Early development of cortical brain responses in newborns and fetuses – cognitive studies with fetal magnetoencephalography

During early developmental stages the brain is more vulnerable to physiological insult than the more mature brain. However, an early diagnosis of deficits might enhance the chances for successful interventions due to the high cortical plasticity of the immature brain. This thesis contains two studies on early cognitive development, conducted with a device called fetal magnetoencephalography (fMEG). It allows non-invasive recordings of cortical responses in utero. Objective: Two study paradigms that assess cognitive functioning, such as integrative processes and the development of speech perception, were applied to neonates and fetuses. Methods: In study 1, brain responses to visual stimuli (VER) in a habituation paradigm were recorded in 25 fetuses (aged between 29 and 37 weeks gestational age (GA)) and 12 newborns (aged between 6 and 22 days). In study 2, auditory evoked responses (AER) to tone pairs were presented to 22 fetuses (aged between 29 and 38 weeks GA) and 15 neonates (aged between 2 and 38 days). This paradigm was applied in two difficulties – with short and long gaps between the tones. In both studies, the newborns already participated in the corresponding antecedent fetal recordings. Results: In study 1, nine of the 12 newborns showed a response decrement for consecutive visual stimuli, indicating habituation. The remaining three recordings were discontinued Early Development 7 early. The prenatal VER rate was only 29%. But these fetuses exhibited a response decrement as well. In study 2, the newborns showed a trend to 2 responses with increasing age in the long gap tone pair. The prenatal study revealed single responses in most cases and no trend was observed. However, the fetal response rate between 76% and 86% was higher than in previous studies. Conclusions: Both paradigms have been successfully applied on neonates and fetuses, and cortical responses were recorded with fMEG technology. Despite the challenges in fetal data analysis, these investigations might help to improve future study paradigms and technological advances. Significance: These studies might contribute to a more accurate detection of early developmental delays and the development of subsequent impairments. Early Development 8 ACKNOWLEDGEMENTS The present investigations were conducted at the University of Arkansas for Medical Sciences (UAMS) in Little Rock, Arkansas, in close collaboration with the MEG Center in Tubingen, Germany. Both were funded by the National Institutes of Health (NIH). I express deepest thanks to my supervisor Dr. Hubert Preissl, who always provided great support and encouragement beyond the standard requirements. I am very grateful to the people from the SARA Lab, who continuously offered their personal and professional advice with patience and warmth: Dr. Hari Eswaran, Maureen Ware, Pamela Murphy, Dr. Joshua Campbell, Dr. Isabelle Kiefer, Mike Oglesby, Eric Siegel and Dr. Curtis Lowery. I express my sincere thanks to Dr. Karin Landerl and Professor Dr. Niels Birbaumer for their help and support. I am indebted to Dr. Rossitza Draganova, who was very helpful with professional and personal advice. Early Development 9 Last but not least, I thank my family and friends who are always there for me, inspire me, support me, or just listen: my husband, Jeff Sheridan, my parents, Werner and Angelika Schaller, my friends, Stephanie Bald, Bianca Puppatti, Kirsten Lindner, Yvonne Zahumensky and Cornelia Weber. December, 2007 Carolin J. Sheridan Early Development 10 -