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Activity‐dependent persisting modification of polysynaptic neural circuits involving layer V pyramidal neurons in rat auditory cortex in vitro
Author(s) -
Kitaura Hiroki,
Hishida Ryuich,
Kudoh Masaharu,
Shibuki Katsuei
Publication year - 2004
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.0953-816x.2003.03136.x
Subject(s) - long term potentiation , bicuculline , neuroscience , gabaa receptor , nmda receptor , chemistry , stimulation , neurotransmission , biophysics , biology , receptor , biochemistry
Synaptic plasticity in polysynaptic neural circuits permits modulation of the dynamic properties of these circuits. We investigated the properties of polysynaptic potentiation in pyramidal neurons in layer V of rat auditory cortex (AC) slices using the perforated patch clamp technique. The GABA A receptor inhibitor bicuculline was used to facilitate polysynaptic activity. The amplitude and duration of the polysynaptic activity were both gradually potentiated with repetitive stimulation (RS) at 12 s intervals. Potentiation was saturated within 10 min of the onset of RS. After the cessation of RS, the polysynaptic responses returned to control levels within 30 min. RS‐induced potentiation was confirmed by fluorescence imaging of slices loaded with the Ca 2+ indicator rhod‐2. Such potentiation was not induced by stimulation at 60 s intervals. The magnitude of the RS‐induced potentiation in layer V pyramidal neurons in the AC was greater than that in either layer II/III pyramidal neurons in the AC or layer V pyramidal neurons in the visual cortex. The NMDA receptor antagonist APV (100 µ m ), inhibited RS‐induced potentiation. When stimulated at 1 Hz, the potentiated response appeared rapidly. In the absence of bicuculline, RS consisting of five pulses at 30 ms intervals, repeated at 12 s intervals for 10 min, elicited potentiation of firing activity, suggesting that the potentiation is independent of bicuculline. The present study demonstrates the dynamic properties of polysynaptic circuits involving layer V pyramidal neurons in the AC are strongly affected by activity‐dependent synaptic potentiation.