Neural Correlates of Both Perception and Memory for Objects in the Rodent Perirhinal Cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• The perirhinal cortex (PER) is anatomically positioned to link perception and memory.
• Traditionally, the PER has been viewed as solely dedicated to object recognition memory.
• Recent debate questions whether the PER also contributes to object perception, lacking direct physiological evidence.

Purpose of the Study:

• To investigate the physiological role of the perirhinal cortex (PER) in object perception.
• To determine if PER neurons encode perceptual features of visual stimuli.
• To examine the relationship between PER neural activity and categorical object responses.

Main Methods:

• Single-unit recordings were performed in the perirhinal cortex (PER) of rats.
• Rats performed categorical responses to visual objects with varying degrees of morphing.
• Neural firing rates were analyzed in relation to stimulus changes and behavioral responses.

Main Results:

• Some PER neurons exhibited monotonic firing rate changes reflecting gradual perceptual alterations in morphed objects.
• Other PER neurons showed abrupt firing rate changes corresponding to learned categorical responses.
• Both gradual and abrupt tuning properties were observed at the neural population level.
• PER neural tuning was more distinct in correct trials compared to error trials.

Conclusions:

• Neurons in the perirhinal cortex (PER) encode perceptual details of objects.
• The PER plays a role in both object perception and memory representation.
• Findings challenge the traditional view of the PER as exclusively involved in memory.