March 15, 2013
Pig Brain Atlas Developed To Provide Clues Into Human Cognitive Development
Alan McStravick for redOrbit.com - Your Universe Online
On February 12, President Obama unveiled an ambitious project intended to map out the activity of the human brain that will be undertaken on the same size and scope as the hugely successful Human Genome Project undertaken in the 1990s. Researchers from the University of Illinois have offered the results of a recent study which may play a role in helping to lay the groundwork for this future endeavor into exactly how the human brain functions and operates.
In order to conduct their study, animal scientists Rod Johnson and Ryan Dilger effectively developed a model of the pig brain which they intend to use to help answer important questions related to the early development of the human brain.
"It is important to characterize the normal brain growth trajectory from the neonatal period to sexual maturity," said Johnson.
"Until we know how the brain grows, we don't know what is going to change," added Dilger.
The two University of Illinois researchers worked in collaboration with the Beckman Institute to obtain data through the use of MRI scans on the brains of 16 piglets. The MRIs were administered at the ages of 2 weeks, 4 weeks, and then again every 4 weeks until the piglets were 24 weeks old.
"We have world-class people at the Beckman Institute who are pushing and developing the next generation of neuroimaging technology, so we're able to connect with them and take advantage of their expertise," said Johnson.
Assisting in the study was Matt Conrad, a student in Johnson´s lab. Conrad utilized 3D visualization software to analyze more than 200 individual images. From this analysis, he was able to manually segment each region of the piglet brains on three planes. The software used was able to combine the collected data to create a three-dimensional image of the piglet brains, allowing the research team to determine the individual volume of the different structures.
Other tests were performed on the piglets while they were at the Beckman Institute for their MRI scans. Dilger subjected the animals to diffusion tensor imaging (DTI). Through the use of DTI, the team was able to observe just how neural tracks develop. The importance of this information helps in allowing for in depth exploration of brain complexity and how neurons form. Additionally, the team was able to measure such neurochemicals as creatine and acetylcholine in the brain. Knowing the concentration of these neurochemicals helps the researchers achieve a unique insight into the brain´s metabolism.
The culmination of all of the data collection resulted in what the team is calling the deformable pig brain atlas.
"It's called a deformable brain atlas because the software takes information from an individual and deforms it until it fits the template, and then you know how much it had to be deformed to fit," Johnson explained. "So from that, you can tell whether a brain region is larger or smaller compared to the average."
"We are taking 16 pigs and averaging them, so it's more representative of all pigs," said Dilger. "You can then apply it to any individual pig to see how it's different."
Ultimately, both Johnson and Dilger state the goal of their research is to develop a tool for pigs that is similar to what has already been developed with regard to the mouse brain. Once completed, they intend to make their tool publicly available for future research endeavors. However, they claim they do not expect their study will stop once a pig-specific tool is developed.
"We want to use this to address important questions," Johnson said.
The results of their study entitled “Brain growth of the domestic pig (Sus scrofa) from 2 to 24 weeks of age: a longitudinal MRI study” has been published in the journal Developmental Neuroscience.
In addition to creating the 3D model of the piglet brains, the team in Johnson´s lab also pursued an additional research direction. In the lab, the team was able to induce viral pneumonia in the piglets at the exact point in time of the post-natal period. It is during this time the brain experiences a period of massive growth. The use of viral pneumonia helped the team to observe how both brain growth and development were altered. Also, the researchers looked at the effects of prenatal infection in the mother. The purpose was to learn if prenatal infection could change the trajectory of normal brain growth in the offspring. While it is known that the likelihood of developing behavioral disorders and reduced stress resilience are greatly increased by pre- and post-natal infection, the reasoning behind why this occurs is currently poorly understood by scientists.
While Johnson´s team is looking at the effects of early infection and its role in brain development, Dilger and his team are focusing on early-life nutrition and how it can positively or negatively affect brain growth and development. Specifically, they are exploring how specific fatty acids act as primary structural components of the human brain and cerebral cortex. Additionally, they explored the effects of choline which is a nutrient known to be important for the production of DNA and normal functioning neurons.
"Choline deficiency has been tied to cognitive deficits in the mouse and human, and we're developing a pig model to study the direct effects choline deficiency has on brain structure and function," Dilger said. "Many women of child-bearing age may not be receiving enough choline in their diets, and recent evidence suggests this may ultimately affect learning and memory ability in their children. Luckily, choline can be found in common foods, especially eggs and meat products, including bacon.”
Through the collaborative efforts of these individual research groups, great strides are being made in achieving an improved understanding of the early brain development of pigs. The results, if able to be translated to the human brain, will be important for future brain studies.