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Titolo:
Macroscopic and subcellular factors shaping population spikes
Autore:
Varona, P; Ibarz, JM; Lopez-Aguado, L; Herreras, O;
Indirizzi:
Hosp Ramon y Cajal, Dept Invest, E-28034 Madrid, Spain Hosp Ramon y CajalMadrid Spain E-28034 pt Invest, E-28034 Madrid, Spain Univ Autonoma Madrid, Dept Ingn Informat, E-28049 Madrid, Spain Univ Autonoma Madrid Madrid Spain E-28049 nformat, E-28049 Madrid, Spain
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 4, volume: 83, anno: 2000,
pagine: 2192 - 2208
SICI:
0022-3077(200004)83:4<2192:MASFSP>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
CA1 PYRAMIDAL NEURONS; SODIUM ACTION-POTENTIALS; SOURCE-DENSITY ANALYSIS; HIPPOCAMPAL-NEURONS; RAT HIPPOCAMPUS; DENDRITIC MORPHOLOGY; MEMBRANE-PROPERTIES; CELL DENDRITES; PATCH-CLAMP; PROPAGATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
57
Recensione:
Indirizzi per estratti:
Indirizzo: Herreras, O Hosp Ramon y Cajal, Dept Invest, Ctra Colmenar Km 9, E-28034 Madrid, Spain Hosp Ramon y Cajal Ctra Colmenar Km 9 Madrid Spain E-28034 in
Citazione:
P. Varona et al., "Macroscopic and subcellular factors shaping population spikes", J NEUROPHYS, 83(4), 2000, pp. 2192-2208

Abstract

Population spikes (PS) are built by the extracellular summation of action currents during synchronous action potential (AP) firing. In the hippocampal CA1, active dendritic invasion of APs ensures mixed contribution of somatic and dendritic currents to any extracellular location. We investigated the macroscopic and subcellular factors shaping the antidromic PS by fitting its spatiotemporal map with a multineuronal CA1 model in a volume conductor. Decreased summation by temporal scatter of APs reduced less than expectedthe PS peak in the stratum pyramidale (st. pyr.) but strongly increased the relative contribution of far dendritic currents. Increasing the number offiring cells also augmented the relative dendritic contribution to the somatic PS, an effect caused by the different waveform of somatic and dendritic unitary transmembrane currents (I-m). Those from somata are short-lastingand spiky, having smaller temporal summation than those from dendrites, which are smoother and longer. The different shape of compartmental I(m)s is imposed by the fitting of backpropagating APs, which are large and fast at the soma and smaller and longer in dendrites. The maximum sodium conductance ((g) over bar(Na)) strongly affects the unitary APs at the soma, but barely the PS at the stratum pyramidale (st. pyr.). This occurred because somatic I-m saturated at low (g) over bar(Na) due to the strong reduction of driving force during somatic APs, limiting the current contribution to the extracellular space. On the contrary, (g) over bar(Na) effec- tively defined the PS amplitude in the st. radiatum. The relative contribution of dendriticcurrents to the st, pyr. increases during the time span of the PS, from similar to 30-40% at the peak up to 100% at its end, a pattern resultant fromthe timing of active inward currents along the somatodendritic axis, whichdelay during backpropagation. Extreme changes imposed on dendritic currents caused only moderate effects on the st, pyr. due to reciprocal shunting of active soma and dendrites that partially counterbalance the net amount ofinstant current. The amplitude of the PS follows an inverse relation to the internal resistance (R-i), which turned out to be a most critical factor. Low Ri facilitated the spread of APs into dendrites and accelerated their speed, increasing temporal overlapping of inward currents along the somatodendritic axis and yielding the best PS reproductions. Model reconstruction of held potentials is a powerful tool to understand the interactions between different levels of complexity. The potential use of this approach to restrain the variability of some experimental measurements is discussed.

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Documento generato il 09/04/20 alle ore 06:55:25