CPGs:

Many of them are rhythmic movements such as breathing, chewing, and walking. These movements are produced by neural circuits called central pattern generators

When activated, the neurons in these circuits generate a certain pattern of predetermined neural activity that smoothly co-ordinates the contraction of the many muscles involved in rhythmic activities such as walking.

These pattern generators free up your conscious mind so that you don't have to send down a voluntary command every time you want to put one foot in front of the other. In this respect, walking resembles a reflex activity. But you do have to issue voluntary commands when you want to start or stop walking, just as you do to pick up your pace to get across the street when the light turns yellow, or to make that little jump up to the curb on the opposite side, or a small sidestep to avoid a puddle along the way.

Thus voluntary commands can also modulate certain reflex movements. This is the most effective compromise that nature has found between the need to free our minds from repetitive movements and the need to retain some ability to adjust to changes and obstacles in our environment.

Location of different networks (central pattern generators, CPGs) that coordinate different motor patterns in vertebrates.

The spinal cord contains the CPGs for locomotion and protective reflexes

the brainstem, those for breathing, chewing, swallowing and saccadic eye movements;

the hypothalamus, centres that regulate eating and drinking.

These areas can coordinate the activation of different CPGs in a behaviourally relevant order. For instance, if the fluid intake area is activated, an animal will look for water, walk towards it, position itself and start drinking. The cerebral cortex is important in particular for fine motor coordination involving hands and fingers and for speech. General control strategy for vertebrate locomotion. Locomotion is initiated by activity in reticulospinal neurons (RS) of the brainstem locomotor centre, which produces the locomotor pattern in close interaction with sensory feedback. With increased activation of the locomotor centre, the speed of locomotion increases and interlimb coordination can change (from a walk to a gallop, for example

The basal ganglia exert a tonic inhibitory influence on motor centres that is released when a motor pattern is selected.