Long-term potentiation and long-term depression: a clinical perspective.

Long-term potentiation and long-term depression are enduring changes in synaptic strength, induced by specific patterns of synaptic activity, that have received much attention as cellular models of information storage in the central nervous system. Work in a number of brain regions, from the spinal cord to the cerebral cortex, and in many animal species, ranging from invertebrates to humans, has demonstrated a reliable capacity for chemical synapses to undergo lasting changes in efficacy in response to a variety of induction protocols. In addition to their physiological relevance, long-term potentiation and depression may have important clinical applications.

Behavioral deficits and subregion-specific suppression of LTP in mice expressing a population of mutant NMDA receptors throughout the hippocampus.

The NMDA receptor (NMDAR) subunit GluN1 is an obligatory component of NMDARs without a known functional homolog and is expressed in almost every neuronal cell type. The NMDAR system is a coincidence detector with critical roles in spatial learning and synaptic plasticity. Its coincidence detection property is crucial for the induction of hippocampal long-term potentiation (LTP).

Impairments in motor coordination without major changes in cerebellar plasticity in the Tc1 mouse model of Down syndrome.

Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of human chromosome 21 (Hsa21). Recently, O'Doherty et al. [An aneuploid mouse strain carrying human chromosome 21 with Down syndrome phenotypes.

Preservation of long-term memory and synaptic plasticity despite short-term impairments in the Tc1 mouse model of Down syndrome.

Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of the human chromosome 21 (Hsa21). Recently, O'Doherty and colleagues in an earlier study generated a new genetic mouse model of DS (Tc1) that carries an almost complete Hsa21. Since DS is the most common genetic cause of mental retardation, we have undertaken a detailed analysis of cognitive function and synaptic plasticity in Tc1 mice.

Autophosphorylation of alphaCaMKII is not a general requirement for NMDA receptor-dependent LTP in the adult mouse.

Autophosphorylation of alpha-Ca2+/calmodulin kinase II (alphaCaMKII) at Thr286 is thought to be a general effector mechanism for sustaining transcription-independent long-term potentiation (LTP) at pathways where LTP is NMDA receptor-dependent. We have compared LTP at two such hippocampal pathways in mutant mice with a disabling point mutation at the Thr286 autophosphorylation site. We find that autophosphorylation of alphaCaMKII is essential for induction of LTP at Schaffer commissural-CA1 synapses in vivo, but is not required for LTP that can be sustained over days at medial perforant path-granule cell synapses in awake mice.

An aneuploid mouse strain carrying human chromosome 21 with Down syndrome phenotypes.

Aneuploidies are common chromosomal defects that result in growth and developmental deficits and high levels of lethality in humans. To gain insight into the biology of aneuploidies, we manipulated mouse embryonic stem cells and generated a trans-species aneuploid mouse line that stably transmits a freely segregating, almost complete human chromosome 21 (Hsa21). This "transchromosomic" mouse line, Tc1, is a model of trisomy 21, which manifests as Down syndrome (DS) in humans, and has phenotypic alterations in behavior, synaptic plasticity, cerebellar neuronal number, heart development, and mandible size that relate to human DS.

Optical quantal analysis reveals a presynaptic component of LTP at hippocampal Schaffer-associational synapses.

The mechanisms by which long-term potentiation (LTP) is expressed are controversial, with evidence for both presynaptic and postsynaptic involvement. We have used confocal microscopy and Ca(2+)-sensitive dyes to study LTP at individual visualized synapses. Synaptically evoked Ca(2+) transients were imaged in distal dendritic spines of pyramidal cells in cultured hippocampal slices, before and after the induction of LTP.

Brain-derived neurotrophic factor induces long-term potentiation in intact adult hippocampus: requirement for ERK activation coupled to CREB and upregulation of Arc synthesis.

Brain-derived neurotrophic factor (BDNF) is implicated in long-term synaptic plasticity in the adult hippocampus, but the cellular mechanisms are little understood. Here we used intrahippocampal microinfusion of BDNF to trigger long-term potentiation (BDNF-LTP) at medial perforant path--granule cell synapses in vivo. BDNF infusion led to rapid phosphorylation of the mitogen-activated protein (MAP) kinases ERK (extracellular signal-regulated protein kinase) and p38 but not JNK (c-Jun N-terminal protein kinase).