Monkey in the middle: why non-human primates are needed to bridge the gap in resting-state investigations

Resting-state investigations based on the evaluation of intrinsic low-frequency fluctuations of the BOLD fMRI signal have been extensively utilized to map the structure and dynamics of large-scale functional network organization in humans. In addition to increasing our knowledge of normal brain connectivity, disruptions of the spontaneous hemodynamic fluctuations have been suggested as possible diagnostic indicators of neurological and psychiatric disease states. Though the non-invasive technique has been received with much acclamation, open questions remain regarding the origin, organization, phylogenesis, as well as the basis of disease-related alterations underlying the signal patterns. Experimental work utilizing animal models, including the use of neurophysiological recordings and pharmacological manipulations, therefore, represents a critical component in the understanding and successful application of resting-state analysis, as it affords a range of experimental manipulations not possible in human subjects. In this article, we review recent rodent and non-human primate studies and based on the examination of the homologous brain architecture propose the latter to be the best-suited model for exploring these unresolved resting-state concerns. Ongoing work examining the correspondence of functional and structural connectivity, state-dependency and the neuronal correlates of the hemodynamic oscillations are discussed. We then consider the potential experiments that will allow insight into different brain states and disease-related network disruptions that can extend the clinical applications of resting-state fMRI (RS-fMRI)

Evaluación biomédica de implantes dentales sometidos a cargas oblicuas: combinación de varias características geométricas

Objective: an efficient and simple methodology, based on virtual simulation and computer modelling, for the assessment and evaluation of dental implants design is proposed in this work. Materials and methods: the finite element method, a very common tool in engineering applications, is used for the evaluation the biomechanical performance of the biomedical devices. Von Mises stress is used as the main parameter to assess the suitability of the implant, when it is subjected to functional and biological loading. Also, this work reports the effects on the implant caused by geometrical variations such as length, diameter, thread, cortical bone thickness and abutment inclination. The useful-life of the implant was estimated by performing, in a virtual way, the fatigue tests required by the ISO:14801 standard. Results: for all the analyzed cases, maximum stress was obtained at the connecting screw under oblique loading. The estimated useful-life of the implant was around 5.000.000 cycles, which satisfies both ISO standard and functional requirements. Also, maximum stress was found in the compact-bone tissue surrounding the implant, which is in very good agreement with previous reports. Conclusion: a dental implant with optimal characteristics is proposed and validated using the discussed methodology.Peer ReviewedPostprint (published version

The History of Nuclidic Masses and of their Evaluation

This paper is centered on some historical aspects of nuclear masses, and their relations to major discoveries. Besides nuclear reactions and decays, the heart of mass measurements lies in mass spectrometry, the early history of which will be reviewed first. I shall then give a short history of the mass unit which has not always been defined as one twelfth of the carbon-12 mass. When combining inertial masses from mass spectrometry with energy differences obtained in reactions and decays, the conversion factor between the two is essential. The history of the evaluation of the nuclear masses (actually atomic masses) is only slightly younger than that of the mass measurements themselves. In their modern form, mass evaluations can be traced back to 1955. Prior to 1955, several tables were established, the oldest one in 1935.Comment: 17 pages, Contribution to the special issue of the International Journal of Mass Spectrometry (IJMS) in the honor of the 65th anniversary of Jurgen Kluge's birthda

Neural competition via lateral inhibition between decision processes and not a STOP signal accounts for the antisaccade performance in healthy and schizophrenia subjects

A commentary on Re-starting a neural race: anti-saccade correction by Noorani, I., and Carpenter, R. H. S. (2014). Eur. J. Neurosci. 39, 159–164. doi: 10.1111/ejn.12396 Decision making is the process of accumulating evidence about the world and the utility of possible outcomes (Cutsuridis, 2010). A paradigm often used by behavioral neuroscientists to investigate decision processes is the antisaccade paradigm (see Figure 1A; Hallett, 1978). In the antisaccade paradigm subjects are required to suppress an erroneous saccade (error prosaccade) toward a peripheral stimulus and instead make an eye movement to a position in the opposite hemifield (antisaccade). The response repertoire of a subject performing the antisaccade task has been reported to be: (1) the subject makes an erroneous response (i.e., looking toward the peripheral stimulus), (2) the subject makes the antisaccade (i.e., looking in the opposite direction of the peripheral stimulus, and (3) the subject makes an erroneous response followed by a corrected antisaccade (Evdokimidis et al., 2002)

