Single genomic enhancers drive experience-dependent GABAergic plasticity to maintain sensory processing in the adult cortex (RNA-Seq II)

Experience-dependent plasticity of synapses modulates information processing in neural circuits and is essential for cognitive functions. Genomic enhancers are thought to modulate specific sets of synapses by regulating experience-induced transcription to thereby promote neural circuit plasticity. However, this idea remains untested. Thus, here we analyze the cellular and circuit functions of the genomic mechanisms that control the experience-induced transcription of Igf1 (Insulin-like growth factor 1) in disinhibitory VIP interneurons in the adult visual cortex. We find that two sensory-induced enhancers selectively and cooperatively drive sensory-induced Igf1 transcription and that these enhancers homeostatically control the ratio between excitation and inhibition (E/I-ratio) and neural activity in VIP interneurons to thereby restrict visual acuity. Thus, single experience-regulated enhancers are essential for maintaining sensory processing. Since cortical plasticity scales with neural activity in VIP interneurons, this also suggests that experience-induced transcription restricts plasticity in adult neural circuits to preserve the brain's functional integrity. Overall design: Assessing the impact of residual neuronal activity in the visual cortex during dark-housing. Cortex was silenced with a viral vector expressing the Kir2.1 channel in all neurons.