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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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.

Click here for the webcast archive.

Click here for the event transcript.

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In a recent study, Sheline and colleagues examined whether patients with major depression were impaired in their ability to regulate the activity of the default mode network, which is characterized by self-referential functions.  To do so, they used fMRI to measure changes in brain activity occurring within this network in 20 individuals with major depression and 21 demographically similar control participants.  The depressed and healthy control participants were asked to examine negative pictures passively and also to reappraise them actively. 

In contrast to the depressed participants, the healthy control participants demonstrated reduced activity in widely distributed regions of the default mode network (ventromedial prefrontal cortex, prefrontal cortex, anterior cingulate, lateral parietal cortex, and lateral temporal cortex) while looking at the negative pictures and reappraising them.  Moreover, compared to the healthy control participants, the depressed participants demonstrated a larger increase in activity in other default mode network regions (amygdala, parahippocampus, and hippocampus) while they looked at negative pictures. 

Based on these data, Sheline and colleagues suggest that depression is characterized by both a stimulus-induced increase in brain activity and a failure to broadly decrease the activity of the default mode network.  Further, the authors suggest that these findings provide a brain network framework within which to consider the pathophysiology of depression.

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Susan Whitfield-Gabrieli, Heidi W. Thermenos, Snezana Milanovic, Ming T. Tsuang, Stephen V. Faraone, Robert W. McCarley, Martha E. Shenton, Alan I. Green, Alfonso Nieto-Castanon, Peter LaViolette, Joanne Wojcik, John D. E. Gabrieli and Larry J. Seidman
Article in PNAS

Abstract
We examined the status of the neural network mediating the default mode of brain function, which typically exhibits greater activation during rest than during task, in patients in the early phase of schizophrenia and in young first-degree relatives of persons with schizophrenia. During functional MRI, patients, relatives, and controls alternated between rest and performance of working memory (WM) tasks. As expected, controls exhibited task-related suppression of activation in the default network, including medial prefrontal cortex (MPFC) and posterior cingulate cortex/precuneus. Patients and relatives exhibited significantly reduced task-related suppression in MPFC, and these reductions remained after controlling for performance. Increased task-related MPFC suppression correlated with better WM performance in patients and relatives and with less psychopathology in all 3 groups. For WM task performance, patients and relatives had greater activation in right dorsolateral prefrontal cortex (DLPFC) than controls. During rest and task, patients and relatives exhibited abnormally high functional connectivity within the default network. The magnitudes of default network connectivity during rest and task correlated with psychopathology in the patients. Further, during both rest and task, patients exhibited reduced anticorrelations between MPFC and DLPFC, a region that was hyperactivated by patients and relatives during WM performance. Among patients, the magnitude of MPFC task suppression negatively correlated with default connectivity, suggesting an association between the hyperactivation and hyperconnectivity in schizophrenia. Hyperactivation (reduced task-related suppression) of default regions and hyperconnectivity of the default network may contribute to disturbances of thought in schizophrenia and risk for the illness.

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Informing the debate over the reality of ‘free will’ requires learning something about the lateral habenula.

From ScienceNews: At the end of The Matrix trilogy, Neo and Agent Smith are engaged in one final, interminable scene of surreal combat, a surrogate competition for an eternal battle between humans and machines. “It’s pointless to keep fighting,” Agent Smith declares to Neo. “Why do you persist?”

“Because I choose to,” Neo replies, just before the computer-generated Smith meets his demise in a cinematic celebration of human free will’s superiority to the programming that enslaves machines. Machines are mindless. The brain is a decider.

All very inspiring, except that the brain itself is a machine, a network of cells that computes its choices based on the sum of sensory inputs and their interactions with neural anatomy. “Free will” is not the defining feature of humanness, modern neuroscience implies, but is rather an illusion that endures only because biochemical complexity conceals the mechanisms of decision making.

Yet belief in free will persists as stubbornly as Neo’s resistance to electronic tyranny. Whether supposedly free choice is actually a Matrix-like mirage remains one of the great questions of human philosophical history. For centuries that question was assessed mostly with thought -uninformed by actual neurobiological knowledge. Nowadays, though, the inner workings of the brain are revealing themselves to modern methods of neuroinquiry, and free will seems merely to emerge from electrochemical networks of neuronal interactions. But like tourists exploring a strange city without a GPS map, scientists don’t know how all the neural neighborhoods are connected and occasionally encounter surprising enclaves-such as a place in the brain called the lateral habenula.

“There’s lots of new research showing that an overactive habenula has behavioral effects,” says neuropharmacologist Martine Mirrione of Brookhaven National Laboratory in Upton, N.Y.

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From The Dana Foundation: Scientists working with rapidly advancing computer technology and electron microscopes hope one day to map the billions of neuronal connections in the brain. The resulting map, or “connectome,” could help us understand memory, intelligence and mental disorders, Dr. Sebastian Seung writes.

