Spatial and temporal distribution enhancement of movement-related brain macropotentials

Conventional brain maps suffer from severe limitations due to both the spat ial blur of potential distributions and the dependence on electrical refere nce. The surface Laplacian (SL) has been used to deblur movement-related br ain macropotentials (MRBM) since it acts as a high-pass spatial filter that reduces the head volume conductor effects. Moreover, the method usually em ployed to improve the signal-to-noise ratio (SNR) is the well-known synchro nized average. However. this method is no loner valid when the object of th e study is the sweep-by-sweep variability. In this case, the SNR of origina l and Laplacian-transformed single-sweep MRBM can be improved by autoregres sive with exogenous input (ARX) filtering. In our study, isolated or combin ed ARX and SL are applied to enhance the spatial distributions of single-sw eep MRBM associated with unilateral voluntary self-paced finger movements i n humans. It shows that single-sweep brain mappings are more coherent to ph ysiological findings when ARX is first used followed by SL. (C) 1999 Academ ic Press.