CalciMAP: High-resolution images showing calbindin- and parvalbumin-expressing neurons across the developing and adult mouse brain.

Calcium-binding proteins are abundant in neurons across the brain, serving as essential regulators of neuronal excitability. Dysfunctional regulation of calcium is implicated in a range of neuropsychiatric and neurodevelopmental disorders. Two highly abundant calcium-binding proteins are calbindin and parvalbumin. Despite their importance in brain development, little is known about when and where neurons expressing calbindin and parvalbumin emerge in different brain regions. Most studies into the development of these neurons or their involvement in atypical brain development are limited to one or a few brain regions, and data from these studies are rarely made available. The scarcity of brain-wide information hampers efforts to understand cellular composition changes occurring in the developing brain. Amending this, we here present a brain-wide histological image collection showing calbindin- and parvalbumin-expressing neurons in the mouse brain across five age groups: postnatal day 9, 14, 21, 35 and adult. All the images have been spatially registered to age-specific brain atlases and are made available for both interactive online viewing and download. This collection provides a comprehensive overview of the development of neurons expressing calcium binding proteins in the mouse brain and is tailored for use in analytical workflows to quantify changes across development.