Alain Artola - Academia.edu (original) (raw)
Papers by Alain Artola
European Journal of Neuroscience, Mar 1, 1990
Pyramidal neurons from layers II and III of rat visual cortex slices were studied with intracellu... more Pyramidal neurons from layers II and III of rat visual cortex slices were studied with intracellular recordings. The involvement of N‐methyl‐D‐aspartate (NMDA) receptors was investigated: (1) in the synaptic response to white matter stimulation; (2) in the induction of long‐term potentiation (LTP); and (3) in the maintenance of LTP. Bath application of 25 μM of 2‐amino‐5‐phosphonovalerate (APV), an NMDA receptor antagonist, caused a slight (< 10%) reduction of the amplitude of the synaptic response elicited by white matter stimulation. The APV‐sensitive excitatory postsynaptic potential (EPSP) had a longer peak latency and duration than the APV‐resistant EPSP. Bath application of 10 μM of 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), a non‐NMDA glutamate receptor antagonist, revealed a CNQX‐resistant EPSP in response to white matter stimulation which was APV‐sensitive. The time course of the CNQX‐resistant EPSP was similar to that of the APV‐sensitive EPSP and its onset latency was similar to that of the synaptic response in normal medium. Bath application of the GABA‐A antagonist bicuculline (0.1 to 0.5 μM) led to a progressive enhancement of the amplitude of the APV‐sensitive EPSP. At bicuculline concentrations above 0.3 μM the amplitude of this EPSP increased with membrane depolarization as was the case for the CNQX‐resistant EPSP implying that the NMDA receptors were located on the recorded neuron. The susceptibility of the cells to undergo LTP was tested at various concentrations of bicuculline. The effectiveness of bicuculline treatment was quantified by comparing the amplitudes of the synaptic response to just subthreshold stimuli at two post‐stimulus delays: (i) at 22 ms, which corresponds to the time to peak of both the initial inhibitory postsynaptic potential and the APV‐sensitive EPSP; and (ii) at 8–11 ms post‐stimulus, which corresponds to the peak of the postsynaptic potential (PSP) in normal medium. Bath application of APV, 20 min after the conditioning tetanus, allowed the authors to measure the amplitude of the APV‐sensitive EPSP in the potentiated response. In normal medium, the ratio of the late over the early PSP amplitude was 33.6 ± 4.1% and tetanic stimulation failed to induce LTP. The conditions remained the same at bicuculline concentrations of 0.1 to 0.2 μM. At higher concentrations of bicuculline the amplitude ratio of late versus early PSP increased and tetanic stimulation induced LTP. In cells, in which bicuculline had caused small ratio increases, only the APV‐sensitive EPSP underwent LTP. In cells in which bicuculline had caused large ratio changes, both the APV‐resistant and the APV‐sensitive EPSP showed LTP. Together with the previous finding that blockade of NMDA receptors prevents LTP (Artola and Singer, 1987) these results suggest that there is a threshold for LTP induction, which is only reached if NMDA receptor‐gated channels are sufficiently activated. The data indicate further that the NMDA receptor‐mediated EPSP is itself susceptible to LTP whereby its LTP threshold is lower than that of the APV‐resistant EPSP. Given the different LTP thresholds of the APV‐resistant and APV‐sensitive EPSPs, the possibility is raised that their potentiation depends on different mechanisms.
Journal of basic and clinical physiology and pharmacology, 1990
Pharmacological Research, 1995
Brain Research, Aug 1, 1989
Using antisera raised against y-aminobutyric acid (GABA), GABA-Iike immunoreactivity was determin... more Using antisera raised against y-aminobutyric acid (GABA), GABA-Iike immunoreactivity was determined in in vitro slices fixed after various incubation times. Synaptic efficacy of GABAergic innervation was concurrently assessed in adjacent slices by intracellular recordings. We show that GABA-Iike immunoreactivity dramatically decreases already after one hour of incubation and remains low throughout the following hours. Nevertheless robust GABA-mediated synaptic potentials are recordable for more than 8 h.
Acta Neurobiologiae Experimentalis, 2003
In a variety of brain structures repetitive activation of synaptic connections can lead to long-t... more In a variety of brain structures repetitive activation of synaptic connections can lead to long-term po- tentiation (LTP) or long-term depression (LTD) of synaptic transmission, and these modifications are held responsible for memory formation. Here we examine the role of postsynaptic Ca2+ concentration in the induction of LTD in the neocortex. In layer III cells of the rat visual cortex, LTD can be induced by tetanic stimulation of afferent fibers ascending from the white matter. We show that LTD induction is reliably blocked by intracellular injection of either EGTA or BAPTA (bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetate), two different Ca2+ chelators. This confirms that the processes underlying the induction of LTD in neocortex are located postsynaptically and indicates that they depend on intracellular Ca2+ concentration. Thus, both LTP and LTD induction appear to involve calcium- mediated processes in the postsynaptic neuron. We propose that LTD is caused by a surge of calcium either through voltage-gated Ca2+ conductances and/or by transmitter- induced release of calcium from intracellular stores.
