Driving to work becomes routine--but could you drive the entire way in reverse gear? Humans, like many animals, are accustomed to seeing objects pass behind us as we go forward. Moving backwards feels unnatural.
In a new study, scientists from The Scripps Research Institute (TSRI) reveal that moving forward actually trains the brain to perceive the world normally.
Hollis Cline, PhD, is the Hahn Professor of Neuroscience and a member of the Dorris Neuroscience Center at The Scripps Research Institute.
Credit: Photo courtesy of The Scripps Research Institute
The findings also show that the relationship between neurons in the eye and the brain is more complicated than previously thought--in fact, the order in which we see things could help the brain calibrate how we perceive time, as well as the objects around us.
"We were trying to understand how that happens and the rules used during brain development," said the study's senior author Hollis Cline, who is the Hahn Professor of Neuroscience and member of the Dorris Neuroscience Center at TSRI.
This research, published this week in the journal Proceedings of the National Academy of Sciences could have implications for treating sensory processing disorders such as autism.
Reversing the Map
The new study began when Masaki Hiramoto, a staff scientist in Cline's lab, asked an important question: "How does the visual system of the brain get better "tuned" over time?"
Previous studies had shown that people use the visual system to create an internal map of the world. The key to creating this map is sensing the "optic flow" of objects as we walk or drive forward. "It's natural because we've learned it," said Cline.
To study how this system develops, Hiramoto and Cline used transparent tadpoles to watch as nerve fibers, called axons, developed between the retina and the brain. The scientists marked the positions of the axons using fluorescent proteins.
The tadpoles were split into groups and raised in small chambers. One group was shown a computer screen with bars of light that moved past the tadpoles from front to back--simulating a normal optic flow as if the animal were moving forward. A second group saw the bars in reverse--simulating an unnatural backwards motion. Using the TSRI Dorris Neuroscience Center microscopy facility, Hiramoto then captured high-resolution images of these neurons as they grew over time.
The researchers found that tadpoles' visual map developed normally when shown bars moving from front to back. But tadpoles shown the bars in reverse order extended axons to the wrong spots in their map. With those axons out of order, the brain would perceive visual images as reversed or squished.
Rewriting the Rules
This discovery challenges a rule in neuroscience that dates back to 1949. Until now, researchers knew it was important that neighboring neurons fired at roughly the same time, but didn't realize that the temporal sequence of firing was important.
"According to the old rule, if there was a stimulus that went backwards, the map would be fine," said Cline.
The new study adds the element of order. The researchers showed that objects moving from front to back in the visual field activated retinal cells in a specific sequence.
Cline and Hiramoto believe that this sequence helps the brain perceive the passage of time. For example, if you drive for a few minutes and pass a street sign, your brain will map its position behind you. If you keep driving and you pass another street sign, your brain will map out not only the street signs' positions relative to each other, but their distance in time as well.
This link between time and space in the visual system might also apply to hearing and the sense of touch. The original question of how the visual system gets "tuned" over time might be applicable across the entire brain.
The researchers believe this study could have implications for patients with sensory and temporal processing disorders, including autism and a mysterious disorder called Alice in Wonderland syndrome, where a person perceives objects as disproportionately big or small. Cline said the new study offers possibilities for retraining the brain to map the world correctly, for instance after stroke.
More information on the study, "Optic flow instructs retinotopic map formation through a spatial to temporal to spatial transformation of visual information," is available at: http://www.pnas.org/content/early/2014/11/05/1416953111.abstract
Support for the work came from the National Institutes of Health (EY011261 and DP1OD000458), the Nancy Lurie Marks Family Foundation and an endowment from the Hahn Family Foundation.
Madeline McCurry-Schmidt | EurekAlert!
Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland
Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy