Featured Research

from universities, journals, and other organizations

Activation of brain region can change a monkey's choice

Date:
May 29, 2014
Source:
Massachusetts General Hospital
Summary:
Artificially stimulating a brain region believed to play a key role in learning, reward and motivation induced monkeys to change which of two images they choose to look at. The study confirms that stimulation of the ventral tegmental area -- a group of neurons at the base of the midbrain -- can change behavior through activation of the brain's reward system.

Artificially stimulating a brain region believed to play a key role in learning, reward and motivation induced monkeys to change which of two images they choose to look at. In experiments reported online in the journal Current Biology, researchers from Massachusetts General Hospital (MGH) and the University of Leuven in Belgium confirm for the first time that stimulation of the ventral tegmental area (VTA) -- a group of neurons at the base of the midbrain -- can change behavior through activation of the brain's reward system.

"Previous studies had correlated increased activity in the primate VTA with positive events experienced by the animal but could not prove that VTA activity actually caused behavioral changes," says Wim Vanduffel, PhD, of the Martinos Center for Biomedical Imaging at MGH, corresponding author of the Current Biology paper. "Studies in rodents have shown that artificially manipulating VTA activity strongly influences behavior, and our work has bridged the gap between rodent and primate." Vanduffel is also head of the Laboratory for Neuro- and Psychophysiology at the University of Leuven.

To investigate the direct impact of VTA activation on primate behavior, the research team used high-resolution magnetic resonance imaging to guide the placement of microelectrodes within the VTAs of macaque monkeys. In the initial set of experiments, the animals were presented with a pair of images -- for example a star and a ball -- and could freely chose to look at one image or the other, with their choice measured by their eye movement. Each animal was trained by means of a juice reward to look first at a white square at the center of the visual field and then at either of the paired images.

After establishing each animal's preference, based on which image was looked at most frequently, mild stimulation was applied to the VTA when the animal happened to look at the initially nonpreferred image. Soon the animal's preference changed, and it most frequently looked at what previously had been the less favored image. When the VTA stimulation was then applied to the initially preferred image, the monkeys soon changed their preference back to the original choice.

In a second set of experiments, after the initial image preference was established, an animal watched a 20-minute video, during which the two images were randomly presented every 5 seconds. Whenever the initially nonpreferred image was presented, it was accompanied by mild VTA stimulation. Subsequent repetition of the preference test showed that the animal's choice had shifted to the image reinforced by VTA stimulation.

Functional MR imaging taken while the animals received either a juice reward or VTA stimulation revealed that both induced activation of brain regions that previous studies in humans and other primates have associated with reward signaling by means of the neurotransmitter dopamine. The level of VTA stimulation required to activate these structures was considerably less than the amount required to reinforce or change behavior in the earlier experiments.

"Our study showed that the timing of VTA stimulation is important -- when stimulation happens immediately after an action is performed, the monkey is more likely to perform that action -- and that it applies 'value' to a particular stimulus and motivates future behavior," says Vanduffel, who is an assistant professor of Radiology at Harvard Medical School. "Other studies have implicated the VTA in learning based on negative, as well as positive reinforcement, and a recent rodent study found that increasing VTA activation can relieve depression, possibly by increasing motivated behavior. Our findings lay the groundwork for further investigation of the role of the VTA in reinforcing and regulating motivated behavior."

John Arsenault, PhD, of the Martinos Center at MGH and the University of Leuven, is first author of the Current Biology paper. Additional co-authors are Samy Rima and Heiko Stemmann, both at the University of Leuven.


Story Source:

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


Journal Reference:

  1. JohnT. Arsenault, Samy Rima, Heiko Stemmann, Wim Vanduffel. Role of the Primate Ventral Tegmental Area in Reinforcement and Motivation. Current Biology, 2014; DOI: 10.1016/j.cub.2014.04.044

Cite This Page:

Massachusetts General Hospital. "Activation of brain region can change a monkey's choice." ScienceDaily. ScienceDaily, 29 May 2014. <www.sciencedaily.com/releases/2014/05/140529142450.htm>.
Massachusetts General Hospital. (2014, May 29). Activation of brain region can change a monkey's choice. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2014/05/140529142450.htm
Massachusetts General Hospital. "Activation of brain region can change a monkey's choice." ScienceDaily. www.sciencedaily.com/releases/2014/05/140529142450.htm (accessed August 23, 2014).

Share This




More Plants & Animals News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Endangered Red Wolves Face Uncertain Future

Endangered Red Wolves Face Uncertain Future

AP (Aug. 22, 2014) A federal judge temporarily banned coyote hunting to save endangered red wolves, but local hunters say that the wolf preservation program does more harm than good. Meanwhile federal officials are reviewing its wolf program in North Carolina. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Farm Resurgence Grows With Younger Crowd

Farm Resurgence Grows With Younger Crowd

AP (Aug. 22, 2014) New England farms are seeing a surge in younger farm hands as the 'buy local' food movement grows across the country. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) According to a new study, spiders that live in cities are bigger, fatter and multiply faster. 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:

More Coverage


'Free Choice' In Primates Altered Through Brain Stimulation

May 29, 2014 When electrical pulses are applied to the ventral tegmental area of their brain, macaques presented with two images change their preference from one image to the other. The study is the first to ... read more
from the past week

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