Delay activity in avian prefrontal cortex--sample code or reward code?

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Animal Behavior

Background:

• The prefrontal cortex (PFC) plays a crucial role in executive functions, including memory and decision-making.
• Understanding the neural mechanisms underlying delay activity in the PFC is essential for deciphering cognitive processes.
• Avian models offer valuable insights into conserved neural mechanisms relevant to mammalian cognition.

Purpose of the Study:

• To investigate whether delay activity in the avian prefrontal cortex (PFC) correlates with a to-be-remembered stimulus or an anticipated reward.
• To differentiate between stimulus-specific coding and outcome-based coding in PFC delay activity.

Main Methods:

• Birds were trained on a directed forgetting paradigm using distinct visual stimuli (red and white) and auditory cues (high-frequency for remember, low-frequency for forget).
• A differential outcomes procedure was implemented, rewarding correct responses after red 'remember' stimuli but not after white 'remember' stimuli.
• Neural activity in the avian PFC during the delay period was recorded and analyzed.

Main Results:

• Delay activity in the avian PFC was observed on trials associated with reward (red-remember) but not on trials without reward (white-remember).
• This pattern contrasts with the expectation if delay activity solely represented memory for the sample stimulus.

Conclusions:

• Activity in the avian PFC during delay periods reflects the anticipated outcome (reward or no reward) rather than a direct neural code for the sample stimulus itself.
• These findings suggest that PFC delay activity is sensitive to the motivational value or expected consequences associated with stimuli.