Cerebral Cortex Advance Access published online on April 10, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp067
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Double Dissociation of Spike Timing–Dependent Potentiation and Depression by Subunit-Preferring NMDA Receptor Antagonists in Mouse Barrel Cortex
1 The Neuronal Oscillations Group, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK, 2 Department of Physiology, Anatomy and Cellular Biology, University Pablo de Olavide, 41013 Seville, Spain, 3 Novartis Institutes for BioMedical Research, CH-4057 Basel, Switzerland
Address correspondence to Dr Ole Paulsen, MD, PhD, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK. Email: ole.paulsen{at}dpag.ox.ac.uk.
Spike timing–dependent plasticity (STDP) is a strong candidate for an N-methyl-D-aspartate (NMDA) receptor-dependent form of synaptic plasticity that could underlie the development of receptive field properties in sensory neocortices. Whilst induction of timing-dependent long-term potentiation (t-LTP) requires postsynaptic NMDA receptors, timing-dependent long-term depression (t-LTD) requires the activation of presynaptic NMDA receptors at layer 4-to-layer 2/3 synapses in barrel cortex. Here we investigated the developmental profile of t-LTD at layer 4-to-layer 2/3 synapses of mouse barrel cortex and studied their NMDA receptor subunit dependence. Timing-dependent LTD emerged in the first postnatal week, was present during the second week and disappeared in the adult, whereas t-LTP persisted in adulthood. An antagonist at GluN2C/D subunit–containing NMDA receptors blocked t-LTD but not t-LTP. Conversely, a GluN2A subunit–preferring antagonist blocked t-LTP but not t-LTD. The GluN2C/D subunit requirement for t-LTD appears to be synapse specific, as GluN2C/D antagonists did not block t-LTD at horizontal cross-columnar layer 2/3-to-layer 2/3 synapses, which was blocked by a GluN2B antagonist instead. These data demonstrate an NMDA receptor subunit-dependent double dissociation of t-LTD and t-LTP mechanisms at layer 4-to-layer 2/3 synapses, and suggest that t-LTD is mediated by distinct molecular mechanisms at different synapses on the same postsynaptic neuron.
Key Words: development • LTD • LTP • rodent • synaptic plasticity
4 Current address: Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, the Netherlands.
Abhishek Banerjee and Rhiannon M. Meredith contributed equally to this work.