Presenters: Rosemary Mwithiga ; Youssef Harraq
Authors: Youssef Harraq, Rosemary Mwithiga, Zakary Harrah, Amy Richards, Arianna Harrington
Faculty Advisor: Arianna Harrington
Institution: Dixie State University
Relative to other primate species, human infants are born with relatively small brains compared to adult brain size. A classic explanation is the “Obstetric Dilemma” hypothesis, which proposes a tradeoff between infant head size and maternal locomotor efficiency. A more recent hypothesis is “Energetic of Gestation and Fetal Growth” hypothesis, which proposes that the timing of human birth coincides with when the maternal body is energetically no longer able to sustain the growth of the fetus. While the human brain has been documented to be one of the most energetically costly organs to grow and maintain after birth, its metabolic rate in utero is poorly known. This project aims to estimate metabolic rates of the fetal brain using anatomical measurements obtained from the carotid canal (CC) in a sample of 9 fetal skulls ranging from 6 months to 8.5 months old. The CC carries the internal carotid artery (ICA), which is a major source of blood to the brain. Previous studies have demonstrated that ICA blood flow is correlated to CC size and ICA blood flow rate is correlated to brain metabolic rate. 3D models of the cast of the CC and the endocranium (which houses the brain) were generated from CT scans of skeletal specimens from the Hamann-Todd collection of the Cleveland Museum of Natural History to document ontogenetic changes in the size of the fetal CC and brain. Anticipated methods include using the radius of the CC and a modified version of the Hagen-Poiseuille equation to estimate ICA blood flow rate and comparing them to umbilical blood flow rates (a proxy for total body metabolism). Brain size will also be compared to those of other organs during late fetal development to test the hypothesis that there is a tradeoff between the growth of the brain and other organs.