ABSTRACT
Noninvasive brain stimulation therapies are a promising field for the development of new protocols for the treatment of neuropsychiatric disorders. They are based on the stimulation of neural networks with the intent of modeling their synaptic activity to adequate levels. For this, it is necessary to precisely determine which networks are related to which brain functions, and the normal activation level of each of these networks, so that it is possible to direct the stimulation to the affected networks in order to induce the desired effects. These relationships are under intense investigation by the scientific community, and will contribute to the advancement of treatments by neurostimulation, with the emergence of increasingly accurate and effective protocols for different disorders. Currently, the most used techniques are Transcranial Direct Current Stimulation and Transcranial Magnetic Stimulation, with the most common applications being for treating Major Depressive Disorder. The advancement of research in this field may determine new target networks for stimulation in the treatment of other disorders, extending the application of these techniques and also our knowledge about brain functioning.
As terapias biológicas não invasivas se apresentam como um campo promissor para o desenvolvimento de novos protocolos de tratamento de transtornos neuropsiquiátricos. Elas se baseiam na estimulação de redes neurais com intuito de modular sua atividade sináptica para níveis adequados. Para isso, é necessário a determinação precisa de quais redes estão relacionadas a quais funções cerebrais, e do nível de ativação normal de cada uma dessas redes, para que então seja possível direcionar a estimulação às redes afetadas a fim de induzir os efeitos desejados. Essas relações estão sob intensa investigação pela comunidade científica, e vão contribuir para o avanço dos tratamentos por neuroestimulação, com o surgimento de protocolos cada vez mais precisos e efetivos para diferentes transtornos. Atualmente, as técnicas mais utilizadas são a Estimulação Transcraniana por Corrente Contínua e a Estimulação Magnética Transcraniana, sendo a aplicação mais comum no tratamento do Transtorno Depressivo Maior. O avanço das pesquisas possivelmente determinará novas redes alvo para estimulação no tratamento de outros transtornos, estendendo a aplicação dessas técnicas e também do nosso conhecimento sobre o funcionamento cerebral.
Subject(s)
Transcranial Magnetic Stimulation/standards , Implantable Neurostimulators , Neuropsychiatry , Nervous System Diseases/diagnosis , Nervous System Diseases/therapyABSTRACT
OBJECTIVES: Cognitive impairment is a common feature in Parkinson's disease (PD) and is an important predictor of quality of life. Past studies showed that some aspects of cognition, such as working memory, can be enhanced following dopaminergic therapy and transcranial magnetic stimulation. The aim of our study was to investigate whether another form of noninvasive brain stimulation, anodal transcranial direct current stimulation (tDCS), which increases cortical excitability, is associated with a change in a working memory task performance in PD patients. METHODS: We studied 18 patients (12 men and 6 women) with idiopathic PD. The patients performed a three-back working memory task during active anodal tDCS of the left dorsolateral prefrontal cortex (LDLPFC), anodal tDCS of the primary motor cortex (M1) or sham tDCS. In addition, patients underwent two different types of stimulation with different intensities: 1 and 2 mA. RESULTS: The results of this study show a significant improvement in working memory as indexed by task accuracy, after active anodal tDCS of the LDLPFC with 2 mA. The other conditions of stimulation: sham tDCS, anodal tDCS of LDLPFC with 1 mA or anodal tDCS of M1 did not result in a significant task performance change. CONCLUSION: tDCS may exert a beneficial effect on working memory in PD patients that depends on the intensity and site of stimulation. This effect might be explained by the local increase in the excitability of the dorsolateral prefrontal cortex.