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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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Related in: MedlinePlus

Behavioural results of the sequential food–water navigation task. (A) Mean numbers of food pellets acquired during each reward condition. (B) Mean distance traveled during the three reward conditions. (C) Time between tone presentation and food site nose-poke. (D) Time between tone presentation and water site nose-poke. All error bars show + SEM (n=10). Asterisks indicate significant differences, as assessed by the paired t-test, *P<0.05, **P<0.01.
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fig03: Behavioural results of the sequential food–water navigation task. (A) Mean numbers of food pellets acquired during each reward condition. (B) Mean distance traveled during the three reward conditions. (C) Time between tone presentation and food site nose-poke. (D) Time between tone presentation and water site nose-poke. All error bars show + SEM (n=10). Asterisks indicate significant differences, as assessed by the paired t-test, *P<0.05, **P<0.01.

Mentions: Among the six rats, three of them were tested with sequence 1 on the first day and sequence 2 on the following day. Three others were tested in the counterbalanced order. We excluded the measurements in which the 5-HT or DA concentration data were smaller than signal-to-noise ratio 3. From this procedure, we obtained 10 task sequence data for 5-HT (5 from sequence 1 and 5 from sequence 2) and 8 task sequence data for DA (4 from sequence 1 and 4 from sequence 2). Probe placements within the DRN are shown in Fig. 2. The numbers of food pellets (mean ± SEM) obtained during the 30 min periods were 56.5 ± 6.5 (n=10) in the immediate reward condition, 37.7 ± 4.5 (n=10) in the delayed reward condition, and 14.8 ± 1.4 (n=10) in the intermittent reward condition (Fig. 3A). These differences are due, at least in part, to the time spent waiting in the delayed reward condition and the omission of the rewards in the intermittent reward condition. The total traveling distance during the 30 min period was significantly shorter in the delayed reward condition than in the other two conditions (paired t-test, immediate vs. delay P=0.011; immediate vs. intermittent, P=0.24; delay vs. intermittent, P=0.0011) (Fig. 3B), again partly due to the time spent waiting at the reward sites. Movement toward the reward sites was quickest during the immediate reward condition and slowest in the intermittent reward condition (paired t-test, P=0.0015 for time to food site; P=0.027 for time to water site) (Fig. 3C and D), suggesting the highest motivation in the immediate reward condition and the lowest motivation in the intermittent reward condition.


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

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

Behavioural results of the sequential food–water navigation task. (A) Mean numbers of food pellets acquired during each reward condition. (B) Mean distance traveled during the three reward conditions. (C) Time between tone presentation and food site nose-poke. (D) Time between tone presentation and water site nose-poke. All error bars show + SEM (n=10). Asterisks indicate significant differences, as assessed by the paired t-test, *P<0.05, **P<0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig03: Behavioural results of the sequential food–water navigation task. (A) Mean numbers of food pellets acquired during each reward condition. (B) Mean distance traveled during the three reward conditions. (C) Time between tone presentation and food site nose-poke. (D) Time between tone presentation and water site nose-poke. All error bars show + SEM (n=10). Asterisks indicate significant differences, as assessed by the paired t-test, *P<0.05, **P<0.01.
Mentions: Among the six rats, three of them were tested with sequence 1 on the first day and sequence 2 on the following day. Three others were tested in the counterbalanced order. We excluded the measurements in which the 5-HT or DA concentration data were smaller than signal-to-noise ratio 3. From this procedure, we obtained 10 task sequence data for 5-HT (5 from sequence 1 and 5 from sequence 2) and 8 task sequence data for DA (4 from sequence 1 and 4 from sequence 2). Probe placements within the DRN are shown in Fig. 2. The numbers of food pellets (mean ± SEM) obtained during the 30 min periods were 56.5 ± 6.5 (n=10) in the immediate reward condition, 37.7 ± 4.5 (n=10) in the delayed reward condition, and 14.8 ± 1.4 (n=10) in the intermittent reward condition (Fig. 3A). These differences are due, at least in part, to the time spent waiting in the delayed reward condition and the omission of the rewards in the intermittent reward condition. The total traveling distance during the 30 min period was significantly shorter in the delayed reward condition than in the other two conditions (paired t-test, immediate vs. delay P=0.011; immediate vs. intermittent, P=0.24; delay vs. intermittent, P=0.0011) (Fig. 3B), again partly due to the time spent waiting at the reward sites. Movement toward the reward sites was quickest during the immediate reward condition and slowest in the intermittent reward condition (paired t-test, P=0.0015 for time to food site; P=0.027 for time to water site) (Fig. 3C and D), suggesting the highest motivation in the immediate reward condition and the lowest motivation in the intermittent reward condition.

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