With 5-HT dysfunction [40]. In addition, Monteggia and colleagues demonstrated that the loss of forebrain BDNF attenuates the actions of desipramine in the order Licochalcone-A forced swim test, suggesting that BDNF affects the efficacy of antidepressants [41]. However, there is contrary evidence that a chronic reduction of BDNF protein content in adult BDNF(+/2) mice is not sufficient to induce neurochemical or behavioral alterations, although some investigators believe that the baseline behaviors of these mice may be difficult to interpret since they display a normal behavioral Hypericin phenotype even when BDNF is expressed at half its normal level [13,42]. Djalali and colleagues also found that the presence of BDNF is not a requirement for the survival and maturation of serotonergic neurons in vivo [43]. Thus, the relationships among BDNF, 5-HT, and depression remain controversial. Our results showed that there were no gender differences in the LDAEP at most of electrodes (Cz, Pz, Fz, and C4) except C3. However, there was evidence that the LDAEP is modulated by gender 
potentially. Oliva and collegues reported that LDAEP for female healthy participants was stronger than that for male healthy participants [44]. There was contrary evidence that female depressed patients showed weaker LDAEP strength than male depressed patients [45]. In addition, there were some findings revealing no gender difference in LDAEP like our results [9,46]. Thus, there was a still controversy about the gender difference in LDAEP.There are several limitations to the generalization of the results of this study. First, we investigated only three SNPs. However, these three SNPs of the BDNF gene exhibit moderate-to-strong linkage disequilibrium. Second, the sample was relatively small. However, healthy subjects were carefully enrolled from a Korean population. In conclusion, the findings of our study support the view that BDNF polymorphisms may be involved in the LDAEP in the Korean population, although further confirmative studies are warranted. In conclusion, it can be assumed from the results of this study that BDNF polymorphisms influence the LDAEP, and hence serotonin levels or serotonin activity. In particular, our study showed that subjects with the Val/Met genotype for rs6265, T/T genotype for rs2030324 or the C/C genotype for rs1491850 had a higher LDAEP, indicating lower central serotonergic activity. In addition, the numbers of subjects with low LDAEP were more than those with high LDAEP in the C-T haplotype (C genetype for rs2030424 and T genotype for rs1491850), indicating higher central serotonergic activity. It is possible that mood-disorder patients with these genotypes will exhibit a different response to medication with SSRIs or lithium. These genetic polymorphisms also seemed to be associated with the interaction between BDNF and the serotonin system.Supporting InformationTable S1 Statistical analyses on demographics as well as allele frequencies of the three SNPs in BDNF gene. (DOC) Table S2 Statistical analyses on the intensity of LDAEPwith genotypes of the three SNPs in BDNF gene at five electrodes (MANOVA). In MANOVA, there was no significant difference among 3 genotype groups at 5 electrodes. There was a statistically significant difference between 2 genotype groups in rs1491850 (C/C vs T/T at Pz), rs 2030324 (C/C vs T/T, C/C vs C/T at Cz; C/C vs T/T, C/C vs C/T at Pz; C/C vs T/T, C/C vs C/T at C3, respectively, p = 0.037, p = 0.029, p = 0.040, p = 0.014,p = 0.033, and p.With 5-HT dysfunction [40]. In addition, Monteggia and colleagues demonstrated that the loss of forebrain BDNF attenuates the actions of desipramine in the forced swim test, suggesting that BDNF affects the efficacy of antidepressants [41]. However, there is contrary evidence that a chronic reduction of BDNF protein content in adult BDNF(+/2) mice is not sufficient to induce neurochemical or behavioral alterations, although some investigators believe that the baseline behaviors of these mice may be difficult to interpret since they 
display a normal behavioral phenotype even when BDNF is expressed at half its normal level [13,42]. Djalali and colleagues also found that the presence of BDNF is not a requirement for the survival and maturation of serotonergic neurons in vivo [43]. Thus, the relationships among BDNF, 5-HT, and depression remain controversial. Our results showed that there were no gender differences in the LDAEP at most of electrodes (Cz, Pz, Fz, and C4) except C3. However, there was evidence that the LDAEP is modulated by gender potentially. Oliva and collegues reported that LDAEP for female healthy participants was stronger than that for male healthy participants [44]. There was contrary evidence that female depressed patients showed weaker LDAEP strength than male depressed patients [45]. In addition, there were some findings revealing no gender difference in LDAEP like our results [9,46]. Thus, there was a still controversy about the gender difference in LDAEP.There are several limitations to the generalization of the results of this study. First, we investigated only three SNPs. However, these three SNPs of the BDNF gene exhibit moderate-to-strong linkage disequilibrium. Second, the sample was relatively small. However, healthy subjects were carefully enrolled from a Korean population. In conclusion, the findings of our study support the view that BDNF polymorphisms may be involved in the LDAEP in the Korean population, although further confirmative studies are warranted. In conclusion, it can be assumed from the results of this study that BDNF polymorphisms influence the LDAEP, and hence serotonin levels or serotonin activity. In particular, our study showed that subjects with the Val/Met genotype for rs6265, T/T genotype for rs2030324 or the C/C genotype for rs1491850 had a higher LDAEP, indicating lower central serotonergic activity. In addition, the numbers of subjects with low LDAEP were more than those with high LDAEP in the C-T haplotype (C genetype for rs2030424 and T genotype for rs1491850), indicating higher central serotonergic activity. It is possible that mood-disorder patients with these genotypes will exhibit a different response to medication with SSRIs or lithium. These genetic polymorphisms also seemed to be associated with the interaction between BDNF and the serotonin system.Supporting InformationTable S1 Statistical analyses on demographics as well as allele frequencies of the three SNPs in BDNF gene. (DOC) Table S2 Statistical analyses on the intensity of LDAEPwith genotypes of the three SNPs in BDNF gene at five electrodes (MANOVA). In MANOVA, there was no significant difference among 3 genotype groups at 5 electrodes. There was a statistically significant difference between 2 genotype groups in rs1491850 (C/C vs T/T at Pz), rs 2030324 (C/C vs T/T, C/C vs C/T at Cz; C/C vs T/T, C/C vs C/T at Pz; C/C vs T/T, C/C vs C/T at C3, respectively, p = 0.037, p = 0.029, p = 0.040, p = 0.014,p = 0.033, and p.