1–9 of 9
As we ascend the scale of cerebral development the possibility of teaching increases. It becomes possible to domesticate and train these higher-brain animals in just the measure that their brains are developed. You can teach very little to a fish or a reptile, but directly you come to the higher cerebral mammals you…
In species that do not use copulatory thrusting, especially insects, penises evolve more obvious tactile stimulators: nubs, spikes, ridges, curls, barbs, hooks, and flagella. Male insects often try to push each other off during copulation, so copulatory thrusting would risk disengagement. Better to lock the genitals…
Experience rearranges anatomical connectivity in the brain, but such plasticity is suppressed in adulthood. We examined the turnover of dendritic spines and axonal varicosities in the somatosensory cortex of mice lacking Nogo Receptor 1 (NgR1). Through adolescence, the anatomy and plasticity of ngr1 null mice are…
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…
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…
Nonetheless, our early touch experiences determine the extent of possible tactile sensitivity. They also play a surprisingly potent role in the overall quality of brain development. We have already seen in Chapter 2 how rats raised in a highly enriched environment develop a thicker cerebral cortex and are actually…
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…
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…
The similarity between different vertebrate embryos is indeed remarkable. Since the early 1800s, embryologists have been struck by the parallel between early development in various animal species and their evolutionary relationship, a resemblance conveniently abbreviated by the saying "ontogeny recapitulates…