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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Produção de mudas de seringueira em viveiro suspenso / Production of rubber tree seedlings in suspended nursery

Karla Borelli 22 January 2016 (has links)
Dentre os métodos utilizados na propagação vegetativa de espécies florestais, a enxertia por borbulhia é a mais empregada para a seringueira (Hevea brasiliensis). Nesse sistema de produção de mudas, os porta-enxertos são formados diretamente no solo ou em sacos de polietileno preenchidos com solo. Embora essa seja uma prática comum nos viveiros, mudanças nos parâmetros legais foram propostas a fim de alterar o sistema de produção de mudas, principalmente no que diz respeito ao cultivo dos porta-enxertos. Para atender essas alterações, objetivou-se desenvolver um protocolo de produção de mudas de seringueira em bancadas suspensas. Para isso, foram conduzidos dois experimentos (descritos no cap. II e III) em Piracicaba - SP. No capítulo II, propõe-se a produção de hastes verdes em minijardim clonal hidropônico com leito de areia. Doses crescentes de nutrientes via fertirrigação foram testadas. Avaliou-se a produtividade do minijardim em função da fertirrigação e o aproveitamento das hastes verdes para a enxertia. Os resultados obtidos, mostraram que a fertirrigação afetou a produção de hastes verdes de seringueira em condições de minijardim clonal, sendo 1,5 mS cm-1 a condutividade elétrica ideal da solução nutritiva para produção de hastes verdes nesse sistema. Mesmo sob sistema hidropônico em casa de vegetação, forte sazonalidade da produção foi observada. As melhores estações do ano para coletar hastes verdes aptas às enxertias por borbulhia e garfagem foram à primavera e o verão. Nesse período recomenda-se elevar a condutividade elétrica da solução para 2,0 mS cm-1. Para o experimento descrito no capítulo III, porta-enxertos foram produzidos em viveiro suspenso, utilizando substrato comercial. Diferentes métodos de enxertia foram testados (borbulhia, garfagem em fenda cheia e fenda lateral) em porta-enxerto com diferentes diâmetros. Os enxertos utilizados foram obtidos no experimento do cap. II. Obteve-se sucesso com a enxertia por borbulhia e a enxertia por garfagem em fenda cheia, sendo possível verificar redução no tempo de produção de mudas de seringueira em condições de viveiro suspenso. No entanto, é necessário ajustes para obter maior sobrevivência das enxertias sob essas condições. / Among methods used for the vegetative propagation of forest species, budding is the most used for rubber tree (Hevea brasiliensis). In this system the rootstocks are produced directly on the soil or in polyethylene bags using soil as substrate. Although this is a common practice in the commercial nurseries, changes in the law were proposed for the planting material production system, particularly in the production of rootstocks. To meet these changes, this work aimed to develop a protocol for the production of rubber tree in suspended benches. There conducted two trials (chapter II and chapter III) in suspended bed in Piracicaba - SP. In chapter II was proposed the production of green scions in hydroponic clonal mini garden in function of fertigation. The mini garden yield was accessed by green scions productions and fertigation. It was found that the fertigation affected the production of green scion of rubber tree under clonal mini garden conditions. The electric conductivity of 1.5 mS cm-1 was the best solution for this system. Even in the hydroponic clonal mini garden in a greenhouse, a strong seasonality of growth was found. The best season to produce green scions in this system was summer and spring. In these seasons it is recommend using the EC of solution of 2.0 mS cm-1. In the experiment described in the chapter III, the rootstocks were produced in suspended benches, using a commercial substrate. Different methods of grafting were tested (budding, grafting in full and lateral cleft) in rootstocks of different diameters. The scions used were obtained in the experiment of chapter II. Success was obtained with the budding and grafting in full cleft, being possible to reduce the period for rubber tree production under suspended benches conditions. Adjustments are needed to get increased grafting survival under these conditions.
42

Análise de imagens no desenvolvimento e status de fósforo do minitomateiro grape cultivado em sistema semi-hidropônico / Image analysis of the development and phosphorus status of the mini tomato grown in a semi-hydroponic system

Leonardo Pinto de Magalhães 29 October 2018 (has links)
A análise de imagens é uma das formas de avaliar o desenvolvimento das plantas, tanto para correlacionar aspectos biofísicos dos mesmos, como para a detecção de doenças. Através das imagens podem ser calculados índices vegetativos que se correlacionem com os teores de nutrientes nas folhas. Com essa perspectiva, o presente trabalho objetivou avaliar quais indices vegetativos melhor se correlacionariam com a taxa de fósforo nas folhas de tomateiros. Foi realizado o cultivo de uma cultivar de minitomate, com cinco doses de fósforo (0, 25, 50, 75 e 100%) do P recomendado (na formulação da solução nutritiva). Em diferentes etapas do desenvolvimento da planta foram coletadas amostras das folhas para obtenção das imagens, através de escâner e máquina fotográfica, e diagnose foliar. Foram determinadas as biorrespostas das plantas ao longo do tempo. Uma rede neural artificial foi desenvolvida para estimar os teores de fósforo foliares no minitomate grape. A análise do desenvolvimento da planta permitiu concluir que a dose 100% de P2O5 utilizada no experimento foi suficiente para suprir a demanda nutricional do minitomateiro. Aos 64 dias após o transplantio (DAT) foi observada a maior queda nos teores de fósforo nas folhas, coincidindo com o amadurecimento dos frutos. Propõe-se, para a cultivar estudada, que a dignose foliar seja feita aos 50 DAT. Os índices vegetativos obtidos pela análise de imagem e selecionados pela análise de componentes principais (ICVE e Bn, tanto da parte abaxial quanto adaxial) podem ser utilizados para estimar a diagnose foliar de P na cultivar de minitomate grape. A avaliação dos índices vegetativos indicou que a obtenção de imagens com o escâner é mais adequado do que com a câmera fotográfica. Para a cultivar estudada, verificou-se que na dosagem de 100% de P2O5 teor de P nas folhas fica abaixo de 4,0 g kg-1. Em relação à rede neural desenvolvida, ao categorizar os valores de P de acordo com a literatura, a mesma obteve uma taxa de acerto de 90%. / The analysis of images is one of the ways to evaluate the development of plants, both to correlate biophysical aspects of the same, as for the detection of diseases. Through the images can be calculated vegetative indexes that correlate with the contents of nutrients in the leaves. With this perspective, the present studied aimed to evaluate which vegetative indexes would best correlate with the phosphorus rate in tomato leaves. A minitomato grape cultivar with five phosphorus doses (0, 25, 50, 75 and 100%) of the recommended P (in the formulation of the nutrient solution) was carried out. At different stages of plant development, leaf samples were collected to obtain the images, with scanner and camera, and foliar diagnosis. The bio-responses of plants were determined over time. An artificial neural network was developed to estimate leaf phosphorus levels in the grape minitomate. The analysis of the development of the plant allowed to conclude that the dose 100% of P2O5 used in the experiment was enough to supply the nutritional demand of the minitomateiro. At 64 days after transplanting (DAT), the highest drop in phosphorus content in the leaves was observed, coinciding with the ripening of the fruits. It is proposed, for the studied cultivar, that the leaf dignity should be made at 50 DAT. The vegetative indexes obtained by the image analysis and selected by the principal components analysis (ICVE and Bn, both abaxial and adaxial) can be used to estimate the leaf diagnosis of P in the minitomate grape cultivar. The evaluation of vegetative indexes indicated that obtaining images with the scanner is more appropriate than with the photographic camera. For the cultivar studied, it was verified that in the dosage of 100% of P2O5 content of P in the leaves is below 4.0 g kg-1. In relation to the developed neural network, when categorizing the P values according to the literature, it obtained a 90% correctness rate.
43

Análise do desenvolvimento vegetativo e produtividade da palmeira pupunha (Bactris gasipaes Kunth) sob níveis de irrigação e adubação nitrogenada. / Vegetative development and production of palm peach (Bactris gasipaes Kunth) under levels of irrigation and n fertilizer.

