Data from: Whole-brain spatial organization of hippocampal single-neuron projectomes

Mapping hippocampal single-neuron projections is essential for
understanding brain-wide circuit organization and diverse functions of the
hippocampus, a brain structure underlying episodic memory and cognition.
Here, we reconstructed 10,100 single-neuron projectomes of the mouse
hippocampus, identified rostral and caudal axon pathways that
preferentially innervated cortical vs. subcortical areas, and classified
43 projectome subtypes with distinct axon targeting patterns. Notably, the
soma locations along hippocampal longitudinal and transverse axes
determined the number of their target areas and the spatial distribution
and complexity of their axon arbors within the targets. We defined
selective hippocampal subdomains based on spatial transcriptomic profiles
and found that many projectome subtypes were enriched in specific
subdomains. Next, we defined the wiring diagram for hippocampal neurons
exclusively projecting to hippocampal formation (HPF) and those projecting
to both intra- and extra-HPF targets with coordinated projection
strengths. Furthermore, bi-hemispheric projecting hippocampal neurons
generally projected to one pair of homologous targets with ipsilateral
preference. These organization principles of single-neuron projectomes
provide a structural basis for understanding diverse but coordinated
functions of hippocampal neurons.