Mahima Sharma, PhD presents at the Spring 2021 BME Seminar Series

Dr. Mahima Sharma, Postdoctoral Fellow in Professor Parra's lab in the CCNY BME Department, is the speaker of the next BME seminar on Wednesday, May 12 at 3pm

Presentation: Synaptic evidence for the cumulative effects of weak DCS in spaced learning in rat hippocampus

Electric fields generated during direct current stimulation (DCS) are known to modulate activity dependent synaptic plasticity in-vitro. This provides a mechanistic explanation for the lasting behavioral effects observed with transcranial direct current stimulation (tDCS) in human learning experiments. However, previous in-vitro synaptic plasticity experiments show relatively small effects despite using strong fields compared to what is expected with conventional tDCS in humans (20 V/m vs. 1 V/m). We propose that effects of DCS on synaptic long-term potentiation (LTP) accumulate over time in a spaced learning paradigm, thus revealing effects at more realistic field intensities. As predicted, DCS applied during repeated bouts of theta burst stimulation (TBS) resulted in an increase of LTP. This spaced learning effect saturated quickly with strong TBS protocols and stronger fields. In contrast, weaker TBS and the weakest electric fields of 2.5 V/m resulted in the strongest relative efficacies (12% boost in LTP per 1 V/m applied). These results support the notion that the effects of weak fields during DCS accumulate through an increasing synaptic strength after repeated bouts of learning and bridge the gap in terms of efficacy between in-vitro DCS and human tDCS experiments.