Papers by Quentin Pauluis
The Journal of Neuroscience, 2001
This study aimed to characterize the synchrony that occurs between cell discharges in the superio... more This study aimed to characterize the synchrony that occurs between cell discharges in the superior colliculus of the awake cat. We trained cats to perform a visual fixation in the presence of a visual moving stimulus and then recorded 686 pairs of neighboring cells in the superior colliculus during task performance. A new method to assess the significance of precise discharge synchronization is described, which permits analysis of nonstationary data. Of 181 pairs with sufficient data for quantitative analysis, 125 showed a cross-correlation histogram (CCH) with features assessed as significant using this approach. CCHs frequently showed an isolated central peak (41 of 125) or a peak flanked by one or two troughs (68 of 125), and in a few cases an oscillatory pattern of ∼65 Hz (16 of 125). This is in contrast to the oscillation frequency reported for the visual cortex and shows that oscillations in the superior colliculus probably arise from a cortex-independent mechanism.Our method ...
Neural Computation, 2000
We present an estimate for the instantaneous discharge probability of a neurone, based on single-... more We present an estimate for the instantaneous discharge probability of a neurone, based on single-trial spike-train analysis. By detecting points where the neurone abruptly changes its firing rate and treating them specially, the method is able to achieve smooth estimates yet avoid the blurring of significant changes. This estimate of instantaneous discharge probability is then applied to the method of unitary event analysis. We show that the unitary event analysis as originally conceived is highly sensitive to firing-rate nonstationarities and covariations, but that it can be considerably improved if calculations of statistical significance use an instantaneous discharge probability instead of a firing-rate estimate based on averaging across multiple trials.
Journal of Neuroscience Methods, 1999
Simultaneous recording from multiple single neurones presents many technical difficulties. Howeve... more Simultaneous recording from multiple single neurones presents many technical difficulties. However, obtaining such data has many advantages, which make it highly worthwhile to overcome the technical problems. This report describes methods which we have developed to permit recordings in awake behaving monkeys using the 'Eckhorn' 16 electrode microdrive. Structural magnetic resonance images are collected to guide electrode placement. Head fixation is achieved using a specially designed headpiece, modified for the multiple electrode approach, and access to the cortex is provided via a novel recording chamber. Growth of scar tissue over the exposed dura mater is reduced using an anti-mitotic compound. Control of the microdrive is achieved by a computerised system which permits several experimenters to move different electrodes simultaneously, considerably reducing the load on an individual operator. Neurones are identified as pyramidal tract neurones by antidromic stimulation through chronically implanted electrodes; stimulus control is integrated into the computerised system. Finally, analysis of multiple single unit recordings requires accurate methods to correct for non-stationarity in unit firing. A novel technique for such correction is discussed.
Journal of Computational Neuroscience, 1999
We have simulated a network of 10,000 two-compartment cells, spatially distributed on a two-dimen... more We have simulated a network of 10,000 two-compartment cells, spatially distributed on a two-dimensional sheet; 15% of the cells were inhibitory. The input to the network was spatially delimited. Global oscillations frequently were achieved with a simple set of connectivity rules. The inhibitory neurons paced the network, whereas the excitatory neurons amplified the input, permitting oscillations at low-input intensities. Inhibitory
European Journal of Neuroscience, 2000
The tectotectal commissural pathway is commonly regarded as responsible for the reciprocal inhibi... more The tectotectal commissural pathway is commonly regarded as responsible for the reciprocal inhibition that takes place between the two superior colliculi (SC). Although this hypothesis has received strong support from electrophysiological studies, more recent investigations have suggested that some collicular cells, e.g. fixation neurons, may establish excitatory connections with cells in the contralateral SC through the collicular commissure. The goal of the present study was to seek immunohistochemical evidence for glutamatergic tectotectal cells in the cat SC by using a double‐labelling technique. Tectotectal cells were retrogradely labelled with wheat germ agglutinin (WGA) –horseradish peroxidase (HRP) coupled to colloidal gold injected in the contralateral SC, and neurons containing glutamate or γ‐aminobutyric acid (GABA) were then identified with immunohistochemical techniques. The present study provides evidence that, in the cat SC, equal numbers of tectotectal cells are immu...
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Papers by Quentin Pauluis