Image: The border between the important brain regions hippocampus and amygdala is visible in high-resolution magnetic resonance images (MRIs) as a fine, light strip (amygdala-hippocampal border [AHB]) (Photo courtesy of AG Ball, Universität Freiburg).
Two small but very important regions situated deep and close together in the brain, the amygdala and the hippocampus, have until now been difficult to distinguish in neuroimaging studies of living humans because of their small size. Now, with the use of ultra-high-field magnetic resonance imaging (MRI) technology to tackle this difficulty, German scientists have succeeded in in revealing the border between these brain regions with extraordinary clarity.
This problem is caused by the insufficient spatial resolution of the standard imaging technology used in identifying the precise course of the fine border between the amygdala and the hippocampus. The team of Dr. Tonio Ball, from the Bernstein Center Freiburg and the Cluster of Excellence BrainLinks-BrainTools at the University of Freiburg (Germany) reported on their MRI findings online March 12, 2014, in the journal Human Brain Mapping.
The investigators examined six healthy study participants in a 7-Tesla MRI scanner at the University of Magdeburg (Germany). These scanners generate a magnetic field several times stronger than that of scanners typically utilized in clinical practice. The stronger field produces a much more detailed image of structures in the human body, however, only a few of these devices are available in Germany.
When examining their study participants in the MRI scanner, the scientists made an amazing finding: The border between the amygdala and the hippocampus was different from individual to individual, and there were differences between hemispheres of the same brain. Because this border is the place where the two regions exchange information with each other, these variations might also be responsible for disparities in personality, according to the scientists. In the future, these brain regions should be comprehensively measured when patients are examined for psychiatric conditions such as anxiety disorders.
Furthermore, the study showed that standardized maps of the brain do not make much sense in the case of the amygdala and the hippocampus. These regions must be measured individually in each patient, the scientists stated, to prevent attributing a part of brain to the wrong region, which may lead to a false diagnosis.
University of Freiburg
University of Magdeburg