Figure 3.

Serotonergic facilitation of LTD and LTP in a single slice preparation depended on electrode position in relation to CTX-gold-positive patches. (A) A chart of tissue sections shows patches of CTX-gold-labeled cells and the locations of recording and stimulating electrodes as identified from lesions made after recording sessions. (B) LTD occurred in a column marked by a CTX-gold-positive patch. The time course of amplitude changes of population EPSPs at the S1-R1 pair of electrodes. Filled circles show averaged responses before, during, and after LFS (1 Hz, 900 pulses) applied conjointly with 5-HT (1 μM). There was a persistent depression of the tested pathway if 1-Hz conditioning was applied in the presence of 5-HT. (C) LTP was evoked in a region falling between patches of CTX-gold-positive neurons. The time course of amplitude changes of population EPSPs at the S2-R2 pair of electrodes is shown. There was a persistent facilitation of the tested pathway if 1-Hz conditioning was applied in the presence of 5-HT. S1, S2, R1, and R2 represent locations of stimulation and recording electrodes. (B and C Insets) Field potentials averaged from 10 consecutive responses taken as indicated on the graphs. The solid and open bars indicate the periods of LFS and 5-HT application, respectively.