Neural encoding

Neural encoding is the way in which information is represented in neurons. Information is encoded into different patterns of action potentials.
Sensory events, such as a light being on or off, can be represented in different ways:

• With a time code, the presence of an event is signaled by neural firing. For example, as long as it is light, a neuron fires; the moment it gets dark, the neuron stops firing.
• With an event code, a change of an event is signaled by neural firing. For example, when the light is turned on, the neuron fires, and when it is turned off, the neuron fires again.
• With a frequency code the intensity of an event can be signaled. For example, the stronger the light, the more frequent the cell fires.
  However, a frequency code can also signal qualitative changes. For instance, an increase in frequency could mean that the light is red, while a decrease in intensity could mean a green light.