Fig. 4.

Effects of paired tone–NBstm training on behavioral memory in Paired and Unpaired groups following training. (A) Examples of respiratory waveforms obtained from a Paired subject. Shown are baseline responses to the CS (8.00 kHz) and a lower (2.75 kHz) and higher (15.00 kHz) frequency during Day 2 (“Before”), Day 6, 24 h post-training (‘24 h After”), and Day 9, 96 h post-training (“96 h After”). RCI values indicate the average over 13 s post-stimulus onset disruption of ongoing respiration. Before training, responses to all three frequencies were minimal (RCI = 0.10–0.11). After training (24 h), the CS frequency produced a large disruption of respiration (RCI = 0.33). The absence of specificity of this example of NB-induced behavioral memory is indicated by the presence of strong responses to the lower (RCI = 0.37) and higher (RCI = 0.35) frequencies. However, 96 h after training, while the CS frequency still produced a large disruption of respiration (RCI = 0.41) the responses to the lower (RCI = 0.10) and higher (RCI = 0.11) frequencies were significantly lower, comparable to pre-training values. (B) Examples of respiratory waveforms from a subject in the Unpaired group. Similar to the Paired group, responses before training were minimal (RCI = 0.09–0.14). In contrast to the Paired group, the response to the CS frequency 24 h after training did not change much (CS RCI = 0.10). The same was true for responses to the lower (RCI = 0.10) and higher (RCI = 0.10) frequencies. Similarly, responses obtained 96 h after training were minimal both at the CS and the lower and higher test frequencies (all RCIs = 0.11). Note that both subjects had comparable level of NBstm (36 μA in Paired group, and 38 μA in Unpaired group) during training. The thick horizontal bars indicate tone presentation.