21 JUL 2011 by ideonexus

 Sound Localization

One trick our brains use to figure out the location of a sound is to compare the time it takes to reach each ear. For example, sound waves emanating from a wind chime located to your right will reach your right ear a few milliseconds earlier than they reach your left ear, and the brain uses this small timing difference to compute exactly how far to your right the chime is located. Researchers have capitalized on this timing difference to test sound localization, using a special experimental t...
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How the brain localizes the origin of a sound by calculating the difference in time between the soundwaves hitting one ear versus the other.

21 JUL 2011 by ideonexus

 Hyperacuity and Obligatory Looking

Beginning about four months of age, the perception of detail takes another leap forward with the emergence of hyperacuity: the ability to discriminate features that are up to ten times finer than the size of the photoreceptors should theoretically permit. It is this ultrafine discrimination that allows us, for instance, to see a very slight glitch in an otherwise straight line. even though the size of the glitch is below our eyes' limit of resolution. It is not yet known how our brains perfor...
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Two visual phenomena in the developing infant. One is the ability to make out visual details for which the eye does not appear physically capable of registering and the other is a conflict between the visual cortex and the brain stem that gets the baby stuck staring at something.

19 JUL 2011 by ideonexus

 Mother's Hormones Impact a Child's Propensity for Shyness

As we learn more about maternal hormones and their influence on the developing brain, scientists are beginning to propose actual biological mechanisms for the kind of folk prophecies that have been around for ages. One recent study, for instance, suggests that a child's shyness is determined, in part, by maternal hormone fluctuations during gestation. Researchers who interviewed several thousand preschoolers in both the United States and New Zealand noted a significant relationship between th...
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There appears to be a correlation between the amount of sunlight to which a mother is exposed mid-pregnancy and how shy her children are later on.

18 JUL 2011 by ideonexus

 How Brains Grow Into Bodies

Brain wiring begins with the outgrowth of axons. Once a newborn neuron has migrated, planting its cell body in a permanent position, it sends out a fine axon shoot with an enlarged tip known as a growth cone. At the end of the growth cone are about a dozen long tentacles that shoot out in all directions and act like radar, picking up all manner of navigational signals. They feel out the best-textured surfaces, sniff around for chemical cues, and even use tiny electrical fields to help the axo...
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Best description yet of the synaptic "pruning" human brains go through as the brain wires up to the body and best reason yet for why children should have rich, mentally-nourishing environments in which to grow so that their synapses don't get unnecessarily pruned, resulting in smaller brains.