Face processing in adolescents with and without epilepsy M.J. Taylor a,c,d, ⁎ , T. Mills a,1 , M.L. Smith b,c,d,2 , E.W. Pang c,d,3 a Department of Diagnostic Imaging, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, Canada M5G 1X8 b Department of Psychology, Hospital for Sick Children, University of Toronto, Room 6264, Black, Toronto, ON, Canada M5G 1X8 c Department of Neurology, Hospital for Sick Children, University of Toronto, Room 6516, Hill, Toronto, ON, Canada M5G 1X8 d Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada M5G 1X8 Received 30 October 2007; received in revised form 4 December 2007; accepted 12 December 2007 Available online 12 February 2008 Abstract Children with temporal lobe epilepsy frequently suffer memory deficits, often marked in face processing. To determine the neural correlates of this dysfunction, we investigated face processing in adolescents with intractable epilepsy compared to typically developing controls. The M170 and M220 MEG event-related fields (ERFs) were recorded while the adolescents completed an n-back task on blocks of upright and inverted faces. Source analyses of the ERF data were performed using an event-related beamforming technique that allowed the detection of multiple sources. The control adolescents showed the expected waveforms and inversion effects, although there were differences in source localization, compared to the adult literature. The participants with epilepsy had poor performance on the tasks. The adolescents with extra-temporal lobe epilepsy showed both the M170 and M220 but the source localizations were highly atypical. The patients with right temporal lobe epilepsy had an absent or highly atypical M220, a component related to face recognition processes. We hypothesize that the children with extra-temporal lobe epilepsy have difficulty with face encoding processes while the patients with right temporal lobe epilepsy have specific difficulty with face recognition. © 2008 Elsevier B.V. All rights reserved. Keywords: Face processing; Adolescents; Epilepsy; M170; M220; Memory 1. Introduction Faces comprise the most important and salient visual stimuli in human social interaction. Behavioural studies confirm that healthy adults enjoy an impressive aptitude for facial processing (Bruce and Young, 1998), which contrasts sharply with the poorer face recognition skills in children. Despite the interest and importance of faces to children, and despite a prolonged and steep learning curve for face recognition, our understanding of the development of the ability to readily recognise faces remains limited. 1.1. Electrophysiological measures of face processing Precise measures of neuronal timing of early face processing can be obtained with electromagnetic recordings: EEG event- related potentials (ERPs) or MEG event-related fields (ERFs). A large literature now exists on a face-sensitive ERP component, the N170, which has been intensively studied since it was first reported (Bentin et al., 1996). N170 is recorded over posterior temporal leads, generally larger over right than left hemisphere, and is much larger to faces than objects. Many ERP studies have investigated the N170 and demonstrated its sensitivity for various aspects of face processing (e.g., Sagiv and Bentin, 2001; Latinus and Taylor, 2006), and to faces compared to a wide range of non-face stimuli (e.g., Itier and Taylor, 2004a). N170 is the middle of a triphasic response and additional information can be obtained from the other peaks. The positive component preceding N170, P1, reflects early, rapid processing of both simple and complex stimuli, and is responsive to task Available online at www.sciencedirect.com International Journal of Psychophysiology 68 (2008) 94 – 103 www.elsevier.com/locate/ijpsycho ⁎ Corresponding author. Department of Diagnostic Imaging, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, Canada M5G 1X8. Tel.: +1 416 813 6321; fax: +1 416 813 7362. E-mail addresses: margot.taylor@sickkids.ca (M.J. Taylor), travis.mills@sickkids.ca (T. Mills), marylou.smith@sickkids.ca (M.L. Smith), elizabeth.pang@sickkids.ca (E.W. Pang). 1 Tel.: +1 416 813 7654x2479; fax: +1 416 813 7362. 2 Tel.: +1 416 813 7654x6771; fax: +1 416 813 8839. 3 Tel.: +1 416 813 6548; fax: +1 416 813 6334. 0167-8760/$ - see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpsycho.2007.12.006