Locus Coeruleus Activation Patterns Differentially Modulate Odor Discrimination Learning and Odor Valence in Rats

ABSTRACT The locus coeruleus (LC) produces phasic and tonic firing patterns that are theorized to have distinct functional consequences. However, how different modes affect learning valence encoding of sensory information unknown. Here, we show bilateral optogenetic activation rat LC neurons using 10-Hz trains either 300 ms or 10 s accelerated acquisition a similar odor discrimination. Similar discrimination was impaired by noradrenergic blockade in the piriform cortex (PC). light-mediated facilitation prevented dopaminergic antagonist PC, ventral tegmental area (VTA) silencing with lidocaine, suggesting LC–VTA–PC dopamine circuitry involvement. Ten-hertz stimulation did not alter acquisition, ineffective activating VTA DA neurons. For encoding, at 25 Hz induced conditioned aversion, whereas stimulations produced an preference. Both conditionings were basolateral amygdala (BLA). Cholera Toxin B retro-labeling showed larger engagement nucleus accumbens-projecting BLA activation, central projecting cells 25-Hz light. These outcomes argue differentially influence both target networks behavior.