Assortment of GABAergic Plasticity in the Cortical Interneuron Melting Pot
Figure 4
Endocannabinoid-independent plasticity of GABAergic synapses. (a) Brief train of action potentials (conditioning) in cortical pyramidal cells depresses unitary inhibitory postsynaptic potentials (uIPSPs) evoked by synaptically connected FS interneurons (top traces, from left to right: before, during and after conditioning). This form of short-term retrograde depression is indicated by the black dots during the conditioning paradigm (conditioned response is measured 250 ms after the conditioning stimulus), and it is not blocked by the selective CB1R antagonist AM-251, ruling out the involvement of eCB signaling. (b) Conditioning mediated depression of uIPSPs from FS interneurons (top traces, from left to right: before, during, and after conditioning) is prevented by the nonselective vesicular glutamate transporter Evans Blue (EB) suggesting a critical role for dendritically released glutamate in this form of plasticity. Modified with permission from [119]. For details see [119, 120]. (c, d) Spike timing-dependent plasticity (STDP) results in potentiation (c) and depression (d) of uIPSPs (top) elicited by FS interneurons onto cortical pyramidal cells. Long-term potentiation (LTP) of uIPSP amplitudes (top traces) is obtained when presynaptic FS cell fires 410 ms after the beginning of a brief train of action potentials (10 action potentials at 50 Hz) in the postsynaptic pyramidal cell (c). Conversely, long-term depression (LTD) of uIPSPs is observed when the presynaptic FS cell fired 250 ms after the start of an identical train (d). (c and d): Modified with permission from [121].
