High-fidelity evoked potential for mapping the rat tail in thalamus

The technique of field potentials (FPs) provides a macroscopic view for exploring brain function, and is supplementary to single-unit recording, a microscopic view that investigates each neuron in great detail. Mapping the rat tail in the ventroposterolateral (VPL) nucleus of the thalamus was carried out by analyzing the current source density (CSD) of the evoked FPs. The results showed a clear somatotopic organization of the tail in the VPL nucleus. Also, to obtain high-fidelity FPs, two recording parameters were determined. Based upon cross-correlation coefficient (rho), the cycles of FPs needed to be averaged should not be less than 50 and the distance between the two recording sites should be no longer than 50 mum in each direction (mediolateral, anteroposterior and ventrodorsal). Under these conditions, the representation (or reproducibility) of an FP can be >95%. The procedures used to determine these parameters can serve as a guide to obtain FPs with high signal-to-noise ratio and without spatial aliasing error.