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Activation of the central serotonergic system in response to delayed but not omitted rewards.

Miyazaki KW, Miyazaki K, Doya K - Eur. J. Neurosci. (2010)

Bottom Line: The forebrain serotonergic system is a crucial component in the control of impulsive behaviours.By contrast, during the intermittent reward condition, in which food was given on only about one-third of the site visits, the level of dopamine was lower than that during the immediate reward condition, whereas the level of serotonin did not change significantly.This is the first direct evidence that activation of the serotonergic system occurs specifically in relation to waiting for a delayed reward.

View Article: PubMed Central - PubMed

Affiliation: Neural Computation Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan. kmiyazaki@oist.jp

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Average changes in 5-HT and DA efflux in the DRN during the three reward conditions. (A) Average time courses of 5-HT during the three reward conditions (n=10; ± SEM). The grey background shows the rest period. (B) Average time courses of DA during the three reward conditions (n=8; + SEM). (C) Average 5-HT levels during the 30 min task periods (n=10; + SEM). (D) Average DA levels during the 30 min task periods (n=8; + SEM). Asterisks indicate significant differences, as assessed by the Tukey’s HSD test, **P<0.01.
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fig05: Average changes in 5-HT and DA efflux in the DRN during the three reward conditions. (A) Average time courses of 5-HT during the three reward conditions (n=10; ± SEM). The grey background shows the rest period. (B) Average time courses of DA during the three reward conditions (n=8; + SEM). (C) Average 5-HT levels during the 30 min task periods (n=10; + SEM). (D) Average DA levels during the 30 min task periods (n=8; + SEM). Asterisks indicate significant differences, as assessed by the Tukey’s HSD test, **P<0.01.

Mentions: The average responses of 5-HT (n=10) and DA (n=8) can be seen in Fig. 5. The 5-HT level increased markedly from the beginning of the delayed reward condition compared with the other two conditions (one-way anova, F2,158 = 27.79, P<0.0001) (Fig. 5A). The DA level built up gradually during the immediate and delayed reward conditions, but was significantly less in the intermittent reward condition (one-way anova, F2,126 = 9.89, P=0.0001) (Fig. 5B). We also show the average time courses of 5-HT and DA efflux separately for task sequences 1 and 2 in Supporting Information Fig. S2. The average 5-HT and DA levels during the 30 min task periods relative to the baseline concentrations can be seen in Fig. 5C and D, respectively. The 5-HT levels were significantly elevated in all reward conditions compared with the baseline concentrations (16 ± 3.5% in the immediate reward condition, 31 ± 5.4% in the delayed reward condition, and 14 ± 2.9% in the intermittent reward condition; mean ± SEM, one-way anova, F3,27 = 25.11, P<0.0001 followed by Tukey’s HSD test, P<0.05). The 5-HT level in the delayed reward condition was significantly higher than that in the other two conditions (one-way anova, F2,18 = 19.00, P<0.0001 followed by Tukey’s HSD test, P<0.05). The DA levels were significantly elevated in immediate and delayed conditions compared with the baseline concentrations (one-way anova, F3,21 = 8.65, P=0.0006 followed by Tukey’s HSD test, P<0.05). For individual rats, five out of six rats showed significantly increased 5-HT efflux during the delayed reward condition compared with during the immediate and intermittent reward conditions (one-way anova, P<0.05 followed by Tukey’s test, P<0.05).


Activation of the central serotonergic system in response to delayed but not omitted rewards.

Miyazaki KW, Miyazaki K, Doya K - Eur. J. Neurosci. (2010)

Average changes in 5-HT and DA efflux in the DRN during the three reward conditions. (A) Average time courses of 5-HT during the three reward conditions (n=10; ± SEM). The grey background shows the rest period. (B) Average time courses of DA during the three reward conditions (n=8; + SEM). (C) Average 5-HT levels during the 30 min task periods (n=10; + SEM). (D) Average DA levels during the 30 min task periods (n=8; + SEM). Asterisks indicate significant differences, as assessed by the Tukey’s HSD test, **P<0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3040841&req=5

fig05: Average changes in 5-HT and DA efflux in the DRN during the three reward conditions. (A) Average time courses of 5-HT during the three reward conditions (n=10; ± SEM). The grey background shows the rest period. (B) Average time courses of DA during the three reward conditions (n=8; + SEM). (C) Average 5-HT levels during the 30 min task periods (n=10; + SEM). (D) Average DA levels during the 30 min task periods (n=8; + SEM). Asterisks indicate significant differences, as assessed by the Tukey’s HSD test, **P<0.01.
Mentions: The average responses of 5-HT (n=10) and DA (n=8) can be seen in Fig. 5. The 5-HT level increased markedly from the beginning of the delayed reward condition compared with the other two conditions (one-way anova, F2,158 = 27.79, P<0.0001) (Fig. 5A). The DA level built up gradually during the immediate and delayed reward conditions, but was significantly less in the intermittent reward condition (one-way anova, F2,126 = 9.89, P=0.0001) (Fig. 5B). We also show the average time courses of 5-HT and DA efflux separately for task sequences 1 and 2 in Supporting Information Fig. S2. The average 5-HT and DA levels during the 30 min task periods relative to the baseline concentrations can be seen in Fig. 5C and D, respectively. The 5-HT levels were significantly elevated in all reward conditions compared with the baseline concentrations (16 ± 3.5% in the immediate reward condition, 31 ± 5.4% in the delayed reward condition, and 14 ± 2.9% in the intermittent reward condition; mean ± SEM, one-way anova, F3,27 = 25.11, P<0.0001 followed by Tukey’s HSD test, P<0.05). The 5-HT level in the delayed reward condition was significantly higher than that in the other two conditions (one-way anova, F2,18 = 19.00, P<0.0001 followed by Tukey’s HSD test, P<0.05). The DA levels were significantly elevated in immediate and delayed conditions compared with the baseline concentrations (one-way anova, F3,21 = 8.65, P=0.0006 followed by Tukey’s HSD test, P<0.05). For individual rats, five out of six rats showed significantly increased 5-HT efflux during the delayed reward condition compared with during the immediate and intermittent reward conditions (one-way anova, P<0.05 followed by Tukey’s test, P<0.05).

Bottom Line: The forebrain serotonergic system is a crucial component in the control of impulsive behaviours.By contrast, during the intermittent reward condition, in which food was given on only about one-third of the site visits, the level of dopamine was lower than that during the immediate reward condition, whereas the level of serotonin did not change significantly.This is the first direct evidence that activation of the serotonergic system occurs specifically in relation to waiting for a delayed reward.

View Article: PubMed Central - PubMed

Affiliation: Neural Computation Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan. kmiyazaki@oist.jp

Show MeSH
Related in: MedlinePlus