Suppose that someone gave you a radio and asked you to figure out how it works. You could try measuring electrical signals inside it, but the measurements might not be sufficient. You might be more successful if you were also given a circuit diagram illustrating all the components of the radio and how they are connected to each other.

Now imagine that your goal is to discover how a brain works. A map of brain connections would be helpful for interpreting measurements of the signals transmitted between neurons. In the human brain, these signals travel in a complex network of 100 billion or so neurons, each of which is connected to 10,000 others.

Such a map of a brain, human or otherwise, does not yet exist. But as technology advances, researchers are setting their sights on the “connectome,” a word coined in a 2005 study by Olaf Sporns and colleagues to describe a complete map of connections in a brain or a piece of a brain.

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Palva S, Palva JM.
Article in Trends in Neurosciences

Abstract
The amplitude of alpha-frequency band (8-14 Hz) activity in the human electroencephalogram is suppressed by eye opening, visual stimuli and visual scanning, whereas it is enhanced during internal tasks, such as mental calculation and working memory. Alpha-frequency band oscillations have hence been thought to reflect idling or inhibition of task-irrelevant cortical areas. However, recent data on alpha-amplitude and, in particular, alpha-phase dynamics posit a direct and active role for alpha-frequency band rhythmicity in the mechanisms of attention and consciousness. We propose that simultaneous alpha-, beta- (14-30 Hz) and gamma- (30-70 Hz) frequency band oscillations are required for unified cognitive operations, and hypothesize that cross-frequency phase synchrony between alpha, beta and gamma oscillations coordinates the selection and maintenance of neuronal object representations during working memory, perception and consciousness.

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What is the nature of thought? And what is the resting state? Moshe Bar and colleagues argues in a new paper (PDF) in the journal Hippocampus that besides the long-held idea that associative processing provides the vehicle of thought, that “one primary outcome of associative processing is the generation of predictions, which approximate the immediately relevant future and thus facilitate perception, action, and the progression of thought”.

From the article:

Associations are proposed to provide the units of thought,b ut they should not be perceived as the actual content of thought; they merely provide the vehicle for linking related representations. In fact, our proposal is that the primary role of associations and associative activation is to generate predictions, which guide our actions, expectations, plans, and thoughts. To elaborate on this it will be useful to consider our broader theoretical framework: We propose that rather than passively ‘‘waiting’’ to be activated by sensations, the human brain is constantly busy generating predictions that approximate the immediate, directly relevant, future. Building on previous work, this proposal posits that rudimentary information is first extracted rapidly from a perceptual input, and then used to derive analogies linking the input with the most similar representations in memory. The linked stored representations in turn selectively activate the associations that are relevant in the specific context, which provides focused, testable predictions. These predictions facilitate perception and cognition by presensitizing representations all the way downstream to primary cortices. For example, we see a fork, the image of which will

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Nature has an interesting report from Marc Raichle’s laboratory that studies the resting states in monkeys. This study not only demonstrates that resting states occur in non-human primates, but that it is possible to find such activity during unconscious states.

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Abstract of The Multi-Source Interference Task: an fMRI task that reliably activates the cingulo-frontal-parietal cognitive/attention network, in Nature.

In this protocol we describe how to perform the Multi-Source Interference Task (MSIT), a validated functional magnetic resonance imaging (fMRI) task that reliably and robustly activates the cingulo-frontal-parietal cognitive/attention network (CFP network) within individual subjects. The MSIT can be used to (i) identify the cognitive/attention network in normal volunteers and (ii) test its integrity in people with neuropsychiatric disorders. It is simple to perform, can be completed in less than 15 min and is not language specific, making it appropriate for children, adults and the elderly. Since its validation, over 100 adults have performed the task. The MSIT produces a robust and temporally stable reaction time interference effect (range 200–350 ms), and single runs of the MSIT have produced CFP network activation in approximately 95% of tested subjects. The robust, reliable and temporally stable neuroimaging and performance data make the MSIT a useful task with which to study normal human cognition and psychiatric pathophysiology.

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Abstract of Self-projection and the brain, in Trends in Cognitive Science:

When thinking about the future or the upcoming actions of another person, we mentally project ourselves into that alternative situation. Accumulating data suggest that envisioning the future (prospection), remembering the past, conceiving the viewpoint of others (theory of mind) and possibly some forms of navigation reflect the workings of the same core brain network. These abilities emerge at a similar age and share a common functional anatomy that includes frontal and medial temporal systems that are traditionally associated with planning, episodic memory and default (passive) cognitive states. We speculate that these abilities, most often studied as distinct, rely on a common set of processes by which past experiences are used adaptively to imagine perspectives and events beyond those that emerge from the immediate environment.

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