Horizontal spread of activity in neocortical inhibitory networks

Academic Article

Abstract

  • In the presence of 4-aminopyridine (4-AP) and excitatory amino acid receptor blockers, GABAergic networks in the neocortex give rise to large spontaneous GABA-mediated depolarizations. We used voltage-sensitive dye techniques to explore the network properties of depolarizing GABA responses. Voltage-sensitive dye signals demonstrated that the superficial layers support the propagation of depolarizing GABA responses, with only minimal signals detected in deeper cortical layers. GABA responses propagated at a speed of 2.7 ± 0.2 mm/s, a rate intermediate to fast synaptic transmission and spreading depression. Changes in the extracellular potassium concentration altered the propagation speed of the depolarizing GABA response. Taken together, these data support a role for both direct synaptic action of GABA at GABA A receptors and nonsynaptic mechanisms in the generation and propagation of depolarizing GABA responses. © 2005 Elsevier B.V. All rights reserved.
  • Authors

    Digital Object Identifier (doi)

    Author List

  • DeFazio RA; Hablitz JJ
  • Start Page

  • 83
  • End Page

  • 92
  • Volume

  • 157
  • Issue

  • 1