Posts tagged brain

There’s a reason genius and solitude seem to go hand in hand, a new study says. Social rejection leads to creative problem solving.

Don’t let rejection get you down—it might be the ticket to creativity, science says. That’s right: If regular rejection doesn’t cause you to lose all self-confidence and withdraw from the world entirely, it just might boost your ability to think outside of the mainstream and draw upon a unique worldview, suggesting that the kind of people society considers “geniuses” might tend to have a go-it-alone, loner mentality.

Research conducted by Cornell and Johns Hopkins University researchers has shown that people who are able to handle rejection in the proper manner—by shrugging it off and blazing their own, independent trails—can experience heightened creativity and even commercial success through an ability to eschew mainstream thought and groupthink and instead pursue their own creative solutions to problems. They tested their hypothesis through a series of experiments in which they manipulated the experience of social rejection; subjects in the study were led to believe that everyone in a group exercise could choose whom to work with on a team project, only to be told later that no one had selected them for a team.

For people with an independent mindset, this rejection inspired them to go on and complete the exercise in a way that was deemed more creative (we’re not exactly sure how “creativity” was measured). For people without an independent mindset—well, we’re not really sure what kind of impact this exclusion had on them (hopefully someone later told them it was just an experiment, it was all in good fun, and really, everyone here thinks you’re great).

The researchers acknowledge that for some, the consequences of rejection can be quite negative. Their research is only intended to show that for those of a certain mindset, social rejection can have a silver lining, driving home something that we more or less already knew: it’s not easy being a genius.

(Source: popsci.com)

The Who asked “who are you?” but Dartmouth neurobiologist Jeffrey Taube asks “where are you?” and “where are you going?” Taube is not asking philosophical or theological questions. Rather, he is investigating nerve cells in the brain that function in establishing one’s location and direction.

Taube, a professor in the Department of Psychological and Brain Sciences, is using microelectrodes to record the activity of cells in a rat’s brain that make possible spatial navigation — how the rat gets from one place to another — from “here” to “there.” But before embarking to go “there,” you must first define “here.”

Survival Value

"Knowing what direction you are facing, where you are, and how to navigate are really fundamental to your survival," says Taube. "For any animal that is preyed upon, you’d better know where your hole in the ground is and how you are going to get there quickly. And you also need to know direction and location to find food resources, water resources, and the like."

Not only is this information fundamental to your survival, but knowing your spatial orientation at a given moment is important in other ways, as well. Taube points out that it is a sense or skill that you tend to take for granted, which you subconsciously keep track of. “It only comes to your attention when something goes wrong, like when you look for your car at the end of the day and you can’t find it in the parking lot,” says Taube.

Perhaps this is a momentary lapse, a minor navigational error, but it might also be the result of brain damage due to trauma or a stroke, or it might even be attributable to the onset of a disease such as Alzheimer’s. Understanding the process of spatial navigation and knowing its relevant areas in the brain may be crucial to dealing with such situations.

The Cells Themselves

One critical component involved in this process is the set of neurons called “head direction cells.” These cells act like a compass based on the direction your head is facing. They are located in the thalamus, a structure that sits on top of the brainstem, near the center of the brain.

He is also studying neurons he calls “place cells.” These cells work to establish your location relative to some landmarks or cues in the environment. The place cells are found in the hippocampus, part of the brain’s temporal lobe. They fire based not on the direction you are facing, but on where you are located.

Studies were conducted using implanted microelectrodes that enabled the monitoring of electrical activity as these different cell types fired.

Taube explains that the two populations — the head direction cells and the place cells — talk to one another. “They put that information together to give you an overall sense of ‘here,’ location wise and direction wise,” he says. “That is the first ingredient for being able to ask the question, ‘How am I going to get to point B if I am at point A?’ It is the starting point on the cognitive map.”

The Latest Research

Taube and Stephane Valerio, his postdoctoral associate for the last four years, have just published a paper in the journal Nature Neuroscience, highlighting the head direction cells. Valerio has since returned to the Université Bordeaux in France.

The studies described in Nature Neuroscience discuss the responses of the spatial navigation system when an animal makes an error and arrives at a destination other than the one targeted — its home refuge, in this case. The authors describe two error-correction processes that may be called into play — resetting and remapping — differentiating them based on the size of error the animal makes when performing the task.

When the animal makes a small error and misses the target by a little, the cells will reset to their original setting, fixing on landmarks it can identify in its landscape. “We concluded that this was an active behavioral correction process, an adjustment in performance,” Taube says. “However, if the animal becomes disoriented and makes a large error in its quest for home, it will construct an entirely new cognitive map with a permanent shift in the directional firing pattern of the head direction cells.” This is the “remapping.”

