Complex effects of reward upshift on consummatory behavior

Area of Science:

• Behavioral Neuroscience
• Animal Models
• Reward Processing

Background:

• Consummatory successive positive contrast (cSPC) is an effect observed when reward magnitude increases.
• cSPC has been proposed as a potential animal model for positive emotion.
• The reliability of cSPC as a distinct behavioral phenomenon is questionable.

Purpose of the Study:

• To investigate the reliability and underlying mechanisms of consummatory successive positive contrast (cSPC).
• To explore factors influencing cSPC, including reward concentration upshifts and novelty.
• To determine if cSPC can be consistently elicited in rats.

Main Methods:

• Ten experiments examined consummatory behavior in rats following sucrose or saccharin concentration upshifts.
• Behavioral responses were compared to preshift levels and unshifted controls.
• One experiment utilized preexposure to sucrose or water to assess novelty effects.

Main Results:

• Evidence for cSPC was occasional; more frequently, behavior increased relative to preshift but decreased relative to unshifted controls.
• This pattern suggests opposing processes, such as taste neophobia and generalization decrement, influence behavior.
• Preexposure to the higher sucrose concentration abolished cSPC, with preexposed rats drinking as much as controls.

Conclusions:

• The unreliability of cSPC may stem from opposing behavioral processes triggered by reward upshifts.
• Novelty-related effects, like generalization decrement, appear to suppress cSPC.
• These findings challenge the distinct ontological status of cSPC as a reliable behavioral effect.