Input-specific effects of acetylcholine on sensory and intracortical evoked responses in the "barrel cortex" in vivo.
The somatosensory neocortex processes extrinsic information from the thalamus and intrinsic information from local circuits. We compared the effects of acetylcholine (Ach) on neocortical field potential responses evoked by stimulation of the whiskers and by local electrical stimulation in the upper layers of the neocortex vibrissae representation ("barrel cortex") of adult rats anesthetized with urethane. In the barrel cortex, the cholinergic system was manipulated using microdialysis by exogenous application of Ach, by increasing the endogenous levels of Ach with physostigmine and by applying specific cholinergic agonists. The results revealed that Ach selectively enhances the sensory response relative to the intracortical response. Thus, pathways in the barrel cortex are differentially regulated by cholinergic inputs.
Oldford
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Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Room WB210, Montreal, Quebec, Canada H3A 2B4.
Castro-Alamancos
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MA
D000818:Animals; D002799:Cholinergic Fibers / Q000502:physiology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005021:Ethylamines / Q000494:pharmacology*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects* / Q000502:physiology; D017551:Microdialysis / Q000379:methods; D009116:Muscarine / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D019579:Neocortex / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D010812:Physical Stimulation; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014738:Vibrissae / Q000294:innervation
D002800:Cholinesterase Inhibitors; D005021:Ethylamines; D018721:Muscarinic Agonists; D018722:Nicotinic Agonists; C049455:acetylcaine; D009538:Nicotine; D009116:Muscarine; D010830:Physostigmine