The amygdala is a key structure involved in memory, emotional processing, and sensory integration. While the cortical connectivity of the amygdala with the frontal and temporal lobes has been extensively studied, its direct connections with the parieto-occipital cortices remain underexplored. This study aims to delineate the direct connectivity between the amygdala and the parietal and occipital cortices via the parahippocampal segment of the cingulum bundle.
Methods
High-resolution diffusion-weighted imaging (DWI) tractography was performed on 30 healthy adult brains. Fiber tracking was conducted using three regions of interest (ROIs) placed in the parietal, occipital, and medial temporal lobes. A fractional anisotropy (FA) threshold of 0.25 and an angle threshold of 70° were applied to reconstruct the fiber pathways.
Results
A consistent bilateral trajectory of the parahippocampal segment of the cingulum bundle was identified, originating in the posterior parietal and lateral occipital cortices and terminating in the amygdala. This pathway was distinct from adjacent fiber tracts such as the amygdalofugal pathway and fornix.
Conclusion
This study confirms the existence of a direct parieto-occipital connection to the amygdala via the parahippocampal cingulum bundle which is an important part of the ventral and dorsal Kamali limbic circuitry. These findings contribute to our understanding of posterior limbic connectivity and may have implications for visuosensory-emotional processing in both health and disease.
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