Children diagnosed with Fetal Alcohol Spectrum Disorder (FASD) exhibit a range of physical, perceptual, cognitive, emotional and behavioral deficits that result from underlying neurobiological damage following prenatal alcohol exposure. The human neocortex, the part of the brain responsible for many of these functions, is a likely location of ethanol-induced alterations to the developing nervous system. To investigate the impact of prenatal ethanol exposure (PrEE) on functional anatomy of the neocortex, we created an FASD mouse model in the CD-1 strain. In our preliminary studies, we found disrupted targeting of motor and sensory intraneocortical connections (INCs) in newborn PrEE mice. Sensory and motor INCs represent a complex neural circuit that regulates behavior, attention and integrates sensori-motor processing. The aberrant developmental targeting of INCs in neocortex may reflect a disorganized circuit or altered cortical area boundaries, as we observed abnormal anatomical connections between the frontal and occipital lobes on the day of birth. In this two-year research proposal, we begin an in-depth analysis of the phenotype throughout the lifespan of our murine model. We plan to first examine potential mechanisms underlying the abnormal INC development. As cortical gene expression has been shown to regulate INC development (Huffman et al., 2004, Dye et al., 2011a, 2011b) we will identify early patterning of 7 genes, including RZR-ss, Id2, Cad8, Ephrin A5, Eph A7, COUP-TFI and Lhx2, in the neocortex of the PrEE mice. Next, we will extend our analyses of INCs, gene expression and anatomical staining to determine whether the phenotype persists in postnatal ages (including postnatal day (P) 0, 6, 10, 20, 50, 90 and 365). Finally, we will conduct multi-unit electrophysiological recording experiments in the neocortex of PrEE mice aged from P50 to P365 to determine the location of functional boundaries and internal features of sensory (Visual, Somatosensory and Auditory) and motor cortical areas. All data obtained in PrEE mice will be compared to age matched controls. We believe that the profoundly abnormal neocortical wiring observed in ethanol-exposed newborn mice may represent an underlying substrate for many perceptual, cognitive, emotional and behavioral deficits observed in children with FASD. Thus, the mechanisms underlying this phenotype must be explored, and the long-term postnatal impact on the anatomy and physiology in the brain of the animal must be determined.
Fetal Alcohol Syndrome and Spectrum Disorders (FAS, FASD) in children are caused by exposure to ethanol during the prenatal period, when higher-level brain structures like the neocortex are developing. Prenatal exposure to ethanol via maternal consumption is the leading preventable cause of mental retardation in the US. This study identifies genetic, anatomical and functional changes in neocortex that occur as a result of prenatal ethanol exposure, and highlights how these changes in brain development may generate some of the cognitive and behavioral problems observed in children diagnosed with FAS or FASD.
|Abbott, Charles W; Kozanian, Olga O; Kanaan, Joseph et al. (2016) The Impact of Prenatal Ethanol Exposure on Neuroanatomical and Behavioral Development in Mice. Alcohol Clin Exp Res 40:122-33|
|El Shawa, Hani; Abbott 3rd, Charles W; Huffman, Kelly J (2013) Prenatal ethanol exposure disrupts intraneocortical circuitry, cortical gene expression, and behavior in a mouse model of FASD. J Neurosci 33:18893-905|