Sleep and Appetitive Conditioned Memory

Abstract

In associative appetitive learning, an individual learns to extract logical information of the conditioned stimulus to predict the potential outcomes. How the conditioned stimulus drives appropriate predictive behavior is not yet known, but it has been found that the association is formed at neural level between the conditioned and unconditioned circuitries. The conditioned stimulus possibly generates many different types of associations with the appetitive unconditioned stimulus. For example, the conditioned stimulus forms an association with food (unconditioned stimulus) through their specific (i) affective and (ii) preparative properties. These properties may be encoded and represented at different neural circuitries in different brain regions. Several neurotransmitters, such as dopamine, glutamate, serotonin, cannabinoids, and opioids, play an important role in appetitive conditioning. Some neuropeptides such as orexin, leptin, ghrelin, etc. are also involved in the modulation of the affective attribute of appetitive conditioning tasks. In addition, a large number of studies consistently revealed the role of sleep in a variety of learning tasks such as declarative memory, procedural memory, and spatial learning tasks. The role of sleep in appetitive conditioning tasks has, however, not been investigated in detail. We have reported that short-term sleep deprivation soon after training impairs the consolidation of appetitive conditioned memory. We have also found that the consolidation of appetitive conditioned memory requires augmented REM sleep after training. In this chapter, we have discussed in detail the role of different brain areas, neural circuitries, and, more specifically, sleep in appetitive conditioning.