Spatially periodic computation in the entorhinal-hippocampal circuit during navigation

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• The human brain navigates physical and mental spaces using cognitive maps.
• The entorhinal cortex (EC) and hippocampus (HPC) are crucial for cognitive mapping.
• The coordination between EC and HPC in navigation is not fully understood.

Purpose of the Study:

• To investigate the coordination between the entorhinal cortex and hippocampus during navigation.
• To elucidate the neural mechanisms underlying spatial and conceptual navigation.

Main Methods:

• Participants performed an object-matching task with variants arranged in a ring.
• Functional MRI (fMRI) was used to measure brain activity.
• A computational model (EC-HPC PhaseSync) was developed to simulate neural interactions.

Main Results:

• fMRI revealed a threefold spatial periodicity in hippocampal activity tracking navigation directions.
• This hippocampal periodicity was phase-locked with the entorhinal cortex's sixfold periodicity.
• Behavioral performance showed a threefold periodicity synchronized with hippocampal activity.
• The EC-HPC PhaseSync model successfully reproduced these periodic neural and behavioral patterns.

Conclusions:

• Entorhinal cortex grid cell activity exhibits a sixfold periodicity.
• This activity projects vectorial representations to the hippocampus, creating a threefold periodicity.
• This periodic mechanism facilitates the structuring of hippocampal vector representations for navigation.