Bilateral Motor Cortex tDCS Effects on Post-Stroke Pain and Spasticity: A Three Cases Study.

Stroke patients frequently suffer from chronic limb pain, but well-suited treatment approaches have been not established so far. Transcranial direct current stimulation (tDCS) is a safe and non-invasive brain stimulation technique that alters cortical excitability, and it has been shown that motor cortex tDCS can reduce pain. Some data also suggest that spasticity may be improved by tDCS in post-stroke patients. Moreover, multiple sessions of tDCS have shown to induce neuroplastic changes with lasting beneficial effects in different neurological conditions. The aim of this pilot study was to explore the effect of multiple anodal tDCS (atDCS) sessions on upper limb pain and spasticity of stroke patients, using a within-subject, crossover, sham-controlled design. Brain damage was of similar extent in the three patients evaluated, although located in different hemispheres. The results showed a significant effect of 5 consecutive sessions of atDCS, compared to sham stimulation, on pain evaluated by the Adaptive Visual Analog Scales -AVAS-, and spasticity evaluated by the Fugl-Meyer scale. In two of the patients, pain was completely relieved and markedly reduced, respectively, only after verum tDCS. The pain improvement effect of atDCS in the third patient was considerably lower compared to the other two patients. Spasticity was significantly improved in one of the patients. The treatment was well-tolerated, and no serious adverse effects were reported. These findings suggest that multiple sessions of atDCS are a safe intervention for improving upper limb pain and spasticity in stroke patients, although the inter-individual variability is a limitation of the results. Further studies including longer follow-up periods, more representative patient samples and individualized stimulation protocols are required to demonstrate the efficacy and safety of tDCS for improving limb symptoms in these patients.

Anodal tDCS over Wernicke's area improves verbal memory and prevents the interference effect during words learning.

BACKGROUND: Wernicke's area is a key component of the cortical language network, and it is functionally related to the comprehension of oral and written language. In addition to its main role in the perception of language, some other functions related to verbal learning also seem to involve the activity of this cortical region. It is unknown whether different degrees of neuromodulation on this area determine its effect on word learning. OBJECTIVE: We aimed to analyze the influence of the application of anodal transcranial DC stimulation (tDCS) over Wernicke's area at two different intensities on word learning. METHOD: We compared the effect of anodal tDCS at an intensity of 0.5 mA and 1.5 mA with sham tDCS, separately in different groups, on performance in a word learning and recall task. RESULTS: The results show that 1.5 mA anodal tDCS improved performance. The number of words learned in this condition was higher compared with stimulation at 0.5 mA current strength and sham stimulation. Furthermore, stimulation with 1.5 mA specifically prevented the interference effect over word learning, compared to the other two tDCS conditions. CONCLUSIONS: These results show an intensity-dependent effect of anodal tDCS on verbal memory formation. These findings are discussed in the context of the various functions of Wernicke's area and the ability of tDCS to modulate the activity and functionality of this cortical area at different intensities. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Effects of temporal contexts and contextual habituation on latent inhibition / Efectos de contextos temporales y habituación contextual sobre inhibición latente

Background: Latent inhibition of conditioned taste aversion (CTA) is sensitive to external and internal cues. Time of day can serve as an internal cue, and latent inhibition may be reduced if the pre-exposure and conditioning stages occur at different times of day. This contextual cue attributed to a change in the time of day may reveal a temporal specificity of latent inhibition. Although the habituation period to spatial contexts is a determinant variable for the spatial specificity of latent inhibition of CTA, the influence of contextual-temporal familiarity (time of day) on latent inhibition of CTA has not been explored through direct comparisons between different periods of habituation to the temporal context. Method: Two different periods of contextual habituation (short vs. long) previous to taste pre-exposures were compared in Wistar rats to analyze the influence of these periods on the temporal specificity of latent inhibition of CTA. Results: A long period of habituation, in relation to a short period, facilitated the effect of a change of the time of day between pre-exposure and conditioning on the magnitude of taste aversion. Conclusions: A long habituation to temporal contexts facilitates the temporal specificity of latent inhibition of CTA (AU)

Antecedentes: la inhibición latente del aprendizaje aversivo gustativo (AAG) es sensible a claves externas e internas. La hora del día puede actuar como una clave interna, y la inhibición latente puede ser reducida si pre-exposición y condicionamiento ocurren a diferentes horas del día. Esta clave contextual atribuida a un cambio en la hora del día puede revelar una especificidad temporal de la inhibición latente. Aunque el período de habituación a contextos espaciales es determinante para la especificidad espacial de la inhibición latente del AAG, la influencia de la familiaridad contextual-temporal (hora del día) sobre la inhibición latente del AAG no ha sido explorada mediante comparaciones directas entre diferentes períodos de habituación al contexto temporal. Método: en ratas Wistar se compararon dos diferentes períodos de habituación contextual (corto versus largo) previos a pre-exposiciones gustativas para analizar la influencia de éstos sobre la especificidad temporal de la inhibición latente del AAG. Resultados: un largo período de habituación, en relación con uno corto, facilitó el efecto de un cambio de la hora del día entre pre-exposición y condicionamiento sobre la magnitud de la aversión gustativa. Conclusiones: una larga habituación a contextos temporales facilita la especificidad temporal de la inhibición latente del AAG (AU)