Modulating Hippocampal Plasticity with In Vivo Brain Stimulation
Technical Report,01 Jan 2015,30 Nov 2016
Oak Ridge Institute for Science and Education Patuxent River United States
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Investigations into the use of transcranial direct current stimulation tDCS in relieving symptoms of neurological disorders and enhancing cognitive or motor performance have exhibited promising results. However, the mechanisms by which tDCS impacts brain function remain under scrutiny. We have demonstrated that in vivo tDCS in rats produced a lasting effect on hippocampal synaptic plasticity, as measured using extracellular recordings. Ex vivo preparations of hippocampal slices from rats that have been subjected to tDCS of 0.10 mA or 0.25 mA for 30 minutes followed by 30 minutes of recovery time displayed a robust 2-fold enhancement in long term potentiation LTP induction accompanied by a 30 increase in paired pulse facilitation PPF. The magnitude of the LTP effect was greater with 0.25 mA compared to 0.10 mA stimulations, suggesting a dose-dependent relationship between tDCS intensity and its effect on synaptic plasticity. To test the persistence of these observed effects, animals were stimulated in vivo for 30 min at 0.25 mA then allowed to return to their home cage for 24 hours. Observation of the enhanced LTP induction, but not the enhanced PPF, continued 24 hours following completion of 0.25 mA of tDCS. Addition of the NMDA blocker AP-5 abolished LTP in both control and stimulated rats but maintained the PPF enhancement in stimulated rats. The observation of enhanced LTP and PPF following tDCS demonstrates that non-invasive electrical stimulation is capable of modifying synaptic plasticity.
- Anatomy and Physiology
- Medicine and Medical Research