Most of the literature on the brain impedance proposes a frequency independent resistive model. Recently, this conclusion was tackled by a series of papers (Bé-dard et al., 2006; Bédard and Destexhe, 2009; Gomes et al., 2016), based on microscopic scale modelling and measurements. Our paper aims to investigate the impedance issue using simultaneous in vivo depth and surface signals recorded during intracerebral electrical stimulation of epileptic patients, involving a pri-ori different tissues with different impedances. Our results confirm the conclusions from (Logothethis et al., 2007): there is no evidence of frequency dependence of the brain tissue impedance (more precisely, there is no difference, in terms of frequency filtering, between the brain and the skull bone), at least at a macroscopic scale. In order to conciliate findings from both microscopic and macroscopic scales, we recall different neural/synaptic current generators models from the literature and we propose an original computational model, based on fractional dynamics.