Alerting network

The alerting network signals when to pay conscious attention (Posner, 2012:28-47). When visual or verbal cues are perceived that something interesting, relevant, or important may happen, this system brings our brain and body into a state of alertness and vigilance. 

The neural basis for the alerting system seems to lie in a cluster of neurons in the brainstem, the locus coeruleus (Schiff & Finns 2007). This neuron cluster is responsible for producing and releasing the neurotransmitter norepinephrine (NE). As shown in Figure 2 by the blue arrows, their axons project to the entire cortex and various subcortical areas.