Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activity

Gloor, P.; Vera, Cristián L.; Sperti, Luigi

doi:10.1016/0013-4694(63)90060-9

Cited by 72 publications

(11 citation statements)

References 41 publications

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“…The increase we see in neuronal differentiation agrees with increased neurogenesis in the hippocampus of epileptic models [14], where elevated firing of neurons produces an extracellular electric potential [9,10,67]. What has not been previously alluded to is that, in the hippocampus, the differentiation of NPCs into oligodendrocytes or astrocytes may not be altered by extracellular EF activity (applied or created by heightened neuronal activity), as indicated by our results.…”

Section: Electric Field Induced Neurogenesissupporting

confidence: 86%

“…In the adult hippocampus, extracellular potential gradients or EFs exist in healthy [5] and highly active epileptic models [6,7]. In vivo evidence of hippocampal EFs include steady 4 mV/mm EFs in physiologic conditions [5]; 0.5-4 mV/mm EF during normal slow wave activity [6,7]; up to 50 mV/mm EF during induced synchronous granule cell activity [8];.and steady 10 mV/mm EF [9] and up to 20 mV/mm EF [10] during epileptic seizure. Similarly, outward and inward currents have been recorded in vitro from isolated hippocampi that were intact and "injured", respectively [11].…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Electric Fields on Hippocampal Neural Progenitor Cells

Ariza

Fleury

Tormos

et al. 2010

Stem Cell Rev and Rep

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The differentiation and proliferation of neural stem/progenitor cells (NPCs) depend on various in vivo environmental factors or cues, which may include an endogenous electrical field (EF), as observed during nervous system development and repair. In this study, we investigate the morphologic, phenotypic, and mitotic alterations of adult hippocampal NPCs that occur when exposed to two EFs of estimated endogenous strengths. NPCs treated with a 437 mV/mm direct current (DC) EF aligned perpendicularly to the EF vector and had a greater tendency to differentiate into neurons, but not into oligodendrocytes or astrocytes, compared to controls. Furthermore, NPC process growth was promoted perpendicularly and inhibited anodally in the 437 mV/mm DC EF. Yet fewer cells were observed in the DC EF, which in part was due to a decrease in cell viability. The other EF applied was a 46 mV/mm alternating current (AC) EF. However, the 46 mV/mm AC EF showed no major differences in alignment or differentiation, compared to control conditions. For both EF treatments, the percent of mitotic cells during the last 14 h of the experiment were statistically similar to controls. Reported here, to our knowledge, is the first evidence of adult NPC differentiation affected in an EF in vitro. Further investigation and application of EFs on stem cells is warranted to elucidate the utility of EFs to control phenotypic behavior. With progress, the use of EFs may be engineered to control differentiation and target the growth of transplanted cells in a stem cell-based therapy to treat nervous system disorders.

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Section: Electric Field Induced Neurogenesissupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

The Influence of Electric Fields on Hippocampal Neural Progenitor Cells

Ariza

Fleury

Tormos

et al. 2010

Stem Cell Rev and Rep

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“…That positive resettings, just as the negative ones, can be elicited by single stimuli applied to either one of the main afferent pathways to the hippocampus, indicates that they are synaptically induced. The positive polarity of these resettings both in the basal and in the apical dendritic layers, suggests that they are related to the positive component V of the hippocampal perforant path evoked response (16), and to the third element of the seizure discharge complex, the former of which is frequently, and the latter always, positive in the basal and in the apical dendritic layers. These potentials thought under normal conditions to be inhibitory, may help to reactivate seizure activity or prevent its arrest by massive cathodal inactivation, if the latter appears to be impending (Fig.…”

Section: A Proposed Negative Feedback Mechanism Involved In the Maintmentioning

confidence: 98%

A Consideration of Feedback Mechanisms in the Genesis and Maintenance of Hippocampal Seizure Activity

