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

September 5, 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: Elementary neural processing units that tile the mouse brain

Related Stories

Elementary neural processing units that tile the mouse brain

November 6, 2017
A hexagonal lattice organizes major cell types in the cerebral cortex, researchers in Japan have discovered. The pattern repeats across the brain, with similar cells synchronizing their activity in 'microcolumns', which could ...

Navigation system of brain cells decoded

October 25, 2017
The human brain contains roughly 100 billion neurons. Information among them is transmitted via a complex network of nerve fibers. Hardwiring of most of this network takes place before birth according to a genetic blueprint, ...

Novel technology ties brain circuits to alertness

November 2, 2017
Stanford University investigators have for the first time tied several brain circuits to alertness.

Novel technology provides powerful new means for studying neural circuits

October 26, 2017
Finding out which neurons are connected with which others, and how they act together, is a huge challenge in neuroscience, and it's crucial for understanding how brain circuits give rise to perception, motion, memory, and ...

Running on autopilot: Scientists find important new role for 'daydreaming' network

October 23, 2017
A brain network previously associated with daydreaming has been found to play an important role in allowing us to perform tasks on autopilot. Scientists at the University of Cambridge showed that far from being just 'background ...

Radical approach to migraine prevention

November 7, 2017
Cutting-edge work by Perth researchers may provide relief to tens of millions of migraine sufferers—with nothing more than a course of vitamins.

Recommended for you

Researchers discover key signaling protein for muscle growth

November 20, 2017
Researchers at the University of Louisville have discovered the importance of a well-known protein, myeloid differentiation primary response gene 88 (MyD88), in the development and regeneration of muscles. Ashok Kumar, Ph.D., ...

New breast cell types discovered by multidisciplinary research team

November 20, 2017
A joint effort by breast cancer researchers and bioinformaticians has provided new insights into the molecular changes that drive breast development.

Brain cell advance brings hope for Creutzfeldt-Jakob disease

November 20, 2017
Scientists have developed a new system to study Creutzfeldt-Jakob disease in the laboratory, paving the way for research to find treatments for the fatal brain disorder.

Hibernating ground squirrels provide clues to new stroke treatments

November 17, 2017
In the fight against brain damage caused by stroke, researchers have turned to an unlikely source of inspiration: hibernating ground squirrels.

Age and gut bacteria contribute to multiple sclerosis disease progression

November 17, 2017
Researchers at Rutgers Robert Wood Johnson Medical School published a study suggesting that gut bacteria at young age can contribute to multiple sclerosis (MS) disease onset and progression.

Molecular guardian defends cells, organs against excess cholesterol

November 16, 2017
A team of researchers at the Harvard T. H. Chan School of Public Health has illuminated a critical player in cholesterol metabolism that acts as a molecular guardian in cells to help maintain cholesterol levels within a safe, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.