, Volume 111, Issue 2, pp 239–243 | Cite as

Effect of lesions of the ascending 5-hydroxytryptaminergic pathways on choice between delayed reinforcers

  • Mary A. Wogar
  • C. M. Bradshaw
  • E. Szabadi
Original Investigations


The possible involvement of the ascending 5-hydroxytryptaminergic (5HTergic) pathways in determining the effectiveness of delayed positive reinforcers was investigated using Mazur's (1984) adjusting-delay paradigm. Fourteen rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei; 12 rats received sham lesions. The rats made repeated choices in a two-lever operant conditioning chamber between a smaller reinforcer delivered after a 2-s delay and a larger reinforcer delivered after a variable delay, the length of which was determined by the subject's previous choices. When the two reinforcers consisted of one and two food pellets, the “indifference point” (the delay to the larger reinforcer that rendered the two reinforcers equally effective) was shorter in the lesioned group than in the control group. Increasing the sizes of the reinforcers to three and six pellets reduced the indifference point in both groups and abolished the between-group difference. The levels of 5HT and 5-hydroxyindoleacetic acid (5HIAA) in the parietal cortex, hippocampus, amygdala, nucleus accumbens and hypothalamus were greatly reduced in the lesioned group, but the levels of noradrenaline and dopamine were not significantly affected. The results are consistent with the suggestion that the 5HTergic pathways play a role in maintaining the effectiveness of delayed reinforcers.

Key words

5-Hydroxytryptamine 5,7-Dihydroxytryptamine Operant behaviour Delayed reinforcement Adjusting-delay paradigm Rat 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Ainslie GW (1974) Impulse control in pigeons. J Exp Anal Behav 21:485–489Google Scholar
  2. Barratt ES (1983) The biological basis of impulsiveness: the significance of timing and rhythm disorders. Person Indiv Diff 4:387–391CrossRefGoogle Scholar
  3. Baumgarten HG, Jenner S, Bjorklund A, Klemm HP, Schlossberger HG (1982) Serotonin neurotoxins. In: Osborne NN (ed) Biology of serotonergic transmission. Wiley, ChichesterGoogle Scholar
  4. Bizot JC, Thiebot MH, LeBihan C, Soubrie P, Simon P (1988) Effects of imipramine-like drugs and serotonin uptake blockers on delay of reward in rats. Possible implication in the behavioral mechanism of action of antidepressants. J Pharmacol Exp Ther 246:1144–1151PubMedGoogle Scholar
  5. Bradshaw CM, Szabadi E (1992) Choice between delayed reinforcers in a discrete-trials schedule: the effect of deprivation level. Q J Exp Psychol 44B:1–16Google Scholar
  6. Deluty MZ (1981) Self-control and impulsiveness involving short-term and long-term punishing events. In: Bradshaw CM, Szabadi E, Lowe CF (eds) Quantification of steady-state operant behaviour. Elsevier, AmsterdamGoogle Scholar
  7. Deakin JFW (1983) Roles of serotonergic systems in escape, avoidance and other behaviours. In: Cooper SJ (ed) Theory in psychopharmacology, vol 2. Academic Press, New YorkGoogle Scholar
  8. Deakin JFW, Graeff FG (1991) 5-HT and mechanisms of defence. J Psychopharmacol 54:305–315Google Scholar
  9. Heffner TG, Hartman JA, Seiden LS (1980) A method for the regional dissection of the rat brain. Pharmacol Biochem Behav 13:453–456CrossRefPubMedGoogle Scholar
  10. Herrnstein RJ (1970) On the law of effect. J Exp Anal Behav 13:243–266Google Scholar
  11. Linnoila M, Virkkunen M (1991) Monoamines, glucose metabolism and impulse control. In: Sandler M, Coppen A, Harnett S (eds) 5-Hydroxytryptamine in psychiatry. Oxford University Press, New YorkGoogle Scholar
  12. Logue AW (1988) Research on self-control: an integrated framework. Behav Brain Sci 11:665–709Google Scholar
  13. Mazur JE (1984) Tests of an equivalence rule for fixed and variable reinforcer delays. J Exp Psychol [Anim Behav Proc] 10:426–436CrossRefGoogle Scholar
  14. Mazur JE (1987) An adjusting procedure for studying delayed reinforcement. In: Commons ML, Mazur JE, Nevin JA, Rachlin H (eds) Quantitative analyses of behavior, vol V: The effect of delay and intervening events. Hillsdale, New JerseyGoogle Scholar
  15. Mazur JE, Herrnstein RJ (1988) On the functions relating delay, reinforcer value and behavior. Behav Brain Sci 11:690–691Google Scholar
  16. O'Hare E, Tierney KJ, Shephard RA (1991) Cyclic-ratio schedule analysis of a serotonin agonist and depletor on consummatory behaviour. Physiol Behav 49:331–334CrossRefPubMedGoogle Scholar
  17. Paxinos G, Watson C (1982) The rat brain in stereotaxic coordinates. Academic Press, New YorkGoogle Scholar
  18. Soubrie P (1986) Reconciling the role of central serotonin neurons in human and animal behavior. Behav Brain Sci 9:319–364Google Scholar
  19. Thiebot MH (1986) Are serotonergic neurons involved in the control of anxiety and in the anxiolytic activity of benzodiazepines? Pharmacol Biochem Behav 24:1471–1477CrossRefPubMedGoogle Scholar
  20. Thiebot MH, Le Bihan C, Soubrie P, Simon P (1985) Benzodiazepines reduce the tolerance to reward delay in rats. Psychopharmacology 86:147–152CrossRefGoogle Scholar
  21. Vaughan WM (1985) Choice: a local analysis. J Exp Anal Behav 43:383–405Google Scholar
  22. Wogar MA, Bradshaw CM, Szabadi E (1991) Evidence for an involvement of 5-hydroxytryptaminergic neurones in the maintenance of operant behaviour by positive reinforcement. Psychopharmacology 105:119–124Google Scholar
  23. Wogar MA, Bradshaw CM, Szabadi E (1992a) Impaired acquisition of temporal differentiation performance following lesions of the ascending 5-hydroxytryptaminergic pathways. Psychopharmacology 107:373–378PubMedGoogle Scholar
  24. Wogar MA, Bradshaw CM, Szabadi E (1992b) Choice between delayed reinforcers in an adjusting-delay schedule: the effects of absolute reinforcer size and deprivation level. Q J Exp Psychol 45B:1–13Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Mary A. Wogar
    • 1
  • C. M. Bradshaw
    • 1
  • E. Szabadi
    • 1
  1. 1.Department of PsychiatryUniversity of ManchesterManchesterUK

Personalised recommendations