Transcranial Magnetic Stimulation for the treatment of tinnitus: Effects on cortical excitability

<p>Abstract</p> <p>Background</p> <p>Low frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an innovative treatment for chronic tinnitus. The aim of the present study was to elucidate the underlying mechanism and to evaluate the relationship between clinical outcome and changes in cortical excitability. We investigated ten patients with chronic tinnitus who participated in a sham-controlled crossover treatment trial. Magnetic-resonance-imaging and positron-emission-tomography guided 1 Hz rTMS were performed over the auditory cortex on 5 consecutive days. Active and sham treatments were separated by one week. Parameters of cortical excitability (motor thresholds, intracortical inhibition, intracortical facilitation, cortical silent period) were measured serially before and after rTMS treatment by using single- and paired-pulse transcranial magnetic stimulation. Clinical improvement was assessed with a standardized tinnitus-questionnaire.</p> <p>Results</p> <p>We noted a significant interaction between treatment response and changes in motor cortex excitability during active rTMS. Specifically, clinical improvement was associated with an increase in intracortical inhibition, intracortical facilitation and a prolongation of the cortical silent period. These results indicate that intraindividual changes in cortical excitability may serve as a correlate of response to rTMS treatment.</p> <p>Conclusion</p> <p>The observed alterations of cortical excitability suggest that low frequency rTMS may evoke long-term-depression like effects resulting in an improvement of subcortical inhibitory function.</p

ATP-Dependent Infra-Slow (<0.1 Hz) Oscillations in Thalamic Networks

An increasing number of EEG and resting state fMRI studies in both humans and animals indicate that spontaneous low frequency fluctuations in cerebral activity at <0.1 Hz (infra-slow oscillations, ISOs) represent a fundamental component of brain functioning, being known to correlate with faster neuronal ensemble oscillations, regulate behavioural performance and influence seizure susceptibility. Although these oscillations have been commonly indicated to involve the thalamus their basic cellular mechanisms remain poorly understood. Here we show that various nuclei in the dorsal thalamus in vitro can express a robust ISO at ∼0.005–0.1 Hz that is greatly facilitated by activating metabotropic glutamate receptors (mGluRs) and/or Ach receptors (AchRs). This ISO is a neuronal population phenomenon which modulates faster gap junction (GJ)-dependent network oscillations, and can underlie epileptic activity when AchRs or mGluRs are stimulated excessively. In individual thalamocortical neurons the ISO is primarily shaped by rhythmic, long-lasting hyperpolarizing potentials which reflect the activation of A1 receptors, by ATP-derived adenosine, and subsequent opening of Ba2+-sensitive K+ channels. We argue that this ISO has a likely non-neuronal origin and may contribute to shaping ISOs in the intact brain

Degraded Forests in Eastern Africa: management and restoration

Forest degradation as a result of logging, shifting cultivation, agriculture and urban development is a major issue throughout the tropics. It leads to loss in soil fertility, water resources and biodiversity, as well as contributing to climate change. Efforts are therefore required to try to minimize further degradation and restore tropical forests in a sustainable way. This is the first research-based book to examine this problem in East Africa. The specific focus is on the forests of Ethiopia, Tanzania and Uganda, but the lessons learned are shown to be applicable to neighboring countries and others in the tropics. A wide range of forest types is covered, from dry Miombo forest and afromontane forests, to forest-savanna mosaics and wet forest types. Current management practices are assessed and examples of good practice presented. The role of local people is also emphasized. The authors describe improved management and restoration through silviculture, plantation forestry and agroforestry, leading to improvements in timber production, biodiversity conservation and the livelihoods of local people

Biofuels in China: an analysis of the opportunities and challenges of Jatropha Curcas in Southwest China

Over the past decade China has quietly emerged as the world’s third largest biofuel producer. Concerned over rising food prices, in June 2007 China’s central government banned the use of grain-based feedstocks for biofuel production and reoriented the country’s bioenergy plans toward perennial crops grown on marginal land. One such crop, Jatropha curcas, has emerged as a high potential biodiesel feedstock because of its adaptability to the diverse growing conditions where China’s marginal land is abundant. Provincial governments in Southwest China, for instance, have drafted ambitious plans to increase Jatropha by over one million hectares in the next decade. This paper analyzes the opportunities and challenges for the development of a Jatropha industry in Southwest China. Given the scarcity of data on Jatropha productivity and economics, we argue that plans to rapidly expand Jatropha acreage and refining capacity could jeopardize the industry’s longer-term viability. Alternatively, a commitment to silvicultural, engineering, and economic research could set the industry on a more sustainable path

Large or small? Rethinking China s forest bioenergy policies

China s forest bioenergy policies are evolving against the backdrop of pressing national energy challenges similar to those faced by OECD countries, and chronic rural energy challenges more characteristic of developing countries. Modern forest bioenergy could contribute to solutions to both of these challenges. However, because of limitations in current technologies and institutions, significant policy and resource commitments would be required to make breakthroughs in either commercializing forest bioenergy or modernizing rural energy systems in China. Given the potential attention, funding, and resource trade-offs between these two goals, we provide an argument for why the focus of China s forest bioenergy policy should initially be on addressing rural energy challenges. The paper concludes with a discussion on strategies for laying the groundwork for a modern, biomass-based energy infrastructure in rural China

Incentives for carbon sequestration and energy production in low productivity collective forests in Southwest China

This paper develops three scenarios for the management of an existing, low productivity, collective forest plot in Southwest China: continuation of the status quo, transition to sustainable forest management (SFM), and conversion to a short rotation species for producing biomass for electricity generation. We examine how economic incentives vary across the three scenarios and how payments for CO2 sequestration and offsets affect incentives. We find that SFM is risky for forest managers and is highly sensitive to revenues from initial thinning; that carbon revenues can lower some of the risks and improve the economics of SFM; but that carbon revenues are effective in incentivizing management changes only if yield response to thinning is moderately high. Energy production from stem wood is too low value to compete with timber, even with revenues from CO2 offsets. However, conversion of existing forests into short rotation species for timber rather than energy is more profitable than any scenario considered here, highlighting the need for regulatory innovations to balance incentives for timber production with conservation goals. The results underscore the importance of improved public sector regulatory, planning, extension, and analysis capacity, as an enabling force for effective climate policies in China s forestry sector