To elicit complex and rich graphical displays, and record neuronal phenomena ofinterest while all... more To elicit complex and rich graphical displays, and record neuronal phenomena ofinterest while all simultaneously being capable to interact in a closed-loop with external devises is a challenging task to all neurophysiologists. To facilitate this process, we have developed an Open-Source software system using a single computer running a well established Linux architecture (Ubuntu) associated to a kernel duo providing hard real-time support (Xenomai). We show that a single computer using our API is capable, for any tasks that require OpenGL displaying, to acheive millisecond accuracy programmed events. In this report, we describe the design of our system, benchmark and its performance in a real-world setting, and describe some key features.
Determining the electrical properties of the extracellular space around neurons is important for ... more Determining the electrical properties of the extracellular space around neurons is important for understanding the genesis of extracellular potentials, as well as for localizing neuronal activity from extracellular recordings. However, the exact nature of these extracellular properties is still uncertain. Here, we introduce a method to measure the impedance of the tissue, one that preserves the intact cell-medium interface using whole-cell patch-clamp recordings in vivo and in vitro. We find that neural tissue has marked non-ohmic and frequency-filtering properties, which are not consistent with a resistive (ohmic) medium, as often assumed. The amplitude and phase profiles of the measured impedance are consistent with the contribution of ionic diffusion. We also show that the impact of such frequency-filtering properties is possibly important on the genesis of local field potentials, as well as on the cable properties of neurons. These results show non-ohmic properties of the extrac...
... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the sear... more ... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes. ... 1996, 15;40(10): 964-80 Stuss DT, Meiran N, Guzman A, Lafleche G, Wilmer J. Do long tests yield a more accurate diagnosis of dementia than short tests ? ...
Our objective was to study the incidence and the severity of match injuries in the professional t... more Our objective was to study the incidence and the severity of match injuries in the professional team of rugby players of Pau, which participate to the French first division championship. It was a four-year retrospective study, from 2002/2003 to 2005/2006 season. Data were gathered about incidence, type, location and severity of injuries. Injury was defined as a traumatism occurring in
Patients with right hemisphere damage and visual neglect have severe problems to orient attention... more Patients with right hemisphere damage and visual neglect have severe problems to orient attention towards left-sided objects, often associated with the tendency to produce inappropriate rightward saccades. In its most severe form, this tendency can assume the compulsive character of a rightward deviation of gaze as soon as the visual scene deploys (so-called "magnetic attraction of gaze"). However, little is known about the exact nature of inappropriate rightward saccades, their relation with impaired conscious perception of left-sided stimuli, and their lesional correlates. To explore these issues, we studied three groups of patients with right brain damage: patients with signs of left visual neglect associated to left homonymous hemianopia, neglect patients without hemianopia, and patients without neglect or hemianopia. Participants searched for a gap missing within a target, presented among distractors. Manual responses for target detection were required, while particip...
... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the sear... more ... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes. ... 1996, 15;40(10): 964-80 Stuss DT, Meiran N, Guzman A, Lafleche G, Wilmer J. Do long tests yield a more accurate diagnosis of dementia than short tests ? ...
It is known that sensory deprivation, including postnatal whisker trimming, can lead to severe de... more It is known that sensory deprivation, including postnatal whisker trimming, can lead to severe deficits in the firing rate properties of cortical neurons. Recent results indicate that development of synchronous discharge among cortical neurons is also activity influenced, and that correlated discharge is significantly impaired following loss of bilateral sensory input in rats. Here we investigate whether unilateral whisker trimming (unilateral deprivation or UD) after birth interferes in the same way with the development of synchronous discharge in cortex. We measured the coincidence of spikes among pairs of neurons recorded under urethane anesthesia in one whisker barrel field deprived by trimming all contralateral whiskers for 60 days after birth (UD), and in untrimmed controls (CON). In the septal columns around barrels, UD significantly increased the coincident discharge among cortical neurons compared with CON, most notably in layers II/III. In contrast, synchronous discharge w...
To elicit complex and rich graphical displays, and record neuronal phenomena ofinterest while all... more To elicit complex and rich graphical displays, and record neuronal phenomena ofinterest while all simultaneously being capable to interact in a closed-loop with external devises is a challenging task to all neurophysiologists. To facilitate this process, we have developed an Open-Source software system using a single computer running a well established Linux architecture (Ubuntu) associated to a kernel duo providing hard real-time support (Xenomai). We show that a single computer using our API is capable, for any tasks that require OpenGL displaying, to acheive millisecond accuracy programmed events. In this report, we describe the design of our system, benchmark and its performance in a real-world setting, and describe some key features.
Determining the electrical properties of the extracellular space around neurons is important for ... more Determining the electrical properties of the extracellular space around neurons is important for understanding the genesis of extracellular potentials, as well as for localizing neuronal activity from extracellular recordings. However, the exact nature of these extracellular properties is still uncertain. Here, we introduce a method to measure the impedance of the tissue, one that preserves the intact cell-medium interface using whole-cell patch-clamp recordings in vivo and in vitro. We find that neural tissue has marked non-ohmic and frequency-filtering properties, which are not consistent with a resistive (ohmic) medium, as often assumed. The amplitude and phase profiles of the measured impedance are consistent with the contribution of ionic diffusion. We also show that the impact of such frequency-filtering properties is possibly important on the genesis of local field potentials, as well as on the cable properties of neurons. These results show non-ohmic properties of the extrac...
... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the sear... more ... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes. ... 1996, 15;40(10): 964-80 Stuss DT, Meiran N, Guzman A, Lafleche G, Wilmer J. Do long tests yield a more accurate diagnosis of dementia than short tests ? ...
Our objective was to study the incidence and the severity of match injuries in the professional t... more Our objective was to study the incidence and the severity of match injuries in the professional team of rugby players of Pau, which participate to the French first division championship. It was a four-year retrospective study, from 2002/2003 to 2005/2006 season. Data were gathered about incidence, type, location and severity of injuries. Injury was defined as a traumatism occurring in
Patients with right hemisphere damage and visual neglect have severe problems to orient attention... more Patients with right hemisphere damage and visual neglect have severe problems to orient attention towards left-sided objects, often associated with the tendency to produce inappropriate rightward saccades. In its most severe form, this tendency can assume the compulsive character of a rightward deviation of gaze as soon as the visual scene deploys (so-called "magnetic attraction of gaze"). However, little is known about the exact nature of inappropriate rightward saccades, their relation with impaired conscious perception of left-sided stimuli, and their lesional correlates. To explore these issues, we studied three groups of patients with right brain damage: patients with signs of left visual neglect associated to left homonymous hemianopia, neglect patients without hemianopia, and patients without neglect or hemianopia. Participants searched for a gap missing within a target, presented among distractors. Manual responses for target detection were required, while particip...
... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the sear... more ... Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes. ... 1996, 15;40(10): 964-80 Stuss DT, Meiran N, Guzman A, Lafleche G, Wilmer J. Do long tests yield a more accurate diagnosis of dementia than short tests ? ...
It is known that sensory deprivation, including postnatal whisker trimming, can lead to severe de... more It is known that sensory deprivation, including postnatal whisker trimming, can lead to severe deficits in the firing rate properties of cortical neurons. Recent results indicate that development of synchronous discharge among cortical neurons is also activity influenced, and that correlated discharge is significantly impaired following loss of bilateral sensory input in rats. Here we investigate whether unilateral whisker trimming (unilateral deprivation or UD) after birth interferes in the same way with the development of synchronous discharge in cortex. We measured the coincidence of spikes among pairs of neurons recorded under urethane anesthesia in one whisker barrel field deprived by trimming all contralateral whiskers for 60 days after birth (UD), and in untrimmed controls (CON). In the septal columns around barrels, UD significantly increased the coincident discharge among cortical neurons compared with CON, most notably in layers II/III. In contrast, synchronous discharge w...
Interpretationsoflocalfieldpotentials(LFPs)aretypicallyshapedonanassumptionthatthebrainisahomogen... more Interpretationsoflocalfieldpotentials(LFPs)aretypicallyshapedonanassumptionthatthebrainisahomogenousconductivemilieu.However,
microscale inhomogeneities including cell bodies, dendritic structures, axonal fiber bundles and blood vessels are unequivocally present and
have different conductivities and permittivities than brain extracellular fluid. To determine the extent to which these obstructions affect electrical
signal propagation on a microscale, we delivered electrical stimuli intracellularly to individual cells while simultaneously recording the
extracellular potentials at different locations in a rat brain slice. As compared with relatively unobstructed paths, signals were attenuated across
frequencies when fiber bundles were in between the stimulated cell and the extracellular electrode. Across group of cell bodies, signals were
attenuated at low frequencies, but facilitated at high frequencies. These results show that LFPs do not reflect a democratic representation of
neuronal contributions, as certain neuronsmaycontribute to the LFP more than others based on the local extracellular environment surrounding
them.
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Papers by Pierre Pouget
microscale inhomogeneities including cell bodies, dendritic structures, axonal fiber bundles and blood vessels are unequivocally present and
have different conductivities and permittivities than brain extracellular fluid. To determine the extent to which these obstructions affect electrical
signal propagation on a microscale, we delivered electrical stimuli intracellularly to individual cells while simultaneously recording the
extracellular potentials at different locations in a rat brain slice. As compared with relatively unobstructed paths, signals were attenuated across
frequencies when fiber bundles were in between the stimulated cell and the extracellular electrode. Across group of cell bodies, signals were
attenuated at low frequencies, but facilitated at high frequencies. These results show that LFPs do not reflect a democratic representation of
neuronal contributions, as certain neuronsmaycontribute to the LFP more than others based on the local extracellular environment surrounding
them.