Journal of Neurophysiology, Vol 74, Issue 6 2437-2444, Copyright © 1995 by APS

ARTICLES

Hebbian induction of LTP in visual cortex: perforated patch-clamp study in cultured neurons

Y. Otsu, F. Kimura and T. Tsumoto
Department of Neurophysiology, Osaka University Medical School, Suita, Japan.

1. To see whether presynaptic activation paired with postsynaptic depolarization is necessary for the induction of long-term potentiation (LTP) in visual cortex or whether an activation of postsynaptic receptors in conjunction with depolarization is sufficient, we carried out perforated patch-clamp recordings with nystatin from cultured cortical neurons of rats. 2. Recorded neurons were monosynaptically activated either by electrical stimulation of an adjacent neuron or by direct activation of glutamate on "hot spots" of dendrites through iontophoresis or pressure ejection. In experiments in which cultured neurons were stained immunocytochemically with antibody against synaptophysin after electrophysiological recordings, hot spots were found to correspond to probable synaptic sites. 3. Excitatory postsynaptic currents (EPSCs) evoked by test stimulation applied to the adjacent neuron at 0.1 Hz were recorded at a holding potential of -60 or -70 mV for 5-10 min after an establishment of the whole cell recording configuration. Then, stimulation was paired with postsynaptic depolarization (0 mV for 200 ms) at 1 Hz for 30 or 60 s. LTP of EPSCs was induced in 7 of the 15 cells from which stable recordings were obtained for 18-30 min after pairing. 4. When postsynaptic depolarization was paired with direct glutamate application in the absence of presynaptic stimulation in 12 cells, only 1 showed LTP. Postsynaptic depolarization alone did not induce LTP in any of the six cells tested. Also, presynaptic stimulation alone did not induce LTP in any of the five cells tested. 5. These results suggest that the concurrent activation of presynaptic elements with postsynaptic depolarization is necessary for the induction of LTP in visual cortex.

This article has been cited by other articles:

				D. J. Uhlrich, K. A. Manning, M. L. O'Laughlin, and W. W. Lytton Photic-Induced Sensitization: Acquisition of an Augmenting Spike-Wave Response in the Adult Rat Through Repeated Strobe Exposure J Neurophysiol, December 1, 2005; 94(6): 3925 - 3937. [Abstract] [Full Text] [PDF]

				K. Kohara, A. Kitamura, M. Morishima, and T. Tsumoto Activity-Dependent Transfer of Brain-Derived Neurotrophic Factor to Postsynaptic Neurons Science, March 23, 2001; 291(5512): 2419 - 2423. [Abstract] [Full Text]

				V. Sourdet and D. Debanne The Role of Dendritic Filtering in Associative Long-Term Synaptic Plasticity Learn. Mem., September 1, 1999; 6(5): 422 - 447. [Abstract] [Full Text]

				F. Kimura, Y. Otsu, and T. Tsumoto Presynaptically Silent Synapses: Spontaneously Active Terminals Without Stimulus-Evoked Release Demonstrated in Cortical Autapses J Neurophysiol, May 1, 1997; 77(5): 2805 - 2815. [Abstract] [Full Text] [PDF]