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Titolo:
Effect of central 5-hydroxytryptamine depletion on performance in the freeoperant psychophysical procedure: facilitation of switching, but no effecton temporal differentiation of responding
Autore:
Chiang, TJ; Al-Ruwaitea, ASA; Ho, MY; Bradshaw, CM; Szabadi, E;
Indirizzi:
Univ Nottingham, Queens Med Ctr, Dept Psychiat, Nottingham NG7 2UH, England Univ Nottingham Nottingham England NG7 2UH , Nottingham NG7 2UH, England
Titolo Testata:
PSYCHOPHARMACOLOGY
fascicolo: 2, volume: 143, anno: 1999,
pagine: 166 - 173
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTERVAL BISECTION TASK; MEDIAN RAPHE NUCLEI; TIMING BEHAVIOR; PACEMAKER RATE; PATHWAYS; SCHEDULE; LESIONS; DORSAL; REINFORCEMENT; DESTRUCTION;
Keywords:
5-hydroxytryptamine; 5,7-dihydroxytryptamine; operant behaviour; timing; switching;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
27
Recensione:
Indirizzi per estratti:
Indirizzo: Bradshaw, CM Univ Nottingham, Queens Med Ctr, Dept Psychiat, Nottingham NG7 2UH, England Univ Nottingham Nottingham England NG7 2UH NG7 2UH, England
Citazione:
T.J. Chiang et al., "Effect of central 5-hydroxytryptamine depletion on performance in the freeoperant psychophysical procedure: facilitation of switching, but no effecton temporal differentiation of responding", PSYCHOPHAR, 143(2), 1999, pp. 166-173

Abstract

This experiment examined the effect of destroying the ascending 5-hydroxytryptaminergic (5-HTergic) pathways on timing and switching behaviour in thefree-operant psychophysical procedure. Rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press levers for sucrose reinforcement; sessions consisted of fifty 50-s trials in which reinforcers were available on a variable-interval 30-s schedule. In the first 25 s,of each trial, reinforcement was only available for responses on lever A: in the Last 25 s, it was availableonly for responses on lever B. In phase 1 (70 sessions) repetitive switching between the levers was prevented by withdrawal of lever A after the first response on lever B in each trial, in phase 3 (40 sessions) this constraint on switching was removed; in phase 3 (40 sessions) the constraint was reinstated. Data were collected from probe trials (four per session) in whichno reinforcers were delivered, during the last ten sessions of each phase. In all phases, both groups showed declining response rates on lever A and increasing response rates on lever B as a function of time from the onset of the trial. Response rate on lever BI expressed as percentage of overall response rate, could be described by a tao-parameter logistic function. Removal of the constraint on switching reduced the slope of the function without changing the indifference point (time corresponding to 50% responding on lever B). The parameters of the timing function did not differ between the groups in any of the phases. However, the lesioned group showed a greater enhancement of switching rate during phase 2 than the control group. The levels of 5-HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine wen not altered. The results provide further evidence for the involvement of the ascending 5-HTergic pathways in switching between response alternatives, but cast doubt on our previous suggestion that the effects of 5-HT depletion on temporal differentiation of behaviour are mediated by facilitated switching.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/03/20 alle ore 05:09:52