A new international study is helping to map the brain, with research concentrating on seven key structures involved in learning and memory. By identifying variations in the human genome that influence the size of these structures, researchers have shed new light into a range of medical conditions including schizophrenia, Alzheimer's disease, and Tourette's syndrome.
The international meta-analysis involved almost 300 scientists and used data from 193 institutions around the world. Published in the latest edition of Nature under the consortium name ENIGMA (Enhancing Neuroimaging Genetics Through Meta-Analysis), the study used data derived from genetic studies together with the MRI scans of more than 30,000 people.
By comparing the size of brain structures with the DNA of participants, scientists developed a deeper understanding of how small variations in the brain affect behaviours such as memory and learning. “We know how the brain forms, the steps in this and the organisation of the brain but there are lots of things we don’t know,” said Prof Gary Donohoe, NUI Galway professor of psychology, adding “We were trying to understand some of the unknown biology that affects neurodevelopment. The more data you have, the more accurate the assessment of the underlying architecture of the brain.”
The study has already revealed five genetic variants that influence the size of certain brain structures. According to study co-author Dr Sarah Medland from Brisbane's QIMR Berghofer Medical Research Institute, "Many neuropsychiatric diseases and conditions, like depression and schizophrenia have effects on the regions we've studied... Improving our understanding of how these structures develop and how they function might help us work out where changes of those structures are coming from in those diseases."
Seven brain structures were studied in detail, including the putamen which is involved in body movements and learning. The research identified key genetic variants that influenced the size of these structures, with genetic variants also found to influence the overall size of the brain, the hippocampus, the amygdala (associated with memory, emotion and decision-making), and the caudate nucleus (associated with voluntary movement and learning along with memory, sleep, emotions and language).
Studies like the ENIGMA project play an essential role in identifying relationships between genetic variants and human brain development, something that would not be possible without such a large collaboration. "Each of the research groups involved in the study ran the same sequence of analysis on the data they had collected. We've combined the results of these analysis generating one of the largest imaging genetics studies to date," said Medland, adding "Research of this kind is prohibitively expensive for one institution to do, and none of this work would be possible without all of the input from scientists and participants from around the world."