Study Finds How the Brain Interprets the Intent of Others

Study Finds How the Brain Interprets the Intent of Others

Two Dartmouth researchers
have learned more about
how the human brain interprets
the actions and intentions of others.

Scott Grafton, professor of psychological and brain sciences, and Antonia Hamilton, a post-doctoral fellow, have learned that the brain's parietal cortex handles how we understand the goals of other people's actions.

Their study was published on January 25 by The Journal of Neuroscience.

"We were able to find the part of the brain involved in interpreting the goal of another person, even if no words are spoken," says Hamilton. "When you see another person reach for an object that they want, like a cookie, a bit of brain called the anterior intraparietal sulcus, which is found in the parietal lobe, is strongly activated."

She explains that their result is surprising because many would have predicted that the frontal cortex, normally associated with language and understanding, would be activated in this situation, not the parietal cortex, usually thought to be involved with space and movement. Also, Hamilton says that with this study, they have shown it's possible to localize abstract things, like goals, in the brain.

"So, as we learn more about how the brain responds to seeing other people do things, we can start to understand the neural basis of human social interactions. This may help us understand what goes wrong in impaired social interactions, like in children with autism, who sometimes fail to interpret actions correctly."

The study involved twenty participants who watched a series of short movies, shown in a random order, while their brain activity was measured by functional magnetic resonance imaging (fMRI). The movies depicted a hand reaching, grasping, and taking one of two objects. For example, a hand takes a cookie or takes a computer disk. The participants then answered yes or no questions that elicited their understanding of the goals involved of the actions represented in movies.

Source: Dartmouth College








Key Signaling Molecule In The Brain That Appears To Trigger The Brain To "learn" A Craving

17 Feb 2006


Researchers have identified a key signaling molecule in the brain that appears to trigger the brain to "learn" a craving for cocaine. Their finding could offer an important target for drugs to treat addiction by short-circuiting that adaptive process.

In an article in the February 16, 2006, issue of Neuron, Antonello Bonci and colleagues established that a short protein, or peptide, called orexin A acts on a brain region central to the adaptation to addictive drugs. Specifically, they found in their studies with rats that orexin A induces an adaptation that is necessary for the development of behaviors associated with drug-craving in human addicts. The latest findings follow an earlier discovery by the same group that another molecule, corticotropin releasing factor (CRF), acts similarly.

Such adaptations are believed to create a need that is far more compelling than the simple memory of drug-induced pleasure and represent a "rewiring" of the brain into an addictive state.

In a preview article on the paper in the same issue of Neuron, NIH neuroscientist Roy Wise commented that "Inasmuch as arousal or stress can trigger drug-seeking in drug-free animals, the neuroadaptations discovered by the Bonci group are important not only for how rewarding the drug is after an animal starts taking it, but, perhaps more importantly, for how likely the animal is to initiate drug-seeking during periods of abstinence.

"Because it is during periods of abstinence, not periods of intoxication, that addicts seek treatment, the peptide signaling pathways for orexin and CRF may prove to be fruitful targets in the search for addiction medications."

Bonci and his colleagues based their experiments on past studies by other researchers showing that orexins are important regulatory peptides released by a brain center called the lateral hypothalamus. It was also known that orexins tend to activate circuitry in a region called the ventral tegmental area (VTA), known to be a critical site of neural adaptation, or plasticity, induced by addictive drugs. However, it wasn't known whether orexin actually induced such plasticity.

In experiments with rat brain slices, the researchers demonstrated that orexin A does increase activity of neurons in the VTA associated with such plasticity.

And in experiments with whole animals, the researchers found that orexin A was required for "behavioral sensitization" to cocaine. This sensitization shows itself as a long-lasting increase in activity by the animals when they receive the drug and is an indicator that the animals are experiencing an increased craving for the drug.

Importantly, when the researchers "microinjected" directly into the VTA region of animals a drug that blocks orexin receptors, they found they could block the development of behavioral sensitization.

"The findings presented here establish a potential mechanism for the role of orexin signaling in plasticity related to addiction," concluded the researchers. The researchers wrote that this orexin-induced plasticity in the VTA "is likely an important substrate of behaviors relevant to addiction, as we show that activation of [orexin] receptors in the VTA is necessary for the development of cocaine-mediated behavioral sensitization. Thus, orexin receptors may provide novel pharmacotherapeutic targets for motivational disorders such as addiction.

