Interneuron and glial mechanisms underlying V1 orientation map dynamics

The functional architecture of the primary visual cortex (V1)-manifesting as orientation selectivity maps (OS maps) in higher mammals and modular tuning clusters in rodents-provides a window into the rules governing cortical circuit organization. Although OS maps emerge from intrinsic activity and the structured sampling of retinothalamic inputs, their maturation and lifelong adaptability depend on cellular mechanisms that extend far beyond excitatory wiring. Recent advances indicate that inhibitory interneurons and glial cells play critical modulatory roles in map assembly, stabilization, and experience-dependent plasticity. Inhibitory interneurons regulate excitatory-inhibitory (E/I) balance, stabilize population responses, and gate developmental and adult plasticity through coordinated local and long-range interactions. In parallel, astrocytes modulate circuit excitability and experience-dependent refinement by regulating synaptic signaling, metabolic and ionic homeostasis, and plasticity-related receptor function, whereas microglia influence map formation and maintenance indirectly through activity-dependent synaptic remodeling and network homeostasis. This minireview synthesizes emerging insights into how inhibitory networks and glial-neuron crosstalk jointly orchestrate the formation and experience-dependent remodeling of orientation maps, offering a cellular framework for understanding the construction and flexibility of cortical sensory representations.