Ramos, Adriana 25 October 2002 (has links)
O presente trabalho tem como objetivo avaliar o efeito da aplicação de lâminas de irrigação com níveis de adubação nitrogenada no desenvolvimento vegetativo, produtividade de palmito e na distribuição espacial do sistema radicular da pupunheira. O experimento foi conduzido dos 12 aos 34 meses após o plantio (abril/2000 a fevereiro/2002), período este que corresponde à fase de maior crescimento da cultura, no campo experimental de Irrigação e Drenagem, da Fazenda Areão da Escola Superior de Agricultura "Luiz de Queiroz" - ESALQ/USP, localizada no município de Piracicaba - S.P. à latitude de 22° 42'30"S e longitude de 47° 30'00"W. O delineamento empregado foi em blocos casualizados, com os tratamentos distribuídos em esquema fatorial 3 x 4. Os tratamentos referentes às lâminas de irrigação foram L1, L2, L3 e L4 equivalentes a 0, 50%, 100% e 120% da evapotranspiraçõo de referência determinada em função do Tanque Classe A. Os níveis de nitrogênio aplicados foram N1, N2 e N3 correspondentes a 0, 200 kg ha -1 ano -1 e 400 kg ha -1 ano -1 de N, aplicado sob a forma de nitrato de potássio, nitrato de cálcio e uréia. Foram realizadas fertirrigações semanais, pelo emprego de uma bomba injetora de diafragma. Já, as avaliações do desenvolvimento vegetativo foram feitas pelas medidas de algumas variáveis de crescimento e produtividade. A distribuição espacial do sistema radicular foi determinada pelos métodos: direto, com abertura de trincheiras e digitalização de imagens e indireto, em que a área potencial de absorção das raízes foi estimada em função da variação de umidade entre dias subseqüentes. Houve efeito significativo dos tratamentos (irrigação e adubação) para todos os parâmetros de crescimento e de produção de palmito, em grande parte dos períodos avaliados. Os tratamentos com déficit hídrico (L2) e sem irrigação (L1) apresentaram os menores crescimentos nos parâmetros avaliados acarretando uma redução de 18% a 27% na produção total de palmito. Apesar de não ter ocorrido diferenças estatísticas entre os tratamentos L3 e L4, os maiores crescimentos e produtividades foram obtidas em L3 (100% ETo). Para nitrogênio, N2 e N3 também não diferiram estatisticamente entre si, entretanto, maiores respostas foram obtidas em N2 (200 kg ha -1 ano -1 ). Portanto, levando-se em conta o crescimento da planta e os custos de aplicação de lâminas e fertilizantes, os resultados indicam que a irrigação com 100% ETo e adubação com 200 kg de N ha -1 ano -1 são as recomendadas para a pupunheira cultivada em condições agroclimatológicas semelhantes à região do presente estudo. As regressões para as lâminas de irrigação apresentaram efeitos lineares significativos para todas as variáveis analisadas, com exceção do número de perfilhos, vindo confirmar o alto consumo de água da cultura e a importância da irrigação quando cultivada em áreas com déficit hídrico. Para o nitrogênio, com exceção dos parâmetros relacionados à produção de palmito, todos os demais apresentaram efeitos lineares das regressões, ressaltando a importância do nitrogênio no desenvolvimento vegetativo da pupunheira. Todos os tratamentos (lâminas) aplicados resultaram em uma distribuição radicular (área e comprimento) bastante superficial, variando de 97,8%, 92%, 86,7% e 97,8% de raízes distribuídas até a profundidade de 0,40 m. / Peach palm (Bactris gasipaes Kunth) plants were subjected to different irrigation and N fertilizer treatments in an experiment field conducted at the Irrigation and Drainage Area (22° 42'30"S and 47° 30"00"W) of Areão Agricultural Experiment Area, ESALQ/USP, Piracicaba, SP, Brazil. The principal aim was to study the growth, development and yield of peach palm in the first plant yield cycle (April 2000 to February 2002), and also the spatial distribution of the root system. The irrigation (0%, 50%, 100% and 120% of ETo) and N fertilizer (0kg.ha -1 .year -1 , 200kg.ha -1 .year -1 and 400kg.ha -1 .year -1 ) treatments were grouped in randomized blocks resulting in a 3x4 factorial experiment. The water and N were applied through the use of a diaphragm-activated injection pump in a weekly basis. Plant parameters (as LAI obtained by the use of LAI 2000) were measured monthly to accompany the plant growth and development and the spatial distribution of the root system was evaluated by the use of a direct method (measuring by image analysis of the length and area of roots exposed by digging a soil-trench within the crop) and an indirect one (recording the moisture level differences between subsequent days). Significative differences among treatments were found in almost the total duration of the experiment. The water deficit treatments (0% and 50% of ETo) showed the lowest values of all parameters resulting in yield losses of 18% to 27%. On the other hand, the 100% of ETo treatment exhibited the highest ones, although the 120% of ETo treatment did not differ statistically from the former. Also, the 200kgN.ha -1 .year -1 and 400kgN.ha -1 .year -1 treatments did not differ statistically, showing the 200kgN.ha -1 .year -1 treatment the highest values. All parameters except offshoot number increased linearly with increasing water and except yield with increasing N. The root system in all treatments concentrated in the shallow layers of the soil with 97,8%, 92%, 86,7% and 97,8% of roots distributed until 40 cm depth.
44

