Fig. 5

Short-term synaptic facilitation and depression achieved via reconfigurable capacitor geometry. a A schematic showing a symmetric bilayer with zero intrinsic bias consisting of DPhPC lipids in both leaflets. b Demonstration of short-term facilitation of capacitive current measured for a symmetric DPhPC bilayer in decane at RT. Facilitation and depression are forms of short-term plasticity found in the presynaptic terminal⁵⁴ evoked by successive voltage stimuli. For this measurement, a series of 150 mV pulses with 2 ms ON-time (T_on) and 0 mV, 1 ms OFF-time (T_off) caused an accumulated, monotonic increase in peak capacitive current output due to the dynamic, history-dependent increase in membrane capacitance. The inset shows individual capacitive spikes induced by the rising edges of voltage pulses (we are not displaying the negative spikes; Supplementary Fig. 13 provides bipolar responses). c Peak capacitive current versus time shows facilitation for a bilayer in hexadecane at RT for the same voltage input as in (b). d An asymmetric membrane with an intrinsic bias of −137 mV due to the difference in lipid dipole potentials is created by joining one DPhPC-coated droplet and one DOPhPC-coated droplet. e Demonstration of short-term depression in peak capacitive current due to a reduction in net membrane potential in response to the same voltage pulses as in (b). Changing to negative pulses increases the net membrane potential \(\left( {{\boldsymbol{v}}_{\boldsymbol{m}} = - {\boldsymbol{v}} - 137\;{\mathrm{mV}}} \right)\), which leads to EW and EC increasing the capacitance of the interface, and results in facilitation in peak current versus time. f Percentage increases in measured peak current relative to the first pulse response for the 2nd (ΔI₂) and 2000th (ΔI₂₀₀₀) voltage pulses at various T_off values for a symmetric DPhPC membrane in decane at RT