Spatial Information Encoding across Multiple Neocortical Regions Depends on an Intact Hippocampus

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Spatial Navigation

Background:

• Neurons in the brain encode spatial information.
• Spatial representations have been identified in the posterior cortex using virtual navigation.
• The role of the wider cortex and hippocampus in spatial representation is unclear.

Purpose of the Study:

• Investigate if spatial representations are a cortex-wide phenomenon.
• Determine if these representations can form without the hippocampus.
• Examine the necessity of hippocampal outflow for organizing cortical spatial representations.

Main Methods:

• Two-photon calcium imaging of the dorsal cortex in mice.
• Mice navigated a treadmill with tactile cues.
• Hippocampal lesions were induced to assess their impact.

Main Results:

• 40-80% of dorsal cortical neurons showed spatially localized activity.
• Activity fields were uniformly distributed across the environment.
• Hippocampal damage impaired the development of location specificity.

Conclusions:

• A widespread population of cortical neurons forms a continuous spatial representation.
• Hippocampal outflow is necessary for organizing these cortical spatial representations.
• Precise cortical spatial representation depends on hippocampal input.