title: Properties of mEPSCs recorded in layer II neurones of rat barrel cortex.
abstract: Voltage-clamp recordings from layer II neurones in somatosensory cortex of rats aged between 12 and 17 days showed a high frequency of spontaneous postsynaptic currents (sPSCs), which on average was 33 +/- 13 Hz (s.d.). sPSCs were mediated largely by glutamatergic AMPA receptors. Their rates and amplitudes were independent of blocking sodium channels with 1 microM tetrodotoxin (TTX). Most of them, therefore, represent genuine miniature excitatory postsynaptic currents (mEPSCs). The rise time of the fastest (10 %) mEPSCs was 288 +/- 86 micros (10-90 %) and the half-width was 1073 +/- 532 micros. The amplitude was -5.9 +/- 1.1 pA with a coefficient of variation (CV) of 0.44 +/- 0.14. The rate of mEPSCs was very temperature sensitive with a Q(10) (33-37 degrees C) of 8.9 +/- 0.9. Due to this temperature sensitivity, we estimated that the microscope lamp contributed an increase in temperature of about 4 degrees C to the tissue in the focal volume of the condenser. Cell-type differences in the rate of mEPSCs were found between pyramidal/multipolar and bipolar cells. The latter had a frequency of about a third of that seen in the other cell groups. Recordings in layer II are ideally suited to investigate mechanisms of spontaneous transmitter release.
authors.affiliation: Institute of Neuroinformatics, University of Zürich and Federal Institute of Technology (ETH), Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
authors.forename: Christopher R L
authors.initials: CR
authors.lastname: Simkus
authors.forename: Christian
authors.initials: C
authors.lastname: Stricker
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000465:Algorithms; D000818:Animals; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D008239:Lysine / Q000031:analogs & derivatives*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D019579:Neocortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013003:Somatosensory Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D013696:Temperature
chemical_list: D018377:Neurotransmitter Agents; D026941:Sodium Channel Blockers; C013411:biocytin; D008239:Lysine