Ageing: Longevity hits a roadblock

Ageing: Longevity hits a roadblock:

Ageing: Longevity hits a roadblock

Nature 477, 7365 (2011). doi:10.1038/477410a

Authors: David B. Lombard, Scott D. Pletcher, Carles Cantó & Johan Auwerx

Increased expression of sirtuin proteins has been shown to enhance lifespan in several organisms. New data indicate that some of the reported effects may have been due to confounding factors in experimental design. Here, experts discuss the significance of these data for research into ageing. See Letter p.482

Equilibrium in the brain: Excitation and inhibition remain balanced, even when the brain undergoes reorganization

Equilibrium in the brain: Excitation and inhibition remain balanced, even when the brain undergoes reorganization: Every second, the brain's nerve cells exchange many billions of synaptic impulses. Two kinds of synapses ensure that this flow of data is regulated: Excitatory synapses relay information from one cell to the next, while inhibitory synapses restrict the flow of information. Scientists can now show that excitatory and inhibitory synapses remain balanced -- even if the brain undergoes reorganization.

Neuroscience: When lights take the circuits out

Neuroscience: When lights take the circuits out:

Neuroscience: When lights take the circuits out

Nature 477, 7363 (2011). doi:10.1038/477165a

Authors: João Peça & Guoping Feng

Circuit-level perturbations in the brain's electrical activity may underlie social-interaction deficits seen in people with schizophrenia and autism. A new optogenetic tool was instrumental in making this discovery. See Article p.171

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

The ageing systemic milieu negatively regulates neurogenesis and cognitive function:

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

Nature 477, 7362 (2011). doi:10.1038/nature10357

Authors: Saul A. Villeda, Jian Luo, Kira I. Mosher, Bende Zou, Markus Britschgi, Gregor Bieri, Trisha M. Stan, Nina Fainberg, Zhaoqing Ding, Alexander Eggel, Kurt M. Lucin, Eva Czirr, Jeong-Soo Park, Sebastien Couillard-Després, Ludwig Aigner, Ge Li, Elaine R. Peskind, Jeffrey A. Kaye, Joseph F. Quinn, Douglas R. Galasko, Xinmin S. Xie, Thomas A. Rando & Tony Wyss-Coray

In the central nervous system, ageing results in a precipitous decline in adult neural stem/progenitor cells and neurogenesis, with concomitant impairments in cognitive functions. Interestingly, such impairments can be ameliorated through systemic perturbations such as exercise. Here, using heterochronic parabiosis we show that blood-borne factors present in the systemic milieu can inhibit or promote adult neurogenesis in an age-dependent fashion in mice. Accordingly, exposing a young mouse to an old systemic environment or to plasma from old mice decreased synaptic plasticity, and impaired contextual fear conditioning and spatial learning and memory. We identify chemokines—including CCL11 (also known as eotaxin)—the plasma levels of which correlate with reduced neurogenesis in heterochronic parabionts and aged mice, and the levels of which are increased in the plasma and cerebrospinal fluid of healthy ageing humans. Lastly, increasing peripheral CCL11 chemokine levels in vivo in young mice decreased adult neurogenesis and impaired learning and memory. Together our data indicate that the decline in neurogenesis and cognitive impairments observed during ageing can be in part attributed to changes in blood-borne factors.

Theory of Psychoneuroenergetics

Number of concepts ~ k_n * Number of synaptic connections ~ k_e * Amount of energy expended

Error and Perfection

Perhaps one consistent aspect of the human condition is the innate struggle to achieve an idealized mental state. At each point in our consciousness, we have a goal, and we seek to meet that goal. The problem is that we always never meet those goals. There is always error, and we cannot stand it.

Our minds then try to reduce this error through adaptation. One method of adaptation is to change the goal so that it is closer to what we can achieve. This can be realized by having a modified goal, or a completely new goal. Interestingly, having a "no goal" state is in itself an idealized goal which can result in error when we seek to achieve it. Another adaptative method is to change the way we achieve the goal. We can re-analyze our previous behavior to reason which actions led to more or less error, and modify those behaviors accordingly.

Formal representations of this heuristics can easily be implemented. However, the question remains as to how the goals come to be about. Contribution from environmental and genetic forces can then be considered this level.

Final resolutions will either be that no error, or goal-relative perfection, is achieved, or else the ability to adapt is halted.

"What" Precedes "Which": Developmental Neural Tuning in Face- and Place-Related Cortex

"What" Precedes "Which": Developmental Neural Tuning in Face- and Place-Related Cortex: "

Although category-specific activation for faces in the ventral visual pathway appears adult-like in adolescence, recognition abilities for individual faces are still immature. We investigated how the ability to represent 'individual' faces and houses develops at the neural level. Category-selective regions of interest (ROIs) for faces in the fusiform gyrus (FG) and for places in the parahippocampal place area (PPA) were identified individually in children, adolescents, and adults. Then, using an functional magnetic resonance imaging adaptation paradigm, we measured category selectivity and individual-level adaptation for faces and houses in each ROI. Only adults exhibited both category selectivity and individual-level adaptation bilaterally for faces in the FG and for houses in the PPA. Adolescents showed category selectivity bilaterally for faces in the FG and houses in the PPA. Despite this profile of category selectivity, adolescents only exhibited individual-level adaptation for houses bilaterally in the PPA and for faces in the 'left' FG. Children only showed category-selective responses for houses in the PPA, and they failed to exhibit category-selective responses for faces in the FG and individual-level adaptation effects anywhere in the brain. These results indicate that category-level neural tuning develops prior to individual-level neural tuning and that face-related cortex is disproportionately slower in this developmental transition than is place-related cortex.

"

How Merkel Decided to End Nuclear Power

How Merkel Decided to End Nuclear Power: "Angela Merkel, her allies say, is ready to lead Germany into an era in which wind and solar energy can replace nuclear plants. But she faces hurdles."

Data are traveling by light

Data are traveling by light: "Regular LEDs can be turned into optical WLAN with only a few additional components thanks to visible light communication (in short, VLC). The lights are then not just lighting up, they also transfer data. They send films in HD quality to your iPhone or laptop, with no loss in quality, quickly and safely."

How Eating Frog Legs Is Causing Frog Extinctions

How Eating Frog Legs Is Causing Frog Extinctions: "

Frog legs are still an amazingly popular food item around the world, including here in the U.S. According to a new report, an average of 2,280 metric tons of frog legs are imported into this country each year--that's the equivalent of somewhere between 450 million and 1.1 billion frogs. Another 2,216 metric tons of live frogs are imported every year for sale in Asian-American markets. [More]

"

First artificial neural network created out of DNA: Molecular soup exhibits brainlike behavior

First artificial neural network created out of DNA: Molecular soup exhibits brainlike behavior: "Researchers have now taken a major step toward creating artificial intelligence -- not in a robot or a silicon chip, but in a test tube. The researchers are the first to have made an artificial neural network out of DNA, creating a circuit of interacting molecules that can recall memories based on incomplete patterns, just as a brain can."

Can humans sense Earth's magnetism? Human retina protein can function as light-sensitive magnetic sensor

Can humans sense Earth's magnetism? Human retina protein can function as light-sensitive magnetic sensor: "New research shows that a protein expressed in the human retina can sense magnetic fields when implanted into Drosophila, reopening an area of sensory biology in humans for further exploration."

Brain-like computing a step closer to reality

Brain-like computing a step closer to reality: "The development of 'brain-like' computers has taken a major step forward. A new study involved the first ever demonstration of simultaneous information processing and storage using phase-change materials. This new technique could revolutionize computing by making computers faster and more energy-efficient, as well as making them more closely resemble biological systems."

Brain performs near optimal visual search

Brain performs near optimal visual search: "Visual search is an important task for the brain. Surprisingly, even in a complex task like detecting an object in a scene with distractions, we find that people's performance is near optimal. That means that the brain manages to do the best possible job given the available information, according to researchers."

Aneyoshi Journal: Tsunami Warnings, Written in Stone

Aneyoshi Journal: Tsunami Warnings, Written in Stone: "Stone tablets in coastal Japan, some more than six centuries old, are inscribed with simple messages about tsunamis, or give the toll from past disasters."

Spatial navigation training protects the hippocampus against age-related changes during early and late adulthood

Spatial navigation training protects the hippocampus against age-related changes during early and late adulthood: "Publication year: 2011
Source: Neurobiology of Aging, In Press, Corrected Proof, Available online 16 April 2011
Martin, Lövdén , Sabine, Schaefer , Hannes, Noack , Nils Christian, Bodammer , Simone, Kühn , ...
It is unknown whether lifestyle, including mental stimulation, and appropriate training interventions, may directly improve spatial navigation performance and its underlying neural substrates. Here we report that healthy younger and older men performing a cognitively demanding spatial navigation task every other day over 4 months display navigation-related gains in performance and stable hippocampal volumes that were maintained 4 months after termination of training. In contrast, control groups displayed volume decrements consistent with longitudinal estimates of age-related decline. Hippocampal barrier density, as indicated by mean diffusivity estimated from diffusion tensor imaging, showed a quadratic shape of increased density after training followed..."

Reversible large-scale modification of cortical networks during neuroprosthetic control

Reversible large-scale modification of cortical networks during neuroprosthetic control: "

Reversible large-scale modification of cortical networks during neuroprosthetic control

Nature Neuroscience.
doi:10.1038/nn.2797

Authors: Karunesh Ganguly, Dragan F Dimitrov, Jonathan D Wallis & Jose M Carmena

"

Better a sprint than a marathon: Brief intense exercise better than endurance training for preventing cardiovascular disease

Better a sprint than a marathon: Brief intense exercise better than endurance training for preventing cardiovascular disease: "Exercise is important for preventing cardiovascular disease, especially in children and adolescents, but is all exercise equally beneficial? New research reveals that high intensity exercise is more beneficial than traditional endurance training."

A synaptic organizing principle for cortical neuronal groups [Neuroscience]

A synaptic organizing principle for cortical neuronal groups [Neuroscience]: "Neuronal circuitry is often considered a clean slate that can be dynamically and arbitrarily molded by experience. However, when we investigated synaptic connectivity in groups of pyramidal neurons in the neocortex, we found that both connectivity and synaptic weights were surprisingly predictable. Synaptic weights follow very closely the number of connections in a group of neurons, saturating after only 20% of possible connections are formed between neurons in a group. When we examined the network topology of connectivity between neurons, we found that the neurons cluster into small world networks that are not scale-free, with less than 2 degrees of separation. We found a simple clustering rule where connectivity is directly proportional to the number of common neighbors, which accounts for these small world networks and accurately predicts the connection probability between any two neurons. This pyramidal neuron network clusters into multiple groups of a few dozen neurons each. The neurons composing each group are surprisingly distributed, typically more than 100 μm apart, allowing for multiple groups to be interlaced in the same space. In summary, we discovered a synaptic organizing principle that groups neurons in a manner that is common across animals and hence, independent of individual experiences. We speculate that these elementary neuronal groups are prescribed Lego-like building blocks of perception and that acquired memory relies more on combining these elementary assemblies into higher-order constructs."

[Review] How to Grow a Mind: Statistics, Structure, and Abstraction

[Review] How to Grow a Mind: Statistics, Structure, and Abstraction: "

Authors: Joshua B. Tenenbaum, Charles Kemp, Thomas L. Griffiths, Noah D. Goodman"