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1.
Vasc Med ; 28(5): 387-396, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37249001

RESUMO

BACKGROUND: Inflammation and immune dysregulation have been associated with adverse outcomes in cardiovascular disease. There is limited understanding of the association of different profiles of white blood cell (WBC) subsets and red cell distribution width (RDW) in patients with chronic limb-threatening ischemia (CLTI). METHODS: Patients with CLTI undergoing endovascular revascularization in our single-center, tertiary care hospital from 2017 to 2019, who had a preceding complete blood count (CBC) with WBC differentials (n =213), were included in the analysis. Patient characteristics, laboratory values, and clinical outcomes were collected. Cox proportional hazards regression models were used to assess for associations between all-cause mortality and leukocyte subset; multivariate analysis was used to account for confounders. Kaplan-Meier curves were generated to depict survival censored at 1 year postrevascularization using baseline CBC indices. RESULTS: Adjusting for confounders, elevated RDW was associated with increased mortality (continuous per % increase, adjusted hazard ratio [HR] 1.33, p < 0.001). Baseline lymphopenia was associated with mortality in univariate analysis. Other leukocyte subtypes were not associated with mortality outcomes in our population. Exploratory analysis showed negative deflections in ∆WBC from pre- to postprocedure day 1 were affiliated with increased mortality when adjusted for age, sex, race, chronic kidney disease, and baseline hemoglobin (∆WBC HR 1.16, p = 0.004). Further exploratory analysis showed an association between RDW and all-comers readmission. CONCLUSIONS: The utilization of a periprocedural WBC subset differential can be a useful adjunct to risk-stratify patients with CLTI undergoing endovascular revascularization. Further studies are needed to understand potential ways to modulate immune dysregulation so as to improve mortality outcomes.


Assuntos
Procedimentos Endovasculares , Doença Arterial Periférica , Humanos , Isquemia Crônica Crítica de Membro , Fatores de Risco , Procedimentos Endovasculares/efeitos adversos , Salvamento de Membro , Doença Arterial Periférica/diagnóstico , Doença Arterial Periférica/cirurgia , Resultado do Tratamento , Isquemia/diagnóstico , Isquemia/cirurgia , Doença Crônica , Estudos Retrospectivos
2.
J Neurosci ; 43(22): 4033-4046, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37142429

RESUMO

Dexterous object manipulation depends critically on information about forces normal and tangential to the fingerpads, and also on torque associated with object orientation at grip surfaces. We investigated how torque information is encoded by human tactile afferents in the fingerpads and compared them to 97 afferents recorded in monkeys (n = 3; 2 females) in our previous study. Human data included slowly-adapting Type-II (SA-II) afferents, which are absent in the glabrous skin of monkeys. Torques of different magnitudes (3.5-7.5 mNm) were applied in clockwise and anticlockwise directions to a standard central site on the fingerpads of 34 human subjects (19 females). Torques were superimposed on a 2, 3, or 4 N background normal force. Unitary recordings were made from fast-adapting Type-I (FA-I, n = 39), and slowly-adapting Type-I (SA-I, n = 31) and Type-II (SA-II, n = 13) afferents supplying the fingerpads via microelectrodes inserted into the median nerve. All three afferent types encoded torque magnitude and direction, with torque sensitivity being higher with smaller normal forces. SA-I afferent responses to static torque were inferior to dynamic stimuli in humans, while in monkeys the opposite was true. In humans this might be compensated by the addition of sustained SA-II afferent input, and their capacity to increase or decrease firing rates with direction of rotation. We conclude that the discrimination capacity of individual afferents of each type was inferior in humans than monkeys which could be because of differences in fingertip tissue compliance and skin friction.SIGNIFICANCE STATEMENT We investigated how individual human tactile nerve fibers encode rotational forces (torques) and compared them to their monkey counterparts. Human hands, but not monkey hands, are innervated by a tactile neuron type (SA-II afferents) specialized to encode directional skin strain yet, so far, torque encoding has only been studied in monkeys. We find that human SA-I afferents were generally less sensitive and less able to discriminate torque magnitude and direction than their monkey counterparts, especially during the static phase of torque loading. However, this shortfall in humans could be compensated by SA-II afferent input. This indicates that variation in afferent types might complement each other signaling different stimulus features possibly providing computational advantage to discriminate stimuli.