Cacaueiro : propagação por estacas caulinares e plantio no semi-árido do Estado da Bahia /

Leite, José Basílio Vieira. January 2006 (has links)
Orientador: Antonio Baldo Geraldo Martins / Banca: Carlos Ruggiero / Banca: João Carlos de Oliveira / Banca: João Alexio Scarpare Filho / Banca: Celio Kersul do Sacramento / Resumo: Foram estudadas a propagação de estacas caulinares de cacaueiro (Theobroma cacao L.) e o plantio de cacaueiro no semi-árido do estado da Bahia. Os resultados permitiram concluir que há interação entre clone e época de coleta de estaca, sendo janeiro e fevereiro os melhores meses. O plantio foi realizado em março de 2003, sob sombreamento provisório de bananeira, da variedade prata anã nos mesmos espaçamentos utilizados para o cacaueiro. Foi realizada irrigação por gotejamento e fertirrigação. As demais técnicas de manejo foram adaptadas levando em consideração as características edafoclimáticas da região. As avaliações foram realizadas a cada três meses, considerando as variáveis: altura e diâmetro das plantas, taxa de crescimento, floração, lançamentos foliares e frutificação. Dos resultados encontrados destacam-se o crescimento, vigor e início da frutificação com 1,5 ano, produção de 90 kg de amêndoas secas ha-1 aos 21 meses, com destaque para o clone PH 16 com 110 kg de amêndoas secas ha-1. A floração ocorreu de forma "gregária" em períodos trimestrais. Não foi observado efeito negativo da umidade relativa do ar e da temperatura no crescimento, polinização e frutificação do cacaueiro. / Abstract: Propagation of rooted cutting of cocoa (Theobroma cacao L.) and planting in the semi-arid of the state of Bahia were studied. The results permit to conclude that there is an interaction between clones and cuttings harvest period, being January and February the best months. Planting was done on March 2003 under temporary shade of prata anã (dwarf silver) banana variety at the same planting spacing used with cocoa. Water was provided by a drip irrigation system and nutrients by fertirrigation. The other management practices were adapted considering the region edaphoclimatic conditions. The evaluations were quarterly measuring: plant height and diameter, flowering, flushing and fruiting. Of the found results is worth noting the growth, vigor, average production of 90 kg ha-1 of dry beans at 21 months, with remark to PH 16 with 110 kg ha-1 of dry beans. Flowering occurred in a "gregarious" form in quarterly periods. It was not observed negative effects of air relative humidity and temperature on growth, pollination and fruiting of the cocoa plant. / Doutor
45

Acúmulo de graus-dia e duração do ciclo para cultivares de trigo em diferentes épocas de semeadura / Growing degree-day sum and crop growth cycle duration for wheat cultivars at different sowing dates

