2007; Grueter et al., 2010). This was surprising giving that eCB LTD in the NAc had been reported previously in slices from wildtype mice in which it was not possible to make targeted recordings (Robbe et al., 2002). However, the techniques used in this previous report, extracellular field recordings, do not allow the source of the postsynaptic responses to be determined. An additional surprising finding was that the eCB LTD in NAc indirect pathway MSNs was not completely blocked by a CB1 receptor antagonist. This observation led to an extensive set of experiments demonstrating that, in addition to standard eCB LTD, NAc indirect pathway MSNs express a novel form of LTD triggered by activation of postsynaptic TRPV1 channels (Grueter et al., 2010). A very similar form of postsynaptic TRPV1-triggered LTD was found in medial perforant path synapses on dentate gyrus granule cells (Chavez et al., 2010) suggesting that this may be a ubiquitous, albeit highly input specific, form of synaptic plasticity.
