(A) Thapsigargin in whole-cell pipette (10 μM)
prevented heterosynaptic excitatory and inhibitory LTD after pre→post
pairing. Top, excitatory inhibitory LTP induced by pre→post pairing at
channel S4 (red, Δt=4 msec). Middle, thapsigargin
prevented heterosynaptic LTD. Bottom, Rs and Ri.
(B) Spike pairing with normal solutions and ACSF on paired
(red), original best unpaired (blue) and other unpaired inputs (black); same
recordings as Figures 2A,B. Filled bars, excitation; open bars, inhibition.
(C) Blocking NMDA receptors (50 μm APV in bath)
prevented plasticity (pre→post n=6: paired EPSCs p>0.7,
Student’s paired two-tailed t-test, paired IPSCs p>0.4,
originally-largest unpaired EPSCs p>0.6, originally-largest unpaired
IPSCs p>0.5; post→pre n=4: paired EPSCs p>0.8, paired IPSCs
p>0.7, originally-largest unpaired EPSCs p>0.6, originally-largest
unpaired IPSCs p>0.5).
(D) Intracellular ruthenium red (20 μm) spared
homosynaptic but prevented heterosynaptic plasticity at original best inputs
(pre→post n=9: paired EPSCs p<0.02, paired IPSCs p<0.05,
originally-largest unpaired EPSCs p>0.6, originally-largest unpaired
IPSCs p>0.3, post→pre n=9: paired EPSCs p<0.004, paired
IPSCs p<0.006, originally-largest unpaired EPSCs p>0.9,
originally-largest unpaired IPSCs p>0.6).
(E) Intracellular thapsigargin (10 μm) spared
homosynaptic but prevented heterosynaptic plasticity (pre→post n=12:
paired EPSCs p<0.006, paired IPSCs p<0.003, originally-largest
unpaired EPSCs p>0.05, originally-largest unpaired IPSCs p>0.1;
post→pre n=10: paired EPSCs p<0.01, paired IPSCs p<0.006,
originally-largest unpaired EPSCs p>0.05, originally-largest unpaired
IPSCs p>0.2).