Effects of chlordiazepoxide on extinction of operant behaviour in mice vary with time of administration and rate of extinction

Facilitation of extinction of operant behaviour in mice by d-cycloserine

“…Marked spontaneous recovery occurred between sessions in both experiments, as is typically found when massed trials are used in extinction (Moody et al 2006;Pavlov 1927) and has been found previously with C57Bl/6 mice in this procedure (Leslie et al 2007). High levels of spontaneous recovery occurred throughout Experiments 1 and 2 with vehicle-and DCS-treated mice.…”

“…1 and 2). Leslie et al (2007) came to the same conclusion comparing experiments in which six-, 60-or 96-trial extinction sessions were used at intervals of 24 h. Dickinson (e.g. 1985) argues that overtrained operant behaviour is habitual and not currently sensitive to changes in the value of the reinforcer maintaining the behaviour.…”

“…The present findings also extend those of previous studies, which showed that GABAergic potentiators, including CDP, facilitate extinction following operant conditioning in C57Bl/6 mice (Leslie et al , 2005McCabe et al 2004;Shaw et al 2004). The extinctionfacilitating effect of CDP, however, only occurs when the drug is administered prior to the extinction sessions (Leslie et al 2007) and thus may depend on the presence of the drug at the time of testing (even though it has been established that at the dose used CDP has no sedative or locomotor effect in this strain of mice, see McCabe et al 2004, Experiment 4). In contrast, the facilitating effect of DCS on extinction in the present experiments occurred with post-session drug administration.…”

“…With daily extinction sessions of six trials (e.g. Leslie et al 2005) or 60 trials (Leslie et al 2007), the effect does not occur until about 40 extinction trials have been completed. The effect of DCS in the present experiments, however, was seen after the first drug administration.…”

“…First, a much larger number of extinction trials (48) were included in each session. Leslie et al (2007) found that if a large number of extinction trials occurred in each session, then facilitation of extinction by CDP still occurred after roughly the same number of trials and thus could be studied over a small number of sessions with fewer drug administrations required. Second, the extinction sessions were spaced at least 3 days apart as this may be sufficient to prevent successive administrations of DCS resulting in desensitisation of receptors (Stewart, J., personal communication).…”