Featured Research

from universities, journals, and other organizations

Brain's balancing act discovered: Wiring determines if neurons communicate

Date:
June 22, 2014
Source:
University of California, San Diego Health Sciences
Summary:
A fundamental mechanism by which the brain maintains its internal balance has been discovered by researchers. The mechanism involves the brain's most basic inner wiring and the processes that control whether a neuron relays information to other neurons or suppresses the transmission of information.

This fluorescent image shows excitatory neurons in green and inhibitory neurons in magenta.
Credit: UC San Diego School of Medicine

Researchers at the University of California, San Diego School of Medicine have discovered a fundamental mechanism by which the brain maintains its internal balance. The mechanism, described in the June 22 advanced online publication of the journal Nature, involves the brain's most basic inner wiring and the processes that control whether a neuron relays information to other neurons or suppresses the transmission of information.

Specifically, the scientists have shown that there is a constant ratio between the total amount of pro-firing stimulation that a neuron receives from the hundreds or thousands of excitatory neurons that feed into it, and the total amount of red-light stop signaling that it receives from the equally numerous inhibitory neurons.

This constant ratio, called the E/I ratio, was known to exist for individual neurons at a given time. This study goes a step further and shows that the E/I ratio is constant across multiple neurons in the cortex of mice and likely also humans, since the fundamental architecture of mammalian brains is highly conserved across species.

"Neurons in our brain drive by pushing the brake and the accelerator at the same time," said Massimo Scanziani, PhD, professor of neurosciences, Howard Hughes Medical Institute investigator and co-author. "This means that there is no stimulus that you can apply that will activate purely excitatory neurons or purely inhibitory ones."

"There is always a tug-of-war. It's weird but very clever. It allows the brain to exert very subtle control on our response to stimuli." For example, Scanziani said it prevents both runaway neuronal firing (excitation) and permanent quiescence (inhibition) because excitation and inhibition are always coupled.

In experiments, the scientists also showed how the brain maintains a constant E/I ratio across neurons: The adjustment is carried out by the inhibitory neurons through the appropriate strengthening or weakening of inhibitory synapses. A synapse is the gap or juncture between two neurons and synaptic strength refers to the degree to which a passed signal is amplified in the juncture.

"Our study shows that the inhibitory neurons are the master regulators that contact hundreds or thousands of cells and make sure that the inhibitory synapses at each of these contacts is matched to the different amounts of excitation that these cells are receiving," Scanziani explained. If, for example, the level of excitatory stimulation that a nerve cell is receiving is doubled, the inhibitory synapses over a period of a few days will also double their strength.

In terms of clinical applications, the scientists said that neurological diseases such as autism, epilepsy and schizophrenia are believed to be a problem, at least in part, of the brain's ability to maintain an optimal E/I ratio.

"If this E/I balance is broken, it completely alters your perception of the world," Scanziani said. "You will be less able to adjust and adapt appropriately to the range of stimulation in a normal day without being overwhelmed or completely oblivious, and E/I imbalances may be most easily noticed in social interactions because these interactions require such nuance and subtle adjusting."

Scientists have also proposed that some neurodegenerative diseases, such as Parkinson's and Huntington's disease, may be associated with a shift in the E/I balance.

Minghan Xue, a postdoctoral researcher in neurobiology and the study's lead author, said "now that we know how this E/I balance is regulated in a normal brain, we can begin to understand what goes wrong in the diseased state. It paves the way for interventions that might restore the balance in the brain."


Story Source:

The above story is based on materials provided by University of California, San Diego Health Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mingshan Xue, Bassam V. Atallah, Massimo Scanziani. Equalizing excitation–inhibition ratios across visual cortical neurons. Nature, 2014; DOI: 10.1038/nature13321

Cite This Page:

University of California, San Diego Health Sciences. "Brain's balancing act discovered: Wiring determines if neurons communicate." ScienceDaily. ScienceDaily, 22 June 2014. <www.sciencedaily.com/releases/2014/06/140622142118.htm>.
University of California, San Diego Health Sciences. (2014, June 22). Brain's balancing act discovered: Wiring determines if neurons communicate. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140622142118.htm
University of California, San Diego Health Sciences. "Brain's balancing act discovered: Wiring determines if neurons communicate." ScienceDaily. www.sciencedaily.com/releases/2014/06/140622142118.htm (accessed July 31, 2014).

Share This




More Mind & Brain News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dieting At A Young Age Might Lead To Harmful Health Habits

Dieting At A Young Age Might Lead To Harmful Health Habits

Newsy (July 30, 2014) Researchers say women who diet at a young age are at greater risk of developing harmful health habits, including eating disorders and alcohol abuse. Video provided by Newsy
Powered by NewsLook.com
It's Not Just Facebook: OKCupid Experiments With Users Too

It's Not Just Facebook: OKCupid Experiments With Users Too

Newsy (July 29, 2014) If you've been looking for love online, there's a chance somebody has been looking at how you're looking. Video provided by Newsy
Powered by NewsLook.com
How Your Face Can Leave A Good Or Bad First Impression

How Your Face Can Leave A Good Or Bad First Impression

Newsy (July 29, 2014) Researchers have found certain facial features can make us seem more attractive or trustworthy. Video provided by Newsy
Powered by NewsLook.com
Losing Sleep Leaves You Vulnerable To 'False Memories'

Losing Sleep Leaves You Vulnerable To 'False Memories'

Newsy (July 27, 2014) A new study shows sleep deprivation can make it harder for people to remember specific details of an event. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins