Fos expression in the prefrontal cortex and ventral striatum after exposure to a free-operant timing schedule

L Valencia-Torres, C M Olarte Sanchez, S Body, T H C Cheung, K C F Fone, C M Bradshaw, E Szabadi

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3 Citations (Scopus)
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It has been proposed that cortico-striato-thalamo-cortical circuits that incorporate the prefrontal cortex and corpus striatum regulate interval timing behaviour. In the present experiment regional Fos expression was compared between rats trained under an immediate timing schedule, the free-operant psychophysical procedure (FOPP), which entails temporally regulated switching between two operanda, and a yoked variable-interval (VI) schedule matched to the timing task for food deprivation level, reinforcement rate and overall response rate. The density of Fos-positive neurones (counts mm(-2)) in the orbital prefrontal cortex (OPFC) and the shell of the nucleus accumbens (AcbS) was greater in rats exposed to the FOPP than in rats exposed to the VI schedule, suggesting a greater activation of these areas during the performance of the former task. The enhancement of Fos expression in the OPFC is consistent with previous findings with both immediate and retrospective timing schedules. Enhanced Fos expression in the AcbS was previously found in retrospective timing schedules based on conditional discrimination tasks, but not in a single-operandum immediate timing schedule, the fixed-interval peak procedure. It is suggested that the ventral striatum may be engaged during performance on timing schedules that entail operant choice, irrespective of whether they belong to the immediate or retrospective categories.
Original languageEnglish
Pages (from-to)273-279
Number of pages7
JournalBehavioural Brain Research
Issue number2
Early online date16 Aug 2012
Publication statusPublished - 1 Dec 2012


  • animals
  • basal ganglia
  • cell count
  • conditioning, operant
  • female
  • food deprivation
  • gene expression regulation
  • oncogene proteins v-fos
  • prefrontal cortex
  • rats
  • rats, wistar
  • reinforcement (psychology)
  • reinforcement schedule
  • time factors
  • time perception


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