Taube acknowledges that others have talked about remapping and resetting, but they have always regarded them as if they were the same process. “What we are trying to argue in this paper is that they are really two different, separate brain processes, and we demonstrated it empirically,” he says. “To continue to study spatial navigation, in particular how you correct for errors, you have to distinguish between these two qualitatively different responses.”

Taube says other investigators will use this distinction as a basis for further studies, particularly in understanding how people correct their orientation when making navigational errors.

(Source: sciencedaily.com)

Neurobiologists at the Research Institute of Molecular Pathology (IMP) in Vienna investigated how the brain is able to group external stimuli into stable categories. They found the answer in the discrete dynamics of neuronal circuits. The journal Neuron publishes the results in its current issue.

How do we manage to recognize a friend’s face, regardless of the light conditions, the person’s hairstyle or make-up? Why do we always hear the same words, whether they are spoken by a man or woman, in a loud or soft voice? It is due to the amazing skill of our brain to turn a wealth of sensory information into a number of defined categories and objects. The ability to create constants in a changing world feels natural and effortless to a human, but it is extremely difficult to train a computer to perform the task.

At the IMP in Vienna, neurobiologist Simon Rumpel and his post-doc Brice Bathellier have been able to show that certain properties of neuronal networks in the brain are responsible for the formation of categories. In experiments with mice, the researchers produced an array of sounds and monitored the activity of nerve cell-clusters in the auditory cortex. They found that groups of 50 to 100 neurons displayed only a limited number of different activity-patterns in response to the different sounds.

The scientists then selected two basis sounds that produced different response patterns and constructed linear mixtures from them. When the mixture ratio was varied continuously, the answer was not a continuous change in the activity patters of the nerve cells, but rather an abrupt transition. Such dynamic behavior is reminiscent of the behavior of artificial attractor-networks that have been suggested by computer scientists as a solution to the categorization problem.

The findings in the activity patters of neurons were backed up by behavioral experiments with mice. The animals were trained to discriminate between two sounds. They were then exposed to a third sound and their reaction was tracked. Whether the answer to the third tone was more like the reaction to the first or the second one, was used as an indicator of the similarity of perception. By looking at the activity patters in the auditory cortex, the scientists were able to predict the reaction of the mice.

The new findings that are published in the current issue of the journal Neuron, demonstrate that discrete network states provide a substrate for category formation in brain circuits. The authors suggest that the hierarchical structure of discrete representations might be essential for elaborate cognitive functions such as language processing.

(Source: alphagalileo.org)

Chronic alcohol abuse can severely damage the nervous system, particularly cognitive functions, cerebral metabolism, and brain morphology. Building upon previous findings that alcoholics can experience brain volume recovery with abstinence, this study found that recovery of cerebral gray matter (GM) can take place within the first two weeks of abstinence, but may vary between brain regions.

Results will be published in the January 2013 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"Shrinkage of brain matter, and an accompanying increase of cerebrospinal fluid, which acts as a cushion or buffer for the brain, are well-known degradations caused by alcohol abuse," explained Gabriele Ende, professor of medical physics in the Department of Neuroimaging at the Central Institute of Mental Health. 
 "This volume loss has previously been associated with neuropsychological deficits such as memory loss, concentration deficits, and increased impulsivity."

"Several processes likely account for changes in brain tissue volume observed through bouts of drinking and abstinence over the course of alcoholism," added Natalie May Zahr, a research scientist in the Department of Psychiatry and Behavioral Sciences at Stanford University School of Medicine. "One process likely reflects true, irreversible neuronal cell death, while another process likely reflects shrinkage, a mechanism that would allow for volume changes in both negative and positive directions, and could account for brain volume recovery with abstinence."

"Gray matter (GM) and white matter (WM) are the main components of the brain that can be distinguished with magnetic resonance imaging (MRI)," explained Ende. "GM consists of neuronal cell bodies, neuropil, glial cells, and capillaries. WM mostly contains myelinated axon tracts."

"Myelin forms an insulating sheath around axons that increases the speed at which they are able to conduct electrical activity," added Zahr. "Because myelin is composed primarily of fat, it gives white matter its color. Cerebrospinal fluid (CSF) is a clear fluid that surrounds and thereby cushions the brain in the skull. Conventional brain structural MRI produces images of protons, with contributions primarily from water and some from fat. Tissue contrast is possible because of the fundamental differences in water content in the primary tissues of the brain: WM consists of about 70 percent water, GM 80 percent, and CSF 99 percent."

(Source: eurekalert.org)

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