Noreto, Lorena Maia 12 March 2013 (has links)
Made available in DSpace on 2017-07-10T17:36:49Z (GMT). No. of bitstreams: 1 2013_Lorena_Maia_Noreto.pdf: 1204258 bytes, checksum: 13d5a3e9e5a92c9d8ebf5436c3142a61 (MD5) Previous issue date: 2013-03-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this study was to determine the growing degree-days sum and the relationship between the period length from sowing to physiological maturity and sowing dates of thirteen wheat cultivars, in the Palotina PR and Cascavel - PR. The data on wheat crop were colected by the Cooperativa Central de Pesquisa Agrícola (COODETEC) and correspond to the harvests of 2006 to 2011. The treatments consisted of 13 wheat cultivars, 3 sowing dates for Cascavel and 4 sowing dates for Palotina. The data used for the analysis were: Total elapsed days from sowing to the silking and to physiological maturity, and of the silking to physiological maturity, along with the growing degree-days sum for these periods, beyond grains yield and hectoliter weight. The results indicate that the average length of sowing to silking was 64 days for Palotina and 71 days for Cascavel. For the period from silking to physiological maturity the average length was 56 days for Palotina and 54 days for Cascavel. The increase in length of time from sowing to silking in cultivars sowed in May 25th (JD 145) was due to the decrease in air temperature. The average of growing degree-days sum between the period from sowing to physiological maturity was 1487, for both locations. The cultivars that stood out presenting a shorter period of silking to physiological maturity and high productivity were the cultivars CD 114, CD 120 and CD 124 for Palotina and CD 114, CD 120, CD 121, CD 122, CD 124 and Onix for Cascavel / O trabalho teve como objetivo determinar o acúmulo de graus-dia e a relação entre a duração do período da semeadura a maturação fisiológica e as datas de semeadura de treze cultivares de trigo, nos municípios de Palotina - PR e Cascavel PR. Os dados referentes a cultura do trigo foram cedidos pela Cooperativa Central de Pesquisa Agrícola (COODETEC) correspondente as safras agrícolas de 2006 a 2011. Os tratamentos foram constituídos de 13 cultivares de trigo, 3 datas de semeadura para Cascavel e 4 datas de semeadura para Palotina. Os dados utilizados para a análise foram: totais de dias transcorridos da semeadura ao espigamento e a maturação fisiológica e do espigamento a maturação fisiológica, juntamente com o acúmulo de graus-dia para estes períodos, além do rendimento de grãos e peso hectolitro. Os resultados indicam que a duração média do período da semeadura ao espigamento foi de 64 dias para Palotina e 71 dias para Cascavel. Para o período do espigamento a maturação fisiológica a duração média foi de 56 dias para Palotina e 54 dias para Cascavel. O aumento na duração do período da semeadura ao espigamento para cultivares semeados em 25 de Maio (DJ 145) ocorreu em virtude da diminuição da temperatura do ar. O acúmulo médio de graus-dia entre o período da semeadura a maturação fisiológica foi de 1487 para as duas localidades. Os cultivares que destacaram-se, apresentando um menor período do espigamento a maturação fisiológica e com boa produtividade foram os cultivares CD 114, CD 120 e CD 124 para Palotina e CD 114, CD 120, CD 121, CD 122, CD 124 e Onix para Cascavel
46

Latex of <em>Sciadopitys verticillata</em> (Thunb.) Siebold and Zuccarini: Antibiotic Properties, Phytochemistry, and Inhibition of Adventitious Rooting of Stem Cuttings.

Yates, David Ira 15 August 2006 (has links)
Sciadopitys verticillata was subjected to three propagation treatments designed to inhibit coagulation of its latex-like sap at the cut ends of the stem cuttings. Twenty-four hour soaking in water prior to rooting hormone application significantly enhanced production of adventitious roots. Old wood stem cuttings from shade-grown trees rooted at higher proportions than stem cuttings collected from sun-grown trees. Height, age, and place of origin of the source trees were not important factors in successful rooting. Antibacterial activity against some human pathogens and soil bacterial species was detected in latex application trials but the antibiotic activity was not related to the bacterial Gram reaction. The latex-like sap inhibited none of four plant pathogens tested. A suspension of the water insoluble latex-like sap of S. verticillata had a pH of 5.8. Antibacterial activity of S. verticillata sap was heat stable, which indicates the activity was not protein-based.
47

Estimating the capture efficiency of a vegetative environmental buffer using Lidar

