Figure 13.

Two processes describing the developmental origins of cortical activity. Synthesis of evoked and spontaneous cortical activity development in the mouse V1. Activity originates as spindle burst oscillations (6 Hz) produced in response to thalamocortical input, which in V1 are generated by retinal waves during the first postnatal week. Circuit changes cause acceleration of these oscillations until they become the broadband high frequencies caused by asynchronous firing in the cortex in response to visual input and arousal. Before the development of feedforward inhibition at P14, thalamocortical input causes long duration rapid activity that can outlast the stimulus (yellow). A second process leads to the development of ongoing activity in the absence of strong input. This activity begins at P10, taking the form of isolated slow waves that become continuous by P12. By P14 (eye opening), slow activity and rapid activity alternate in cortex with arousal state and sensory input.