Baby Photograph

Making Connections — Wiring the Brain

Illustration of a NeuronNeurons communicate with each other by sending electrical signals from one neuron to another across a small space called a synapse. Chemicals work in the synapses to transmit the electrical impulses between neurons. Neurons communicate with each other in a predictable pattern that repeats itself from neuron to neuron.

  • The cell body tells the neuron to send an electrical signal.
  • The signal travels out through the axon.
  • The signal passes across the synapse.
  • dendrites of other neurons receive the signal.

Brain development is largely a wiring process, where connections between neurons are made and refined. Neurons communicate with each other through networks of connections. These connections determine the pathways of the electrical signals. Connections used regularly become stronger and more complex, but connections that are not used are eventually eliminated through the process called pruning, described in the section with other brain development processes.

Every baby is born with approximately 100 billion neurons. The numbers of connections formed among neurons in an infant's brain are amazing:

  • At birth the baby has 50 trillion connections or synapses.
  • In the first three months of life, the synapses multiply more than 20 times.
  • At one year the brain has 1,000 trillion synapses.