Willis, William Brandon 01 May 2016 (has links)
Particulate matter expelled from tunnel-ventilated animal feeding operations (AFOs) is known to transport malodorous compounds. As a mitigation strategy, vegetative environmental buffers (VEBs) are often installed surrounding AFOs in order to capture particulates and induce lofting and dispersion. Many farmers are or are interested in implementing VEBs, yet research supporting their efficacy remains sparse. Currently, point measurements, often combined with models, are the primary means by which emission rates from AFOs and VEB performance has been investigated. The existing techniques lack spatial resolution and fail to assign the observed particulate reduction to capture, lofting, or dispersion. In recent years, lidar has emerged as a suitable partner to point measurements in agricultural research. Lidar is regarded for its ability to capture entire plume extents in near real time. Here, a technique is presented for estimating the capture efficiency of a VEB using lidar. An experiment was conducted in which dust was released upwind of a VEB at a known rate, and the emission rate downwind of the VEB was estimated using an elastic scanning lidar. Instantaneous lidar scans showed periodic lofting well above the VEB, but when scans were averaged over several hours, the plumes appeared Gaussian. The experiment revealed a capture efficiency ranging from 21-74β, depending on the time of day. The methodology presented herein addresses deficiencies in the existing techniques discussed above, and the results presented add to the lacking body of research documenting VEB capture efficiency.
48

Incorporating Vegetative Diversity Measures in Forest- Level Planning: A Case Study on the Utah State University School Forest

Holland, David N. 01 May 1994 (has links)
Three indices of forest stand structural and compositional diversity were incorporated into a linear programming, timber-harvest scheduling model to examine the tradeoffs between managing stands for timber production and biodiversity objectives. While harvest-level objectives were fairly compatible with the maintenance of biodiversity, present net worth maximization resulted in substantial reductions in all three measures of biodiversity.
49

Altération et récupération de la conscience chez les patients cérébro-lésés : Une approche comportementale, électrophysiologique et par neuro-imagerie fonctionnelle

Schnakers, Caroline 30 April 2008 (has links)
Les états de conscience altérée représentent un réel problème au niveau social, économique et éthique et constituent un défi au niveau diagnostique et thérapeutique. Nos résultats ont permis de montrer que lutilisation dune échelle comportementale standardisée reste indispensable pour éviter lerreur diagnostique et que la Coma Recovery Scale-Revised (Giacino et al, 2004) réprésente loutil diagnostique le plus efficace pour détecter des signes de conscience et donc, distinguer les patients végétatifs des patients en état de conscience minimale. Nos résultats suggérent également que lutilisation de paradigmes actifs électrophysiologiques permet dévaluer les capacités cognitives résiduelles de patients sévèrement cérébro-lésés et de détecter une activité cérébrale consciente, même en présence, au niveau de lévaluation comportementale, de comportements peu complexes tels quune fixation et/ou une poursuite visuelle. Enfin, au niveau du traitement, nous avons pu démontrer, à laide de limagerie fonctionnelle, lefficacité de lamantadine sur la récupération de la conscience chez un patient anoxique chronique en état de conscience minimale. Ainsi, nous pensons que lutilisation combinée de techniques comportementales et de techniques objectives telles que lélectrophysiologie et la neuro-imagerie est primordiale et permettra à lavenir, dune part, de clarifier ce quest un comportement conscient et donc, de mieux caractériser les états de conscience altérée et, dautre part, dinvestiguer lefficacité de thérapeutiques invasives ou non et donc, de mieux traiter les patients sévèrement cérébro-lésés récupérant du coma.
50

ÉVALUATION DE LA PERCEPTION CONSCIENTE CHEZ DES PATIENTS NON COMMUNICATIFS :Approche comportementale et par neuroimagerie

