Effort-related functions of nucleus accumbens dopamine and associated forebrain circuits

Background Over the last several years, it has become apparent that there are critical problems with the hypothesis that brain dopamine (DA) systems, particularly in the nucleus accumbens, directly mediate the rewarding or primary motivational characteristics of natural stimuli such as food. Hypotheses related to DA function are undergoing a substantial restructuring, such that the classic emphasis on hedonia and primary reward is giving way to diverse lines of research that focus on aspects of instrumental learning, reward prediction, incentive motivation, and behavioral activation. Objective The present review discusses dopaminergic involvement in behavioral activation and, in particular, emphasizes the effort-related functions of nucleus accumbens DA and associated forebrain circuitry. Results The effects of accumbens DA depletions on food-seeking behavior are critically dependent upon the work requirements of the task. Lever pressing schedules that have minimal work requirements are largely unaffected by accumbens DA depletions, whereas reinforcement schedules that have high work (e.g., ratio) requirements are substantially impaired by accumbens DA depletions. Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related decision making. Rats with accumbens DA depletions reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead, these rats select a less-effortful type of food-seeking behavior. Conclusions Along with prefrontal cortex and the amygdala, nucleus accumbens is a component of the brain circuitry regulating effort-related functions. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as energy-related disorders such as psychomotor slowing, fatigue, or anergia in depression

Indicadores ambientais para áreas de preservação permanente Environmental indicators for areas of permanent preservation

Apesar da conscientização pelas questões ambientais, existe uma crescente pressão sobre os recursos naturais. A análise do uso e da ocupação das terras é um ponto de partida para adequação do ambiente antrópico cuja capacidade de suporte é, portanto, fundamental para a criação de modelos de gestão. O trabalho trata de uma pesquisa que utiliza o geoprocessamento e a gestão de informações do uso e ocupação para estudos ambientais. O objetivo foi selecionar indicadores para gestão das Áreas de Preservação Permanente (APP) e aprimoramento do uso de informações para gestão ambiental. O estudo foi realizado na bacia hidrográfica do rio Jundiaí-Mirim, Jundiaí, SP; utilizaram-se os dados de um levantamento prévio das suas condições ambientais. A técnica empregada permitiu a seleção de oito indicadores que se mostraram capazes de caracterizar o estado das áreas avaliadas. Os resultados obtidos mostraram que somente 44,6% da APP se encontram em conformidade com a legislação.Despite awareness of environmental issues, there is a growing human pressure on natural resources. The analysis of the land use can be considered as a starting point for studies of anthropogenic environmental adjustment and it is essential to propose models of management with emphasis on land sustainability. The work consists of a research conducted on environmental studies, using GIS and information management of land use. The goal was to select environmental indicators for management of Permanent Preservation Areas (APP), where eight indicators were selected. The study was carried out in the Jundiaí-Mirim watershed, in the State of São Paulo, Brazil. The technique allowed the selection of eight indicators that were able to characterize the state of the evaluated areas. The results showed that only 44.6% of APP are in accordance with the law

Fístulas oroantrais: diagnóstico e propostas de tratamento Oroantral fistulas: diagnosis and management purposes

A comunicação buco-sinusal ou oro-antral é um dos acidentes mais comuns após extrações dentárias na região maxilar posterior, envolvendo principalmente o primeiro molar. O diagnostico é realizado através de métodos clínicos, radiográficos e endoscópico. O tratamento deve ser efetuado o mais precocemente possível, evitando-se a infecção do seio e instalação de uma sinusite maxilar. Nos casos da instalação prévia de uma sinusite, deve-se proceder ao tratamento da mesma antes do fechamento cirúrgico da fístula buco-sinusal. O propósito deste trabalho é relatar três casos clínicos de comunicação oro-antral bem como orientar os profissionais quanto ao diagnóstico e tratamento cirúrgico.<br>The oroantral communication is one of the accidents most common after dental extractions in posterior maxillary region, involving mainly the first molar. The diagnosis must be realized through radiographic and clinical methods (Valsalva's Maneuver) and the treatment must be effect early, avoiding infection of the sinus and installing itself maxillary sinusitis. The treatment of the previous maxillary sinusitis must be instituted before the oroantral fistula plastic closure. The purpose of the study was to report three clinical cases of oroantral communication, furthermore to direct the professionals to the diagnosis and surgical treatmen

Soil properties under Amazon forest and changes due to pasture installation in Rondônia, Brazil Soil properties under Amazon forest and changes due to pasture installation in Rondônia, Brazil

Scope of the journal The primary intention of the journal is to stimulate wide interdisciplinary cooperation and understanding among workers in the different fields of pedology. Therefore, the journal tries to bring together papers from the entiire field of soil research, rather than to emphasize any one subdiscipline. Interdisciplinary work should preferably be focused on occurrence and dynamic charactlerizatiorn in space and time of soils in the field. Publication information Geoderma . For 1996 volumes 69-74 are sclheduled for publication. Subscription prices are available upon request from the publisher. Subscriptions are accepted on a prepaid basis only ar;d are entered on a calendar year basis. Issues are sent by surface mail except to the following countries where air delivery via SAL is ensured: Argentina, Australia, Brazil, Canada, Hong Kong, India, Israel, Japan, Malaysia, Mexico, New Zealand, Pakistan, PR China, Singapore, South Africa, South Korea, Taiwan, Thailand, USA. For all other countries airmail rates are available upon request. Claims for missing issues must be made within six months of our publication Abstract We examined the consequences of deforestation and pasture establishment for soil chemical and physical properties and for soil organic matter content, in Rondônia, in the southwestem part of the Brazilian Amazon basin. Two chronosequences were selected. One chronosequence consisted of a forest and pasture established in 1989, 1987, 1983, 1979 and 1972. The main soil type in this area is the red yellow podzolic latosol (Kandiudult). The second chronosequence consisted of a forest site and pasture established in 1987, 1983, 1972 and 1911, and the main soil type is a red yellow podzolic soil (Paleudult, Tropudult). The first soil type is the most base-depleted soil and has a higher clay content than the second one. Despite the initial differences in clay and cations contents between the forest sites the total soil carbon content at 0-30 cm in both forest were circa 3.7 kg C m-*. After pasture installation soil bulk density were higher in the first 0-5 cm soil layer, mainly in one chronosequence but small changes were detected in deeper soil layers. Forest&apos;conversion to pasture caused appreciable increases in soil pH and exchangeable cation content, at least until nine years after pasture installation. pH levels were greater in the first chronosequence, with highest values (6.8 to 7.6) found in 3 and 5 years old pastures respectively. In the most base-depleted soil Ca content increased from 0.07 kg m-2 in the forest site to 0.25 kg m-2 in the 5 year old pasture. After normalization by clay content total soil carbon contents to 30 cm in the 20 year old pastures were 17 to 20% higher than in the original forest sites. Calculations of carbon derived from forest (Cdf) and from pasture (Cdp) using soil 6I3C values showed that Cdf decrease sharply in the first 9 years after pasture establishment in both chronosequences and reached stable values of 2.12 kg C m -2 and 2.02 kg C mb2 in chronosequences 1 and 2,, respectively. Soil carbon derived from pasture increased with time and represented 50% of total (1996) 63-81 soil carbon in the top 30 cm after 20 years of pasture. In general we observed that forest conversion to pasture is associated to a pattern of increasing of soil cations and pH levels for at least 5 years under pasture establishment. The removal of the original forest for pasture establishment resulted in an accumulation of carbon derived from pasture in the soil