Assuntos
Dedos , Tato , Feminino , Humanos , Torque , Tato/fisiologia , Dedos/fisiologia , Pele/inervação , Mãos , Mecanorreceptores/fisiologia , Neurônios Aferentes/fisiologia
3.
Europace ; 25(4): 1441-1450, 2023 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-36794441

RESUMO

AIMS: Patients who undergo permanent pacemaker (PPM) implantation after transcatheter aortic valve replacement (TAVR) have a worse outcome. The aim of this study was to identify risk factors of worse outcomes in patients with post-TAVR PPM implantation. METHODS AND RESULTS: This is a single-centre, retrospective study of consecutive patients who underwent post-TAVR PPM implantation from 11 March 2011 to 9 November 2019. Clinical outcomes were evaluated by landmark analysis with cut-off at 1 year after the PPM implantation. Of the 1389 patients underwent TAVR during the study duration and a total of 110 patients were included in the final analysis. Right ventricular pacing burden (RVPB) ≥ 30% at 1 year was associated with a higher likelihood of heart failure (HF) readmission [adjusted hazard ratio (aHR): 6.333; 95% confidence interval [CI]: 1.417-28.311; P = 0.016] and composite endpoint of overall death and/or HF (aHR: 2.453; 95% CI: 1.040-5.786; P = 0.040). The RVPB ≥30% at 1 year was associated with higher atrial fibrillation burden (24.1 ± 40.6% vs. 1.2 ± 5.3%; P = 0.013) and a decrease in left ventricular ejection fraction (-5.0 ± 9.8% vs. + 1.1 ± 7.9%; P = 0.005). The predicting factors of the RVPB ≥30% at 1 year were the presence of RVPB ≥40% at 1 month and the valve implantation depth measured from non-coronary cusp ≥4.0 mm (aHR: 57.808; 95% CI: 12.489-267.584; P < 0.001 and aHR: 6.817; 95% CI: 1.829-25.402; P = 0.004). CONCLUSIONS: The RVPB ≥30% at 1 year was associated with worse outcomes. Clinical benefit of minimal RV pacing algorithms and biventricular pacing needs to be investigated.


Assuntos
Estenose da Valva Aórtica , Marca-Passo Artificial , Substituição da Valva Aórtica Transcateter , Humanos , Substituição da Valva Aórtica Transcateter/efeitos adversos , Estimulação Cardíaca Artificial/efeitos adversos , Estudos Retrospectivos , Volume Sistólico , Resultado do Tratamento , Estenose da Valva Aórtica/cirurgia , Função Ventricular Esquerda , Fatores de Risco , Valva Aórtica/cirurgia
4.
Am. j. cardiol ; 15(175): 80-87, July. 2022.
Artigo em Inglês | CONASS, Sec. Est. Saúde SP, SESSP-IDPCPROD, Sec. Est. Saúde SP | ID: biblio-1377949

RESUMO

ABSTRACT Previous studies reported that new-onset persistent left bundle branch block (NOP-LBBB) was related to worse outcomes after transcatheter aortic valve implantation (TAVI). However, these results can be confounded by the presence of permanent pacemaker (PPM) implantation before and after TAVI. Long-term outcomes and the risk stratification of NOP-LBBB not having PPM implantation before and after TAVI have not been fully investigated. This is an international, multicenter, retrospective study of patients who underwent TAVI from July 31, 2007, to May 8, 2020. A total of 2,240 patients were included, and 17.5% of patients developed NOP-LBBB. NOP-LBBB was associated with cardiac mortality (adjusted hazard ratio [aHR] 1.419, 95% confidence interval [CI] 1.014 to 1.985, p = 0.041) and the composite outcomes of cardiac mortality and/or heart failure readmission (aHR 1.313, 95% CI 1.027 to 1.678, p = 0.030). Patients who developed NOP-LBBB with pre-TAVI left ventricular ejection fraction (LVEF) <40% were significantly associated with cardiac mortality (aHR 2.049, 95% CI 1.039 to 4.041, p = 0.038), heart failure (aHR 3.990, 95% CI 2.362 to 6.741, p <0.001), and the composite outcome (aHR 2.729, 95% CI 1.703 to 4.374, p <0.001). Although NOP-LBBB with pre-TAVI LVEF >40% had a significant decrease in LVEF 6 to 12 months after TAVI (-1.8 ± 9.7% vs +0.6 ± 8.1%, p = 0.003), NOP-LBBB with pre-TAVI LVEF <40% had a significant increase in LVEF 6 to 12 months after TAVI (+9.7 ± 13.6% vs +13.0 ± 11.7%, p = 0.157). In conclusion, patients with NOP-LBBB without pre-TAVI and post-TAVI PPM developed significantly worse long-term outcomes, especially in patients with pre-TAVI LVEF <40%. Further prospective investigation should be undertaken.