1964

Self Cite

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SUMMARY Hippocampal seizure discharge was investigated in lightly anaesthetized cats using extracellular microelectrodes. The interrelationships of rapid transients, unit discharge and slow DC‐shifts were studied. The genesis of hippocampal seizure discharge seems to depend upon the development of a positive feedback mechanism consisting of the mutually reenforcing action of increased firing of the pyramidal cells and the development of a radial DC‐gradient with negativity in the basal layers. Such a system has no inherent stability and one would expect it to lead rapidly to massive cathodal inactivation and arrest of seizure activity. This outcome is, however, not the rule, because seizure activity becomes stabilized by the development of a negative feedback mechanism involving probably the recruitment of inhibitory neurons and perhaps also partial cathodal inactivation of nerve cells. The seizure discharge may become arrested by one of the following three mechanisms: Failure of synaptic transmission within mutually interconnected neurons of the epileptogenic pool; Decay of the radial DC‐gradient (under natural conditions always resulting from factor (1)); Massive cathodal inactivation of nerve cells leading to spreading depression. RÉSUMÉ Les décharges critiques de l'hippocampe sont enregistrées chez le chat légèrement anesthésié, à l'aide de micro‐électrodes extra‐cellulaires. L'étude porte sur les interrelations entre les décharges unitaires et les variations lentes de potentiel. Les décharges critiques de l'hippocampe semblent dépendre du développement d'un mécanisme de “feedback” positif constitué par l'action mutuellement renforcée de la décharge progressivement croissante des cellules pyramidales et du développement d'un gradient “radial” de potentiel continu avec négativité dans les couches basales. Un tel système ne possédant aucune stabilité inhérente, on pourrait s'attendre a ce qu'il aboutisse rapidement à une inactivation cathodique massive et à un arrêt de la décharge critique. Une telle évolution n'est cependant pas la règle car l'activité critique se stabilise sous l'effet du développement d'un mécanisme de “feedback” négatif intéressant probablement le recrutement de neurones inhibiteurs et peut‐être aussi une inactivation cathodique partielle de cellules nerveuses. La décharge critique peut s'interrompre sous l'effet d'un des trois mécanismes suivants: Défaut de transmission synaptique dans les neurones mutuellement interconnectés d'un “pool”épileptogène; Diminution du gradient “radial” de potentiel continu (sous l'effet de conditions naturelles résultant toujours du mécanisme (no. 1)); Inactivation cathodique massive des cellules nerveuses aboutissant à une “spreading‐depression”.

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“…CA3 pyramidal cells are the first hippocampal neurons to respond to perforant path activation, often preceding the firing of DG granule cells (Yeckel and Berger, 1990;Breindl et al, 1994). Anatomical (Amaral et al, 1990), electrophysiological (Yeckel and Berger, 1990;Berzhanskaya et al, 1998), and functional metabolic (Jorgensen and Wright, 1988) studies report a strong, monosynaptic MPP-CA3 connection, which is well defined in the cat (Gloor et al, 1963), rabbit (Yeckel and Berger, 1998), and rat (Wu and Leung, 1998). Stimulation of this pathway is strong enough to activate synchronous firing of CA3 neurons and MPP-CA3 LTP can be induced in an NMDA receptor-dependent and opioid receptor-independent (Breindl et al, 1994) fashion.…”

Section: Introductionmentioning

confidence: 99%

Aging impairs the late phase of long‐term potentiation at the medial perforant path‐CA3 synapse in awake rats

Dieguez

Barea-Rodrı́guez

2004

Synapse

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The effects of aging on long-term potentiation (LTP) in the dentate gyrus (DG) and CA1 are well documented, but LTP at the medial perforant path (MPP)-CA3 synapse of aged animals has remained unexplored. Because the MPP-DG and Schaffer-collateral-CA1 synapses account for only about 20% of total hippocampal synapses, global understanding of how aging affects hippocampal plasticity has remained limited. Much is known about LTP induction in the hippocampal formation, whereas the mechanisms that regulate LTP maintenance are less understood, especially during aging. We investigated the effects of aging on MPP-CA3 LTP induction and maintenance in awake rats. As is the case in the DG and CA1, high-frequency stimulation-induced LTP at the MPP-CA3 synapse is normal in aged rats. These data indicate that N-methyl-D-aspartate (NMDA) receptor-mediated processes are intact at the MPP-CA3 synapse in aged rats. In contrast, aging impaired the magnitude and duration of MPP-CA3 LTP over a period of days. Also, these data are consistent with reports that area CA3 is especially susceptible to age-related changes. Our data suggest that aging impairs mechanisms that regulate the late phase of MPP-CA3 LTP and contribute to a more global understanding of how aging affects hippocampal plasticity.

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Electrophysiological studies of hippocampal neurons I. Configuration and laminar analysis of the “resting” potential gradient, of the main-transient response to perforant path, fimbrial and mossy fiber volleys and of “spontaneous” activity

Cited by 72 publications

References 41 publications

The Influence of Electric Fields on Hippocampal Neural Progenitor Cells

The Influence of Electric Fields on Hippocampal Neural Progenitor Cells

A Consideration of Feedback Mechanisms in the Genesis and Maintenance of Hippocampal Seizure Activity

Aging impairs the late phase of long‐term potentiation at the medial perforant path‐CA3 synapse in awake rats

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