By combining sophisticated mathematical techniques more commonly used by spies instead of scientists with the power and versatility of functional magnetic resonance imaging (fMRI), a Penn neurologist has developed a new approach for studying the inner workings of the brain.
A hidden pattern is encoded in the seemingly random order of things presented to a human subject, which the brain reveals when observed with fMRI. The research is published in the journal NeuroImage.
University of Pennsylvania scientists have shown that the mathematics used to find an efficient route through a complicated, connected network can be used to decode how the brain represents information.
Geoffrey K. Aguirre, MD, Assistant Professor of Neurology at the University of Pennsylvania School of Medicine, says “the same math that could break into your car can be used to crack the brain’s codes.” It’s called a de Bruijn sequence, which is a set or “alphabet” of things (letters, pictures, sounds) in a cyclic order such that every possible “word” or combination of things occurs only once. De Bruijn sequences are what mathematicians call “pseudo-random” because they appear to be a confused jumble but actually contain an underlying structure. To break into a car protected by an electronic lock with a five-digit numerical keycode, for example, a thief could try every possible combination. However, such a brute-force technique is time-consuming because it involves a great deal of repetition. But a de Bruijn sequence uses “every possible combination squeezed together,” explains Aguirre. The overlapping combinations encode a pattern scientists can observe in brain activity using fMRI, revealing how nerve cells work to represent the world.Breaking Codes in Brain Studies
Previous experiments have presented information to study participants in more or less completely random order. This can be inefficient and inaccurate, making it difficult to discern important patterns and correlations between stimuli and neural responses. “We use the de Bruijn sequence to design the experiment,” Aguirre says. “It tells us how to present things to the subject. By presenting a series of faces in different combinations and orders, as dictated by the de Bruijn sequence, it’s possible to measure the brain response to each face individually.”
“The amazing thing is the person in the experiment just sees random pictures,” Aguirre notes. “But in fact, we’re hiding in this seemingly random sequence a signal that’s invisible to the person but can be decoded by the MRI scanner. We can measure the nerve cells’ response to that hidden pattern and then use that to understand how the brain is representing information.”
Aguirre’s unique marriage of advanced mathematics with the latest neuroimaging techniques promises to both open up new areas of research and improve current experimental designs in the study of the brain. The next step is to apply the new algorithm to actual fMRI studies in one of Aguirre’s special research areas, visual perception and representation in the brain.For More Information
Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4 billion enterprise.
Penn's School of Medicine is currently ranked #2 in U.S. News & World Report's survey of research-oriented medical schools and among the top 10 schools for primary care. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $507.6 million awarded in the 2010 fiscal year.
The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania â€“ recognized as one of the nation's top 10 hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; and Pennsylvania Hospital – the nation's first hospital, founded in 1751. Penn Medicine also includes additional patient care facilities and services throughout the Philadelphia region.
Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2010, Penn Medicine provided $788 million to benefit our community.
Kim Menard | EurekAlert!
A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg
Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction