A specific role for serotonin in overcoming effort cost
- Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, France
- INSERM UMRS 1127, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC-P6), France
- INSERM U992, Institut d'Imagerie Biomédicale, Direction de la recherche fondamentale, Commissariat à l'énergie atomique et aux énergies alternatives, France
- University of Oxford, United Kingdom
- The University of Manchester, United Kingdom
- Service de Psychiatrie, France
- Université Paris Descartes, Sorbonne Paris Cité, France
- INSERM U894, Université Paris Descartes, Sorbonne Paris Cité, France
- Institut Pasteur, France
Figures
Figure 1
Task design and behavioral performance.
(A) The screenshots depict a trial as it was presented to subjects.Subjects were free to allocate their effort as they wished over the 30s corresponding to the trial duration. They were instructed …
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Figure 1—source data 1
The MATLAB data file contains the payoff earned by each participant at each visit, in the placebo and escitalopram groups.
- https://doi.org/10.7554/eLife.17282.004
Figure 2
Computational results.
(A) The cost-evidence accumulation model assumes that effort and rest durations are respectively determined by the accumulation (mean slope Sem) and dissipation (mean slope Srm) of cost evidence …
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Figure 2—source data 1
The MATLAB data file contains the fitted value of parameters Ai, Sem, Sed, Srm, Sri (see Materials and methods, Equation 2), for each participant at each visit, in the placebo and escitalopram groups.
- https://doi.org/10.7554/eLife.17282.006
Figure 3
Behavioral results.
(A) Plots show inter-subject means and Student's 95% confidence intervals obtained from linear regression.Regression coefficients were averaged over visits at the subject level. To facilitate visual …
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Figure 3—source data 1
The MATLAB data file contains a description of the behavior obtained by linear regressions for each participant at each visit, in the placebo and escitalopram groups.
The regression weights correspond to the mean effort duration and mean rest duration, and their modulation by incentive levels and difficulty levels.
- https://doi.org/10.7554/eLife.17282.011
Tables
Table 1
Details on participants N corresponds to the number of subjects per treatment type and phase. A few datasets were not available due technical problems and late withdrawals. Based on criteria …
| Treatment type | Treatment phase | N not available | N excluded | N after exclusion | Sex (Male / female) | Age (years) ± SD of included subjects | Time since treatment onset (days) ± SD for included subjects |
|---|---|---|---|---|---|---|---|
Placebo | Initial | 0 | 5 | 27 | 14/13 | 23.4 ± 4.35 | 3.0 ± 0.68 |
Placebo | Intermediate | 0 | 6 | 26 | 14/12 | 23.2 ± 4.33 | 13.8 ± 1.13 |
Placebo | Late | 0 | 4 | 28 | 15/13 | 23.4 ± 4.27 | 54.7 ± 4.98 |
Escitalopram | Initial | 1 | 8 | 23 | 11/12 | 24.5 ± 4.71 | 3.1 ± 0.63 |
Escitalopram | Intermediate | 1 | 6 | 25 | 12/13 | 24.5 ± 4.51 | 14.0 ± 0.87 |
Escitalopram | Late | 2 | 6 | 24 | 10/14 | 24.6 ± 4.61 | 55.3 ± 4.69 |
Table 2
Treatment effect on computational parameters and behavioral measures.
All numbers are p-values obtained from ANOVAs. p-values lower than 0.05/5=0.01 (computational parameters) and 0.05/6=0.008 (behavioral measures) appears in bold to show significant effects that survive correction for multiple comparisons.
| Variable | Treatment | Visit | Interaction |
|---|---|---|---|
Ai | 0.388 | 0.197 | 0.406 |
Sem | 0.003 | 0.039 | 0.260 |
Sed | 0.0797 | 0.543 | 0.137 |
Srm | 0.186 | 0.778 | 0.612 |
Sri | 0.130 | 0.196 | 0.557 |
Effort duration – mean | 0.002 | 0.199 | 0.875 |
Effort duration – sensitivity to incentive | 0.023 | 0.187 | 0.115 |
Effort duration – sensitivity to difficulty | 0.247 | 0.813 | 0.318 |
Rest duration – mean | 0.213 | 0.482 | 0.531 |
Rest duration – sensitivity to incentive | 0.162 | 0.937 | 0.807 |
Rest duration – sensitivity to difficulty | 0.115 | 0.423 | 0.681 |
Table 3
Model comparison assessing the specificity of treatment effect.
Data in the escitalopram group were fitted with the cost-evidence accumulation model. The parameters were fixed to the values fitted onto the placebo group, excepted when a modulation was permitted. The first row contains models that permit the modulation of one single parameter, whereas the remaining rows correspond to models that permit a combination of two modulations. Each cell gives log Bayes Factor (i.e. log model evidence) relative to the null model. Higher values denote better models.
Sem | Sed | Srm | Sri | Ai | |
|---|---|---|---|---|---|
Only one modulation | 173.6 | 19.9 | −4.2 | −3.8 | 3.7 |
Also includes Sem | 176.6 | 169.6 | 169.7 | 170.7 | |
Also includes Sed | 15.7 | 16.1 | 21.7 | ||
Also includes Srm | −7.3 | −1.1 | |||
Also includes Sri | 1.2 |
Additional files
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Reporting standards 1
Consort 2010 checklist.
- https://doi.org/10.7554/eLife.17282.012
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Reporting standards 2
Consort 2010 flow diagram.
- https://doi.org/10.7554/eLife.17282.013
