Hippocampal and Retrosplenial Goal Distance Coding After Long-term Consolidation of a Real-World Environment

Area of Science:

• Neuroscience
• Cognitive Psychology
• Spatial Navigation

Background:

• The hippocampus is implicated in coding goal-directed navigation distances in novel environments.
• The role of the hippocampus in familiar environments, post-systems consolidation, remains less understood.

Purpose of the Study:

• To investigate hippocampal and retrosplenial cortex activity during navigation in both newly learned and highly familiar environments.
• To determine if spatial coding mechanisms differ based on environmental familiarity and route complexity.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to record brain activity.
• Participants navigated virtual reality simulations of familiar and newly learned university campuses.
• Navigation tasks involved varying degrees of route complexity and the presence of external cues.

Main Results:

• Posterior hippocampal activity correlated with goal distance in newly learned environments and familiar environments with complex routes.
• Retrosplenial cortex activity specifically tracked goal distance in familiar environments.
• External guidance cues abolished hippocampal and retrosplenial cortex navigation-related activity.

Conclusions:

• The hippocampus remains dynamically involved in navigation, particularly when detailed spatial processing is required, even in familiar settings.
• Environmental familiarity and route complexity modulate the engagement of hippocampal and retrosplenial cortex in spatial coding.
• Findings challenge the notion of complete hippocampal disengagement after extensive spatial memory consolidation.