A biophysical model of decision making in an antisaccade task through variable climbing activity

We present a biophysical model of saccade initiation based on competitive integration of planned and reactive cortical saccade decision signals in the intermediate layer of the superior colliculus. In the model, the variable slopes of the climbing activities of the input cortical decision signals are produced from variability in the conductances of Na+, K+, Ca2+ activated K+, NMDA and GABA currents. These cortical decision signals are integrated in the activities of buildup neurons in the intermediate layer of the superior colliculus, whose activities grow nonlinearly towards a preset criterion level. When the level is crossed, a movement is initiated. The resultant model reproduces the unimodal distributions of saccade reaction times (SRTs) for correct antisaccades and erroneous prosaccades as well as the variability of SRTs (ranging from 80ms to 600ms) and the overall 25% of erroneous prosaccade responses in a large sample of 2006 young men performing an antisaccade task

Tendências genéticas e fenotípicas para características produtivas e reprodutivas para fêmeas da raça Nelore.

Objetivou-se estimar as tendências genéticas e fenotípicas, utilizando Inferência Bayesiana, para um indicador de produtividade e para características reprodutiva e produtivas para fêmeas da raça Nelore. O arquivo de trabalho estava constituído de 3.029 registros de animais, filhas de 357 touros e 3.029 vacas. Foi adotado um modelo animal tetracaracterística, considerando como aleatórios os efeitos genéticos aditivos diretos e os residuais e como fixos o efeitos do ano de nascimento e do grupo de contemporâneos. As tendências genéticas diretas para o peso aos 365 e aos 550 dias de idade, para a idade da vaca ao parto e para o indicador de produtividade total, foram: 101,1 e 126,2 g/ano; -1,10 dias/ano e 116,2 g/bezerro desmamado/ano, respectivamente. As tendências fenotípicas foram desfavoráveis para todas as características avaliadas. As tendências genéticas obtidas para as características avaliadas indicam que a seleção realizada vem promovendo progresso genético; contudo, melhorias nas condições de ambiente devem ser implementadas, para que o genótipo dos indivíduos se expresse com maior eficiência

Estimação de parâmetros genéticos sob enfoque bayesiano para indicadores de produtividade na raça Nelore.

Objetivou-se com este trabalho estimar os componentes de variâncias, utilizando análise bayesiana multicaracterística, de um indicador de produtividade e de características produtivas e reprodutivas para fêmeas da raça Nelore. O arquivo estava constituído de 3.029 registros de animais, filhos de 357 touros e 3.029 vacas, nascidos no período de 1976 a 2001. Estimaram-se os parâmetros genéticos, sob enfoque Bayesiano, utilizando os programas REMUNF90 e GIBBS2F90, sob modelo animal tetra-característica que apresentava como aleatórios os efeitos genéticos aditivos diretos e os residuais e como fixos o efeitos do ano de nascimento e o efeito do grupo de contemporâneos. Observou-se que os valores pontuais para os coeficientes de herdabilidades apresentaram pequena variação em relação aos valores mínimos e máximos, seguindo a tendência das variâncias aditivas, sendo também evidenciadas graficamente. As magnitudes das estimativas de herdabilidade do efeito genético direto obtidas para o peso aos 365 e aos 550 dias de idade, para a idade ao primeiro parto e para o índice de produtividade total foram respectivamente: 0,48; 0,60; 0,37 e 0,24; sugerindo que parte considerável da variação existente entre os animais, para estas características, está sob influência de componente genético aditivo; deste modo, todas as características abordadas no presente trabalho, podem responder de forma satisfatória à seleção.Zootec 2010