Homeostasis of a representational map in the neocortex.

Cortical function, including sensory processing, is surprisingly resilient to neuron loss during aging and neurodegeneration. In this Article, we used the mouse auditory cortex to investigate how homeostatic mechanisms protect the representational map of sounds after neuron loss. We combined two-photon calcium imaging with targeted microablation of 30-40 sound-responsive neurons in layer 2/3. Microablation led to a temporary disturbance of the representational map, but it recovered in the following days. Recovery was primarily driven by neurons that were initially unresponsive to sounds but gained responsiveness and strengthened the network's correlation structure. By contrast, selective microablation of inhibitory neurons caused prolonged disturbance, characterized by destabilized sound responses. Our results link individual neuron tuning and plasticity to the stability of the population-level representational map, highlighting homeostatic mechanisms that safeguard sensory processing in the neocortex.