pISSN 1226-4512 eISSN 2093-3827

Article

home Article View

Original Article

Korean J Physiol Pharmacol 2019; 23(5): 317-328

Published online September 1, 2019 https://doi.org/10.4196/kjpp.2019.23.5.317

Copyright © The Korean Journal of Physiology & Pharmacology.

Layer-specific cholinergic modulation of synaptic transmission in layer 2/3 pyramidal neurons of rat visual cortex

Kwang-Hyun Cho1, Seul-Yi Lee1, Kayoung Joo1, and Duck-Joo Rhie1,2,*

1Department of Physiology, 2Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea

Correspondence to:*Duck-Joo Rhie, E-mail: djrhie@catholic.ac.kr

Received: February 13, 2019; Revised: June 28, 2019; Accepted: July 15, 2019

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

It is known that top-down associative inputs terminate on distal apical dendrites in layer 1 while bottom-up sensory inputs terminate on perisomatic dendrites of layer 2/3 pyramidal neurons (L2/3 PyNs) in primary sensory cortex. Since studies on synaptic transmission in layer 1 are sparse, we investigated the basic properties and cholinergic modulation of synaptic transmission in layer 1 and compared them to those in perisomatic dendrites of L2/3 PyNs of rat primary visual cortex. Using extracellular stimulations of layer 1 and layer 4, we evoked excitatory postsynaptic current/potential in synapses in distal apical dendrites (L1-EPSC/L1-EPSP) and those in perisomatic dendrites (L4-EPSC/L4-EPSP), respectively. Kinetics of L1-EPSC was slower than that of L4-EPSC. L1-EPSC showed presynaptic depression while L4-EPSC was facilitating. In contrast, inhibitory postsynaptic currents showed similar paired-pulse ratio between layer 1 and layer 4 stimulations with depression only at 100 Hz. Cholinergic stimulation induced presynaptic depression by activating muscarinic receptors in excitatory and inhibitory synapses to similar extents in both inputs. However, nicotinic stimulation enhanced excitatory synaptic transmission by ~20% in L4-EPSC. Rectification index of AMPA receptors and AMPA/NMDA ratio were similar between synapses in distal apical and perisomatic dendrites. These results provide basic properties and cholinergic modulation of synaptic transmission between distal apical and perisomatic dendrites in L2/3 PyNs of the visual cortex, which might be important for controlling information processing balance depending on attentional state.

Keywords: Cholinergic modulation, Layer 2/3, Layer-specific, Synaptic transmission, Visual cortex