Perceptron
In the early days of machine learning, researchers were trying to imitate the functionality of the human brain. At the beginning of the 20th century, people thought that the human brain consisted entirely of cells that are called neurons—cells with long appendages called axons that were able to transmit signals by means of electric impulses. The AI researchers were trying to replicate the functionality of neurons by a perceptron, which is a function that is firing, based on a linearly-weighted sum of its input values:
This is a very simplistic representation of the processes in the human brain—biologists have since then discovered other ways in which information is transferred besides electric impulses such as chemical ones. Moreover, they have found over 300 different types of cells that may be classified as neurons (http://neurolex.org/wiki/Category:Neuron). Also, the process of neuron firing is more complex than just linear transmission of voltages as it involves complex time...