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. 2006 Apr 12;26(15):4139–4146. doi: 10.1523/JNEUROSCI.0489-06.2006

Figure 4.

Figure 4.

Conditioning induces a novel feeding stimulatory lip CS pathway. A, Conditioning reverses feeding suppressive CS effect in the intact animal. Animals that received an explicitly unpaired presentation of the CS and US during conditioning (Control) showed a significant suppression of feeding activity during the 0.02% CS application (CS) compared with the water score (water). This feeding suppressive effect was reversed in conditioned animals, in which 0.02% CS caused a significant increase in feeding activity (Conditioned). B, CS application (0.02%) to the lips causes a significant increase in fictive feeding activity in reduced CNS preparations (see Fig. 2Ai) from conditioned animals but not from control animals. C, Conditioning reverses feeding suppressive effect of CS in whole CNS preparations. CS application (0.02%) to the lips causes a significant reduction in fictive feeding activity in whole CNS preparations from control animals but not from conditioned animals. Baseline, Fictive feeding activity during 2 min before CS application; CS, fictive feeding activity during 2 min of CS application. D, Conditioning does not change the inhibitory pathway that mediates feeding suppressive CS effect in naive animals. The feeding suppressive effect of CS application to the lips is only present in the whole CNS (whole control CNS) but not in the reduced CNS preparation (reduced control CNS). Therefore, the absolute difference between the CS effect in whole CNS and reduced CNS preparations from control animals provides an estimate of the inhibitory component (Δi). If this inhibitory component is unchanged by conditioning, adding Δi to the observed CS effect in whole CNS preparations from conditioned animals (predicted) should provide a good prediction for the CS effect in reduced CNS preparations from conditioned animals (reduced cond CNS) that lack the inhibitory pathway (observed). This is in fact the case, because there is no significant difference between the predicted and observed CS effect in reduced CNS preparations from conditioned animals (t test, p < 0.05). This strongly suggests that conditioning does not alter the inhibitory CS pathway. *p < 0.05; **p < 0.01; ***p < 0.001. ns, Not significant.