Endopiriform neurons projecting to ventral CA1 are a critical node for recognition memory

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• The claustrum complex is vital for higher-order cognition, but its subregion organization and function remain unclear.
• Understanding the specific roles of neuroanatomical subregions within the claustrum complex is essential for advancing cognitive neuroscience.

Purpose of the Study:

• To elucidate the circuit organization and function of neuroanatomical subregions within the claustrum complex.
• To identify specific neuronal populations in the endopiriform nucleus (EN) and their contribution to cognitive functions.

Main Methods:

• Identification of EN neurons projecting to the ventral CA1 (ENvCA1-proj neurons) using projection mapping.
• Analysis of recurrent circuits involving EN neurons and the piriform cortex.
• Chemogenetic manipulation of ENvCA1-proj neuron activity in mice.
• Assessment of behavioral responses to novelty, distinguishing between memory-guided and innate behaviors.

Main Results:

• ENvCA1-proj neuron activity showed a bias toward novelty across different stimulus categories.
• Chemogenetic inhibition of ENvCA1-proj neurons selectively impaired memory-guided responses to novelty, while innate responses remained unaffected.
• Functional connectivity analysis revealed recurrent circuits involving EN neurons and the piriform cortex.

Conclusions:

• ENvCA1-proj neurons are a key subpopulation within the endopiriform nucleus, critical for recognition memory.
• These neurons act as an essential node for novelty detection and memory-guided behavior through recurrent circuits that sustain attention.
• ENvCA1-proj neurons facilitate a shift in behavior from familiarity to novelty via feed-forward inhibition of distal ventral CA1 neurons.