Catálogo de publicaciones - revistas

<jats:p>An effort to develop biomarkers for Alzheimer's disease is churning out new data and making plans to expand.</jats:p>

<jats:p>In the past few years, several international projects inspired in varying degrees by the Alzheimer's Disease Neuroimaging Initiative (see main text) have gotten off the ground.</jats:p>

<jats:p>Mark Schnitzer is building tools to visualize neural activity in the fruit fly brain—100 flies at a time.</jats:p>

<jats:p>Although memory allocation is a subject of active research in computer science, little is known about how the brain allocates information within neural circuits. There is an extensive literature on how specific types of memory engage different parts of the brain, and how neurons in these regions process and store information. Until recently, however, the mechanisms that determine how specific cells and synapses within a neural circuit (and not their neighbors) are recruited during learning have received little attention. Recent findings suggest that memory allocation is not random, but rather specific mechanisms regulate where information is stored within a neural circuit. New methods that allow tagging, imaging, activation, and inactivation of neurons in behaving animals promise to revolutionize studies of brain circuits, including memory allocation. Results from these studies are likely to have a considerable impact on computer science, as well as on the understanding of memory and its disorders.</jats:p>

<jats:p>An emerging set of methods enables an experimental dialogue with biological systems composed of many interacting cell types—in particular, with neural circuits in the brain. These methods are sometimes called “optogenetic” because they use light-responsive proteins (“opto-”) encoded in DNA (“-genetic”). Optogenetic devices can be introduced into tissues or whole organisms by genetic manipulation and be expressed in anatomically or functionally defined groups of cells. Two kinds of devices perform complementary functions: Light-driven actuators control electrochemical signals, while light-emitting sensors report them. Actuators pose questions by delivering targeted perturbations; sensors (and other measurements) signal answers. These catechisms are beginning to yield previously unattainable insight into the organization of neural circuits, the regulation of their collective dynamics, and the causal relationships between cellular activity patterns and behavior.</jats:p>

<jats:p>In this, the 21st century, human-brain mapping celebrates 21 years of cognitive activation studies. This review looks at imaging neuroscience and key ideas it has pursued; some ideas portend exciting developments, and others have failed gloriously. In terms of achievements, there is much to celebrate, in the sense that it is difficult to imagine modern neuroscience without brain imaging. I will look at recent advances from the perspectives of functional segregation and integration in the brain, paying special attention to approaches that deal with the distributed and integrated nature of neuronal processing and the questions they address.</jats:p>

<jats:p>Functional magnetic resonance imaging of the human spinal cord reveals a mechanism for placebo analgesia.</jats:p>

<jats:title>Confined Germanium Thermodynamics</jats:title> <jats:p> When a material is confined to nanoscale volumes, the very high proportion of surface to bulk can alter its thermodynamic properties. This has been studied using in situ electron microscopy, but in most cases the volume of the material is not constrained. <jats:bold> Holmberg <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="405" related-article-type="in-this-issue" vol="326" xlink:href="10.1126/science.1178179">405</jats:related-article> ) studied the thermodynamics of a germanium nanowire attached to a gold seed and coated with a carbon shell to restrict its volume, measuring the reaction temperature, as well as the liquid composition without changes in volume throughout the heating cycle. This enabled monitoring of phase behavior while the germanium was being heated, and tracking solid-state diffusion across the confined interface. </jats:p>