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1.
Exp Brain Res ; 227(4): 477-86, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23625076

RESUMO

While the process of hand preshaping during grasping has been studied for over a decade, there is relatively little information regarding the organization of digit contact timing (DCT). This dearth of information may be due to the assumption that DCT while grasping exhibits few regularities or to the difficulty in obtaining information through traditional movement recording techniques. In this study, we employed a novel technique to determine the time of digit contacts with the target object at a high precision rate in normal healthy participants. Our results indicate that, under our task conditions, subjects tend to employ a radial to ulnar pattern of DCT which may be modulated by the shape of the target object. Moreover, a number of parameters, such as the total contact time, the frequency of first contacts by the thumb and index fingers and the number of simultaneous contacts, are affected by the relative complexity of the target object. Our data support the notion that a great deal of information about the object's physical features is obtained during the early moments of the grasp.


Assuntos
Dedos/fisiologia , Força da Mão/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
2.
Chaos ; 22(1): 013119, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22462995

RESUMO

Parkinson's disease is a degenerative condition whose severity is assessed by clinical observations of motor behaviors. These are performed by a neurological specialist through subjective ratings of a variety of movements including 10-s bouts of repetitive finger-tapping movements. We present here an algorithmic rating of these movements which may be beneficial for uniformly assessing the progression of the disease. Finger-tapping movements were digitally recorded from Parkinson's patients and controls, obtaining one time series for every 10 s bout. A nonlinear delay differential equation, whose structure was selected using a genetic algorithm, was fitted to each time series and its coefficients were used as a six-dimensional numerical descriptor. The algorithm was applied to time-series from two different groups of Parkinson's patients and controls. The algorithmic scores compared favorably with the unified Parkinson's disease rating scale scores, at least when the latter adequately matched with ratings from the Hoehn and Yahr scale. Moreover, when the two sets of mean scores for all patients are compared, there is a strong (r = 0.785) and significant (p<0.0015) correlation between them.


Assuntos
Diagnóstico por Computador/métodos , Dedos/fisiopatologia , Movimento , Oscilometria/métodos , Doença de Parkinson/diagnóstico , Doença de Parkinson/fisiopatologia , Exame Físico/métodos , Algoritmos , Humanos , Dinâmica não Linear
3.
Int J Neurosci ; 119(10): 1905-24, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19922392

RESUMO

Several studies have found that Parkinson's disease (PD) disrupts the organization of complex motor sequences regardless of the influence of parkinsonian medications. A clear candidate for the neural bases of such deficits, which we term "coordinative," is the failure to integrate propioceptive and visual information by cortico-striatal circuits in a timed fashion. Recent reports, however, have indicated that deep-brain stimulation of the subthalamic nucleus (STN DBS) may result in an improvement in coordinative deficits beyond the amelioration of "intensive deficits" such as bradykinesia and scaling errors. The present study examined the spatio-temporal organization underlying the shaping of the hand during reaching to grasp objects differing in shape. Six PD patients ON and OFF their STN DBS when OFF their concomitant medications and six age-matched controls participated in this study. STN DBS improved the coordination involved in preshaping the hand while grasping. We discuss these results in light of our earlier work with PD patients on and off dopamine replacement therapy.


Assuntos
Estimulação Encefálica Profunda/métodos , Doença de Parkinson/fisiopatologia , Doença de Parkinson/terapia , Desempenho Psicomotor/fisiologia , Núcleo Subtalâmico/fisiologia , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Fenômenos Biomecânicos , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Entrevista Psiquiátrica Padronizada , Tempo de Reação/fisiologia , Estatística como Assunto
4.
Behav Neurosci ; 115(6): 1257-72, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11770057

RESUMO

The activation of amygdaloid nuclei, the ventral perirhinal cortex (vPRh), and several other brain areas in the rat during the acquisition and expression of olfactory fear conditioning was assessed through Fos immunocytochemistry in 3 separate experiments. The results of Experiment 1 suggest that olfactory and somatosensory inputs may functionally converge in the anterior region ot the medial nucleus (aMe). The results of Experiment 2 indicate that the aMe exhibited significantly greater Fos-like immunoreactivity (FLI) in subjects acquiring conditioned stimulus-unconditioned stimulus associations than in those presented with the same olfactory and somatosensory stimuli in a manner that precluded acquisition. The results of Experiment 3 indicate that the vPRh appeared to exhibit learning-related increases in FLI during the expression of previously acquired associations. Collectively, these data suggest that the aMe and vPRh may be critically involved in different aspects of olfactory fear conditioning.


Assuntos
Tonsila do Cerebelo/fisiologia , Aprendizagem da Esquiva , Córtex Cerebral/fisiologia , Regulação da Expressão Gênica , Olfato , Animais , Medo , Genes fos , Imuno-Histoquímica , Masculino , Ratos , Ratos Sprague-Dawley
5.
Science ; 279(5359): 2115-8, 1998 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-9516114

RESUMO

The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.

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