Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study shows how judgment of sensory simultaneity may develop in the brain

06.06.2016

Most people encounter most things by sensing them in multiple ways. As we hear the words people speak, we also see their lips move. We smell, see and hear the onions as we chop them -- and we feel them with teary eyes.

It turns out that the ability to judge such sensory inputs as simultaneous, and therefore likely pertaining to the same thing, is something animal brains must develop through experience. A new study using tadpoles as a model organism shows how that appears to happen.


A new study in the model organism of tadpoles reveals how the brain develops the ability to sense when different sensory inputs are simultaneous rather than close in time.

Courtesy Carlos Aizenman

In making their findings, the scientists hope they can better understand how this sensory integration may sometimes go askew, perhaps contributing to disorders including autism. Some studies have suggested that difficulty merging sound and vision in some autism disorders may lead to language deficits.

"People have tried to distill how the brain detects this temporal coincidence," said study corresponding author Carlos Aizenman, a professor of neuroscience at Brown University. "We created a preparation where we could study how the different inputs are combined in a single cell and what types of brain circuits are involved."

In the study online in the journal eLife, Aizenman, lead author Daniel Felch and Bard College colleague Arseny Khakhalin were able to electrically stimulate the senses of vision and vibration in the brains of tadpoles at key stages of their neural development. They did so with very precise timing (small fractions of a second apart) and then tracked the responses of neurons in the optic tectum of the tadpole brains, where sensory information is processed and integrated. In humans and other mammals, the same part of the brain is called the superior colliculus, and neurons there do the same job.

The scientists found that sensory integration neurons in the optic tectum in relatively immature tadpole brains would become and remain excited by receiving two stimuli even if they were somewhat far apart in time. As the tadpole brains matured into later stages of development the same neural circuits would squelch their initial excitement if the sensory inputs came similarly far apart. More mature brains became better at determining when stimuli were nearly simultaneous and suppressing excitement when they weren't.

The results suggest that as tadpole brains mature, inhibitory neurons gain more sway in their balance with excitatory neurons, leading to more refined discrimination between sensory inputs that are truly simultaneous rather than merely proximate in time. In one experiment of the study, the scientists blocked inhibition. That stunted the tadpole brains' ability to discriminate.

Perturbing the process

The study illustrates, as others have as well, how sensory experiences shape the developing brain, Aizenman said.

"The brain normally starts out poorly wired," he said. "Activity in the brain sculpts the response of the brain to have a much more refined and fine-tuned function."

What's new is that the research also explains the mechanism by which that happens and shows that it can be derailed.

"The balance of excitation and inhibition in the brain is important for creating this type of temporal window," Aizenman said. "If you disrupt it, you get abnormal multisensory processing."

In future work, Aizenman said he hopes to do more of that: experiment with different ways of perturbing the process at different times during development to see what effect that may have on tadpole behaviors such as finding food or avoiding danger.

Tadpoles do not experience language, of course, but the results may still contribute, at a basic level, to generating hypotheses about how sensory integration may be affected in human development. Even though they develop somewhat differently and encounter different experiences, tadpoles and people share the same basic brain organization.

"What's important here are not the things that are different, but the things that are the same," Aizenman said. "The fundamental principles are conserved."

###

The National Science Foundation (grant IOS-1353044), the National Eye Institute (grant: 5T32-EY018080) and Brown University funded the research.

David Orenstein | EurekAlert!

More articles from Health and Medicine:

nachricht Team discovers how bacteria exploit a chink in the body's armor
20.01.2017 | University of Illinois at Urbana-Champaign

nachricht Rabies viruses reveal wiring in transparent brains
19.01.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

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...

Im Focus: Studying fundamental particles in materials

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

Quantum optical sensor for the first time tested in space – with a laser system from Berlin

23.01.2017 | Physics and Astronomy

The interactome of infected neural cells reveals new therapeutic targets for Zika

23.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>