What happens to inspiratory muscles during the "off" state of the DRG?

During the "off" state of the dorsal respiratory group (DRG), which is integral in the control of breathing, the inspiratory muscles relax. The DRG is primarily responsible for activating these muscles during inhalation. When the DRG is not firing, there is a cessation of neuronal activity that leads to the contraction of the muscles involved in inspiration. This lack of stimulation allows the inspiratory muscles, such as the diaphragm and intercostal muscles, to return to a relaxed state, which is essential for the passive phase of exhalation. This process is part of the normal respiratory cycle, where periods of muscle contraction (during inhalation) alternate with periods of relaxation (during exhalation).

In this context, the other options do not accurately depict what occurs during the "off" state. The inspiratory muscles do not contract since there is a lack of stimulation from the DRG during this phase. Stopping firing (another choice) would imply muscular contraction has ceased, which is indeed part of the process but does not capture the resultant effect - that is, relaxing muscles. Hyperventilation implies an increased rate and depth of breathing, which would not occur during the "off" state, as this is characterized by a decreased respiratory drive