Paper Review 

A study published in Science, titled "Whole-brain spatial organization of hippocampal single-neuron projectomes" addresses this critical gap by reconstructing single-neuron projectomes of 10,100 single hippocampal neurons in mice, offering unprecedented insights into their brain-wide connectivity. Stereo-seq in this study was used to "map the gene expression patterns in serial coronal sections of the hippocampus."

The hippocampus (HIP), a crucial brain structure, connects widely with different brain areas, including the cortex, thalamus, hypothalamus, olfactory regions, and amygdala. However, the precise manner in which single HIP neurons project to these brain-wide target areas and how their soma location influences these projections remained largely unknown.

The researchers reconstructed the somata, axon arbors, and dendrites of 10,100 individual neurons from the mouse HIP using sparse-labeling methods combined with fluorescence micro-optical sectioning tomography. From this extensive dataset, they identified 341 distinct projection patterns, which were further classified into 43 projectome subtypes based on axon morphology and brain-wide target areas. Among the key findings, the study revealed previously unknown axon projection patterns, demonstrated target-dependent soma distribution within HIP subdomains, elucidated general rules for bihemispheric projections, and uncovered topographic correlations between axon arbors and soma locations along the hippocampal axes.

Stereo-seq data showed that specific gene expression clusters in the CA1 region correspond to neurons with distinct projection patterns. This molecular-structural integration provides a deeper understanding of how genetic factors shape neural circuits, offering new avenues for studying the molecular basis of brain function. The Stereo-seq data, visualized alongside projectome data at the Hippocampal Projectome Database, enhances the study's accessibility and utility for the scientific community. The dataset is accessible at: https://mouse.digital-brain.cn/hipp

Find out more about the study: https://www.science.org/doi/10.1126/science.adj9198

About STOmics' Stereo-seq:
STOmics offers the most advanced spatiotemporal multi-omics technology, enabling unbiased discovery to answer biological questions in scientific research and clinical applications. Currently, we offer spatial transcriptomics solutions, including Stereo-seq v1.3 for fresh frozen samples, Stereo-seq OMNI for FFPE samples, Stereo-seq Large Chip Designs (LCD) for centimeter-level fresh frozen samples (now up to 2cm x 3cm), and a spatial multi-omics solution - Stereo-CITE for high-plex spatial proteo-transcriptome co-detection. https://en.stomics.tech/