Assuntos
Bloqueio de Ramo , Substituição da Valva Aórtica Transcateter , Insuficiência Cardíaca
5.
Am J Cardiol ; 175: 80-87, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35597627

RESUMO

Previous studies reported that new-onset persistent left bundle branch block (NOP-LBBB) was related to worse outcomes after transcatheter aortic valve implantation (TAVI). However, these results can be confounded by the presence of permanent pacemaker (PPM) implantation before and after TAVI. Long-term outcomes and the risk stratification of NOP-LBBB not having PPM implantation before and after TAVI have not been fully investigated. This is an international, multicenter, retrospective study of patients who underwent TAVI from July 31, 2007, to May 8, 2020. A total of 2,240 patients were included, and 17.5% of patients developed NOP-LBBB. NOP-LBBB was associated with cardiac mortality (adjusted hazard ratio [aHR] 1.419, 95% confidence interval [CI] 1.014 to 1.985, p = 0.041) and the composite outcomes of cardiac mortality and/or heart failure readmission (aHR 1.313, 95% CI 1.027 to 1.678, p = 0.030). Patients who developed NOP-LBBB with pre-TAVI left ventricular ejection fraction (LVEF) <40% were significantly associated with cardiac mortality (aHR 2.049, 95% CI 1.039 to 4.041, p = 0.038), heart failure (aHR 3.990, 95% CI 2.362 to 6.741, p <0.001), and the composite outcome (aHR 2.729, 95% CI 1.703 to 4.374, p <0.001). Although NOP-LBBB with pre-TAVI LVEF >40% had a significant decrease in LVEF 6 to 12 months after TAVI (-1.8 ± 9.7% vs +0.6 ± 8.1%, p = 0.003), NOP-LBBB with pre-TAVI LVEF <40% had a significant increase in LVEF 6 to 12 months after TAVI (+9.7 ± 13.6% vs +13.0 ± 11.7%, p = 0.157). In conclusion, patients with NOP-LBBB without pre-TAVI and post-TAVI PPM developed significantly worse long-term outcomes, especially in patients with pre-TAVI LVEF <40%. Further prospective investigation should be undertaken.


Assuntos
Estenose da Valva Aórtica , Insuficiência Cardíaca , Marca-Passo Artificial , Substituição da Valva Aórtica Transcateter , Valva Aórtica/cirurgia , Bloqueio de Ramo/epidemiologia , Bloqueio de Ramo/etiologia , Bloqueio de Ramo/terapia , Insuficiência Cardíaca/epidemiologia , Humanos , Estudos Retrospectivos , Medição de Risco/métodos , Volume Sistólico , Substituição da Valva Aórtica Transcateter/efeitos adversos , Resultado do Tratamento , Função Ventricular Esquerda
6.
Prog Cardiovasc Dis ; 70: 16-21, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34756951

RESUMO

Exercise intolerance with dyspnea and fatigue is pervasive amongst individuals with heart failure (HF) due to both central and peripheral mechanisms. Cardiac rehabilitation (CR) is a cornerstone therapy for numerous cardiovascular disease (CVD) processes, and it's use in HF with reduced ejection fraction (HFrEF) has shown significant benefit in improved mortality and quality of life (QoL). Less is known about the benefit of CR in the setting of HF with preserved ejection fraction (HFpEF), and optimal exercise therapy (ET) may vary based on underlying disease phenotype. Here we offer review of existing data for ET in both HFrEF and HFpEF with proposed exercise treatment modalities based on underlying comorbidities and variable phenotypes.


