A dopaminergic visuomotor gateway to the zebrafish optic tectum

In vertebrates, the superior colliculus, also known as the optic tectum in fish, is a conserved visual center that is influenced by dopaminergic (DA) neurons. Researchers have now identified a specific cluster of pretectal DA (PrDA) neurons in larval zebrafish whose axons extensively innervate the tectum, primarily in its deep neuropil.

By employing anatomical and molecular analyses, the study demonstrates that PrDA neurons respond consistently to visual stimulation. However, a majority of these neurons also display heightened activity during spontaneous locomotion. When visual stimuli and motor output occur simultaneously, the activity of PrDA neurons is further augmented, suggesting that these neurons integrate input from both visual and motor centers.

The synchronization of PrDA neuron activity is even more pronounced when influenced by visual or motor activity. Interestingly, the direction-selective response of PrDA neurons to visual stimuli becomes apparent only when motor activity is considered, indicating that these neurons provide a rapid visuomotor-related dopaminergic modulation of tectal circuits, transforming visual information into context-dependent motor commands. This mechanism may also be present in analogous mammalian midbrain circuits.