Table 5.

Animal studies on the mechanism of long-term potentiation (LTP) by anodal tDCS.

Study	Age or weight, species	Stimulation intensity, duration	Stimulation site	Results
Hattori et al. (1990)	190–240 g Wistar rats	0.3, 3, or 30 μA 30–240 min, 3–5 times per day for several days	Sensory-motor cortex	Increased cAMP accumulation in the polarized cortex in 3 μA. Decreased cAMP accumulation in the polarized cortex in 0.3 μA.
Fritsch et al. (2010)	Male 6–8 weeks old mice	10 μA	Motor cortex (M1) slices	Induced synaptic plasticity in vitro by DCS, which was dependent on enhanced BDNF-secretion and TrkB-activation.
Jiang et al. (2012)	Adult, Sprague-Dawley rats, model of middle cerebral artery occlusion	mA, 30 min 3, 7, or 14 sessions	Primary motor cortex	Enhanced density of dendritic spines after stroke. No change in the up-regulated PX1 mRNA expression after stroke. Improved post-stroke motor function on days 7 and 14.
Ranieri et al. (2012)	150–200 g Wistar rats	200–250 μA, 20 min	Hippocampal slices	Modulated LTP at rat hippocampal CA3-CA1 synapses.
Podda et al. (2016)	Male 30–45 days old mice	350 μA, 20 min	Left hippocampus	Exhibited 1-week lasting enhancement in hippocampal LTP, learning, and memory, which were associated with enhanced acetylation of BDNF promoter I, expression of BDNF exons I and IX, and BDNF protein levels. Enhanced CREB phosphorylation, pCREB binding to BDNF promoter I, and recruitment of CREB-binding protein.
Monai et al. (2016)	8–12 weeks old mice	0.1 mA, 10 min	Primary visual cortex	Induced surges of Ca2+ influx into astrocytes across the entire cortex by using a transgenic mouse expressing G-CaMP7 in astrocytes. Changed the meta-plasticity of the cortex through astrocytic Ca2+/IP3 signaling.
Yu et al. (2019)	8 weeks old male Sprague-Dawley rats	250 μA, 30 min	Hippocampal CA1 slices	Enhanced LTP in hippocampal CA1 slices from rats. Exhibited high levels of BDNF in the hippocampal CA1 region.