<p>A: Ventral view of the hindbrain over the area encompassing the FMN and the active region. Preparations were obtained from an E15.5 <i>+/+</i> embryo, loaded with calcium Green 1-AM and observed in direct fluorescence (left panel) or as relative changes in fluorescence (ΔF/F, right panel). The yellow oval indicates the position of the FMN, the e-pF network is encircled in red. Traces below indicate calcium transients (ΔF/F) measured in the e-pF region in control conditions (top trace), pH 7.2 (second trace), 10 µM CNQX (third trace), 10 µM Riluzole (fourth trace) and 10<sup>−7</sup> M Substance P (SP, fifth trace). B and C: Same legend as in A for a <i>Lp/+</i> embryo (B) and a <i>Lp/Lp</i> embryo (C). D: Graphs representing the mean frequency of calcium transients measured in the e-pF region in different experimental conditions (indicated below and color coded) for <i>+/+</i> (left part), <i>Lp/+</i> (middle part) and <i>Lp/Lp</i> (right part). Numbers in brackets indicate the number of preparations tested. Asterisks indicate statistically different means. Frequency is increased in the presence of CNQX, SP and in pH 7.2 for all genotypes, while riluzole blocks the rhythmic activity in the active region. The active network found in the mutant shares pharmacological characteristics of the e-pF recorded in the wild type littermates. L: lateral, R: rostral.</p
