Environmental Barriers Disrupt Grid-like Representations in Humans during Navigation.

Area of Science:

• Neuroscience
• Cognitive Science
• Spatial Navigation

Background:

• Environmental structures significantly influence behavior and spatial understanding.
• Rodent studies show barriers disrupt grid cell firing symmetry, creating fragmented spatial submaps.
• This suggests barriers impact cognitive maps via entorhinal cortex spatial metric representation.

Purpose of the Study:

• To investigate how environmental barriers affect spatial metric representation in the human entorhinal cortex.
• To test the hypothesis that barriers reorganize spatial metrics.
• To compare human entorhinal cortex activity in open versus barrier-containing virtual environments.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used in human participants.
• A virtual navigation paradigm with manipulated barrier structures was employed.
• Participants performed a fixed-route foraging task in both open-field and compartmentalized environments.

Main Results:

• In an open-field environment, human right entorhinal cortex showed a 6-fold periodic modulation, consistent with grid cell firing.
• In environments with barriers, the 6-fold symmetry was abolished.
• A 4-fold modulation of the entorhinal signal was observed in barrier environments, suggesting a vectorized spatial metric organization.

Conclusions:

• Environmental barriers fundamentally influence spatial representation in the human entorhinal cortex.
• Barriers abolish the typical 6-fold grid-like spatial metric, replacing it with a 4-fold pattern.
• These findings provide mechanistic insight into how segmented environments are mapped cognitively, with implications for naturalistic navigation.