Acta Neurobiologiae Experimentalis, 2003
In a variety of brain structures repetitive activation of synaptic connections can lead to long-t... more In a variety of brain structures repetitive activation of synaptic connections can lead to long-term po- tentiation (LTP) or long-term depression (LTD) of synaptic transmission, and these modifications are held responsible for memory formation. Here we examine the role of postsynaptic Ca2+ concentration in the induction of LTD in the neocortex. In layer III cells of the rat visual cortex, LTD can be induced by tetanic stimulation of afferent fibers ascending from the white matter. We show that LTD induction is reliably blocked by intracellular injection of either EGTA or BAPTA (bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetate), two different Ca2+ chelators. This confirms that the processes underlying the induction of LTD in neocortex are located postsynaptically and indicates that they depend on intracellular Ca2+ concentration. Thus, both LTP and LTD induction appear to involve calcium- mediated processes in the postsynaptic neuron. We propose that LTD is caused by a surge...
Journal of Neurophysiology, 1996
1. In many brain areas, including neocortex and hippocampus, excitatory synapses can undergo both... more 1. In many brain areas, including neocortex and hippocampus, excitatory synapses can undergo both long-term potentiation (LTP) and long-term depression (LTD). It is established that a change in the postsynaptic calcium concentration ([Ca2+]i) is critical for the induction of both LTP and LTD. Protocols that induce these long-term synaptic modifications typically involve afferent stimulation. But, in hippocampus, LTP can also be induced by a transient increase of the extracellular calcium concentration ([Ca2+]o). The purpose of the present study was to determine whether raising [Ca2+]o also induces long-term modifications of excitatory synaptic transmission in the neocortex. 2. Intracellular recordings were obtained from regular spiking cells in layers II-III of slices of the rat visual cortex. Test stimuli were evoked with stimulation electrodes located in the white matter (w.m.) below the recorded cell and intracortically (i.c.) adjacent to the cell. Both the depolarizing slope and...
Medicina Oral Patologia Oral Y Cirugia Bucal, 2014
Objetivos: Este estudio evaluo las tendencias y los factores asociados a las fracturas maxilofaci... more Objetivos: Este estudio evaluo las tendencias y los factores asociados a las fracturas maxilofaciales tratadas desde 1997 hasta 2007 en el Departamento de Cirugia Oral y Maxilofacial del Hospital Universitario Clermont-Ferrand. Material y metodos: Este estudio incluyo 364 pacientes de los cuales el 82% fueron hombres y el 45% tenian entre 20-29 anos de edad. Se examino la etiologia, distribucion anatomica, modalidades de tratamiento y las complicaciones de las fracturas maxilofaciales. Resultados: En global, las agresiones, los accidentes de trafico y las caidas fueron las causas mas frecuentes de lesion. Durante los 11 anos de realizacion de este estudio hubo una tendencia decreciente en los accidentes de trafico como causa de fractura, al contrario que las caidas. Los pacientes varones jovenes fueron sobretodo victimas de accidentes de trafico y agresiones, mientras que los de mediana edad sufrieron mas caidas y accidentes laborales. Las causas predominantes en mujeres de mediana ...
Cells
Mechanical allodynia (pain to normally innocuous tactile stimuli) is a widespread symptom of infl... more Mechanical allodynia (pain to normally innocuous tactile stimuli) is a widespread symptom of inflammatory and neuropathic pain. Spinal or medullary dorsal horn (SDH or MDH) circuits mediating tactile sensation and pain need to interact in order to evoke mechanical allodynia. PKCγ-expressing (PKCγ+) interneurons and inhibitory controls within SDH/MDH inner lamina II (IIi) are pivotal in connecting touch and pain circuits. However, the relative contribution of GABA and glycine to PKCγ+ interneuron inhibition remains unknown. We characterized inhibitory inputs onto PKCγ+ interneurons by combining electrophysiology to record spontaneous and miniature IPSCs (sIPSCs, mIPSCs) and immunohistochemical detection of GABAARα2 and GlyRα1 subunits in adult rat MDH. While GlyR-only- and GABAAR-only-mediated mIPSCs/sIPSCs are predominantly recorded from PKCγ+ interneurons, immunohistochemistry reveals that ~80% of their inhibitory synapses possess both GABAARα2 and GlyRα1. Moreover, nearly all inhi...
