Block of spike-generated synaptic input fluctuations with TTX minimally alters membrane input resistance and time constant values in layer 2/3 pyramidal cells and interneurons. A, Example trace of pyramidal cell membrane voltage in response to step hyperpolarizations before (i, top) and after (i, bottom) TTX application, along with example traces indicating a lack of spike generation with TTX (ii). B, Plots of SD (i), membrane input resistance (ii), and time constant (iii) before and after the application of TTX. C, Example trace of interneuron membrane voltage in response to step hyperpolarizations before (i, top) and after (i, bottom) TTX application, along with example traces indicating a lack of spike generation with TTX (ii). D, Plots of SD (i), membrane input resistance (ii), and time constant before and after the application of TTX.