The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Congruence of brain and skull in endocast reconstruction of the infant brain

LISA G. HOWELL1,2, JORDAN R. AUSTIN1, RESHA J. DESAI1, KIMBERLY K. COLE1, ERIN N. SMALLMON1, CHERYL A. HILL1, IAN D. GEORGE1, JOAN T. RICHTSMEIER2, JEFFREY L. MARSH3, ALEX A. KANE4, JAYESH PANCHAL5 and KRISTINA ALDRIDGE1.

1Pathology & Anatomical Sciences, University of Missouri School of Medicine, 2Anthropology, Pennsylvania State Univerisity, 3Plastic Surgery, St. John's Mercey Medical Center, 4Plastic Surgery, Children's Medical Center, 5Plastic Surgery, Genesis Plastic Surgery

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Endocasts provide the only means for studying brain morphology in fossil and museum specimens. However, we do not know whether endocasts reproduce brain morphology with uniform accuracy across the cranium, or whether there are regional differences in the level of detail. Further, it is also unclear whether endocasts reconstruct brain morphology in the same detail when cranial morphologies differ. Here we test two null hypotheses: 1) the space between endocranium and brain is uniformly distributed throughout the cranium, and 2) this distribution does not vary with divergent cranial morphologies.

We used 3D whole brain magnetic resonance images (MRIs) of age-matched infants between 7-80 weeks old with sagittal synostosis (N=10), right unicoronal synostosis (N=10), and infants without synostosis (N=10). We manually segmented brain and endocranial surfaces using Amira 5.2© and then collected 30 homologous landmarks from 3D surface reconstructions of brain and endocranial surfaces in etdips©. Linear distances between the paired homologous landmarks were calculated to determine localized measures of proximity of brain and endocranium. Volumes of endocranium, brain, and their difference were calculated. Results indicate that the volume of the space between endocranium and brain varies from 10-24% of total endocranial volume in all three groups. Further, there are significant localized differences in proximity between brain and endocranial surfaces both within and among the three groups. These results indicate that the relationship between the brain and skull is complex and varies with the shape of the skull. These findings should be considered when comparing endocranial morphologies among species.

Work supported in part by NIH/NIDCR R01DE018500; R01DE018500-02S1

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