Brain Research Bulletin, 2022
Experimental Neurology, 2014
European Journal of Neuroscience, Mar 1, 1990
Pyramidal neurons from layers II and III of rat visual cortex slices were studied with intracellu... more Pyramidal neurons from layers II and III of rat visual cortex slices were studied with intracellular recordings. The involvement of N‐methyl‐D‐aspartate (NMDA) receptors was investigated: (1) in the synaptic response to white matter stimulation; (2) in the induction of long‐term potentiation (LTP); and (3) in the maintenance of LTP. Bath application of 25 μM of 2‐amino‐5‐phosphonovalerate (APV), an NMDA receptor antagonist, caused a slight (< 10%) reduction of the amplitude of the synaptic response elicited by white matter stimulation. The APV‐sensitive excitatory postsynaptic potential (EPSP) had a longer peak latency and duration than the APV‐resistant EPSP. Bath application of 10 μM of 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), a non‐NMDA glutamate receptor antagonist, revealed a CNQX‐resistant EPSP in response to white matter stimulation which was APV‐sensitive. The time course of the CNQX‐resistant EPSP was similar to that of the APV‐sensitive EPSP and its onset latency was similar to that of the synaptic response in normal medium. Bath application of the GABA‐A antagonist bicuculline (0.1 to 0.5 μM) led to a progressive enhancement of the amplitude of the APV‐sensitive EPSP. At bicuculline concentrations above 0.3 μM the amplitude of this EPSP increased with membrane depolarization as was the case for the CNQX‐resistant EPSP implying that the NMDA receptors were located on the recorded neuron. The susceptibility of the cells to undergo LTP was tested at various concentrations of bicuculline. The effectiveness of bicuculline treatment was quantified by comparing the amplitudes of the synaptic response to just subthreshold stimuli at two post‐stimulus delays: (i) at 22 ms, which corresponds to the time to peak of both the initial inhibitory postsynaptic potential and the APV‐sensitive EPSP; and (ii) at 8–11 ms post‐stimulus, which corresponds to the peak of the postsynaptic potential (PSP) in normal medium. Bath application of APV, 20 min after the conditioning tetanus, allowed the authors to measure the amplitude of the APV‐sensitive EPSP in the potentiated response. In normal medium, the ratio of the late over the early PSP amplitude was 33.6 ± 4.1% and tetanic stimulation failed to induce LTP. The conditions remained the same at bicuculline concentrations of 0.1 to 0.2 μM. At higher concentrations of bicuculline the amplitude ratio of late versus early PSP increased and tetanic stimulation induced LTP. In cells, in which bicuculline had caused small ratio increases, only the APV‐sensitive EPSP underwent LTP. In cells in which bicuculline had caused large ratio changes, both the APV‐resistant and the APV‐sensitive EPSP showed LTP. Together with the previous finding that blockade of NMDA receptors prevents LTP (Artola and Singer, 1987) these results suggest that there is a threshold for LTP induction, which is only reached if NMDA receptor‐gated channels are sufficiently activated. The data indicate further that the NMDA receptor‐mediated EPSP is itself susceptible to LTP whereby its LTP threshold is lower than that of the APV‐resistant EPSP. Given the different LTP thresholds of the APV‐resistant and APV‐sensitive EPSPs, the possibility is raised that their potentiation depends on different mechanisms.
Journal of basic and clinical physiology and pharmacology, 1990
Pharmacological Research, 1995
Brain Research, Aug 1, 1989
Using antisera raised against y-aminobutyric acid (GABA), GABA-Iike immunoreactivity was determin... more Using antisera raised against y-aminobutyric acid (GABA), GABA-Iike immunoreactivity was determined in in vitro slices fixed after various incubation times. Synaptic efficacy of GABAergic innervation was concurrently assessed in adjacent slices by intracellular recordings. We show that GABA-Iike immunoreactivity dramatically decreases already after one hour of incubation and remains low throughout the following hours. Nevertheless robust GABA-mediated synaptic potentials are recordable for more than 8 h.
Acta Neurobiologiae Experimentalis, 2003
In a variety of brain structures repetitive activation of synaptic connections can lead to long-t... more In a variety of brain structures repetitive activation of synaptic connections can lead to long-term po- tentiation (LTP) or long-term depression (LTD) of synaptic transmission, and these modifications are held responsible for memory formation. Here we examine the role of postsynaptic Ca2+ concentration in the induction of LTD in the neocortex. In layer III cells of the rat visual cortex, LTD can be induced by tetanic stimulation of afferent fibers ascending from the white matter. We show that LTD induction is reliably blocked by intracellular injection of either EGTA or BAPTA (bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetate), two different Ca2+ chelators. This confirms that the processes underlying the induction of LTD in neocortex are located postsynaptically and indicates that they depend on intracellular Ca2+ concentration. Thus, both LTP and LTD induction appear to involve calcium- mediated processes in the postsynaptic neuron. We propose that LTD is caused by a surge of calcium either through voltage-gated Ca2+ conductances and/or by transmitter- induced release of calcium from intracellular stores.
