Brain's timing linked with timescales of the natural visual world

Sep 05, 2007

Researchers have long attempted to unravel the cryptic code used by the neurons of the brain to represent our visual world. By studying the way the brain rapidly and precisely encodes natural visual events that occur on a slower timescale, a team of Harvard bioengineers and brain scientists from the State University of New York have moved one step closer towards solving this riddle. The findings were reported in a September 6th Nature article.

“Visual perception is limited by the relatively slow way in which the neurons in our eyes integrate light. This is why, for example, a Hollywood movie consisting of a series of flickering images appears to us as seamless motion,” explains Garrett Stanley, Associate Professor of Biomedical Engineering at the Harvard School of Engineering and Applied Sciences. “However, when the brain responds to some kind of visual event, such as a ball bouncing, the activity of the neurons responsible for sending information can be precise down to the millisecond, despite the fact that the motion of the ball is much slower.”

To determine why the brain might encode visual information with such precision, the researchers relied on data obtained by directly recording neuronal activity in animals while they viewed natural scene movies. Doing so enabled Garrett and his colleagues to pinpoint the pattern of neuronal firings in cells that respond to form and motion.

Their analysis of the data suggests that the brain’s timescale depends on the nature of the visual stimulus. In other words, the precise timing of the neurons (i.e. their internal clock) changes relative to the timescale of the visual scene. For example, a faster bouncing ball results in more precise brain activity than a slower one. In each case, however, the precision of the neurons’ activity was several times that of the speed of the bouncing ball.

It turns out that the extreme precision of the brain’s neural response to visual stimuli is, paradoxically, necessary to accurately represent the more slowly changing visual world. The neuron’s response must be more precise to recover the important aspects of the visual environment.

“We believe that this type of relative precision may be a general feature of sensory neuron communication,” says Stanley. “You can think of it like digital sampling used for audio recordings. The brain ‘digitizes’ the visual stimulus. As with digital audio recordings, for clear and representational ‘playback’, the encoding frequencies must be at least double that of the signal information.”

In future research, the researchers plan to further clarify why and how the brain encodes visual information across larger networks of cells and across functional units of the brain. They also will investigate how the visual pathway of the brain adapts to changes in the visual scene. They believe cracking the neural code will help other scientists and engineers better “communicate” with the brain. Understanding the speed at which the brain encodes information is critical for designing interfaces such as neural prosthetics, that seek to augment or replace brain function lost to trauma or disease.

Source: Harvard University

Explore further: Dual role: Key cell division proteins also power up mitochondria

add to favorites email to friend print save as pdf

Related Stories

Touch, feel, see and hear the data

Feb 14, 2014

It is now possible to sense scientific data as a means to deal with the mountains of information we face in our environment by applying subconscious processing to big data analysis

Researchers discover how squid perceive distance

Jan 21, 2014

(Phys.org) —Researchers at The University of Queensland have discovered how a species of squid perceives distance, providing an evolutionary solution to a problem divers regularly encounter in featureless ...

Social robotics: Beyond the uncanny valley

Dec 29, 2011

(PhysOrg.com) -- From science fiction and academia through assembly lines and telemedicine, robots have become both conceptually and physically ubiquitous. Technologically, robotics technology has advanced ...

Recommended for you

Proper stem cell function requires hydrogen sulfide

2 hours ago

Stem cells in bone marrow need to produce hydrogen sulfide in order to properly multiply and form bone tissue, according to a new study from the Center for Craniofacial Molecular Biology at the Herman Ostrow School of Dentistry ...

Bionic ankle 'emulates nature'

7 hours ago

These days, Hugh Herr, an associate professor of media arts and sciences at MIT, gets about 100 emails daily from people across the world interested in his bionic limbs.

Firm targets 3D printing synthetic tissues, organs

9 hours ago

(Medical Xpress)—A University of Oxford spin-out, OxSyBio, will develop 3D printing techniques to produce tissue-like synthetic materials for wound healing and drug delivery. In the longer term the company ...

User comments : 0

More news stories

Turning off depression in the brain

Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain's reward circuit and experimentally reversed it – but there's ...

Is Parkinson's an autoimmune disease?

The cause of neuronal death in Parkinson's disease is still unknown, but a new study proposes that neurons may be mistaken for foreign invaders and killed by the person's own immune system, similar to the ...