Assuntos
Reabilitação Cardíaca , Insuficiência Cardíaca , Exercício Físico , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Humanos , Fenótipo , Qualidade de Vida , Volume Sistólico
7.
Patient Prefer Adherence ; 15: 1639-1646, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34345165

RESUMO

BACKGROUND: Adherence to recommended medications is a key issue in the care of patients with cardiovascular disease (CVD) and barriers to adherence are well established during the medication adherence cascade, the processes of prescribing, obtaining, taking, and maintaining medication use. Aspirin avoids many of the barriers in the medication adherence cascade as it does not require a prescription (prescribing) and is inexpensive, easily accessible (obtaining), prescribed once-daily (taking) as an over-the-counter medication and is generally perceived by patients as safe (maintaining). The purpose of this paper is to report aspirin adherence and propose the Medication Adherence Cascade Tool to assist clinicians to consider all aspects of medication adherence. METHODS: Adherence to aspirin was monitored with an electronic pillbox. Frequency analysis, independent T-tests, and ANOVA were completed on 151 patients with underlying heart failure who were prescribed aspirin within a larger parent study. Chi-square tests were completed to assess differences in baseline demographic characteristics. FINDINGS: Mean aspirin adherence was 82.2% overall, with 11.9% of sample with adherence 50%, 18.5% with adherence 50-80%, and 69.5% with adherence ≥80%. Greater adherence was observed in self-identified White as compared to Black patients (84.47% vs 73.53%; p = 0.014), and patients ≥70 years of age compared to <70 years (87.00% vs 77.49%; p = 0.009). INTERPRETATION: Aspirin adherence was suboptimal despite the fact that it addresses most of the barriers on the medication adherence cascade (ie, relatively easy access, low cost, and low risk). A Medication Adherence Cascade Tool (MACT) is proposed as a clinical guide to facilitate patient-provider co-production of strategies to address medication adherence. The tool can assist patients and providers to co-produce adherence to achieve optimal medication benefits.

8.
SAGE Open Med Case Rep ; 9: 2050313X211025922, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34178356

RESUMO

Fibromuscular dysplasia is an uncommon non-inflammatory arteriopathy. Hormonal factors are believed to play a role in disease pathogenesis given the overwhelming female predominance of this disease. We describe a case of a 56-year-old transgender man on prolonged testosterone therapy diagnosed with renal fibromuscular dysplasia after presenting with hypertensive urgency.

9.
J Card Surg ; 36(1): 392-395, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33225482

RESUMO

Ventricular septal ruptures are an uncommon complication following acute myocardial infarction. Operative repair, utilizing a patch for closure of the defect, is the primary treatment modality to achieve hemodynamic stability. The use of an extracellular matrix derived from small intestinal submucosa as a scaffold for tissue repair is becoming increasingly common. Here, we present the case of a 58-year-old female found to have a ventricular septal rupture and posterior left ventricular aneurysm following late presentation after a myocardial infarction that required operative repair with a CorMatrix patch. Upon readmission for dyspnea and poor exercise tolerance several months later, the patch was subsequently found to have near-completely reabsorbed. There is a paucity of long-term outcomes data following the use of CorMatrix for septal defects, with rare reports of such reabsorption. Further study is required to identify the incidence and implications of such findings.


Assuntos
Aneurisma Cardíaco , Comunicação Interventricular , Defeitos dos Septos Cardíacos , Infarto do Miocárdio , Ruptura do Septo Ventricular , Feminino , Comunicação Interventricular/etiologia , Comunicação Interventricular/cirurgia , Humanos , Pessoa de Meia-Idade
10.
Am J Med ; 133(8): e448, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32741455
11.
JACC Clin Electrophysiol ; 6(3): 295-303, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32192680

RESUMO

OBJECTIVES: The aim of this study was to develop and validate a risk prediction model for high-grade atrioventricular block requiring cardiac implantable electronic device (CIED) implantation after transcatheter aortic valve replacement (TAVR). BACKGROUND: High-grade atrioventricular block requiring CIED remains a significant sequelae following TAVR. Although several pre-operative characteristics have been associated with the risk of post-operative CIED implantation, an accurate and validated risk prediction model is not established yet. METHODS: This was a single center, retrospective study of consecutive patients who underwent TAVR from March 10, 2011, to October 8, 2018. This cohort sample was randomly divided into a derivation cohort (group A) and a validation cohort (group B). A scoring system for risk prediction of post-TAVR CIED implantation was devised using logistic regression estimates in group A and the calibration and validation were done in group B. RESULTS: A total of 1,071 patients underwent TAVR during the study period. After excluding pre-existing CIED, a total of 888 cases were analyzed (group A: 507 and group B: 381). Independent predictive variables were as follows: self-expanding valve (1 point), hypertension (1 point), pre-existing first-degree atrioventricular block (1 point), and right bundle branch block (2 points). The resulting score was calculated from the total points. The internal validation in group B showed an ideal linear relationship in calibration plot (R2 = 0.933) and a good predictive accuracy (area under the curve: 0.693; 95% confidence interval: 0.627 to 0.759). CONCLUSIONS: This prediction model accurately predicts post-operative risk of CIED implantation with simple pre-operative parameters.


Assuntos
Bloqueio Atrioventricular/cirurgia , Estimulação Cardíaca Artificial/estatística & dados numéricos , Marca-Passo Artificial/estatística & dados numéricos , Substituição da Valva Aórtica Transcateter , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Estudos Retrospectivos , Medição de Risco , Substituição da Valva Aórtica Transcateter/efeitos adversos , Substituição da Valva Aórtica Transcateter/métodos , Substituição da Valva Aórtica Transcateter/estatística & dados numéricos
12.
Sleep ; 39(2): 393-404, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26564126

RESUMO

STUDY OBJECTIVES: This study tested the hypothesis that Regulators of G protein Signaling (RGS) proteins contribute to the regulation of wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep, and to sleep disruption caused by volatile anesthetics. METHODS: The three groups used in this study included wild-type (WT; n = 7) mice and knock-in mice that were heterozygous (+/GS; n = 7) or homozygous (GS/GS; n = 7) for an RGS-insensitive allele that causes prolonged Gαi2 signaling. Mice were implanted with electrodes for recording sleep and conditioned for 1 week or more to sleep in the laboratory. Using within and between groups designs, 24-h recordings of wakefulness, NREM sleep, and REM sleep were compared across three interventions: (1) baseline (control) and after 3 h of being anesthetized with (2) isoflurane or (3) sevoflurane. RESULTS: Baseline recordings during the light phase revealed that relative to WT mice, homozygous RGS-insensitive (GS/GS) mice exhibit significantly increased wakefulness and decreased NREM and REM sleep. During the dark phase, these state-specific differences remained significant but reversed direction of change. After cessation of isoflurane and sevoflurane anesthesia there was a long-lasting and significant disruption of sleep and wakefulness. The durations of average episodes of wakefulness, NREM sleep, and REM sleep were significantly altered as a function of genotype and isoflurane and sevoflurane anesthesia. CONCLUSIONS: RGS proteins and Gαi2 play a significant role in regulating states of wakefulness, NREM sleep, and REM sleep. Genotype-specific differences demonstrate that RGS proteins modulate sleep disruption caused by isoflurane and sevoflurane anesthesia. The results also support the conclusion that isoflurane and sevoflurane anesthesia do not satisfy the homeostatic drive for sleep.


Assuntos
Anestesia , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/metabolismo , Isoflurano/farmacologia , Éteres Metílicos/farmacologia , Proteínas RGS/metabolismo , Sono/efeitos dos fármacos , Sono/fisiologia , Vigília/efeitos dos fármacos , Vigília/fisiologia , Animais , Eletrodos Implantados , Eletroencefalografia , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/genética , Homeostase/efeitos dos fármacos , Masculino , Camundongos , Sevoflurano , Sono REM/efeitos dos fármacos , Sono REM/fisiologia
13.
J Physiol ; 588(Pt 7): 1057-72, 2010 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-20142274

RESUMO

Torsional loads are ubiquitous during everyday dextrous manipulations. We examined how information about torque is provided to the sensorimotor control system by populations of tactile afferents. Torsional loads of different magnitudes were applied in clockwise and anticlockwise directions to a standard central site on the fingertip. Three different background levels of contact (grip) force were used. The median nerve was exposed in anaesthetized monkeys and single unit responses recorded from 66 slowly adapting type-I (SA-I) and 31 fast adapting type-I (FA-I) afferents innervating the distal segments of the fingertips. Most afferents were excited by torque but some were suppressed. Responses of the majority of both afferent types were scaled by torque magnitude applied in one or other direction, with the majority of FA-I afferent responses and about half of SA-I afferent responses scaled in both directions. Torque direction affected responses in both afferent types, but more so for the SA-I afferents. Latencies of the first spike in FA-I afferent responses depended on the parameters of the torque. We used a Parzen window classifier to assess the capacity of the SA-I and FA-I afferent populations to discriminate, concurrently and in real-time, the three stimulus parameters, namely background normal force, torque magnitude and direction. Despite the potentially confounding interactions between stimulus parameters, both the SA-I and the FA-I populations could extract torque magnitude accurately. The FA-I afferents signalled torque magnitude earlier than did the SA-I afferents, but torque direction was extracted more rapidly and more accurately by the SA-I afferent population.


Assuntos
Axônios/fisiologia , Dedos/fisiologia , Torque , Tato/fisiologia , Adaptação Fisiológica , Vias Aferentes/fisiologia , Animais , Potenciais Somatossensoriais Evocados/fisiologia , Dedos/inervação , Força da Mão/fisiologia , Macaca nemestrina , Nervo Mediano , Desempenho Psicomotor
14.
Annu Rev Neurosci ; 27: 53-77, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15217326

RESUMO

For humans to manipulate an object successfully, the motor control system must have accurate information about parameters such as the shape of the stimulus, its position of contact on the skin, and the magnitude and direction of contact force. The same information is required for perception during haptic exploration of an object. Much of these data are relayed by the mechanoreceptive afferents innervating the glabrous skin of the digits. Single afferent responses are modulated by all the relevant stimulus parameters. Thus, only in complete population reconstructions is it clear how each of the parameters can be signaled to the brain independently when many are changing simultaneously, as occurs in most normal movements or haptic exploration. Modeling population responses reveals how resolution is affected by neural noise and intrinsic properties of the population such as the pattern and density of innervation and the covariance of response variability.


Assuntos
Potenciais de Ação/fisiologia , Mecanorreceptores/fisiologia , Mecanotransdução Celular/fisiologia , Neurônios Aferentes/fisiologia , Tato/fisiologia , Animais , Mãos/inervação , Mãos/fisiologia , Força da Mão/fisiologia , Humanos , Pele/inervação
15.
J Neurosci ; 24(13): 3394-401, 2004 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-15056719

RESUMO

When humans manipulate objects, the sensorimotor system coordinates three-dimensional forces to optimize and maintain grasp stability. To do this, the CNS requires precise information about the magnitude and direction of load force (tangential to skin surface) plus feedback about grip force (normal to skin). Previous studies have shown that there is rapid, precise coordination between grip and load forces that deteriorates with digital nerve block. Obviously, mechanoreceptive afferents innervating fingerpad skin contribute essential information. We quantify human capacity to scale tangential and normal forces using only cutaneous information. Our paradigm simulated natural manipulations (a force tangential to the skin superimposed on an indenting force normal to the skin). Precisely controlled forces were applied by a custom-built stimulator to an immobilized fingerpad. Using magnitude estimation, subjects (n = 8) scaled the magnitude of tangential force (0.25-2.8 N) in two experiments (normal force, 2.5 and 4 N, respectively). Performance was unaffected by normal force magnitude and tangential force direction. Moreover, when both normal (2-4 N) and tangential forces were varied in a randomized-block factorial design, the relationship between applied and perceived tangential force remained near linear, with a minor but statistically significant nonlinearity. Our subjects could also discriminate small differences in tangential force, and this was the case for two different reference stimuli. In both cases, the Weber fraction was 0.16. Finally, scaling functions for magnitude estimates of normal force (1-5 N) were also approximately linear. These data show that the cutaneous afferents provide a wealth of precise information about both normal and tangential force.


Assuntos
Discriminação Psicológica/fisiologia , Dedos/fisiologia , Força da Mão/fisiologia , Mecanorreceptores/fisiologia , Tato/fisiologia , Adulto , Dedos/inervação , Humanos , Estimulação Física/instrumentação , Estimulação Física/métodos , Pressão , Estresse Mecânico , Torque
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