Learning what to expect and when to expect it involves dissociable neural systems.

Area of Science:

• Neuroscience
• Behavioral Psychology
• Learning and Memory

Background:

• Understanding how animals learn about reward attributes is crucial for neuroscience.
• Distinguishing between learning 'what' reward to expect and 'when' it will occur is key to understanding reward processing.

Purpose of the Study:

• To investigate the independence of learning about the identity ('what') versus the timing ('when') of food rewards.
• To examine the role of the basolateral amygdala (BLA) in these learning processes.

Main Methods:

• Two experiments using Long-Evans rats and instrumental/Pavlovian peak timing tasks.
• Selective devaluation of one of two distinct food rewards using LiCl injections.
• Assessment of responding in the presence of stimuli signaling devalued versus valued rewards.
• Evaluation of the impact of pre-training basolateral amygdala (BLA) lesions on reward devaluation and timing.

Main Results:

• Rats selectively reduced responding to stimuli associated with devalued rewards, leaving timing functions largely intact.
• Pre-training BLA lesions abolished the selective reward devaluation effect.
• BLA lesions did not impact the interval timing performance in the peak timing tasks.

Conclusions:

• Learning about the 'what' and 'when' features of reward may be mediated by distinct neural systems.
• The basolateral amygdala (BLA) appears critical for learning the identity of rewards but not for interval timing itself.