Mind And Brain

MIND, BRAIN AND LANGUAGE
     I first explain some basic concepts of neuroscience and new knowledge about brain development, including the effects of instruction and learning on the brain. I then look at language in learning as an example of the mind-brain connection. Lastly, I examine research on how memory is represented in the brain and its implications for learning. From a neuroscienceperspective, instruction and learning are very important parts of a child's brain development and psychological development processes. Brain development and psychological development involve continuous interactions between a child and the external environment.
SOME BASICS
A nerve cell, or neuron, is a cell that receives information from other nerve cells or from the sensory organs and then projectsthat information to other nerve cells, while still other neurons project it back to the parts of the body that interact with the environment, such as the muscles. Nerve cells are equipped with a cell body The junctions through which information passes from one neuron to another are called synapses, which can be excitatory or inhibitory in nature. The neuron integrates the information it receivesfrom all of its synapses and this determines its output.
     During the development process, the "wiring diagram" of the brain is created through the formation of synapses. At birth, the human brain has in place only a relatively small proportion of the trillions of synapses it will eventually have; it gains about two-thirds of its adult size after birth. The rest of the synapses are formed afterbirth, and a portion of this process is guided by experience.
     Synaptic connections are added to the brain in two basic ways. The first way is that synapses are overproduced, then selectively lost. Synapse overproduction and loss is a fundamental mechanism that the brain uses to incorporate information from experience. It tends to occur during the early periods of development. The secondmethod of synapse formation is through the addition of new synapses--like the artist who creates a sculpture by adding things together until the form is complete. Unlike synapse overproduction and loss, the process of synapse addition operates throughout the entire human life. This process is not only sensitive to experience, it is actually driven by experience. Synapse addition probably lies at thebase of some, or even most, forms of memory.
WIRING THE BRAIN
 The role of experience in wiring the brain has been illuminated by research on the visual cortex in animals and humans.   Neuroscientists discovered this phenomenon by studying humans with visual abnormalities, such as a cataract or a muscle irregularity that deviates the eye. If the eye is deprived of the appropriate visualexperience at an early stage of development (because of such abnormalities), it loses its ability to transmit visual information into the central nervous system.
     In the case of deprivation from birth, one eye completely takes over. The later the deprivation occurs after birth, the less effect it has. By about 6 months of age, closing one eye for weeks on end will produce no effect whatsoever. Thecritical period has passed; the connections have already sorted themselves out, and the overlapping connections have been eliminated.
     This anomaly has helped scientists gain insights into normal visual development. In normal development, the pathway for each eye is sculpted (or "pruned") down to the right number of connections The more a person interacts with the world, the more a person needsinformation from the world incorporated into the brain structures.
     Synapse overproduction and selection may progress at different rates in different parts of the brain (Huttenlocher and Dabholkar, 1997): synapse production starts before birth and synapse density continues to increase until 5 or 6 years of age. The selection process, which corresponds conceptually to the main organization...