Spatial and temporal representations are organized along a stable coding gradient in the medial entorhinal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• The medial entorhinal cortex (MEC) is traditionally known for spatial coding.
• Emerging evidence suggests the MEC also processes temporal information.
• The organization of spatial and temporal codes within the MEC is not well understood.

Purpose of the Study:

• To investigate the organization of spatial and temporal representations in the MEC.
• To determine how individual neurons in the MEC represent spatial versus temporal information.
• To explore the flexibility of MEC neural codes based on cognitive demands.

Main Methods:

• High-density silicon probes were used to record MEC neuronal activity in mice.
• Mice performed both a timing task and a virtual reality spatial navigation task.
• Neuronal activity was analyzed for spatial tuning and temporal coding during different tasks.

Main Results:

• Spatial and temporal representations were found to be partially overlapping but biased within the MEC population.
• Neurons with strong spatial tuning showed less reliable temporal coding.
• Neurons with weaker spatial tuning demonstrated more flexible shifts to temporal coding.
• The relationship between spatial tuning strength and temporal coding was consistent across different environments.

Conclusions:

• The MEC exhibits a coding gradient, with neurons ranging from dedicated spatial coders to flexible spatial/temporal coders.
• Individual neuron coding preferences are influenced by a stable network-level organization.
• MEC neurons adapt their coding strategies to meet the specific cognitive demands of tasks.