Acta Neurobiologiae Experimentalis, 2003
In a variety of brain structures repetitive activation of synaptic connections can lead to long-t... more In a variety of brain structures repetitive activation of synaptic connections can lead to long-term po- tentiation (LTP) or long-term depression (LTD) of synaptic transmission, and these modifications are held responsible for memory formation. Here we examine the role of postsynaptic Ca2+ concentration in the induction of LTD in the neocortex. In layer III cells of the rat visual cortex, LTD can be induced by tetanic stimulation of afferent fibers ascending from the white matter. We show that LTD induction is reliably blocked by intracellular injection of either EGTA or BAPTA (bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetate), two different Ca2+ chelators. This confirms that the processes underlying the induction of LTD in neocortex are located postsynaptically and indicates that they depend on intracellular Ca2+ concentration. Thus, both LTP and LTD induction appear to involve calcium- mediated processes in the postsynaptic neuron. We propose that LTD is caused by a surge...
Journal of Neurophysiology, 1996
1. In many brain areas, including neocortex and hippocampus, excitatory synapses can undergo both... more 1. In many brain areas, including neocortex and hippocampus, excitatory synapses can undergo both long-term potentiation (LTP) and long-term depression (LTD). It is established that a change in the postsynaptic calcium concentration ([Ca2+]i) is critical for the induction of both LTP and LTD. Protocols that induce these long-term synaptic modifications typically involve afferent stimulation. But, in hippocampus, LTP can also be induced by a transient increase of the extracellular calcium concentration ([Ca2+]o). The purpose of the present study was to determine whether raising [Ca2+]o also induces long-term modifications of excitatory synaptic transmission in the neocortex. 2. Intracellular recordings were obtained from regular spiking cells in layers II-III of slices of the rat visual cortex. Test stimuli were evoked with stimulation electrodes located in the white matter (w.m.) below the recorded cell and intracortically (i.c.) adjacent to the cell. Both the depolarizing slope and...
Medicina Oral Patologia Oral Y Cirugia Bucal, 2014
Objetivos: Este estudio evaluo las tendencias y los factores asociados a las fracturas maxilofaci... more Objetivos: Este estudio evaluo las tendencias y los factores asociados a las fracturas maxilofaciales tratadas desde 1997 hasta 2007 en el Departamento de Cirugia Oral y Maxilofacial del Hospital Universitario Clermont-Ferrand. Material y metodos: Este estudio incluyo 364 pacientes de los cuales el 82% fueron hombres y el 45% tenian entre 20-29 anos de edad. Se examino la etiologia, distribucion anatomica, modalidades de tratamiento y las complicaciones de las fracturas maxilofaciales. Resultados: En global, las agresiones, los accidentes de trafico y las caidas fueron las causas mas frecuentes de lesion. Durante los 11 anos de realizacion de este estudio hubo una tendencia decreciente en los accidentes de trafico como causa de fractura, al contrario que las caidas. Los pacientes varones jovenes fueron sobretodo victimas de accidentes de trafico y agresiones, mientras que los de mediana edad sufrieron mas caidas y accidentes laborales. Las causas predominantes en mujeres de mediana ...
Cells
Mechanical allodynia (pain to normally innocuous tactile stimuli) is a widespread symptom of infl... more Mechanical allodynia (pain to normally innocuous tactile stimuli) is a widespread symptom of inflammatory and neuropathic pain. Spinal or medullary dorsal horn (SDH or MDH) circuits mediating tactile sensation and pain need to interact in order to evoke mechanical allodynia. PKCγ-expressing (PKCγ+) interneurons and inhibitory controls within SDH/MDH inner lamina II (IIi) are pivotal in connecting touch and pain circuits. However, the relative contribution of GABA and glycine to PKCγ+ interneuron inhibition remains unknown. We characterized inhibitory inputs onto PKCγ+ interneurons by combining electrophysiology to record spontaneous and miniature IPSCs (sIPSCs, mIPSCs) and immunohistochemical detection of GABAARα2 and GlyRα1 subunits in adult rat MDH. While GlyR-only- and GABAAR-only-mediated mIPSCs/sIPSCs are predominantly recorded from PKCγ+ interneurons, immunohistochemistry reveals that ~80% of their inhibitory synapses possess both GABAARα2 and GlyRα1. Moreover, nearly all inhi...
Brain Research Bulletin, 2022
Experimental Neurology, 2014