Vanhaudenhuyse, Audrey 11 May 2010 (has links)
RÉSUMÉ Suite à un accident cérébral grave, quil soit traumatique ou hypoxique-ischémique, les patients peuvent évoluer dun coma (patient non-éveillable et inconscient) vers un état végétatif (patient éveillé mais inconscient), un état de conscience minimale (patient éveillé et conscient, mais non-communiquant), ou un locked-in syndrome (patient éveillé, conscient, mais ne pouvant exprimer cette conscience que par le biais de mouvements oculaires) (Vanhaudenhuyse et al., 2009a). Notre but est de mettre au point des techniques permettant de détecter des signes de conscience chez ces patients incapables de communiquer, que ce soit par des évaluations comportementales, lélectroencéphalographie ou la neuroimagerie. Etudes comportementales : Actuellement, malgré les nouveaux critères de conscience proposés par Giacino et al. en 2002, nous avons pu démontrer que jusquà 40% des patients étaient diagnostiqués comme étant en état végétatif, alors quils étaient en réalité en état de conscience minimale (Schnakers, Vanhaudenhuyse et al., 2009b). Nos travaux ont mis en évidence que labsence doutil dévaluation de la conscience standardisé pouvait expliquer la difficulté à détecter des signes de conscience. Nous avons démontré que la poursuite visuelle, qui est un des premiers signes de conscience réapparaissant chez les patients récupérant de létat végétatif, était significativement mieux détectée lorsquelle était évaluée à laide dun miroir (Vanhaudenhuyse et al., 2008c). Labsence de consensus sur la signification de certains comportements, en termes de conscience, peut également être à la source de problèmes diagnostiques. Nous avons, par exemple, démontré que le clignement à la menace visuelle, comportement ambigu de conscience, était compatible avec le diagnostic détat végétatif et quil navait pas de valeur pronostique de récupération de conscience (Vanhaudenhuyse et al., 2008a). Marqueurs électrophysiologiques : Distinguer un comportement volontaire dun comportement réflexe reste difficile, ce qui nous pousse à étudier dautres techniques permettant dobtenir des marqueurs objectifs de conscience. Nous avons souligné lintérêt des potentiels évoqués de courte latence comme marqueurs dun mauvais pronostic, ainsi que des potentiels évoqués cognitifs pour évaluer la récupération dune conscience et les fonctions cognitives résiduelles des patients en coma et post-coma (Vanhaudenhuyse et al., 2008b). Neuroimagerie fonctionnelle et structurelle : Par lImagerie par Résonance Magnétique fonctionnelle (IRMf), nous avons pu mettre au point différents paradigmes daide au diagnostic détat de conscience altérée de ces patients. Létude du réseau du mode par défaut, cest-à-dire de lensemble des régions cérébrales activées lorsque nous sommes au repos et éveillés (précunéus, cortex mésio-frontal, jonctions temporo-pariétales), nous a permis de développer un outil facile à appliquer en routine clinique. Nous avons mis en évidence une corrélation négative non-linéaire entre la connectivité au sein du réseau du mode par défaut et le degré de conscience des patients (coma, état végétatif, état de conscience minimale et locked-in syndrome Vanhaudenhuyse et al., 2010b). Par ailleurs, en collaboration avec léquipe du MRC Cognition and Brain Sciences Unit de Cambridge, nous avons appliqué des paradigmes actifs en IRMf, durant lesquels 54 patients devaient réaliser activement des tâches cognitives (simaginer jouer au tennis, simaginer visiter sa maison). Sur 23 patients diagnostiqués comme étant en état végétatif, 4 dentre eux (17%) étaient capables de moduler volontairement leur activité neuronale (Monti & Vanhaudenhuyse et al., 2010). De plus, ce paradigme a permis à un de ces patients, chez qui aucune communication nétait possible, de répondre à laide dun code oui (imaginez jouer au tennis) / non (imaginez visiter votre maison) à des questions autobiographiques. Cependant, ce type de méthode est difficilement utilisable au quotidien. Dès lors, nous développons des interfaces cerveau-ordinateur transportables grâce au projet européen WF7 DECODER. Une de ces techniques de communication a pu être proposée par la modulation du pH salivaire chez un sujet sain (Vanhaudenhuyse et al., 2007a). Enfin, dans le cadre détudes multicentriques dirigées par le Pr. Louis Puybasset (Hôpital de la Pitié-Salpétrière, Paris), nous avons mis en évidence lintérêt diagnostique et pronostique de séquences telles que limagerie par tenseur de diffusion et la spectroscopie (Tshibanda & Vanhaudenhuyse et al., 2009 ; 2010). Au terme de ce travail, nous proposons des perspectives de nouvelles études à entreprendre afin daméliorer les évaluations comportementales, mais aussi les paradigmes dacquisition en IRM et en EEG que nous avons à notre disposition. Notre projet est de développer des recherches translationnelles validées pour une application clinique individuelle. Nous espérons que cette approche multimodale permettra daméliorer la prise en charge des patients