In the communal imagination, dopamine is about rewards, and feeling good, and wanting to feel good again, and if you don’t watch out, you’ll be hooked, a slave to the pleasure lines cruising through your brain.
The hard sciences are interpenetrating the social sciences. This isn’t dehumanizing. It shines attention on the things poets have traditionally cared about: the power of human attachments. It may even help policy wonks someday see people as they really are. (Brooks - NYTimes.com)
Adult neurogenesis is the process of generating new neurons which integrate into existing circuits after fetal and early postnatal development has ceased. In most mammalian species, adult neurogenesis only appears to occur in the olfactory bulb and the hippocampus.
To study the environmental effects, Nottebohm compared the brains of birds kept in cages with those of birds that lived in the wild. Again, the differences were striking: a free-ranging chickadee, which has to avoid predators and forage for its food, produced larger numbers of new neurons in the hippocampus--the part of the brain that plays an essential role in the storage of memories--than a caged chickadee. In cold weather, a chickadee becomes desperate for calories; it must eat before it sleeps or it will die. So remembering the many places where it stashes seeds is of urgent importance.
Scientists have suspected for decades that exercise, particularly regular aerobic exercise, can affect the brain. But they could only speculate as to how. Now an expanding body of research shows that exercise can improve the performance of the brain by boosting memory and cognitive processing speed. Exercise can, in fact, create a stronger, faster brain.
For decades, it was believed that the adult mammalian brain could not generate new neurons, but during the 1990s, that concept changed. Evidence of the birth of new neurons in adult mammals, including humans, raised expectations for improved treatment for patients with central nervous system injury or illness. But this enthusiasm has been tempered since then, as more recent studies indicate that excess adult neurogenesis can be as detrimental as a deficit. In some cases, the clinical relevance of increasing neurogenesis may need to be reconsidered.
From a single fertilised egg of about 0.14 millimetres in diameter, to an adult human being, the neurophysiology of development of the brain and nervous system is nothing short of remarkable. We are born with around 100 billion neurons, and the development of the brain continues long after birth, with dendrites of some neurons in the neocortex continuing to grow well into old age