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Ageing reduces persistent inward current contribution to motor neurone firing: Potential mechanisms and the role of exercise

Nervous system deterioration is a primary driver of age-related motor impairment. The motor neurones, which act as the interface between the central nervous system and the muscles, play a crucial role in amplifying excitatory synaptic input to produce the desired motor neuronal firing output. For this, they utilise their ability to generate persistent (long-lasting) depolarising currents that increase cell excitability, and both amplify and prolong the output activity of motor neurones for a given synaptic input. Modulation of these persistent inward currents (PICs) contributes to the motor neurones’ capacities to attain the required firing frequencies and rapidly modulate them to competently complete most tasks. Thus, PICs are crucial for adequate movement generation. Impairments in intrinsic motor neurone properties can impact motor unit firing capacity, with convincing evidence indicating that the PIC contribution to motor neurone firing is reduced in older adults. Indeed, this could be an important mechanism underpinning the age-related reductions in strength and physical function. Furthermore, resistance training has emerged as a promising intervention to counteract age-associated PIC impairments, with changes in PICs being correlated with improvements in muscular strength and physical function after training. In this review, we present the current knowledge of the PIC magnitude decline during ageing and discuss whether reduced serotonergic and noradrenergic input onto the motor neurones, voltage-gated calcium channel dysfunction or inhibitory input impairments are candidates that: (i) explain age-related reductions in the PIC contribution to motor neurone firing and (ii) underpin the enhanced PIC contribution to motor neurone firing following resistance training in older adults. (Figure presented.)

Sensoriamento remoto e geoprocessamento aplicados ao zoneamento geoambiental: bacia hidrográfica do Açude Camará - PB.

A diversidade de paisagens da bacia hidrográfica da barragem Camará, principalmente no que se refere às formas de relevo, de solos e de sistemas de produção, induziu a realização deste zoneamento geoambiental. Sua importância reside nas preocupações com a conservação do meio ambiente e com o desenvolvimento sócio-econômico e a preservação dos recursos naturais na área em busca do desenvolvimento sustentável. Este trabalho teve como objetivo criar um banco de dados atualizado e, com o zoneamento geoambiental, realizar uma análise simplifi cada dos atributos fi siográfi cos, solo, clima, relevo e uso da terra, separando e descrevendo unidades da paisagem, suas potencialidades e limitações. Foram utilizadas nesta pesquisa imagem do satélite CBERS e técnicas de geoprocessamento a partir do programa SPRING, bases para os trabalhos descritivos em campo. A partir das informações de solo, relevo e uso da terra foram descritas as áreas susceptíveis a degradação ambiental

Acute effects of three different stretching protocols on the Wingate test performance

The purpose of this study was to examine the acute effects of different stretching exercises on the performance of the traditional Wingate test (WT). Fifteen male participants performed five WT; one for familiarization (FT), and the remaining four after no stretching (NS), static stretching (SS), dynamic stretching (DS), and proprioceptive neuromuscular facilitation (PNF). Stretches were targeted for the hamstrings, quadriceps, and calf muscles. Peak power (PP), mean power (MP), and the time to reach PP (TP) were calculated. The MP was significantly lower when comparing the DS (7.7 ± 0.9 W/kg) to the PNF (7.3 ± 0.9 W/kg) condition (p \u3c 0.05). For PP, significant differences were observed between more comparisons, with PNF stretching providing the lowest result. A consistent increase of TP was observed after all stretching exercises when compared to NS. The results suggest the type of stretching, or no stretching, should be considered by those who seek higher performance and practice sports that use maximal anaerobic power

Facilitation–inhibition control of motor neuronal persistent inward currents in young and older adults

A well-coordinated facilitation–inhibition control of motor neuronal persistent inward currents (PICs) via diffuse neuromodulation and local inhibition is essential to ensure motor units discharge at required times and frequencies. Present best estimates indicate that PICs are reduced in older adults; however, it is not yet known whether PIC facilitation–inhibition control is also altered with ageing. We investigated the responses of PICs to (i) a remote handgrip contraction, which is believed to diffusely increase serotonergic input onto motor neurones, and (ii) tendon vibration of the antagonist muscle, which elicits reciprocal inhibition, in young and older adults. High-density surface electromyograms were collected from soleus and tibialis anterior of 18 young and 26 older adults during triangular-shaped plantar and dorsiflexion contractions to 20 % (handgrip experiments) and 30 % (vibration experiments) of maximum torque (rise-decline rate of 2 % / s). A paired-motor-unit analysis was used to calculate ∆F, which is assumed to be proportional to PIC strength. ΔF increased in both soleus (0.55 peaks per second (pps), 16.0 %) and tibialis anterior (0.42 pps, 11.4 %) after the handgrip contraction independent of age. Although antagonist tendon vibration reduced ΔF in soleus (0.28 pps, 12.6 %) independent of age, less reduction was observed in older (0.42 pps, 10.7 %) than young adults (0.72 pps, 17.8 %) in tibialis anterior. Our data indicate a preserved ability of older adults to amplify PICs following a remote handgrip contraction, during which increased serotonergic input onto the motor neurones is expected, in both lower leg muscles. However, PIC deactivation in response to reciprocal inhibition was impaired with ageing in tibialis anterior despite being preserved in soleus. (Figure presented.). Key points: Motor neuronal persistent inward currents (PICs) are facilitated via diffuse neuromodulation and deactivated by local inhibition to ensure motor units discharge at required times and frequencies, allowing normal motor behaviour. PIC amplitudes appear to be reduced with ageing; however, it is not known whether PIC facilitation–inhibition control is also altered. Remote handgrip contraction, which should diffusely increase serotonergic input onto motor neurones, facilitated PICs similarly in both soleus and tibialis anterior of young and older adults. Antagonist tendon vibration, which induces reciprocal inhibition, reduced PICs in soleus in both young and older adults but had less effect in tibialis anterior in older adults. Data from lower-threshold motor units during low-force contractions suggest that PIC facilitation is preserved with ageing in soleus and tibialis anterior. However, the effect of reciprocal inhibition on the contribution of PICs to motor neurone discharge seems reduced in tibialis anterior but preserved in soleus

Uso de imagem CBERS no zoneamento geoambiental em bacia hidrográfica do estado da Paraíba, Brasil.

