Contributions of area Te2 to rat recognition memory

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Memory Research

Background:

• Object recognition memory is vital for survival.
• The perirhinal cortex (PRH) is known to be critical for this function.
• The role of the adjacent temporal association cortex (area Te2) remains less understood.

Purpose of the Study:

• To elucidate the specific role of rat area Te2 in object recognition memory.
• To compare the function of area Te2 with that of the adjacent PRH.
• To investigate the neurochemical basis of Te2's involvement in memory.

Main Methods:

• Bilateral ablations of area Te2 in rats.
• Local intracerebral infusions into area Te2 using CNQX, lidocaine, AP5, UBP302, and scopolamine.
• Behavioral testing of object recognition memory at various delays (5 min, 20 min, 24 h).
• Comparison of Te2 manipulations with similar manipulations in the PRH.

Main Results:

• Bilateral Te2 lesions impaired recognition memory at delays ≥20 min, but not at 5 min.
• Infusions of AMPA/kainate receptor antagonist (CNQX), axonal blocker (lidocaine), or NMDA receptor antagonist (AP5) into Te2 impaired memory at 24 h but not 20 min.
• A GluK1 kainate receptor antagonist (UBP302) impaired 24-h memory in Te2 but only 20-min memory in PRH.
• Muscarinic receptor antagonist (scopolamine) had no effect in Te2, unlike in PRH.
• Perceptual deficits were ruled out as the cause of Te2 impairments.

Conclusions:

• Area Te2 is essential for object recognition memory at delays greater than 5 or 20 minutes.
• Both area Te2 and PRH are necessary for long-term object recognition memory.
• Area Te2's role in object recognition memory differs temporally and neurochemically from PRH.