sévèrement cérébrolésés qui sont toujours un véritable défi pour le corps médical, mais aussi daccroître nos connaissances sur la conscience humaine. SUMMARY Survivors of severe traumatic or hypoxic-ischemic brain damage classically go through different clinical entities such as coma (unarousable unconsciousness), vegetative state (characterized by wakefulness without awareness), minimally conscious state (minimal but definite evidence of awareness without communication) or locked-in syndrome (fully aware but unable to move or speak) (Vanhaudenhuyse et al., 2009a). Our goal is to improve and develop methods to detect consciousness in these non-communicative patients by using bedside behavioral examinations and para-clinical electroencephalography or neuroimaging techniques. Behavioral examination: Bedside assessment is one of the main methods used to detect awareness in severely brain injured patients recovering from coma. However, our prospective multicentric study showed that up to 40% of patients may be diagnosed as vegetative while they are in reality in a minimally conscious state (Schnakers, Vanhaudenhuyse et al., 2009b). The failure to use standardized behavioral assessment tools and the absence of consensus about some clinical behaviors could explain the difficulty to identify signs of consciousness. For example, we showed that clinicians should use a mirror when evaluating visual pursuit, a behavior that is one of the first differentiating minimally conscious from vegetative patients (Vanhaudenhuyse et al., 2008c). Similarly, the blinking to visual threat remains an ambiguous clinical sign of consciousness. We showed that this behavior may be a common clinical feature of the vegetative state and that its presence does not necessarily herald consciousness nor recovery of consciousness in patients with severe brain injury (Vanhaudenhuyse et al., 2008a). Electrophysiological markers: EEG methods offer objective assessment procedures and the possibility to determine whether an unresponsive patient is aware without explicit verbal or motor response. While early evoked-potentials are good prognosticators of bad outcome, cognitive evoked-potentials appear to be good predictors of favourable outcome and may be helpful to estimate the residual cognitive functions of comatose and post-comatose patients (Vanhaudenhuyse et al., 2008b). Functional and structural neuroimaging: By using functional Magnetic Resonance Imaging (fMRI), we first studied the brain spontaneous activity and next used it to identify signs of consciousness and communication in these patients. Studies of default mode network in fMRI, i.e. brain regions encompassing precuneus, medial prefrontal cortex and temporo-parietal junctions which are more active at rest, are easy to perform and could have a potentially broader and faster translation into clinical practice. We showed a negative non-linear correlation between default mode network connectivity and the level of consciousness of brain-damaged patients (ranging from coma, vegetative state, minimally conscious state to locked-in syndrome Vanhaudenhuyse et al., 2010b). In collaboration with the MRC Cognition and Brain Sciences Unit in Cambridge, we applied active paradigms in fMRI (in which patients were asked to imagine playing tennis and visiting their house) in 54 patients. We showed that out of 23 vegetative patients, 4 (17%) were able to voluntary modulate their neuronal brain activity. Moreover, one of these patients, who was not able to behaviorally communicate, showed the ability to apply the imagery technique in order to answer accurately simple yes (imagine playing tennis) / no (imagine visiting your house) questions (Monti & Vanhaudenhuyse et al., 2010). However, this technique will not be useful in the daily life of these patients. Thus, we developed appropriate brain computer interfaces with our European partners of the WF7 DECODER project. For example, we showed that one of these methods could be the mental manipulation of salivary pH as a form of non-motor mediated communication (Vanhaudenhuyse et al., 2007a). Finally, international multi-centric studies leaded by Pr. Louis Puybasset (Pitié-Salpétrière Hospital, Paris) are validating the diagnostic and prognostic interests of MRI sequences such as diffusion tensor and spectroscopy imaging to evaluate the prognosis of recovery of severely brain injured patients (Tshibanda & Vanhaudenhuyse et al., 2009 ; 2010). Future ongoing studies are continuing to improve our actual behavioral assessments, MRI and EEG measurements in disorders of consciousness. Our project is to validate translational research models that can be applied at the individual patient level. We hope that our multimodal and multidisciplinary approach will improve our medical care for brain-damaged patients suffering from disorders of consciousness and additionally shed some light to our understanding of the neural correlates of human consciousness.

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