Figure 4.

LTP is reversed by novelty exploration. High-frequency stimulation at 100 Hz induces long-term potentiation in (a) Wistar (n = 6) and (b) Hooded Lister rat strains. Exposure of the animals to a novel holeboard 60 min after induction of LTP resulted in reversal of LTP to basal values in both Wistar (a, P < 0.001) and Hooded Lister Wistar (b, P < 0.001) rats. (c) LTD is not facilitated by stress. Placement of recording-naive Hooded Lister or Wistar rats in an unfamiliar brightly lit recording chamber, followed 30 min later by LFS, does not facilitate LTD induction. (Insets) Field potentials (average of five consecutive sweeps) from typical experiments at the times indicated by the numbers. Horizontal bar = 5 ms; vertical bar = 2 mV. Line-breaks indicate change in time scale.