A newly-developed mathematical method can detect geometric structure in neural activity in the brain. "Previously, in order to understand this structure, scientists needed to relate neural activity to some specific external stimulus," said Vladimir Itskov, associate professor of mathematics at Penn State University.
"Our method is the first to be able to reveal this structure without our knowing an external stimulus ahead of time. We've now shown that our new method will allow us to explore the organizational structure of neurons without knowing their function in advance."
"The traditional methods used by researchers to analyze the relationship between the activities of neurons were adopted from physics," said Carina Curto, associate professor of mathematics at Penn State, "but neuroscience data doesn't necessarily play by the same rules as data from physics, so we need new tools. Our method is a first step toward developing a new mathematical toolkit to uncover the structure of neural circuits with unknown function in the brain."
The method -- clique topology -- was developed by an interdisciplinary team of researchers at Penn State, the University of Pennsylvania, the Howard Hughes Medical Institute, and the University of Nebraska-Lincoln. The method is described in a paper that will be posted in the early online edition of the journal Proceedings of the National Academy of Sciences during the week ending October 23, 2015.
"We have adopted approaches from the field of algebraic topology that previously had been used primarily in the domain of pure mathematics and have applied them to experimental data on the activity of place cells -- specialized neurons in the part of the brain called the hippocampus that sense the position of an animal in its environment," said Curto.
The researchers measured the activity of place cells in the brains of rats during three different experimental conditions. They then analyzed the pairwise correlations of this activity -- how the firing of each neuron was related to the firing of every other neuron.
In the first condition, the rats were allowed to roam freely in their environment -- a behavior where the activity of place cells is directly related to the location of the animal in its environment. They searched the data to find groups of neurons, or "cliques," in which the activity of all members of the clique was related to the activity of every other member. Their analysis of these cliques, using methods from algebraic topology, revealed an organized geometric structure. Surprisingly, the researchers found similar structure in the activities among place cells in the other two conditions they tested, wheel-running and sleep, where place cells are not expected to have geometric organization.
"Because the structure we detected was similar in all three experimental conditions, we think that we are picking up the fundamental organization of place cells in the hippocampus," said Itskov.
In addition to Itskov and Curto, other members of the research team include Chad Giusti at the University of Pennsylvania and Eva Pastalkova at the Howard Hughes Medical Institute.
The research was supported by the National Science Foundation (grant numbers DMS 1122519, DMS 122566, and DMS 1537228), the Alfred P. Sloan Foundation, the Defense Advanced Research Projects Agency Young Faculty Award (grant number W911NF-15-1-0084), and the Howard Hughes Medical Institute.
Vladimir Itskov: firstname.lastname@example.org
Carina Curto: email@example.com
Barbara Kennedy (PIO): firstname.lastname@example.org, (+1) 814-863-4682
This press release will be archived online at http://science.
Barbara K. Kennedy | EurekAlert!
Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg
Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy