From the Dana Foundation:For most of human history, food was not readily available; storing energy helped ensure survival. Humans thus evolved to eat whenever food is at hand-a tendency that in the modern world may contribute to widespread obesity. Researchers are starting to determine the brain circuitry responsible for this default “eat” message. Marcelo Dietrich and Tamas Horvath tell the story of false starts and measured successes in obesity research. They propose that developing successful obesity therapy may require combining drug therapy with psychological or psychiatric approaches, as well as exercise. In the sidebar, they examine the opposite of obesity: anorexia nervosa.

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In a recent study, Sebastian Guderian and colleagues examined the relation between theta oscillations and memory performance. During the study phase of this memory experiment, participants were presented with words and either performed a semantic or phonemic encoding task (there were two levels of processing used in this experiment). During the study phase, the researchers obtained whole-head MEG recordings. Later on during the test phase, the participants were given a free-recall test on the words that were presented to them during the study phase.

Interestingly, Guderian and colleagues found that amplitudes of theta oscillations that shortly preceded the presentation of the words were higher for those words that were later recalled during the free-recall test, compared to those words that were later forgotten.

Although past studies have shown that specific patterns of brain activity are associated with the encoding of items, this study by Guderian and colleagues is one of a handful of more recent studies that demonstrate pre-stimulus brain activity that is associated with later memory performance (another example is a study by Otten and colleagues).

Moreover, although semantic study tasks typically lead to better memory performance compared to phonemic tasks, the results of the study by Guederian and colleagues suggest that this study task benefit is not only statistically independent from the theta-related recall benefit, but that these benefits are additive.

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From the Dana Foundation: Dr. Pierre Magistretti and Dr. Francois Ansermet spoke with Dana Foundation Chairman William Safire about their book, Biology of Freedom: Neural Plasticity, Experience, and the Unconscious, and the bridge between neuroscience and psychoanalysis. The event took place on November 14, 2007 at the Dana Center in Washington, DC. 

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From the Dana Foundation: The Dana Foundation released at a news conference on March 4, Learning, Arts, and the Brain, a three-year study at seven universities, which finds strong links between arts education and cognitive development. Speakers included Michael Gazzaniga, Ph.D., UC, Santa Barbara; Michael Posner, Ph.D., University of Oregon;  Elizabeth Spelke, Ph.D., Harvard University  and Brian Wandell, Ph.D., Stanford University.  Guy Mckhann, M.D., Johns Hopkins University gave a summary and Dana Gioia, chairman of the National Endowment for the Arts spoke of the study’s importance to the field of education.

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Click here for the event transcript.

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Roland D. Thijs, Bastiaan R. Bloem, J. Gert van Dijk
Article in Journal of Neurology

Abstract
In this practically oriented review, we will outline the clinical approach of patients with falls due to an impairment or loss of consciousness. Following a set of definitions, we describe the salient clinical features of disorders leading to such falls. Among falls caused by true loss of consciousness, we separate the clinical characteristics of syncopal falls (due to reflex syncope, hypovolemia, orthostatic hypotension or cardiac syncope) from falls due to other causes of transient unconsciousness, such as seizures. With respect to falls caused by an apparent loss of consciousness, we discuss the presentation of cataplexy, drop attacks, and psychogenic falls. Particular emphasis will be laid upon crucial features obtained by history taking for distinguishing between the various conditions that cause or mimic a transient loss of consciousness.

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Ken A. Paller, Joel L.Voss, Carmen E. Westerberg
Article in Perspectives on Psychological Science

Abstract
There is a marked lack of consensus concerning the best way to learn how conscious experiences arise. In this article, we advocate for scientific approaches that attempt to bring together four types of phenomena and their corresponding theoretical accounts: behavioral acts, cognitive events, neural events, and subjective experience. We propose that the key challenge is to comprehensively specify the relationships among these four facets of the problem of understanding consciousness without excluding any facet. Although other perspectives on consciousness can also be informative, combining these four perspectives could lead to significant progress in explaining a conscious experience such as remembering. We summarize some relevant findings from cognitive neuroscience investigations of the conscious experience of memory retrieval and of memory behaviors that transpire in the absence of the awareness of remembering. These examples illustrate suitable scientific strategies for making progress in understanding consciousness by developing and testing theories that connect the behavioral expression of recall and recognition, the requisite cognitive transactions, the neural events that make remembering possible, and the awareness of remembering.

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From The Dana Foundation: My great-grandmother lived to the ripe old age of 98. While many of her friends and neighbors had lost critical cognitive function decades before, requiring assistance for day-to-day activities, she somehow maintained her faculties well enough to live on her own well into her 90s. What was it about my great-grandmother’s brain-and those of others like her-that allowed her to retain these essential cognitive capabilities? Researchers at Northwestern University and elsewhere are shedding some light on the so-called “super-aged,” offering new insight into the aging brain and memory.

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Mitchell F Roitman, Robert A Wheeler, R Mark Wightman and Regina M Carelli
Article in Nature Neuroscience

Abstract
Rewarding and aversive stimuli evoke very different patterns of behavior and are rapidly discriminated. Here taste stimuli of opposite hedonic valence evoked opposite patterns of dopamine and metabolic activity within milliseconds in the nucleus accumbens. This rapid encoding may serve to guide ongoing behavioral responses and promote plastic changes in underlying circuitry.

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From physorg.com — You study the menu at a restaurant and decide to order the steak rather than the salmon. But when the waiter tells you about the lobster special, you decide lobster trumps steak. Without reconsidering the salmon, you place your order—all because of a trait called “transitivity.”

“Transitivity is the hallmark of rational economic choice,” says Camillo Padoa-Schioppa, a postdoctoral researcher in HMS Professor of Neurobiology John Assad’s lab. According to transitivity, if you prefer A to B and B to C, then you ought to prefer A to C. Or, if you prefer lobster to steak, and steak to salmon, then you will prefer lobster to salmon.

Padoa-Schioppa is lead author on a paper that suggests this trait might be encoded at the level of individual neurons. The study, which appears online Dec. 9 in Nature Neuroscience, shows that some neurons in a part of the brain called the orbitofrontal cortex encode economic value in a “menu invariant” way. That is, the neurons respond the same to steak regardless if it’s offered against salmon or lobster.

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From ScienceDaily (Nov. 7, 2007) — School shootings. Muggings. Murder. Road rage. After decreasing for more than a decade, the rate of violent crime in the United States has begun to inch up again. According to the FBI’s Uniform Crime Reporting Program, violent crime rose 2.3 percent in 2005 and 1.9 percent in 2006, the first steady increase since 1993.

And new studies are helping scientists gain deeper insight into the neurobiology of aggression and violence. One analysis of brain imaging studies has revealed that brain structures involved in making moral judgments are often damaged in violent individuals. Another study involving teenage boys suggests that disruptions in a brain region linked to impulsive, aggressive behavior may underlie a certain type of violent, reactive behavior.

Still other research has shed new light on the role that certain brain chemicals play in aggressive behavior, including in maternal aggression. And new animal studies reveal that aggressive encounters cause changes in the brains of aggressors as well as their victims that increase vulnerability to depression and immune-related illnesses.

“Violence in our society is a major concern, indeed, a national health problem,” says Craig Ferris, PhD, of Northeastern University in Boston. “Understanding the confluence of events, both environmental and biological, that trigger a violent act has been the focus of educators, health professionals, and scientists for decades.

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From MindHacks
An article in this week’s Science News discusses whether the brain stem may play a more central role in consciousness than it’s usually given credit for.

It focuses on children with hydranencephaly, a where the cortex fails to develop in children and instead, the space is filled with cerebral spinal fluid.

Typically, affected children survive only a few months after birth, but those that do survive seem to remarkably more conscious than you would guess based on theories that suggest the cortex is where all the action happens to support consciousness.

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Danish scientists challenge the accepted scientific views of how nerves function and of how anesthetics work. Their research suggests that action of nerves is based on sound pulses and that anesthetics inhibit their transmission.

Every medical and biological textbook says that nerves function by sending electrical impulses along their length. “But for us as physicists, this cannot be the explanation. The physical laws of thermodynamics tell us that electrical impulses must produce heat as they travel along the nerve, but experiments find that no such heat is produced,” says associate professor Thomas Heimburg from the Niels Bohr Institute at Copenhagen University. He received his Ph.D. from the Max Planck Institute in Göttingen, Germany, where biologists and physicists often work together – at most institutions these disciplines are worlds apart. Thomas Heimburg is an expert in biophysics, and when he came to Copenhagen, he met professor Andrew D. Jackson, who is an expert in theoretical physics. They decided to work together in order to study the basic mechanisms which govern the way nerves work.

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Surgeons have managed to give an amputee not only a prosthetic arm that moves as directed by her thoughts, but also the feeling of touch — albeit in the wrong part of her body.

When Claudia Mitchell presses an area on her chest, where surgeons re-wired the nerves that used to run to her hand, it feels to her as if her fingers are being touched.

The technique opens the door to additional technologies that could one day relay signals from the prosthesis back to the ‘fingers’ on the chest, allowing an amputee to get sensory information such as touch and temperature from their artificial limb.

Mitchell’s success story was revealed in a press conference last year, but now the details have been published: they are reported this week in the Lancet. (from Nature)

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