Abstract: |
Understanding the genetic basis of brain function is a daunting task given the enormous complexity of the central nervous system (CNS). There are approximately one trillion cells in the human brain, with 10-100 billion neuronal cells displaying more than 50 distinct neurotransmitter phenotypes. Each of these neurons receives an average of over 1000 afferent synaptic inputs and will contact neighboring cells and organs via 1000 efferent synapses. Axonal arbors of single neuron in the corticospinal tract can travel through the whole length of the body and innervate targets at distances of more than one meter apart from the neuronal cell body. Understanding the function of such a complex structure requires knowledge about the basic elements that give rise to the extraordinary cell diversity in the brain. Developmental studies indicate that all the cells of the central nervous system are generated from a single layer of neuroepithelial cells. © CRC Press LLC, 2000. |