In response to a visual stimulation, "replicated triplets" of impulses may appe... more In response to a visual stimulation, "replicated triplets" of impulses may appear in many spike trains recorded from the cat dorsal lateral geniculate nucleus (dLGN). The number and the temporal structure of these triplets depend upon the general organization of the geniculate impulse trains. In this study, we show that a pharmacological blockade of the corticothalamic activity, obtained through microinjection of GABA into area 17, affects the replicated triplet production and leads to an increase in the dispersal of their structure. These results suggest that the corticothalamic pathway closely influences the fine temporal organization of the geniculate messages.
Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be ac... more Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be accounted for by change production. A comparison of the number of triplets of spikes present two times with the number of doublets replicated three times in the same window duration gives a frequency-insensitive measure of this type of fine temporal organisation. By varying the tolerance with which such precisely replicating patterns are detected, one can evaluate the accuracy of spike timing in spike trains. In the sample of data here analysed, it was found that replicating patterns were best seen in the precision range 0.4-1.4 ms (a result evidently at variance with a simple 'integrate and fire' model of neurons). Surprisingly, the fine temporal structure of spike trains thus evidenced was stronger at relatively low firing rate discharges and was present in both the 'spontaneous' and 'evoked' responses.
Summary The π+ π− system produced in the reaction K− p→ K−(π+ π−) p at 14.3 GeV/c is strongly enh... more Summary The π+ π− system produced in the reaction K− p→ K−(π+ π−) p at 14.3 GeV/c is strongly enhanced in the ππ near-threshold region and is consistent with having a large ππS-wave component. The double-pomeron-exchange mechanism contribution to its ...
The idea of continuous progress occupies an essential place in the personal metaphysics of many o... more The idea of continuous progress occupies an essential place in the personal metaphysics of many of our contemporaries. It is so embedded in their minds that they would have a hard time living without it. This is why the reminder of what evolution owes to chance, coming from certain contemporary biologists and paleontologists like Stephen Jay Gould, is salutory. The recent book by the latter, Full House, forces us to reexamine the applications of the notion of chance in the domain of biological evolution. This said, we must recognize that the specificity of the living creature, by incorporating in its very genome the history of the presumably victorious variations of its ancestors, draws the evolution of each separately considered branch along a precise trajectory, subject to constraints rooted in its history. If we must repudiate the idea of progress as too tainted by ideology, mustn’t we conclude that these trajectories carry certain living creatures toward an accrued complexity, and across certain thresholds from which they cannot turn back, thereby creating new, emerging qualities?
ABSTRACT Summary Evidence of double diffractive dissociation in 5 GeV/c π+p reactions is found by... more ABSTRACT Summary Evidence of double diffractive dissociation in 5 GeV/c π+p reactions is found by analysing angular distributions in selected longitudinal phase-space regions. The size of the observed effect is compatible with expectations from factorization.
By a thorough analysis of the moments of the angular distributions, evidence is obtained of a wid... more By a thorough analysis of the moments of the angular distributions, evidence is obtained of a wide (≈ 300 MeV)πρ threshold effect ofJ P = 1+, mainlyS-wave. OtherJ P assignments are improbable. This 1+-state is produced peripherally, with ϱ00 close to 1 in the Jackson system, and initial helicity more nearly conserved in the Jackson than in the c.m. helicity system. Evidence for interference between A 1+ and A 2+ is found. A detailed discussion of the method of analysis is presented.
In response to a visual stimulation, "replicated triplets" of impulses may appe... more In response to a visual stimulation, "replicated triplets" of impulses may appear in many spike trains recorded from the cat dorsal lateral geniculate nucleus (dLGN). The number and the temporal structure of these triplets depend upon the general organization of the geniculate impulse trains. In this study, we show that a pharmacological blockade of the corticothalamic activity, obtained through microinjection of GABA into area 17, affects the replicated triplet production and leads to an increase in the dispersal of their structure. These results suggest that the corticothalamic pathway closely influences the fine temporal organization of the geniculate messages.
Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be ac... more Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be accounted for by change production. A comparison of the number of triplets of spikes present two times with the number of doublets replicated three times in the same window duration gives a frequency-insensitive measure of this type of fine temporal organisation. By varying the tolerance with which such precisely replicating patterns are detected, one can evaluate the accuracy of spike timing in spike trains. In the sample of data here analysed, it was found that replicating patterns were best seen in the precision range 0.4-1.4 ms (a result evidently at variance with a simple 'integrate and fire' model of neurons). Surprisingly, the fine temporal structure of spike trains thus evidenced was stronger at relatively low firing rate discharges and was present in both the 'spontaneous' and 'evoked' responses.
Summary The π+ π− system produced in the reaction K− p→ K−(π+ π−) p at 14.3 GeV/c is strongly enh... more Summary The π+ π− system produced in the reaction K− p→ K−(π+ π−) p at 14.3 GeV/c is strongly enhanced in the ππ near-threshold region and is consistent with having a large ππS-wave component. The double-pomeron-exchange mechanism contribution to its ...
The idea of continuous progress occupies an essential place in the personal metaphysics of many o... more The idea of continuous progress occupies an essential place in the personal metaphysics of many of our contemporaries. It is so embedded in their minds that they would have a hard time living without it. This is why the reminder of what evolution owes to chance, coming from certain contemporary biologists and paleontologists like Stephen Jay Gould, is salutory. The recent book by the latter, Full House, forces us to reexamine the applications of the notion of chance in the domain of biological evolution. This said, we must recognize that the specificity of the living creature, by incorporating in its very genome the history of the presumably victorious variations of its ancestors, draws the evolution of each separately considered branch along a precise trajectory, subject to constraints rooted in its history. If we must repudiate the idea of progress as too tainted by ideology, mustn’t we conclude that these trajectories carry certain living creatures toward an accrued complexity, and across certain thresholds from which they cannot turn back, thereby creating new, emerging qualities?
ABSTRACT Summary Evidence of double diffractive dissociation in 5 GeV/c π+p reactions is found by... more ABSTRACT Summary Evidence of double diffractive dissociation in 5 GeV/c π+p reactions is found by analysing angular distributions in selected longitudinal phase-space regions. The size of the observed effect is compatible with expectations from factorization.
By a thorough analysis of the moments of the angular distributions, evidence is obtained of a wid... more By a thorough analysis of the moments of the angular distributions, evidence is obtained of a wide (≈ 300 MeV)πρ threshold effect ofJ P = 1+, mainlyS-wave. OtherJ P assignments are improbable. This 1+-state is produced peripherally, with ϱ00 close to 1 in the Jackson system, and initial helicity more nearly conserved in the Jackson than in the c.m. helicity system. Evidence for interference between A 1+ and A 2+ is found. A detailed discussion of the method of analysis is presented.
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Papers by Remy Lestienne