[1] Univ Modena, Physiol Sect, Dept Biomed Sci, I-41100 Modena, Italy
[2] Russian Acad Sci, St Petersburg Inst Informat & Automat, St Petersburg 196140, Russia
[3] NIDA, Behav Neurosci Branch, NIH, DHHS, Bethesda, MD 20817 USA
[4] Karolinska Inst, Dept Neurosci, Div Cellular & Mol Neurochem, S-17177 Stockholm, Sweden
[5] Univ Padua, Dept Anat & Physiol, Padua, Italy