When neurons fire up: Study sheds light on rhythms of the brain

August 05, 2008

BLOOMINGTON, Ind. -- In our brains, groups of neurons fire up simultaneously for just milliseconds at a time, in random rhythms, similar to twinkling lightning bugs in our backyards. New research from neuroscientists at Indiana University and the University of Montreal provides a model -- a rhyme and reason -- for this random synchronization.

The findings, both of which appear in the Journal of Neuroscience this week, draw on the variability and creative nature of neurons -- no two are exactly the same, providing for a rich and ever-changing repertoire of brain activity. The findings expand scientists' understanding of brain rhythms, both reoccurring and random, and shed light on the decades-old mystery of how the brain learns temporal patterns.

"Our model is proposing a way that the brain processes temporal information and how this can vary over time" said Jean-Philippe Thivierge, a post-doctorate researcher in IU Bloomington's Department of Psychological and Brain Sciences.

A better understanding of rhythms in the brain -- how to create them or stop them -- would help researchers studying such neural diseases as epilepsy, which involves seizures or uncontrollable rhythms in the brain.

Thivierge and co-author Paul Cisek, an assistant professor at the University of Montreal, created a mathematical model for how hundreds of neurons interact after being stimulated by an electric current. They propose that the random synchronization, which occurs in large populations of neurons, results from "positive excitatory feedback originating from recurrent connections between the cells."

The synchronization involves most of the cells in the group but begins with a preferred small group of cells -- like "elite" cells -- that tend to become active just before all the others do. When enough cells in the group become active, a threshold, or "point of no return" is reached where all the cells become active and their activity spikes.

The study also demonstrates how neural activity can spike periodically or rhythmically. When researchers introduced a specific rhythm to the model, they discovered that the model could learn and repeat the rhythm. Scientists have known for 50 years that the brain could do this, but the mechanism was unknown until now. Thivierge said the mechanism is based on how the neurons come together to motivate each other to fire in a specific, periodic way, following the rhythmic stimuli.

The spontaneous neural activity modeled in this study has been detected in several regions of the brain as well as in other species. The authors conjecture that the benefits of such spontaneity come in the brain's ability to be more flexible and responsive to external events, that the random synchronization can prevent the brain from remaining "stuck" in a particular state.

"It seems like when you're in a more flexible brain state, it's easier for you to redirect your attention to new and important things," Thivierge said.
-end-
The study was supported by the Fonds Québéçois de Recherche sur la Nature et les Technologies (FQRNT), the National Science and Engineering Research Council (NSERC) and the Fonds de Recherche en Santé du Québec (FRSQ).

For a copy of the study, contact Tracy James at 812-855-0084 and traljame@indiana.edu.

Thivierge can be reached at jthivier@indiana.edu or by contacting James.

"Nonperiodic Synchronization in Heterogeneous Networks of Spiking Neurons," The Journal of Neuroscience, Aug. 6, 28 (32).

Indiana University

Related Neurons Articles from Brightsurf:

Paying attention to the neurons behind our alertness
The neurons of layer 6 - the deepest layer of the cortex - were examined by researchers from the Okinawa Institute of Science and Technology Graduate University to uncover how they react to sensory stimulation in different behavioral states.

Trying to listen to the signal from neurons
Toyohashi University of Technology has developed a coaxial cable-inspired needle-electrode.

A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.

Extraordinary regeneration of neurons in zebrafish
Biologists from the University of Bayreuth have discovered a uniquely rapid form of regeneration in injured neurons and their function in the central nervous system of zebrafish.

Dopamine neurons mull over your options
Researchers at the University of Tsukuba have found that dopamine neurons in the brain can represent the decision-making process when making economic choices.

Neurons thrive even when malnourished
When animal, insect or human embryos grow in a malnourished environment, their developing nervous systems get first pick of any available nutrients so that new neurons can be made.

The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.

Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.

How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.

A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.

Read More: Neurons News and Neurons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.