title: Bidirectional Hebbian Plasticity Induced by Low-Frequency Stimulation in Basal Dendrites of Rat Barrel Cortex Layer 5 Pyramidal Neurons.
abstract: According to Hebb's original hypothesis (Hebb, 1949), synapses are reinforced when presynaptic activity triggers postsynaptic firing, resulting in long-term potentiation (LTP) of synaptic efficacy. Long-term depression (LTD) is a use-dependent decrease in synaptic strength that is thought to be due to synaptic input causing a weak postsynaptic effect. Although the mechanisms that mediate long-term synaptic plasticity have been investigated for at least three decades not all question have as yet been answered. Therefore, we aimed at determining the mechanisms that generate LTP or LTD with the simplest possible protocol. Low-frequency stimulation of basal dendrite inputs in Layer 5 pyramidal neurons of the rat barrel cortex induces LTP. This stimulation triggered an EPSP, an action potential (AP) burst, and a Ca2+spike. The same stimulation induced LTD following manipulations that reduced the Ca2+spike and Ca2+signal or the AP burst. Low-frequency whisker deflections induced similar bidirectional plasticity of action potential evoked responses in anesthetized rats. These results suggest that bothin vitroandin vivosimilar mechanisms regulate the balance between LTP and LTD. This simple induction form of bidirectional hebbian plasticity could be present in the natural conditions to regulate the detection, flow, and storage of sensorimotor information.
authors.affiliation: Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Díez-García
authors.affiliation: Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain.
authors.forename: Natali
authors.initials: N
authors.lastname: Barros-Zulaica
authors.affiliation: Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain.
authors.forename: Ángel
authors.initials: Á
authors.lastname: Núñez
authors.affiliation: Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC) Madrid, Spain.
authors.forename: Washington
authors.initials: W
authors.lastname: Buño
authors.affiliation: Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de MadridMadrid, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC)Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Fernández de Sevilla
keywords: Ca2+spikes; L-type VGCC; NMDARs; STDP; dentritic excitabilty