Emergence of cortical inhibition by coordinated sensory-driven plasticity at distinct synaptic loci.
Feedforward GABAergic inhibition sets the dendritic integration window, thereby controlling timing and output in cortical circuits. However, the manner in which feedforward inhibitory circuits emerge is unclear, despite this being a critical step for neocortical development and function. We found that sensory experience drove plasticity of the feedforward inhibitory circuit in mouse layer 4 somatosensory barrel cortex in the second postnatal week via two distinct mechanisms. First, sensory experience selectively strengthened thalamocortical-to-feedforward interneuron inputs via a presynaptic mechanism but did not regulate other inhibitory circuit components. Second, experience drove a postsynaptic mechanism in which a downregulation of a prominent thalamocortical NMDA excitatory postsynaptic potential in stellate cells regulated the final expression of functional feedforward inhibitory input. Thus, experience is required for specific, coordinated changes at thalamocortical synapses onto both inhibitory and excitatory neurons, producing a circuit plasticity that results in maturation of functional feedforward inhibition in layer 4.
Chittajallu
Ramesh
R
Developmental Synaptic Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA. chittajallur@ninds.nih.gov
Isaac
John T R
JT
D000200:Action Potentials / Q000502:physiology; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D004558:Electric Stimulation / Q000379:methods; D056228:Feedback, Sensory / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011724:Pyridazines / Q000494:pharmacology; D012683:Sensory Deprivation / Q000502:physiology; D013003:Somatosensory Cortex / Q000166:cytology*; D018709:Statistics, Nonparametric; D013569:Synapses / Q000502:physiology*; D013788:Thalamus / Q000166:cytology; D014738:Vibrissae / Q000294:innervation; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018756:GABA Antagonists; D011724:Pyridazines; D049452:Green Fluorescent Proteins; D005680:gamma-Aminobutyric Acid; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C049853:gabazine; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1