramétricas , Análise e Desempenho de Tarefas , Tato/fisiologia , Adulto Jovem
18.
Nat Commun ; 11(1): 3341, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620746

RESUMO

The oculomotor system keeps the eyes steady in expectation of visual events. Here, recording microsaccades while people performed a tactile, frequency discrimination task enabled us to test whether the oculomotor system shows an analogous preparatory response for unrelated tactile events. We manipulated the temporal predictability of tactile targets using tactile cues, which preceded the target by either constant (high predictability) or variable (low predictability) time intervals. We find that microsaccades are inhibited prior to tactile targets and more so for constant than variable intervals, revealing a tight crossmodal link between tactile temporal expectation and oculomotor action. These findings portray oculomotor freezing as a marker of crossmodal temporal expectation. Moreover, microsaccades occurring around the tactile target presentation are associated with reduced task performance, suggesting that oculomotor freezing mitigates potential detrimental, concomitant effects of microsaccades and revealing a crossmodal coupling between tactile perception and oculomotor action.


Assuntos
Movimentos Oculares/fisiologia , Desempenho Psicomotor/fisiologia , Percepção do Tempo/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Músculos Oculomotores/inervação , Músculos Oculomotores/fisiologia , Estimulação Luminosa , Tempo de Reação/fisiologia , Movimentos Sacádicos/fisiologia , Adulto Jovem
19.
Nat Commun ; 11(1): 3342, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620835

RESUMO

Subdivisions of mouse whisker somatosensory thalamus project to cortex in a region-specific and layer-specific manner. However, a clear anatomical dissection of these pathways and their functional properties during whisker sensation is lacking. Here, we use anterograde trans-synaptic viral vectors to identify three specific thalamic subpopulations based on their connectivity with brainstem. The principal trigeminal nucleus innervates ventral posterior medial thalamus, which conveys whisker-selective tactile information to layer 4 primary somatosensory cortex that is highly sensitive to self-initiated movements. The spinal trigeminal nucleus innervates a rostral part of the posterior medial (POm) thalamus, signaling whisker-selective sensory information, as well as decision-related information during a goal-directed behavior, to layer 4 secondary somatosensory cortex. A caudal part of the POm, which apparently does not receive brainstem input, innervates layer 1 and 5A, responding with little whisker selectivity, but showing decision-related modulation. Our results suggest the existence of complementary segregated information streams to somatosensory cortices.


Assuntos
Córtex Cerebral/fisiologia , Vias Neurais/fisiologia , Córtex Somatossensorial/fisiologia , Tálamo/fisiologia , Tato/fisiologia , Vibrissas/fisiologia , Animais , Tronco Encefálico/citologia , Tronco Encefálico/fisiologia , Córtex Cerebral/citologia , Feminino , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/fisiologia , Córtex Somatossensorial/citologia , Transmissão Sináptica , Tálamo/citologia , Vibrissas/inervação
20.
Nat Commun ; 11(1): 2753, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32488078

RESUMO

Imbuing bio-inspired sensory devices with intelligent functions of human sensory organs has been limited by challenges in emulating the preprocessing abilities of sensory organs such as reception, filtering, adaptation, and sensory memory at the device level itself. Merkel cells, which is a part of tactile sensory organs, form synapse-like connections with afferent neuron terminals referred to as Merkel cell-neurite complexes. Here, inspired by structure and intelligent functions of Merkel cell-neurite complexes, we report a flexible, artificial, intrinsic-synaptic tactile sensory organ that mimics synapse-like connections using an organic synaptic transistor with ferroelectric nanocomposite gate dielectric of barium titanate nanoparticles and poly(vinylidene fluoride-trifluoroethylene). Modulation of the post-synaptic current of the device induced by ferroelectric dipole switching due to triboelectric-capacitive coupling under finger touch allowed reception and slow adaptation. Modulation of synaptic weight by varying the nanocomposite composition of gate dielectric layer enabled tuning of filtering and sensory memory functions.


Assuntos
Órgãos Artificiais , Células Receptoras Sensoriais/fisiologia , Tato/fisiologia , Técnicas Biossensoriais/instrumentação , Humanos , Aprendizagem/fisiologia , Memória/fisiologia , Células de Merkel , Neuritos , Sinapses/fisiologia , Percepção do Tato , Transistores Eletrônicos
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