Timing is everything in brain development. New research by scientists at Newcastle University, UK, reviewed brain research over the past 15 years. The researchers found that, in addition to genetics and environment, the exact time of development of each neuron and its position in the brain are absolutely key to ensuring the right connections are made. This new research provides some insights. For example, short-distance connections occur more often than long-distance connections during brain development. Also, neurons follow chemical signals but can only detect chemicals over a distance of 1cm. But the connections between different brain regions are often longer than 10cm and through the spinal cord they can be longer than 1m. Neurons must, therefore, develop the connections very early on in development while the organism is small. These connections ultimately determine how the adult brain is wired. Cognition, behavior, and brain conditions such as schizophrenia, autism, and ADHD are linked to changes in the network organization in the brain. The researchers believe that computer simulations of brain development will provide the tools to use these insights to better understand the formation of the human brain.