The human brain is a highly complex multilayered organ composed of many billions of neurons, organized into very complicated interconnecting neural networks. Typically, each neuron is connected to tens of thousands of other neurons through connections called synapses. Electrochemical signals that are passed between neurons through these synapses allow them to communicate. The connections between neurons are not static, but change over time. The more signals sent between two neurons, the stronger the connection grows, and so, with each new experience, the brain slightly rewires its physical and functional structure.
Unique local physical and functional connections between neurons are called neural networks. Neural networks are typically characterized by preferred signaling pathways, and it is the interactions within and between these networks of neurons that enable us to perform various functions including cognitive functions, such as attention, working memory, pattern recognition and problem-solving.
It is this simultaneous cooperative function of brain areas working together as large-scale networks which is at the root of the sophistication and computational power of the human brain.