HOW THE BRAIN FINDS WHAT IT IS LOOKING FOR
Study reveals how the brain processes color and motion, provides new understanding of attention
From FMS Global News Desk of Jeanne Hambleton Embargoed: 4-Sep-2014
Source: University of Chicago Medical Center
Newswise — Despite the barrage of visual information the brain receives, it retains a remarkable ability to focus on important and relevant items. This fall, for example, NFL quarterbacks will be rewarded handsomely for how well they can focus their attention on color and motion – being able to quickly judge the jersey colors of teammates and opponents and where they’re headed is a valuable skill. How the brain accomplishes this feat, however, has been poorly understood.
Now, University of Chicago scientists have identified a brain region that appears central to perceiving the combination of color and motion. They discovered a unique population of neurons that shift in sensitivity toward different colors and directions depending on what is being attended – the red jersey of a receiver headed toward an end zone, for example. The study, published Sept. 4 in the journal Neuron, sheds light on a fundamental neurological process that is a key step in the biology of attention.
“Most of the objects in any given visual scene are not that important, so how does the brain select or attend to important ones?” said study senior author David Freedman, PhD, associate professor of neurobiology at the University of Chicago.
“We have zeroed in on an area of the brain that appears central to this process. It does this in a very flexible way, changing moment by moment depending on what is being looked for.”
The visual cortex of the brain possesses multiple, interconnected regions that are responsible for processing different aspects of the raw visual signal gathered by the eyes. Basic information on motion and color are known to route through two such regions, but how the brain combines these streams into something usable for decision-making or other higher-order processes remained unclear.
To investigate this process, Freedman and postdoctoral fellow Guilhem Ibos, PhD, studied the response of individual neurons during a simple task. Monkeys were shown a rapid series of visual images. An initial image showed either a group of red dots moving upwards or yellow dots moving downwards, which served as an instruction for which specific colors and directions were relevant during that trial.
The subjects were rewarded when they released a lever when this image later reappeared. Subsequent images were composed of different colors of dots moving in different directions, among which was the initial image.
Freedman and Ibos looked at neurons in the lateral intraparietal area (LIP), a region highly interconnected with brain areas involved in vision, motor control and cognitive functions. As subjects performed the task and looked for a specific combination of color and motion, LIP neurons became highly active. They did not respond, however, when the subjects passively viewed the same images without an accompanying task.
When the team further investigated the responses of LIP neurons, they discovered that the neurons possessed a unique characteristic. Individual neurons shifted their sensitivity to color and direction toward the relevant color and motion features for that trial. When the subject looked for red dots moving upwards, for example, a neuron would respond strongly to directions close to upward motion and to colors close to red. If the task was switched to another color and direction seconds later, that same neuron would be more responsive to the new combination.
“Shifts in feature tuning had been postulated a long time ago by theoretical studies,” Ibos said.
“This is the first time that neurons in the brain have been shown to shift their selectivity depending on which features are relevant to solve a task.”
Freedman and Ibos developed a model for how the LIP brings together both basic color and motion information. Attention likely affects that process through signals from higher-order areas of the brain that affect LIP neuron selectivity. The team believes that this region plays an important role in making sense of basic sensory information, and they are trying to better understand the brain-wide neuronal circuitry involved in this process.
“Our study suggests that this area of the brain brings together information from multiple areas throughout the brain,” Freedman said.
“It integrates inputs – visual, motor, cognitive inputs related to memory and decision making – and represents them in a way that helps solve the task at hand.”
The study, “Dynamic Integration of Task-Relevant Visual Features in Posterior Parietal Cortex,” was supported by the National Institutes of Health and National Science Foundation, with additional support from a McKnight Scholar award, the Alfred P. Sloan Foundation, The Brain Research Foundation and the Fyssen Foundation.
COCAINE REWIRES THE BRAIN: NEW STUDY TO UNLOCK KEYS THAT COULD DISRUPT ADDICTION
From the FMS Global News Desk of Jeanne Hambleton Released: 4-Sep-2014 Source: University at Buffalo
Newswise — BUFFALO, N.Y. – Why do cocaine addicts relapse after months or years of abstinence? The National Institute on Drug Abuse has awarded a University at Buffalo scientist a $2 million grant to conduct research that will provide some answers.
The UB research has the potential to identify novel therapies for treating cocaine addiction and other psychostimulants, for which no effective drug therapy exists.
“Why is it that after staying clean for a month or a year, an addict will, seemingly without reason, start using drugs again?” asks David Dietz, PhD, principal investigator and assistant professor in the Department of Pharmacology and Toxicology in the UB School of Medicine and Biomedical Sciences.
“It is because addiction has rewired the brain.”
The five-year grant focuses on the short- and long-term neurobiological changes in the brain that are induced by addiction.
Dietz explains that an addict’s brain undergoes these dramatic and profound changes, known as neuroplasticity, while being exposed to cocaine.
This plasticity, he says, includes cellular changes that, in turn, control changes in the shape of neurons and the number of connections they have with other neurons, ultimately causing changes in the addict’s behavior.
“These changes persist and become permanent,” Dietz continues. “The addict’s brain is forever rewired.
“The question is, how can we interfere with those changes?” he asks.
“How can we either prevent the rewiring in the addicted state or somehow reverse it?”
A key component of the grant is the ability to understand how the brain changes at different time-points following abstinence from drugs.
“You may need to treat a person who has been in withdrawal for one day very differently from someone who has been in withdrawal for one month or even longer,” explains Dietz.
The UB research, which will be conducted in vivo, is the first to focus on a signaling pathway called transforming growth factor-beta (TGF-beta) signaling, which Dietz says may be a master regulator of pathways previously discovered to be important in addiction.
According to Dietz, TGF-beta is able to control changes both by directly regulating mechanisms that alter the structural reorganization of these neurons, and by controlling long-term, transcriptional effects of genes that maintain these adaptations. This long-term effect sustains the rewiring in the brain and makes it permanent, he says.
MAJOR IVORY POACHING ARREST IN MOZAMBIQUE
From FMS Global News Desk of Jeanne Hambleton Released: 8-Sep-2014
Source: Wildlife Conservation Society
Six Elephant Poachers Arrested in Niassa National Reserve
Group Suspected of Killing 39 Elephants This Year Alone
Early Morning Raid Results in Capture of Poaching Ring and Confiscation of Ivory and Guns
Wildlife Conservation Society Praises Joint Operation
PHOTO: Confiscated guns, ammunition and elephant tusks in raid in Niassa National Reserve in Mozambique which resulted in the arrest of 6 suspects responsible for killing 39 elephants just in 2014. Raid was conducted Sept. 7.
Newswise — Marrupa, Mozambique, Sept. 8, 2014 – A significant arrest of six suspected poachers took place here on Sept. 7 in a joint operation conducted by the Mecula District police, Luwire scouts and Niassa National Reserve WCS scouts. The arrests resulted after a 10-month investigation informed by vital on-the-ground intelligence.
During the early morning raid, 12 tusks and two rifles were confiscated. Two of the tusks, 23 kilograms or 57 pounds each, were from an elephant about 40 years old. The worth of the tusks was estimated at well over U.S. $150,000. The suspects have been charged with such crimes as cooperating with poachers; illegal possession of firearms; participating in poaching; and organized crime. If convicted, all suspects face fines and jail time.
Officials estimated that this group of poachers has killed 39 elephants this year alone based on interviews with the suspects. In addition, this arrest is a major crack down on one of five well-organized groups suspected of poaching elephants in Niassa.
“This is an important raid that has shut down a group of poachers responsible for killing many of Niassa’s elephants” said Alastair Nelson, Director of the WCS Mozambique Program. “In this raid, we have arrested professional poachers, recovered weapons, ivory, ammunition, and gained additional information to crack down on poachers. This is the clear result of an important partnership between the Mozambique government, Luwire, Niassa National Reserve, and WCS. It is partnerships like this that will help us advance important efforts to protect Niassa’s elephants, promote security and governance, and secure national assets for the people of Mozambique.”
WCS President and CEO Cristian Samper, who is currently in Niassa, said: “With this arrest we have charged a shooter, porters and poacher informers who are driving the elephant crisis in Niassa Reserve.
“During a fly-over across a portion of the reserve, I personally witnessed an elephant that had been killed by poachers. The elephant was brought down with an AK-47. We need to combine our strategies and firepower to take on these brutal criminals. WCS extends its appreciation and congratulations to the Mozambique government, especially our partner, the National Administration of Conservation Areas and National Niassa Reserve Warden for their commitment to combat this crisis.
“This work on the ground is part of a three-part strategy to stop the killing of elephants and stop the trafficking and demand for ivory. To solve this crisis, we need to focus efforts in Africa and on the other end of the supply chain in places such as China and the U.S.”
It is estimated there are 13,000 elephants remaining in Niassa National Reserve which is located in northern Mozambique. The reserve holds Mozambique’s largest remaining population of elephants. WCS has been co-managing the reserve with the Mozambique government since 2012.
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