Model fitting as an aid to bridge balancing in neuronal recording

When recording intracellularly, the resistance across the cell membrane must be monitored. However the resistance seen by the recording ampli"er consists of the access resistance (between the electrode and the cell) in series with the cell resistance. When the stray capacitance is low, the time constant of the cell and that associated with the recording setup are di!erent and the two resistance values can be easily determined visually. We describe a model-"tting method which can automatically infer the electrode and cell capacitances and resistances in more di$cult cases. 2001 Published by Elsevier Science B.V.