Fig. 2: Postintervention VEP component amplitude change [postintervention-baseline] depending on condition. | Translational Psychiatry

Fig. 2: Postintervention VEP component amplitude change [postintervention-baseline] depending on condition.

From: Transcranial direct current stimulation induces long-term potentiation-like plasticity in the human visual cortex

Fig. 2

All amplitudes were measured in component direction for better comparability (i.e., amplitudes of negative-going components are positive). It is to note, that the estimated coefficients as given by the linear mixed effects models need to be added to each other to get the overall estimation of effect sizes for a specific stimulation type. For example, for the stimulation condition PVS, the respective coefficient for PVS+ needs to be added to the coefficient for “no stimulation.” To correctly display the influence of combined stimulation, the coefficients of “no stimulation”, PVS+, tDCS+, and the additional coefficient for the PVS/tDCS interaction needs to be summed up. While all VEP components are estimated to slightly increase in the absence of stimulation in the linear mixed effects models, both experimental conditions displayed significantly different effects. Mainly, C1 amplitudes decreased after PVS, tDCS, and combined stimulation. N1 increased, but to a significantly smaller degree than without stimulation after PVS and combined stimulation and decreased following tDCS. P1N1 peak-to-peak difference increased following all conditions, but to a significantly smaller amount following tDCS and combined stimulation than estimated for the absence of stimulation. Combined stimulation in general displayed effect seizes similar to the single stimulation conditions and did not reach levels as expected for additive effects. VEP, visually evoked potential; PVS+, sum of coefficients for prolonged visual stimulation and “no stimulation”; tDCS+, sum of coefficients for transcranial direct current stimulation and “no stimulation”, PVS+/tDCS+, sum of coefficients for PVS+, tDCS+, PVS/tDCS interaction and “no stimulation”; β-coefficients ± SE. Asterisk indicates significant difference in amplitude changes following the stimulation condition compared to “no stimulation” (significant coefficient in linear mixed effects model).

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