MB-96IMPAIRED NEURAL FUNCTION DURING VISUAL-MOTOR PERFORMANCE IN CHILDREN TREATED FOR BRAIN TUMOURS

Abstract

MB-96. IMPAIRED NEURAL FUNCTION DURING VISUAL-MOTOR PERFORMANCE IN CHILDREN TREATED FOR BRAIN TUMOURS Sonya Bells1, Colleen Dockstader1, Suzanne Laughlin3, Eric Bouffet2, Jovanka Skocic1, and Donald Mabbott1; The Hospital for Sick Children, Department of Psychology, Toronto, ON, Canada; The Hospital for Sick Children, Department of Haematology/Oncology, Toronto, ON, Canada; The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto, ON, Canada Children treated with cranial radiation therapy for brain tumours exhibit substantial cognitive deficits that may be mediated by impaired neural functioning. We used magnetoencephalography to investigate whether aberrant neural oscillations are present in pediatric brain tumour survivors compared to healthy children during a visual-motor reaction time task. MEG recording (151 channels, VSM MedTech) was acquired for 9 previously irradiated patients and age-matched controls during the visual-motor reaction time task (100 trials in total). Reaction time (RT) was measured along with localized power changes within the visual and motor cortex using beamformer analysis. Patients showed a significantly delayed RT compared to controls (t(2,9) 1⁄4 2.68, p , 0.05). Beamformer analysis revealed that relative to controls, patients had muted event-related desynchrony and synchrony in the beta (13-29 Hz) and alpha (8-12 Hz) bandwidths in motor and visual cortex and potentiated high gamma activity (50-100 Hz) in the contralateral motor cortex. Furthermore, we found differences in peak gamma frequency of the visually-induced oscillations. Peak frequency was measured in the low gamma range (30-50 Hz) in patients and in the high gamma range (50-100 Hz) in controls. Our findings indicate that aberrant neural responses, characterized by reduced alpha and beta power and increased gamma power within the contralateral motor area, and reduced peak gamma in visual areas, underlie impaired visual-motor reaction time in patients. Gamma-band oscillations play an important role in visual processing and are associated with measures of cortical thickness. These oscillatory results may reflect structural differences between these two populations. Neuro-Oncology 18:iii97–iii122, 2016. doi:10.1093/neuonc/now076.92 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.