Correlated network activity is important in the development of many neural circuits.
Purkinje cells are among the first neurons to populate the cerebellar cortex, where
they sprout exuberant axon collaterals. We used multiple patch-clamp recordings targeted
with two-photon microscopy to characterize monosynaptic connections between the Purkinje
cells of juvenile mice. We found that Purkinje cell axon collaterals projected asymmetrically
in the sagittal plane, directed away from the lobule apex. On the basis of our anatomical
and physiological characterization of this connection, we constructed a network model
that robustly generated waves of activity that traveled along chains of connected
Purkinje cells. Consistent with the model, we observed traveling waves of activity
in Purkinje cells in sagittal slices from young mice that require GABA(A) receptor-mediated
transmission and intact Purkinje cell axon collaterals. These traveling waves are
absent in adult mice, suggesting they have a developmental role in wiring the cerebellar
cortical microcircuit.
