âI think about it every day and dream about it at night. It’s been five years now that it’s my whole life â, declares Enrico Amico, scientist and SNSF Ambizione Fellow at the EPFL Medical Image Processing Laboratory and at the EPFL Neuroprosthesis Center. He talks about his research on the human brain in general, and brain fingerprints in particular. He learned that each of us has a brain âfingerprintâ and that this fingerprint is constantly changing over time. Its findings have just been published in Scientists progress.
âMy research examines the networks and connections within the brain, and in particular the links between different areas, in order to better understand how things work,â says Amico. “We do this largely using MRIs, which measure brain activity over a period of time.” His research group processes scans to generate graphs, represented as colored matrices, that summarize a subject’s brain activity. This type of modeling technique is known in scientific circles as network neuroscience or brain connectomics. âAll the information we need is in these graphs, commonly known as ‘functional brain connectomes.’ The connectome is a map of the neural network. They let us know what subjects were doing during their MRI – whether they were resting or performing other tasks, for example. Our connectomes change depending on the activity being performed and the parts of the brain used, âexplains Amico.
Two scans are enough
A few years ago, neuroscientists at Yale University studying these connectomes discovered that each of us has a unique brain imprint. By comparing graphs generated from MRI scans of the same subjects taken a few days apart, they were able to correctly match the two scans of a given subject almost 95% of the time. In other words, they could accurately identify an individual based on their brain fingerprint. âIt’s really impressive because the identification was done using only functional connectomes, which are basically sets of correlation scores,â Amico explains.
He decided to go further in this discovery. In previous studies, brain fingerprints were identified using MRI scans that lasted for several minutes. But he wondered if these footprints could be identified after just a few seconds, or if there was a specific moment when they appeared – and if so, how long would that moment last? âSo far, neuroscientists have identified brain fingerprints using two MRI scans taken over a fairly long period of time. But do fingerprints actually appear after just five seconds, for example, or do they need longer? What if fingerprints from different areas of the brain appeared at different times? No one knew the answer. So we tested different timescales to see what would happen, âAmico explains.
A brain print in just 1 minute and 40 seconds
His research group found that seven seconds was not long enough to detect payload, but about 1 minute and 40 seconds were. âWe realized that the information needed to deploy a brainprint could be obtained over very short periods of time,â explains Amico. âThere’s no need for an MRI that measures brain activity for five minutes, for example. Shorter timescales might also work. His study also showed that the fastest brain fingerprints begin to appear from sensory areas of the brain, and specifically areas related to eye movement, visual perception, and visual attention. Over time, regions of the frontal cortex, those associated with more complex cognitive functions, also begin to reveal information unique to each of us.
The next step will be to compare the brain prints of healthy patients with those of patients with Alzheimer’s disease. âBased on my early findings, it seems that the characteristics that make a brain imprint unique gradually disappear as the disease progresses,â says Amico. âIt’s getting harder and harder to identify people based on their connectomes. It is as if a person with Alzheimer’s disease loses their brain identity.
Along this line, potential applications could include the early detection of neurological disorders where brain fingerprints go missing. The Amico technique can be used in patients with autism, stroke or even drug addicts. “This is just one more step towards understanding what makes our brains unique: the opportunities this idea could create are limitless.”
A success story of the FNS Ambizione program
Enrico Amico’s research was made possible thanks to an SNSF Ambizione grant. âThis unique program was able to attract a promising young researcher to Switzerland when he was a post-doctoral fellow at Purdue University,â says Professor Van De Ville, head of the medical image processing laboratory. âAmbizione enabled it to pursue its research ideas in complete independence, but also to choose fruitful collaborations with the host laboratory. It is gratifying to see these goals achieved.