Pigs can be used to investigate human brain development. This is the remarkable conclusion of researchers from scientists at the University of Illinois at Urbana-Champaign.
Researchers Matthew S. Conrad, Ryan N. Dilger and Rodney W. Johnson found that the large increase in brain volume in the postnatal period is similar to that of human neonates. Their findings have been published online in the scientific journal Developmental Neuroscience.
The researchers aimed to develop an animal model with brain growth similar to humans, that can be used in MRI studies to investigate brain development. Human infants can simply not be used in laboratory conditions.
The laboratory therefore developed and validated MRI methods for regional brain volume quantification in the neonatal piglet. The aim of this study was to utilise the MRI-based volume quantification technique in a longitudinal study to determine brain growth in domestic pigs from two to 24 weeks of age. MRI data were acquired from pigs two to 24 weeks of age using a three-dimensional magnetisation-prepared gradient echo sequence on a Magnetom Trio 3-tesla imager.
Manual segmentation was performed for volume estimates of total brain, cortical, diencephalon, brainstem, cerebellar and hippocampal regions. Logistic modeling procedures were used to characterize brain growth. Total brain volume increased 130% (±12%) and 121% (±7%) from two to 24 weeks in males and females, respectively. The maximum increase in total brain volume occurred about the age of four weeks and 95% of whole brain growth occurred by the age of 21–23 weeks.
Logistical modeling suggests there are sexually dimorphic effects on brain growth. For example, in females, the cortex was smaller. Furthermore, the maximum growth of the hippocampus occurred about five weeks earlier in females than males, and the window for hippocampal growth was significantly shorter in females than males.
These sexual dimorphisms are similar to what is seen in humans. In addition to providing important data on brain growth for pigs, this study shows pigs can be used to obtain longitudinal MRI data.