Insights from Animal Models and Brain Slice

3.1 Meaningful Animal Studies of tDCS and the Quasi-Uniform Assumption .... 56 3.1.1 Classification of Animal Studies ........................................................ 56 3.1.2 tDCS Dose in Human and Animals, and the Quasi-Uniform Assumption ........................................................................ ................ 58 3.1.3 Stimulator and Electrode Techniques, and Nomenclature ................. 61 3.1.4 Dose Control and Meaningful Animal Studies ..................................64 3.1.5 Outcome Measures .............................................................................65 3.2 Somatic Doctrine and Need for Amplification ...............................................65 3.2.1 Neuronal Polarization .........................................................................66 3.2.2 Modulation of Excitability, Polarity-Specific Effects .........................66 3.2.3 Quantifying Polarization with Coupling Constants ........................... 67 3.2.4 Amplification through Rate and Timing ............................................69 3.2.5 Seizure Threshold and Modulation .................................................... 71 3.2.6 Limitations of the Somatic Doctrine .................................................. 71 3.3 Plasticity, Synaptic Processing, and a “Terminal Doctrine” .......................... 73 3.3.1 Paradigms for DC Modulation of Synaptic Efficacy .......................... 73 3.3.2 Relation with Tetanic Stimulation Induced LTP/LTD ........................ 75 3.3.3 Which Compartments are Influenced by DC Stimulation: Soma and Dendrites ...................................................................................... 77 3.3.4 Which Compartments Are Influenced by DC Stimulation: Synaptic Terminals ............................................................................. 78