Article posted Thursday, July 16, 2015 12:12pm

Neurons in the brain communicate with one another by means of tiny contact points called synapses. Soon after a baby is born, many more synaptic contacts are formed than required to form functional brain pathways later in life. During childhood and adolescence a process called “pruning” occurs, whereby thousands and thousands of unnecessary neurons and synapses are pruned away (destroyed) to leave viable neuron pathways necessary for normal brain development. Scientists at Columbia University counted synaptic contacts in the brains of 33 people, aged two to 20 years old. Thirteen of these individuals were autistic and 20 were not. Up to about five years of age, the number of synapses was roughly the same in each group. However, in older autistic youngsters the number of synapses greatly exceeded the number found in non-autistic individuals in the same age group. The researchers concluded that autism may result when there is a failure to prune away the excess neurons during childhood. Thus the brain of an autistic person has too many spurious synapses transmitting signals that impede his or her ability to behave in a “normal” manner. (Sulzer, D., et al, 2014, Neuron, Sept. issue)