Prêmio de Melhor Trabalho – 16º Simpósio em Emoção de Wisconsin

2010 – Travel Award Winner

O Dr. Moacyr Rosa, fundador do IPAN, recebe mais um importante prêmio internacional de melhor trabalho apresentado no 16º Simpósio em Emoção de Wisconsin (16th annual Symposium on Emotion).

A Premiação aconteceu no dia 22 de Abril de 2010, na cidade de Madison-Wisconsin (EUA).

O simpósio abrange temas sobre as mudanças neuronais em resposta à doença e tratamento. Este ano, o tema discutido foi a neuroplasticidade da emoção: psicopatologia e tratamento.

Pesquisadores de diferentes lugares do mundo apresentaram o que há de mais recente em neuroplasticidade cerebral e, desta forma, colaboram com o entendimento e tratamento dos transtornos mentais.

Confira abaixo o prêmio:

Trata-se da pesquisa translacional realizada na Universidade de Columbia intitulada Os novos paradigmas para otimizar a Magnetoconvulsoterapia: Estimulação Magnética por Theta-Burst.

O estudo analisa, pela primeira vez, o valor da Estimulação Magnética por Theta-Burst (ETB) como um novo paradigma para a indução terapêutica de convulsões em macacos. Resultados iniciais pretendem otimizar o uso desta técnica inédita em seres humanos, assim como sua segurança e benefícios.

“Novel paradigms for optimizing magnetic seizure therapy: Theta Burst Stimulation”.

Objective: This study analyzed, for the first time, the value of theta burst stimulation (TBS) as a novel paradigm for therapeutic seizure induction in a pre-clinical model. Feasibility, neurophysiology patterns and safety issues were addressed. These initial results will inform the optimization of magnetic seizure therapy (MST) paradigms for human use, and will also inform safety guidelines for the use of TBS at subconvulsive levels.

Background: Repetitive transcranial magnetic stimulation (rTMS) is already an approved clinical tool for the treatment of major depression. It uses subconvulsive magnetic pulses that induce electric current in the brain in order to modulate its excitability. The use of rTMS as a means of deliberately inducing therapeutic seizures (magnetic seizure therapy) is now being tested in controlled trials with the goal of bringing the therapeutic power of electroconvulsive therapy (ECT) to severely depressed patients who need it, while sparing them the cognitive side effects. One main advantage of the MST approach is the more focal stimulation that passes unimpeded through the scalp, allowing more control over current paths, density and distribution within cortical tissue. On the other hand, engineering constraints limit output of MST devices, making the identification of more efficient stimulation paradigms important. An innovative way of improving the efficiency of rTMS is called TBS, which uses a combination of frequencies (bursts of high frequency – 50 Hz – delivered in a theta rhythm, i.e. 4-7 Hz). Conventional rTMS devices can deliver it and this pattern has shown to induce longer lasting and more robust changes in cortical excitability than those seen with conventional TMS. TBS is based on protocols optimized for inducing long-term potentiation (LTP) and long-term depression (LTD) with direct electrical stimulation, which were developed to resemble the normal patterns of neural firing occurring in the hippocampus of rats during exploratory behavior. TBS can be delivered in a continuous fashion (cTBS) or in an intermittent fashion (with variable intervals between the trains; iTBS) and has never before been used as a means of inducing seizures.

Design/Methods: Four macaca mulatta were tested, on separate days one week apart, and received two forms of conventional MST (50 Hz and 18 Hz) and two forms of TBS (continuous or intermittent). The efficiency to induce a generalized seizure was defined as the lowest number of pulses needed to observe motor (controlled with a cuffed upper limb) and electroencephalographic (controlled with two fronto-mastoid EEG leads) generalization. Subjects were anesthetized during the procedures (methohexital 0.5 mg/Kg IV) and received muscle relaxant (succinylcholing 2.4 mg/Kg IV), in a similar fashion as that used for clinical ECT and MST. Seizure threshold titration was performed for each modality of treatment. Results: Both forms of MST nd the continuous form of TBS were efficient in inducing generalized seizures in all subjects. MST delivered at 50 Hz frequency needed the highest number of pulses (100 for 3 subjects and 150 for one), while MST 18 Hz and cTBS showed a similar seizure threshold (48 to 108 pulses). Intermittent TBS was the less efficient of all, unable to induce a seizure in two of the animals and needing a high number of pulses in another (480 pulses). No complications were observed during the experiments.

Conclusions: Continuous TBS has shown to be as effective as conventional MST for inducing seizures in this pre-clinical model. There were no apparent differences in seizure quality or duration between both modalities. Results open up the possibility of translating the findings to the use of theta-burst paradigms for therapeutic seizure induction in humans.