Abnormal wiring of CCK+ basket cells disrupts spatial information coding

The function of cortical GABAergic interneurons is largely determined by their integration into specific neural circuits, but the mechanisms controlling the wiring of these cells remain largely unknown. This is particularly true for a major population of basket cells that express the neuropeptide cholecystokinin (CCK). Here we found that the tyrosine kinase receptor ErbB4 is required for the normal integration of CCK+/VGlut3+ basket cells into cortical circuits. The number of inhibitory synapses made by CCK+/VGlut3+ basket cells and the inhibitory drive they exert on pyramidal cells are severely reduced in conditional mice lacking ErbB4. Developmental disruption of the connectivity of these cells diminishes the power of theta oscillations during exploratory behavior, disrupts spatial coding by place cells, and causes selective alterations in spatial learning and memory in adult mice. These results suggest that normal integration of CCK+ basket cells in cortical networks is key to support spatial coding information in hippocampus.