3D imaging illuminates skull/brain evolution

The skull is often thought of as packaging for the brain, but a new study suggests that the skull and brain are linked developmentally and evolutionarily.

Dr. Joan T. Richtsmeier, a professor of biological anthropology at Penn State University, and colleagues from several institutions examined 3D CT scans and MR images of infants diagnosed with craniosynostosis, or premature closure of cranial sutures.

Their analysis demonstrated a strong integration of brain and skull and showed that significant associative differences between the two did not occur local to the prematurely closed suture.

"We expected to see higher correlation among those brain and skull measures that were close to each other anatomically, but we did not. We found that the stronger statistical relationships existed between neural structures located near the top of the brain and bony features at the base of the skull," Richtsmeier said.

The study represents the first empirical evidence of observed integration of brain and skull in 3D, although indirect evidence has been accumulating for years, she said.

The two types of craniosynostosis studied were early closure of the sagittal suture and unilateral coronal craniosynostosis.

Researchers had few CT and MR images to work with because they required that the two types of images be taken within a 24-hour period.

"Early brain and skull growth are so rapid that if the images were taken weeks apart, they would not be an exact fit," Richtsmeier said.

While researchers want to understand craniosynostosis, they also suggest that such an understanding can shed light on the evolution of the skull and brain - given that premature suture closure reduces the number of cranial bones and that vertebrate evolution trends toward fewer skull and jaw bones and loss of some intercranial joints.

They propose that the genetic basis of the changes documented in craniosynostosis infants may also account for the changes observed in the evolution of the skull.

The study appeared March 8, in an early online publication of the Journal of Experimental Zoology: Molecular and Developmental Evolution.

For more information from the Diagnostic Imaging archives:

Volumetric brain MR helps evaluate premature babies

Parental nurturing in neonatal ICU units helps babies survive

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