Synapse‐specific mGluR1‐dependent long‐term potentiation in interneurones regulates mouse hippocampal inhibition

Persistent Transcription- and Translation-Dependent Long-Term Potentiation Induced by mGluR1 in Hippocampal Interneurons

“…Pairs of EPSCs were evoked at 0.5 Hz by constant current pulses (50 s duration, 50 ms interpulse interval) using a bipolar -glass electrode filled with ACSF and positioned in the stratum oriens. Putative single-fiber EPSCs were evoked using minimal stimulation as previously described (Perez et al, 2001;Lapointe et al, 2004). Briefly, at the beginning of each experiment, the stimulus strength was adjusted to a value that yielded ϳ 50% successes (range 40 -60%).…”

Learning Cross-Modal Spatial Transformations through Spike Timing-Dependent Plasticity

“…A classic example is the different NMDA dependence of commissuralassociational and mossy fiber synaptic plasticity in hippocampal CA3 pyramidal neurons (Nicoll and Malenka, 1995). It has been shown more recently that synapses onto hippocampal CA1 interneurons that express group II metabotropic glutamate receptors (mGluRs) presynaptically exhibit mGluR-dependent long-term potentiation, whereas those that express group III mGluRs do not (Lapointe et al, 2004). To our knowledge, differential plasticity at different synapses has not been shown for postsynaptically expressed plasticity, although it has been shown that the subunit composition of AMPA receptors on hippocampal interneurons can be determined by the afferent identity (Tó th and McBain, 1998), which implies that the enzymatic machinery underlying plasticity with a postsynaptic locus might also be so regulated.…”

Differential Regulation of Metabotropic Glutamate Receptor- and AMPA Receptor-Mediated Dendritic Ca2+Signals by Presynaptic and Postsynaptic Activity in Hippocampal Interneurons

“…2؉ signals induced by pairing synaptic stimulation with postsynaptic depolarization Because a stimulation protocol pairing repetitive stimulation with postsynaptic depolarization induces a mGluR1a-and Ca 2ϩ -dependent LTP in O/A interneurons (Perez et al, 2001;Lapointe et al, 2004), we examined whether CP-AMPAR-and mGluRmediated Ca 2ϩ signals were differentially activated by pairing synaptic theta-burst stimulation (TBS) [five bursts at 200 ms intervals (5 Hz), each burst consisting of four pulses at 100 Hz] with depolarization (five 60-ms-long depolarizing steps to Ϫ20 mV). We measured Ca 2ϩ signals activated by the pairing protocol in two recording conditions, using Ca 2ϩ indicators with low-affinity Fluo-5F (Fig.…”

“…Hippocampal CA1 interneurons in stratum oriens/alveus (O/A) demonstrate a Hebbian form of LTP that depends on the activation of the metabotropic glutamate receptor (mGluR) 1a subtype of mGluRs, occurs at synapses containing Ca 2ϩ -permeable (CP)-AMPARs, and requires postsynaptic Ca 2ϩ rises (Perez et al, 2001;Lapointe et al, 2004). This form of LTP does not depend on the activation of NMDA receptors (NMDARs).…”