Featured Research

from universities, journals, and other organizations

Exploring The Brain's Internal Stopwatch

Date:
January 6, 2005
Source:
Cell Press
Summary:
From pouring a glass of milk to typing a news article, precise timing--down to the thousandth of a second--is key to the brain's control of movement. By studying how monkeys track a visual target, Javier Medina and his colleagues have gained new insights into the strategies that the brain uses to measure time.

From pouring a glass of milk to typing a news article, precise timing--down to the thousandth of a second--is key to the brain's control of movement. By studying how monkeys track a visual target, Javier Medina and his colleagues have gained new insights into the strategies that the brain uses to measure time. Their findings indicate that the brain measures time by assessing the duration of a process--using the internal equivalent of a neural stopwatch--as well as by computing the distance that an object being tracked has moved. However, they found that the monkeys did not use the target position as a cue about when to expect its shift to vertical motion.

Related Articles


In their experiments, the researchers trained monkeys to track a target moving horizontally across a screen. After a fixed time interval, the target would abruptly move vertically. To probe how the monkeys were judging time, the researchers would infrequently insert an instance in which the target moved only horizontally. In such cases, because of their previous experience, the monkeys would briefly shift their gaze upward at the appropriate time to pursue the expected vertical target movement.

To learn how the monkeys' brains were processing the movement information, the researchers conducted a series of experiments. The scientists measured the animals' vertical-motion eye responses when they systematically varied (1) the time interval of the horizontal motion before vertical movement, (2) the position of the target when it went vertical, and (3) the speed of horizontal target movement.

In further tests, the researchers attempted to promote the animals' learning of horizontal distance by coordinating the horizontal distance and speed so that the distance traveled remained the same.

"We concluded that the pursuit system determines when to emit a learned eye movement by keeping track of elapsed time and distance traveled by the target and that the relative contributions that these two signals make to motor timing can be influenced by the conditions in the learning trials," wrote the researchers. They concluded, thus "that this temporal precision can be achieved explicitly, by measuring the duration of a time interval, and implicitly, by keeping track of the distance a target has traveled," the wrote.

They also wrote that their findings contradict other studies suggesting that visually guided movements cannot employ an explicit representation of time. And, they wrote, "our findings seem to contradict a recent hypothesis that the neural circuits representing time explicitly might be separate from those that make use of motion signals to keep track of the passage of time. Instead, our results demonstrate that the neural circuitry driving smooth pursuit in primates has access to both time and distance cues, and it appears that these two signals are used concurrently to guide learned timing."

Javier F. Medina, Megan R. Carey, and Stephen G. Lisberger: "The Representation of Time for Motor Learning"

###

The research team includes Javier F. Medina, Megan R. Carey, and Stephen G. Lisberger of the Howard Hughes Medical Institute at University of California, San Francisco.

This work was supported by the Howard Hughes Medical Institute and grant NS34835.

Publishing in Neuron, Volume 45, Number 1, January 6, 2005, pages 157–167. http://www.neuron.org


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Exploring The Brain's Internal Stopwatch." ScienceDaily. ScienceDaily, 6 January 2005. <www.sciencedaily.com/releases/2005/01/050106120112.htm>.
Cell Press. (2005, January 6). Exploring The Brain's Internal Stopwatch. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2005/01/050106120112.htm
Cell Press. "Exploring The Brain's Internal Stopwatch." ScienceDaily. www.sciencedaily.com/releases/2005/01/050106120112.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Mind & Brain News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Tryptophan Isn't Making You Sleepy On Thanksgiving

Tryptophan Isn't Making You Sleepy On Thanksgiving

Newsy (Nov. 27, 2014) — Tryptophan, a chemical found naturally in turkey meat, gets blamed for sleepiness after Thanksgiving meals. But science points to other culprits. Video provided by Newsy
Powered by NewsLook.com
Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. Video provided by Newsy
Powered by NewsLook.com
Winter Can Cause Depression — Here's How To Combat It

Winter Can Cause Depression — Here's How To Combat It

Newsy (Nov. 23, 2014) — Millions of American suffer from seasonal depression every year. It can lead to adverse health effects, but there are ways to ease symptoms. Video provided by Newsy
Powered by NewsLook.com
Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) — Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. 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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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