Master's Theses

Date of Award

2016

Document Type

Thesis

Department

Biomedical Engineering

First Advisor

Lucas C. Parra

Second Advisor

Marom Bikson

Keywords

synaptic plasticity, +DCS, dendrites

Abstract

Transcranial direct current stimulation (tDCS) has been reported to improve various forms of learning in humans. Stimulation is often applied during training, producing lasting enhancements that are specific to the learned task. These learning effects are thought be mediated by altered synaptic plasticity. However, the effects of DCS during the induction of endogenous synaptic plasticity remain largely unexplored. To model endogenous plasticity I induced long-term potentiation (LTP) and depression (LTD) at Schaffer collateral synapses in CA1 of rat hippocampal slices. When induction was paired with concurrent DCS, the resulting plasticity was biased towards potentiation, such that LTP was enhanced and LTD was reduced. Remarkably, both anodal and cathodal stimulation can produce these effects, depending on the dendritic location of plasticity induction. DCS did not affect synapses that were weakly active or when NMDA receptors were blocked, suggesting a sensitivity for active synapses that are already undergoing endogenous plasticity. These results highlight the role of DCS as a modulator, rather than inducer of synaptic plasticity, as well as the complex dependence of DCS effects on the spatial and temporal properties of endogenous synaptic activity.

 
 

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