Parvalbumin is a small calcium-binding protein that belongs to the EF-hand protein family. It is expressed in vertebrates and is typically found in high concentrations in certain skeletal muscle fibers and neurons. Parvalbumin plays a crucial role as a mobile cytosolic Ca2+ buffer, influencing the duration of intracellular Ca2+ signals and is key in muscle relaxation following contraction and neuronal recovery following excitation. In the context of neuroscience, parvalbumin is highly expressed in the nervous system during development and is associated with the maturation of functional circuits. It is predominantly found in a specific subgroup of cortical interneurons and is involved in the inhibition of neuronal activity. Parvalbumin-expressing neurons are known for their fast-spiking behavior and are involved in various neurological processes, including the regulation of neuronal circuits and the modulation of synaptic transmission.