We have found that the more impaired the synaptic-neuronal activity is the more unstable becomes its activity. Its instability is expressed in terms of normalized power variance (NPV) of the EEG potential measured with each scalp electrode. The pattern of NPV of the beta component is given in Fig.8. The left figure is NPV map of an AD patient and the right map is the regional cerebral blood flow reduction map measured by SPECT in the same patient. The red and blue regions indicate hyper-active (unstable) and hypo-active (inactive) regions corresponding to young and old impairments, respectively. This technique is named L-DIMENSION.

Ref.: T. Musha, et al. "Z-score Pattern Matching Diagnosis of AD," Int. Conf. on Prevention of Dementia, June 18-21, 2005, Washington DC: T. Musha, et al. "Localization of impaired cortical neurons by EEG power fluctuations," 15th World Cong. Int. Soc. Brain Electromag. Topol., Urayasu, Japan, 2004.