On page 480, in Fig. 4, the trace indicated ‘L-histidine’ is a digitally corrupted version of the real response to histidine, while the real response to histidine is erroneously shown as the trace indicated as ‘BAS’. The response to the mixture of basic amino acids (‘BAS’) is not given. Here we show the correct responses to L-histidine and to the mixture of basic amino acids (BAS). The authors apologize for this mistake.