The study by Znamenskiy et al. investigates the functional specificity of recurrent inhibition in the visual cortex of mice. Parvalbumin (PV)-positive (PV+) inhibitory neurons, known for their dense and heterogeneous connectivity, are found to strongly inhibit pyramidal cells that provide them with strong excitation. The strength of these inhibitory connections is tuned according to the similarity of visual responses between PV+ and pyramidal cells. Specifically, PV+ cells preferentially inhibit pyramidal cells that share similar visual selectivity, such as orientation and direction preferences. This structured organization of inhibitory synaptic weights helps stabilize activity within feature-specific excitatory ensembles while supporting competition between different ensembles. The findings are supported by both in vivo visual responses and synaptic connectivity measurements, and are further validated through network simulations. These results provide insights into how inhibitory neurons shape neural circuits and contribute to sensory processing in the visual cortex.The study by Znamenskiy et al. investigates the functional specificity of recurrent inhibition in the visual cortex of mice. Parvalbumin (PV)-positive (PV+) inhibitory neurons, known for their dense and heterogeneous connectivity, are found to strongly inhibit pyramidal cells that provide them with strong excitation. The strength of these inhibitory connections is tuned according to the similarity of visual responses between PV+ and pyramidal cells. Specifically, PV+ cells preferentially inhibit pyramidal cells that share similar visual selectivity, such as orientation and direction preferences. This structured organization of inhibitory synaptic weights helps stabilize activity within feature-specific excitatory ensembles while supporting competition between different ensembles. The findings are supported by both in vivo visual responses and synaptic connectivity measurements, and are further validated through network simulations. These results provide insights into how inhibitory neurons shape neural circuits and contribute to sensory processing in the visual cortex.