Nucleus accumbens and delay discounting in rats: evidence from a new quantitative protocol for analysing inter-temporal choice

Abstract

Destruction of the AcbC increased the rate of delay discounting.

A theory of behaviour on progressive ratio schedules, with applications in behavioural pharmacology

“…This suggests that the lesion did not alter the incentive value of the food reinforcer, a conclusion that is in accord with recent interpretations of the effect of AcbC lesions on inter-temporal choice behaviour (Bezzina et al 2007;Valencia-Torres et al 2012). However, visual inspection of the parameter values shown in Fig.…”

Nucleus accumbens core lesions induce sub-optimal choice and reduce sensitivity to magnitude and delay in impulsive choice tasks

“…The results provide some direct evidence indicating that changes in reward magnitude and delay can impact the observed effect of NAc lesions and concurs with the present findings in the NAc lesion group. In contrast, previous research using adjusting delay schedules has suggested that NAc lesions do not disrupt sensitivity to short-term changes in delay [24, 26]. Due to the inherent oscillations in choice parameters in adjusting delay schedules, these latter studies employed Fourier transform analyses to show that the periodicity of these oscillations was not affected by NAc lesions, thus concluding that NAc lesions did not impair rats’ ability to detect local changes in reward delay.…”

“…Both permanent and reversible NAc lesions increase impulsive choice in rats [23–26]. NAc lesions have been suggested to diminish rats’ sensitivity to changes in the delay to reward [27], such that the NAc may be critical for the discounting of reward value due to overestimation of reward delays [3, 28–32].…”

“…However, unlike many previous experiments that have analyzed NAc lesion effects on time-based decision making [23, but see 24, 26, e.g., 28], the present experiment tested the effect of NAc lesions on impulsive choice behavior when reward magnitude and delay were manipulated in separate experiments to isolate each of these components.…”

“…In previous studies of NAc lesion effects on impulsive choice, choice behavior was studied within more dynamic environments, in which the delays to reward increased systematically over the session [23, 28, 35] or as a function of the rats’ recent choices [24, 26, 35]. Galtress and Kirkpatrick [33] employed a task in which the delay to the SS delay increased with each trial until a rat made an LL choice, at which point the SS delay was reset to 0 s. However, in this sort of dynamic task, inherently involving more complex forms of learning, it is difficult to definitively determine whether NAc dysfunction impairs the weighting of reward delay versus reward magnitude (i.e., impulsive choice).…”