Long Term Potentiation

the receptor acts as a coincidence detector. It allows calcium ions to flow through its channel if and only if it detects the coincidence of two neural events, one presynaptic and the other postsynaptic... thereby triggering long-term potentiation.

This passage establishes the NMDA receptor as the molecular coincidence detector whose activation of calcium influx is the foundational trigger of long-term potentiation, operationalizing Hebbian learning at the synaptic level.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006thesis

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Repeated trains of electrical stimuli produce a late phase of long-term potentiation that lasts for more than a day... the late phase of long-term potentiation is strongly affected by modulatory interneurons, which in mice are recruited to switch a short-term, homosynaptic into long-term, heterosynaptic change.

Kandel argues that the late phase of LTP, mediated by dopamine, cAMP, PKA, and CREB activation, is structurally homologous to long-term synaptic facilitation in Aplysia, constituting a conserved molecular mechanism of memory consolidation.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006thesis

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the reduction in hippocampal PKA activity was paralleled by a significant decrease in late LTP, while basal synaptic transmission and early LTP remained unchanged... this deficit in the late phase of LTP was paralleled by behavioral deficits in hippocampus-dependent long-term memory for extrapersonal space.

Using transgenic mice with inhibited PKA, Kandel demonstrates that late-phase LTP is the specific synaptic correlate of hippocampus-dependent spatial long-term memory, with short-term memory and early LTP remaining intact.

Kandel, Eric R., The Molecular Biology of Memory Storage: A Dialogue between Genes and Synapses, 2001thesis

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Although O'Keefe had discovered place cells in 1971, and Bliss and Lømo had discovered long-term potentiation in the hippocampus in 1973, no attempt had been made to connect the two findings.

Kandel identifies the conceptual gap between place-cell research and LTP, and frames his own interdisciplinary program as the first systematic attempt to link the molecular biology of LTP with the formation and stabilization of the hippocampal spatial map.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006thesis

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Age-related defects in spatial memory are correlated with defects in the late phase of hippocampal long-term potentiation in vitro and are attenuated by drugs that enhance the cAMP signaling pathway.

This bibliographic citation documents empirical evidence that age-related spatial memory decline corresponds specifically to deficits in late-phase LTP, and that pharmacological enhancement of cAMP signaling can ameliorate both.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006supporting

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For an excellent review of long-term potentiation, see T. Bliss, G. Collingridge, and R. Morris, eds., LTP: Long-Term Potentiation (Oxford: Oxford University Press, 2003).

Kandel's bibliographic apparatus situates LTP within its canonical scholarly literature, directing readers to foundational reviews on AMPA receptor trafficking, LTP expression mechanisms, and the LTP–memory relationship.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006supporting

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inhibiting protein synthesis indeed destabilized the place fields in the long-term much as does inhibiting PKA... a key feature in the stabilization of PKA and protein synthesis-dependent phase of memory is attention.

Kandel extends LTP research to demonstrate that protein synthesis and PKA-dependent processes — the same molecular machinery underlying late-phase LTP — are required for the long-term stabilization of hippocampal place fields, with attentional state as a critical modulatory variable.

Kandel, Eric R., The Molecular Biology of Memory Storage: A Dialogue between Genes and Synapses, 2001supporting

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Late LTP (4 trains) (dopamine)... Early LTP (1 train)... Ca2+/calmodulin... AMPA

This schematic diagram encapsulates the two-phase architecture of LTP — early and late — and their respective molecular mediators, providing a structural summary of the signaling cascade from calcium-calmodulin through AMPA receptor modulation.

Kandel, Eric R., The Molecular Biology of Memory Storage: A Dialogue between Genes and Synapses, 2001supporting

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The vast majority of symptoms in the late, debilitating stages of the disease are attributed to the loss of synaptic connections and to the death of nerve cells.

In the context of Alzheimer's disease, Kandel implicitly invokes the LTP framework by attributing cognitive decline to the disruption of the synaptic plasticity mechanisms that LTP research has illuminated.

Kandel, Eric R., In search of memory the emergence of a new science of mind, 2006aside

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