This work aims at generating georeferred maps of the main landscape elements from the geoenvironmental mapping of the Camará hydrographic basin. The map was generated from the interpretation and digital processing of CBERS images using the SPRING/INPE software with RGB composition of bands 2, 3 and 4, and data obtained from field sampling. The results indicate that the greatest part of the hydrographic basin is composed by Regosols (45%) and Acrisols (36%) associated with Leptosols, Fluvisols, Cambisols, and Luvisols. Capoeira brushwood ? which is mistaken for pasture by automatic classification due to the fact that it is an abandoned, recovering area historically used for agriculture and pasture ? covers an area of almost 38%, whereas 13% of the total area are explored for banana and citrus crops, especially in humid regions. Pangola grass (Digitaria decumbens Stent), guinea grass (Panicum maximum Jacq. var. gongyloides Doell), and napier grass (Pennisetum purpureum Schum.) dominate pasture areas, and take up 27% of the total area. The geoenvironmental unit that presented high environmental vulnerability was Encosta São Tomé, which comprises 3.5% of the basin, due to the fact that 90% of this area presents a strongly undulate to mountainous landscape, and 80% of its soil is shallow or very shallow, whereas low environmental vulnerability was detected in areas with associations of deeper soils, such as Regosols and Acrisols, which present plain to mildly undulate landscape, which occurred in 5% of the total area

Infraestrutura Nacional de Dados Espaciais: Aspectos Computacionais.

O objetivo deste documento é apresentar os principais conceitos relacionados aos pilares ?tecnologia? e ?padrões?, com enfoque em seus aspectos computacionais. A intenção é sumarizar os fundamentos teóricos envolvidos na especificação da INDE e reunir as principais referências de softwares open source atualmente disponíveis e amplamente adotados pela comunidade para a implantação da INDE.bitstream/item/84963/1/COMUN-TECNICO-1-GESTAO-TERRITORIAL-Infraestrut-Nac-Dados-Espac-ed01-2013.pd

Metodologia de monitoramento de cobertura vegetal: estudo de caso no município de Goiânia, GO.

Este trabalho apresenta uma proposta para a análise da variação da cobertura vegetal, utilizando dados de acesso público. Os procedimentos de análise multitemporal propostos foram aplicados no município de Goiânia, GO, como estudo de caso. Aplicou-se o índice de vegetação por diferença normalizada (NDVI), obtido a partir de imagens Landsat-5, em três anos de referência: 1997, 2004, 2011. Consideraram-se três classes de cobertura: ?corpos d?água?, ?vegetação? e ?outros usos?. Foram utilizadas técnicas de processamento digital de imagens, visando à correção de erros gerados pela influência da atmosfera e à obtenção de uma melhor qualidade espectral dos alvos. Para esse fim, o modelo adotado foi o dark object subtraction (DOS). O resultado mostrou-se satisfatório, considerando-se a disponibilidade dos dados e suas limitações.bitstream/item/84894/1/0000010346-BPD-Cobert-vegetal.pd

Análise Morfométrica de Bacia Hidrográfica: Subsídio à Gestão Territorial Estudo de Caso no Alto e Médio Mamanguape.

Para esta análise, foram criados os mapas da drenagem e hipsométrico, levando em conta que o relevo é um dos aspectos mais importantes deste estudo, pois permite compreender a disposição da drenagem e tem aplicação direta para a gestão territorial. A análise da morfometria utilizou 17 índices morfométricos entre os mais de 50 existentes na literatura, dentre os quais podem-se destacar: fator de forma; índice de circularidade; coeficiente de compacidade; índice de rugosidade; padrão de drenagem; canais de drenagem; amplitude altimétrica; densidade de drenagem; textura topográfica; e coeficiente de manutenção. Com base na análise dos resultados, pode-se concluir que o fator de forma (0,44), o índice de circularidade (0,78), o coeficiente de compacidade (1,12) e o índice de rugosidade (0,72) demonstraram que a bacia hidrográfica em estudo exibe um formato alongado contribuindo, dessa forma, para o processo de escoamento e apresentando, portanto, baixa suscetibilidade à ocorrência de enchentes. Enfim, esses parâmetros podem ser utilizados para comparação entre os diversos tipos de áreas como microbacias, fazendas ou municípios, auxiliando, no monitoramento, análise e gestão territorial.bitstream/item/84896/1/0000010346-BPD-Analise-morfometrica.pd

GeoPAC: Sistema de Monitoramento de Obras do PAC.

O objetivo deste documento é descrever o sistema GeoPAC. São apresentados seu histórico de desenvolvimento, sua arquitetura de software, suas principais funcionalidades e alguns exemplos de análises de contexto territorial elaboradas pela Embrapa, a partir dos dados espaciais dos empreendimentos do PAC catalogados pelo sistema. O GeoPAC está disponível remotamente para o Ministério do Planejamento, Orçamento e Gestão (MPOG) e é fornece diversos parâmetros e indicadores utilizados no acompanhamento territorial dos empreendimentos do PAC.bitstream/item/98227/1/20140225-GeoPAC2.pd