Publication:
TRANSCRANIAL DIRECT-CURRENT STIMULATION MODULATES SYNAPTIC MECHANISMS INVOLVED IN ASSOCIATIVE LEARNING IN BEHAVING RABBITS

No Thumbnail Available
Publication date
2012-04-24
Reading date
Event date
Start date of the public exhibition period
End date of the public exhibition period
Advisors
Authors of photography
Person who provides the photography
Journal Title
Journal ISSN
Volume Title
Publisher
Proceedings of the National Academy of Sciences of the United States of America
Export
Research Projects
Organizational Units
Journal Issue
Abstract
Transcranial direct-current stimulation (tDCS) is a noninvasive brain stimulation technique that has been successfully applied for modulation of cortical excitability. tDCS is capable of inducing changes in neuronal membrane potentials in a polarity-dependent manner. When tDCS is of sufficient length, synaptically driven aftereffects are induced. The mechanisms underlying these after-effects are largely unknown, and there is a compelling need for animal models to test the immediate effects and after-effects induced by tDCS in different cortical areas and evaluate the implications in complex cerebral processes. Here we show in behaving rabbits that tDCS applied over the somatosensory cortex modulates cortical processes consequent to localized stimulation of the whisker pad or of the corresponding area of the ventroposterior medial (VPM) thalamic nucleus. With longer stimulation periods, poststimulation effects were observed in the somatosensory cortex only after cathodal tDCS. Consistent with the polarity-specific effects, the acquisition of classical eyeblink conditioning was potentiated or depressed by the simultaneous application of anodal or cathodal tDCS, respectively, when stimulation of the whisker pad was used as conditioned stimulus, suggesting that tDCS modulates the sensory perception process necessary for associative learning. We also studied the putative mechanisms underlying immediate effects and after-effects of tDCS observed in the somatosensory cortex. Results when pairs of pulses applied to the thalamic VPM nucleus (mediating sensory input) during anodal and cathodal tDCS suggest that tDCS modifies thalamocortical synapses at presynaptic sites. Finally, we show that blocking the activation of adenosine A1 receptors prevents the long-term depression (LTD) evoked in the somatosensory cortex after cathodal tDCS.
Doctoral program
Related publication
Research projects
EC/FP7/FET/222079/EU
Description
Este estudio constituye una de las primeras aproximaciones realizadas en modelos animales para comprobar los efectos de la estimulación eléctrica transcraneal. En particular, la estimulación transcraneal con corriente continua (tDCS) es una técnica de estimulación cerebral no invasiva que se ha aplicado con éxito para la modulación de la excitabilidad cortical, siendo capaz de inducir cambios en los potenciales de membrana neuronal de una manera dependiente de la polaridad. Al respecto, los estudios han demostrado en conejos que la estimulación transcraneal con corriente continua puede modificar (incrementar o decrementar) la capacidad de aprendizaje de los animales y se ha descubierto que el post-efecto de la corriente catódica (que disminuye la actividad cerebral) se debe a la activación de un receptor para la adenosina. Los mecanismos subyacentes a estos post-efectos se desconocen en gran parte, por lo que existe la necesidad de disponer de modelos animales para probar los efectos inmediatos y los post-efectos inducidos por la tDCS en diferentes áreas corticales y para evaluar sus implicaciones en los procesos cerebrales complejos. En este artículo se demuestra que el bloqueo de la activación de los receptores de adenosina A1 previene la depresión a largo plazo evocada en la corteza somatosensorial después de la tDCS catódica.
Bibliographic reference
PNAS USA, vol 109, nº 17, p. 6710-6715
Photography rights