Patients and methods: Seventy-seven neurosurgical patients participated in this study. Patients were instructed to silently read a word immediately after visual presenta- tion of the word. Totally 100 words were presented. Using synthetic aperture magnetometry (SAM), local oscillatory changes were obtained as spatial distribution of Student’s t statistics by comparing 1 s before and after stimulus onset. Language dominance was determined by the lateral- ity index derived from maximum t values of the left and right frontal desynchronization. Language dominance and localization were compared with Wada test (N = 48) and stimulation mapping (N = 12, subdural electrodes: 10, intraoperative cortical stimulation: 2), respectively. Results: Language dominance by SAM was concordant with Wada test in 42 cases (87.5%). Localization of the frontal language areas could be detected in 72 patients (93.5%). Localization of the frontal language areas by SAM was compared with stimulation mapping in eight cases. Estimated frontal language areas were well concor- dant with stimulation mapping. However, there was a ten- dency that the anterior part of the frontal language areas was not detected. Discussion: Our method is a noninvasive alternative to Wada test. As for language localization, our method is use- ful to determine the stimulation sites for invasive mapping. Additional tasks such as sentence reading might improve to detect the anterior part of the frontal language areas. doi:10.1016/j.clinph.2006.06.016 FC5.2 The ‘‘human visceral homonculus’’ to pain evoked in the oesophagus, stomach, duodenum and sigmoid colon M. Valeriani 1 , G. Dimcevski 2 , S.A. Sami 2 , P. Funch-Jensen 3 , K. Dinh Huynh 2 , D. Le Pera 4 , L. Arendt-Nielsen 5 , A.M. Drewes 2 1 Ospedale Pediatrico Bambino Gesu ` , IRCCS, Neurology, Italy 2 Aalborg University Hospital, Center for Visceral Biome- chanics and Pain, Denmark 3 Aarhus University Hospital, Surgical Gastroenterology, Denmark 4 IRCSS San Raffaele Pisana, Motor Rehabilitation, Italy 5 Aalborg University, Center for Sensory-Motor Interac- tions (SMI), Denmark Background: Although the cerebral processing of the nociceptive input coming from a certain gut tract has been investigated, the differences in the neural matrix activated by the stimulation of different gut tracts in the same sub- jects have never been studied. Aim: To build a ‘‘visceral homunculus’’ to painful stim- ulation of the oesophagus, stomach, duodenum, and sig- moid colon. Methods: The oesophagus, stomach, duodenum and sigmoid colon were electrically stimulated in 12 healthy volunteers. The painful cortical evoked potentials (EPs) were recorded from 64 surface electrodes. Results: The electrical current intensities needed to evoke pain were highest in the stomach and duodenum, compared to the other segments (F = 7.8; P < 0.001; post hoc analysis P < 0.05). The EP latencies after stimulation of the stomach and sigmoid colon were shorter compared with those to stimulation of the oesophagus and duodenum (all P-values <0.001). The EP amplitudes were higher to oesophagus stimulation (all P-values <0.001). The poten- tial fields obtained after stimulation of the most distal seg- ments (duodenum and sigmoid colon) were in general distributed more posteriorly compared to those recorded in the more proximal regions. The EP topographies to stimulation of all gut tracts were explained by a bilateral source in the second somatosensory (SII) area, by a dipole in the anterior cingulate cortex (ACC), and by a bilateral generator in the insular cortex. However, the position of the sources significantly changed depending on the stimu- lated gut tract. Moreover, while the SII and ACC sources were initially activated to oesophagus and stomach stimu- lation, the ACC and insular activities were the earliest ones after stimulation of the lower gut segments. Conclusion: Our findings reflect differences in pathways and brain processing of visceral nociceptive inputs coming from either upper or lower gut and may improve our understanding of the brain–gut axis in health and disease. doi:10.1016/j.clinph.2006.06.017 FC5.3 Navigated brain stimulation for exact mapping of several discrete motor areas S. Teitti 1 , S. Ma ¨a ¨tta ¨ 1 , L. Eskola 1 , M. Ko ¨no ¨nen 2 , R. Vanninen 3 , J. Karhu 4 1 Kuopio University Hospital, NBS laboratory, Finland 2 Kuopio University Hospital, NBS laboratory, Department of Clinical Radiology, Finland 3 Kuopio University Hospital, Department of Clinical Radiology, Finland 4 Kuopio University Hospital, NBS laboratory, Nexstim Ltd., Finland Background: Navigated brain stimulation (NBS) pro- vides a new tool to investigate discrete cortical areas with motor capacity. Most of the axons in the corticospinal tracts originate from primary motor cortex (M1) with minor contributions from supplementary motor cortex (SMA), premotor cortical areas (PMA) and somatic senso- ry cortex (S1). The function of direct corticospinal connec- tions from motor areas outside M1 has remained unknown. Our aim was to investigate the motor capacity of cortical areas residing outside M1. Subjects and methods: We examined 13 health subjects (age 22–36, eight females, five males) using NBS. First, every subject’s motor thresholds (MT) for both opponens Oral Communications / Clinical Neurophysiology 117 (2006) S49–S111 S53