Entorhinal cortex represents task-relevant remote locations independent of CA1

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Neurons represent sensory experiences and remote memories during movement and immobility, respectively.
• Medial entorhinal cortex (MEC) neurons encode location during movement, but their role during immobility is less understood.
• Remote neural representations are crucial for learning associations.

Purpose of the Study:

• To investigate the collective neural representations of the medial entorhinal cortex (MEC) during immobility.
• To understand the role of MEC non-local coding in learning associations between locations.
• To compare MEC activity with dorsal CA1 during associative learning.

Main Methods:

• Recorded neural activity from thousands of neurons in superficial MEC and dorsal CA1 in mice.
• Trained mice to associate two pairs of rewarded locations.
• Analyzed neural population activity during periods of immobility and movement, focusing on non-local coding patterns.

Main Results:

• During immobility, MEC neural populations frequently represented non-local positions, termed 'non-local coding'.
• Cells with spatial firing fields at remote locations drove this non-local coding, even with concurrent local representations.
• Non-local coding occurred more often outside of sharp-wave ripples and was task-relevant, prioritizing rewarded locations.

Conclusions:

• MEC exhibits significant non-local coding during immobility, representing remote locations relevant to learned associations.
• This non-local coding appears to function independently of CA1 activity, particularly outside of sharp-wave ripples.
• MEC non-local coding may play a distinct role in strengthening spatial associations, potentially independent of CA1's involvement.