Differential regulation of neocortical synapses by neuromodulators and activity.
Synapses are continually regulated by chemical modulators and by their own activity. We tested the specificity of regulation in two excitatory pathways of the neocortex: thalamocortical (TC) synapses, which mediate specific inputs, and intracortical (IC) synapses, which mediate the recombination of cortical information. Frequency-sensitive depression was much stronger in TC synapses than in IC synapses. The two synapse types were differentially sensitive to presynaptic neuromodulators: only IC synapses were suppressed by activation of GABA(B) receptors, only TC synapses were enhanced by nicotinic acetylcholine receptors, and muscarinic acetylcholine receptors suppressed both synapse types. Modulators also differentially altered the frequency sensitivity of the synapses. Our results suggest a mechanism by which the relative strength and dynamics of input and associational pathways of neocortex are regulated during changes in behavioral state.
Gil
Z
Z
Department of Physiology, Zlotowski Center for Neuroscience, Ben-Gurion University, Beer-Sheva, Israel.
Connors
B W
BW
Amitai
Y
Y
D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058786:GABA-B Receptor Agonists; D008464:Mecamylamine / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D018721:Muscarinic Agonists / Q000494:pharmacology; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D009475:Neurons, Afferent / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000494:pharmacology; D017966:Pyramidal Cells / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013788:Thalamus / Q000166:cytology / Q000502:physiology
D018755:GABA Agonists; D018756:GABA Antagonists; D058786:GABA-B Receptor Agonists; D018721:Muscarinic Agonists; D018377:Neurotransmitter Agents; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D009943:Organophosphorus Compounds; D008464:Mecamylamine; D009538:Nicotine; C066430:CGP 35348; D001418:Baclofen