Clouds in the head
A new model of the brain's thought processes explains the apparently chaotic activity patterns of individual neurons.
They do not correspond to a simple stimulus/response linkage, but arise from the networking of different neural circuits. Scientists funded by the Swiss National Science Foundation (SNSF) propose that the field of brain research should expand its focus.
Many brain researchers cannot see the forest for the trees. When they use electrodes to record the activity patterns of individual neurons, the patterns often appear chaotic and difficult to interpret. “But when you zoom out from looking at individual cells, and observe a large number of neurons instead, their global activity is very informative,” says Mattia Rigotti, a scientist at Columbia University and New York University who is supported by the SNSF and the Janggen-Pöhn-Stiftung. Publishing in “Nature” together with colleagues from the United States, he has shown that these difficult-to-interpret patterns in particular are especially important for complex brain functions.
What goes on in the heads of apes
The researchers have focussed their attention on the activity patterns of 237 neurons that had been recorded some years previously using electrodes implanted in the frontal lobes of two rhesus monkeys. At that time, the apes had been taught to recognise images of different objects on a screen. Around one third of the observed neurons demonstrated activity that Rigotti describes as “mixed selectivity”. A mixed selective neuron does not always respond to the same stimulus (the flowers or the sailing boat on the screen) in the same way. Rather, its response differs as it also takes account of the activity of other neurons. The cell adapts its response according to what else is going on in the ape’s brain.
Chaotic patterns revealed in context
Just as individual computers are networked to create concentrated processing and storage capacity in the field of Cloud Computing, links in the complex cognitive processes that take place in the prefrontal cortex play a key role. The greater the density of the network in the brain, in other words the greater the proportion of mixed selectivity in the activity patterns of the neurons, the better the apes were able to recall the images on the screen, as demonstrated by Rigotti in his analysis. Given that the brain and cognitive capabilities of rhesus monkeys are similar to those of humans, mixed selective neurons should also be important in our own brains. For him this is reason enough why brain research from now on should no longer be satisfied with just the simple activity patterns, but should also consider the apparently chaotic patterns that can only be revealed in context.
(*) Mattia Rigotti, Omri Barak, Melissa R. Warden, Xiao-Jing Wang, Nathaniel D. Daw, Earl K. Miller, and Stefano Fusi (2013). The importance of mixed selectivity in complex cognitive tasks. Nature online. doi: 10.1038/nature12160
(Manuscript available from the SNSF; e-mail: firstname.lastname@example.org)
Dr Mattia Rigotti
Center for Theoretical Neuroscience
New York, USA
Tel: +1 212 543 5965
Media - Abteilung Kommunikation | idw
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...