Movement-related neuromagnetic fields in preschool age children

• ¹ Hospital for Sick Children, Neurosciences and Mental Health, Canada
• ² University of Toronto, Medical Imaging, Canada
• ³ Macquarie University, Department of Cognitive Science, Australia
• ⁴ Macquarie University, ARC Centre of Excellence in Cognition and Its Disorders, Australia
• ⁵ Macquarie University, Department of Linguistics, Australia

We report the first recordings of movement-related brain activity in preschool age children using a custom-sized pediatric MEG system. A videogame-like task was used to generate self-initiated right or left index finger movements in seventeen healthy right-handed preschool age children (8 female, ages 3.2 to 4.8 years). Using beamformer source analysis and a surrogate MRI normalization procedure, we were able to identify sources of movement-related brain activity, including pre-movement motor fields and transient movement-evoked fields (MEFs), in the contralateral sensorimotor cortex. However, both motor fields and movement-evoked fields demonstrated different timing and polarity in comparison to adults, similar to that observed for somatosensory and auditory evoked responses during early development. In addition, the timing and frequency of movement induced oscillatory activity differed from the typical adult pattern, with greater co-modulation of mu and beta rhythms at lower peak frequency. Transient high-frequency gamma oscillations in motor cortex were observed at movement onset, similar to that observed in adults, but with some children also showing bursts in the lower gamma range. We also observed a movement-locked activation of the right superior temporal gyrus for both left and right movements, which has not been previously reported in adults. These findings indicate that basic sensorimotor activation patterns are markedly different in children prior to 5 years of age, and are undergoing maturational changes from early to later childhood. Such changes have implications for both early brain development and our understanding of the role of this activity in normal and abnormal cognitive development. Supported by grants from the Australian Research Council to S.C. and B.J. (LEO668421, LP0669471), CE110001021), NSERC of Canada to D.C. (RGPIN 184018) and the Kanazawa Institute of Technology.