Neuroscience Letters 399 (2006) 1–5 Bereitschaftspotentials recorded from the lateral part of the superior frontal gyrus in humans Shinji Ohara a,1 , Akio Ikeda a,b,* , Masao Matsuhashi a , Takeshi Satow c , Takeharu Kunieda c , Nobuhiro Mikuni c , Koichi Baba d , Tadahiro Mihara d , Susumu Miyamoto c , Hiroshi Shibasaki e,2 a Human Brain Research Center, Kyoto University Graduate School of Medicine, Shogoin, Sakyo, Kyoto 606-8507, Japan b Department of Neurology, Kyoto University Graduate School of Medicine, Shogoin, Sakyo, Kyoto 606-8507, Japan c Department of Neurosurgery, Kyoto University Graduate School of Medicine, Shogoin, Sakyo, Kyoto 606-8507, Japan d National Epilepsy Center, Shizuoka Medical Institute of Neurological Disorders, Urushiyama, Shizuoka 420-8688, Japan e NINDS, NIH, Bethesda, MD, USA Received 27 April 2005; received in revised form 12 June 2005; accepted 28 June 2005 Abstract To demonstrate the Bereitschaftspotentials (BPs) over the high lateral convexity in the superior frontal gyrus, movement-related cortical potentials with respect to the middle finger extension were recorded in seven patients with refractory epilepsy who underwent subdural implantation of platinum electrode grids and/or strips covering the high lateral frontal convexity. In two out of the seven patients, BPs were recorded from the electrodes placed on the superior frontal gyrus in the vicinity of the border between the medial and lateral frontal lobes, which were distinct from those recorded from the primary sensorimotor cortex. The results suggest the possible contribution of either the lateral dorsal non-primary motor area or the SMA to the generation of the BPs. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Bereitschaftspotential; Supplementary motor area; Superior frontal gyrus; Epicortical recording Cortical potentials associated with voluntary movements, movement-related cortical potentials (MRCPs) [10,23], have been investigated to clarify the neuronal mechanisms under- lying voluntary motor control in humans. The early compo- nent of MRCP known as Bereitschaftspotential (BP), when recorded on the scalp electroencephalogram (EEG), starts 2–2.5 s prior to the movement onset and shows a wide and symmetric distribution with the maximum at the ver- tex [10,23,25]. Despite direct evidence showing that the contralateral primary motor cortex (M1) and bilateral sup- plementary motor areas (SMAs) in the medial frontal lobe * Corresponding author. Tel.: +81 75 751 3601; fax: +81 75 751 3202. E-mail address: akio@kuhp.kyoto-u.ac.jp (A. Ikeda). 1 Present address: Department of Neurosurgery, The Johns Hopkins Hos- pital, Baltimore, MD, USA. 2 Present addresses: Takeda General Hospital, Kyoto, Japan. generate BPs [8], the precise mechanisms by which scalp- recorded BPs are generated are unclear. Here we present the results of MRCP recorded from seven patients who had subdural electrode grids implanted over the high frontal convexity. In two of them, BPs were recorded from the high lateral frontal convexity in the superior frontal gyrus, which were distinct from those recorded from the M1. MRCPs were recorded in seven patients with refractory partial epilepsy who underwent subdural implantation of plat- inum electrode grids and/or strips (Ad-Tech Co., Racine, WI, USA) covering the high frontal convexity. Each electrode was electrically stimulated for the purpose of functional mapping. Details of the stimulation method have been described pre- viously [8,13]. Primary somatosensory cortex (S1) and M1 were identified based on subjective sensations and muscle contraction, respectively, evoked by the electrical stimula- tion. On the interhemispheric surface of the frontal lobe, SMA proper and pre-SMA were identified by predominantly tonic 0304-3940/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2005.06.062