title: Alterations in membrane and firing properties of layer 2/3 pyramidal neurons following focal laser lesions in rat visual cortex.
abstract: Focal cortical injuries are well known to cause changes in function and excitability of the surviving cortical areas but the cellular correlates of these physiological alterations are not fully understood. In the present study we employed a well established ex vivo-in vitro model of focal laser lesions in the rat visual cortex and we studied membrane and firing properties of the surviving layer 2/3 pyramidal neurons. Patch-clamp recordings, performed in the first week post-injury, revealed an increased input resistance, a depolarized spike threshold as well as alterations in the firing pattern of neurons in the cortex ipsilateral to the lesion. Notably, the reported lesion-induced alterations emerged or became more evident when an exciting perfusing solution, known as modified artificial cerebrospinal fluid, was used to increase the ongoing synaptic activity in cortical slices. Conversely, application of glutamatergic or GABAA receptor blockers reduced the observed alterations and GABAB receptor blockers abolished the differences completely. All together the present findings suggest that changes in synaptic receptors function, following focal cortical injuries, can modulate membrane and firing properties of layer 2/3 pyramidal neurons. This previously unknown functional interplay between synaptic and membrane properties may constitute a novel cellular mechanism to explain alterations in neuronal network function and excitability following focal cortical injuries.
authors.affiliation: Institute of Physiology and Pathophysiology, University Medical Center of the Johannes-Gutenberg University Mainz, D-55128 Mainz, Germany. Electronic address: imbrosci@uni-mainz.de.
authors.forename: B
authors.initials: B
authors.lastname: Imbrosci
authors.forename: T
authors.initials: T
authors.lastname: Mittmann
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002462:Cell Membrane / Q000528:radiation effects*; D003627:Data Interpretation, Statistical; D055724:Electrophysiological Phenomena / Q000528:radiation effects*; D066298:In Vitro Techniques; D007834:Lasers; D009474:Neurons / Q000528:radiation effects; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000528:radiation effects*; D051381:Rats; D020318:Rats, Long-Evans; D013569:Synapses / Q000528:radiation effects; D009435:Synaptic Transmission / Q000502:physiology / Q000528:radiation effects; D014793:Visual Cortex / Q000293:injuries*
keywords: (m)ACSF; (modified) artificial cerebrospinal fluid; 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; 6,7-dinitroquinoxaline-2,3-dione; ADP; AHP; DNQX; EGTA; GABA(A) receptor; GABA(A)R; GABA(B) receptor; GABA(B) receptors; GABA(B)R; HEPES; ISI; PTX; Ri; SFA; afterdepolarization; afterhyperpolarization; cortical lesions; ethylene glycol tetraacetic acid; input resistance; interspike interval; mACSF; patch clamp recordings; picrotoxin; resting Vm; resting membrane potential; sEPSCs; sIPSCs; spike frequency adaptation; spike threshold; spontaneous EPSCs; spontaneous IPSCs