###

The researchers include Stephanie L. Borgland, Sharif A. Taha, Federica Sarti, Howard L. Fields, and Antonello Bonci1 of the University of California, San Francisco in San Francisco, CA. This work was supported by a NARSAD Essel Foundation young investigator grant to S.L.B., the State of California for medical research on alcohol and substance abuse through the University of California, San Francisco (A.B. and H.L.F.), The Wheeler Center for the Neurobiology of Addiction (A.B. and H.L.F.), the National Institute on Drug Abuse, and the National Institutes of Health 1RO1DA15096-01 (A.B.).

Borgland et al.: "Orexin A in the VTA is critical for the induction of synaptic plasticity and behavioral sensitization to cocaine." Publishing in Neuron 49, 589-601, February 16, 2006. DOI 10.1016/j.neuron.2006.01.016 http://www.neuron.org/

Contact: Heidi Hardman
hhardman@cell.com
Cell Press



www.internetnews.net/ec-news/article.php/3585576

Search With the Human Touch

By Susan Kuchinskas
February 16, 2006

A new crop of search engines bases relevance on the human mind instead of algorithms. On Thursday, PreFound.com said it would begin to share ad revenue with active users of its site.

PreFound is a community-oriented search engine that lets people search, tag and share their searches with others; it launched in January 2006. Members can create their own personal pages containing organized groups of links sorted by topic and sub-topic.

Experts known as "Featured Finders" who take the time to gather the most relevant and recent information on specific topics will receive 100 percent of the Google (Quote, Chart) AdSense revenue that their individual pages generate.

Featured Finders will be responsible for finding, tagging, and sharing organized sets of links and annotations on their expert topic areas that they have found on the Web. Searchers will be able to visit each expert's page and view the Featured Finder's PreFound selections. "Our plan is to reward experts in their fields along with regular users who've proven they can share useful and popular material," said Steve Mansfield, CEO of PreFound.com and its parent company, iLOR, in a statement.

According to Mansfield, paying people will help ramp up the site's content, while reducing the visibility of spammy or slopping pages. Experts interested in participating in the PreFound.com Featured Finders program can apply at www.profound.com. Other sites too are looking for the human touch in improving search results.

Dumbfind, a two-year-old search provider, also plans to offer an online community where users can submit and tag content to help determine search relevancy and discover new sites. Dumbfind combines tag search with keyword search to better refine results. Dumbfind automatically tags all the content in its database, groups them, determines which are most relevant, and displays them in clusters. Founder Chris Seline said the concepts of tagging and "folksonomies," wherein users create their own categories, are a good jumping off point. "We have a large seed database of tags," he said, "but it could benefit from user input. There may be certain ways people might describe things that our technology might not capture." Improving results could also improve ad revenue. PreFound's Mansfield pointed out that users of his site's topic-specific pages are more easily targeted by advertisers.

Eurekster recently launched Swicki, a search/wiki combo that lets Web publishers and bloggers offer topic-centric searches designed to give their communities of users more relevant results. Publishers can focus and train their Swickis by typing in keywords and relevant URLS.

Then, Swicki technology automatically learns from search behavior on the publisher's site, constantly refining search results in response to what site users clicked on. For example, a traditional Web search for the word "labor" might return results focused on childbirth, labor legislation and unions. On a site catering to pregnant women, searchers consistently clicking on links related to childbirth would eventually increase the relevance ranking of such links, so that only they would be shown to users.

In a statement, Eurekster CEO Steven Marder said, "Currently, publishers lose traffic to generic search engines because they don't offer their users a Web search with a differentiated or specialized value-add that retains them. Unique search results not only help build user loyalty, but also lead to greater search-driven advertising revenue, he said.

The idea of human editors is as old as Web search itself, of course. The original Yahoo was a simple, human-edited list of links to sites. About.com, founded in 1996 as The Mining Co., paid subject-expert Guides to create channels. About.com was sold to the New York Times Company (Quote, Chart) in February 2005.