Table 1.

Operating requirements of CNS arousal systems

Operational definition

Provide alertness to sensory stimuli, body-wide, all sensory modalities

Drive voluntary motor activity, body-wide, from fidgeting to running marathons

Fuel emotional reactivity, positive and negative

Operational requirements

Lability: “Hair triggered,” rapid, not sluggish

Sensitivity: Especially to the momentary state of the organism

Convergence: All sensory stimuli activate the same set of arousal subsystems, which, in turn, support each other

Divergence: Activate cerebral cortex, autonomic nervous systems, and endocrine organs to initiate behavior

Robustness: Does not fail. Survival of the organism depends on adequate CNS arousal