Premium
Synaptic Currents in Thalamo‐cortical Neurons of the Rat Lateral Geniculate Nucleus
Author(s) -
Leresche N.
Publication year - 1992
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.1460-9568.1992.tb00168.x
Subject(s) - postsynaptic potential , bicuculline , postsynaptic current , excitatory postsynaptic potential , time constant , neuroscience , gabaa receptor , inhibitory postsynaptic potential , chemistry , lateral geniculate nucleus , gabaergic , stimulus (psychology) , biophysics , receptor , visual cortex , biology , psychology , biochemistry , electrical engineering , psychotherapist , engineering
Thalamo‐cortical neurons were identified in slices of the rat dorsal lateral geniculate nucleus and whole‐cell currents were recorded using the patch‐clamp technique. Postsynaptic currents occurring spontaneously, or elicited by extracellular stimulation in the vicinity of the recorded neuron, were analysed. Spontaneous postsynaptic currents were observed in every recorded neuron. At a holding potential of –60 mV, and with a high internal Cl − , the currents were inward and had amplitudes ranging from <10 to 425 pA. All the spontaneous currents were blocked by 10 μM bicuculline, indicating that they were due to the activation of postsynaptic α‐aminobutyric acid (GABA A ) receptors. The 10–90% rise time of these spontaneous GABAergic currents was 0.86 ± 0.19 ms. Their time course of decay could be fitted to an exponential function with one time constant of 18.19 ± 3.02 ms (mean ± SD), or two time constants of 4.47 ± 0.77 and 33.27 ± 3.74 ms. This activity was frequently organized in bursts. Stimulus‐evoked postsynaptic currents were recorded and shown to be due to the activation of glutamatergic receptors. Under similar experimental conditions a bicuculline‐sensitive component was also recorded. These stimulus‐evoked GABAergic currents had a 10–90% rise time of 1.93 ± 0.54 ms. Their time course of decay could also be fitted to an exponential function with one time constant of 24.42 ms or two time constants of 10.26 ± 2.46 and 49.30 ± 10.98 ms. The difference in the time course between spontaneous and evoked GABAergic currents suggests that these responses may arise from synapses having different locations.