Positive and Negative Retinotopic Codes in the Human Hippocampus

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• The hippocampus integrates sensory and mnemonic information, but the underlying mechanisms are unclear.
• A retinotopic code, common in visual cortex, might organize information in the hippocampus.
• Opponent interactions within this code may facilitate information processing.

Purpose of the Study:

• To investigate if a bivalent retinotopic code structures activity in the human hippocampus.
• To determine if this code mediates hippocampal-cortical interactions.
• To explore the role of retinotopic coding in sensory-mnemonic integration.

Main Methods:

• Utilized high-resolution 7T functional MRI in seven individuals.
• Mapped retinotopic preferences of hippocampal and cortical voxels using a visual task.
• Analyzed functional connectivity during resting-state fixation.

Main Results:

• Discovered a robust retinotopic code in the hippocampus with stable population receptive fields (pRFs).
• Observed an equal proportion of positive and negative pRFs, suggesting a role in mnemonic processing.
• Found that hippocampal pRF signed amplitude predicts hippocampal-cortical functional connectivity.

Conclusions:

• Retinotopic coding appears to organize sensory and mnemonic information within the hippocampus.
• This coding mechanism may scaffold hippocampal-cortical interactions for information processing.
• Findings suggest a broader role for retinotopic codes beyond visual areas.