Disturbances of energy metabolism in rat brain after frontal lobectomy and post-traumatic effects of monosialic ganglioside GM1 on brain energy metabolism were studied by 31P NMR in vivo. Frontal lobectomy caused the statistically significant reversible decrease of ATP and increase of ADP during the compensatory period. In a presence of GM1 these post-operational effects were not observed. The mean value of normalized correlation coefficients between NMR-measured phosphomonoesters, P(i), pH, phosphocreatine, gamma-ATP + beta-ADP, alpha-ATP + alpha-ADP +NAD/NADH + diphosphodiesters and beta-ATP for a given group of animals (Z-index) was used to estimate brain energetic status. It has been shown that the variation of the Z-index correlates with the dynamics of locomotor activity during the compensatory period. The Z-index increased by more than 100% for the subgroup with an increased moving activity and only by about 20% for the subgroup with a decreased activity. Moreover, the compositions of these subgroups were almost the same as those from the solution of the reverse task, i.e., the studied group was divided into two subgroups by the Z-index. The Z-index is proposed as a possible criterion of pathology detection in brain energetics.