A rodent version of the Iowa Gambling Task: 7 years of progress

Abstract

In the Iowa Gambling Task (IGT) subjects need to find a way to earn money in a context of variable wins and losses, conflicting short-term and long-term pay-off, and uncertainty of outcomes. In 2006, we published the first rodent version of the IGT (r-IGT; Behavior Research Methods 38, 470-478). Here, we discuss emerging ideas on the involvement of different prefrontal-striatal networks in task-progression in the r-IGT, as revealed by our studies thus far. The emotional system, encompassing, among others, the orbitofrontal cortex, infralimbic cortex and nucleus accumbens (shell and core area), may be involved in assessing and anticipating the value of different options in the early stages of the task, i.e., as animals explore and learn task contingencies. The cognitive control system, encompassing, among others, the prelimbic cortex and dorsomedial striatum, may be involved in instrumental goal-directed behavior in later stages of the task, i.e., as behavior toward long-term options is strengthened (reinforced) and behavior toward long-term poor options is weakened (punished). In addition, we suggest two directions for future research: (1) the role of the internal state of the subject in decision-making, and (2) studying differences in task-related costs. Overall, our studies have contributed to understanding the interaction between the emotional system and cognitive control system as crucial to navigating human and non-human animals alike through a world of variable wins and losses, conflicting short-term and long-term pay-offs, and uncertainty of outcomes.

Keywords: behavioral models; decision-making; foraging behavior; humans; prefrontal cortex; rats.

FIGURE 1

Schematic model of the role of different systems in task-progression in the IGT. The horizontal axis represents the progression of the task, while the vertical axis represents relative activity. The upper and lower triangle represent the relative contribution of the different brain systems which may be involved in the different stages of the test: learning relevant task-relevant features (emotional (limbic) system; transparent red), and consistently directing behavior toward choosing cards from the long-term advantageous decks [cognitive control (associative) system; transparent blue, see text for further explanation].

FIGURE 2

Hypothetical neurobehavioral model of task-progression in the r-IGT (Yin and Knowlton, 2006; Yin et al., 2008). It should be noted that the cingulate areas and insular cortex are not included (see New Directions for the r-IGT). Furthermore the subdivisions of the OFC are not shown (see van den Bos et al., 2013b). In transparent red, the emotional system is shown, of which striatal areas are involved in Pavlovian behavior (see Yin et al., 2008): while the shell is involved in immediate (hedonic) responses (stimulus-outcome; (un)conditioned consummatory/hedonic responses), the core is involved in anticipatory/preparatory behavior (stimulus–stimulus relation). In transparent blue, the cognitive control system [dorsomedial (DM) striatum; action-outcome; goal-directed behavior] and sensorimotor/habit system [dorsolateral (DL) striatum; stimulus-response; habit-like behavior], of which striatal areas are involved in instrumental behavior. Thus far, we have not trained animals to the point of showing habitual behavior. Arrows indicate mutual interactions between midbrain dopaminergic areas and striatal areas, while the dotted arrows indicate disinhibition of dopaminergic areas by striatal areas [see Yin and Knowlton (2006) for discussion]. Dopaminergic projections to the prefrontal cortex are not shown. Also the interaction with the serotonergic (5-HT) system is not shown (see for discussion: Homberg et al., 2008; Koot et al., 2012; van den Bos et al., 2013b). Abbreviations: amy, amygdala; OFC, orbitofrontal cortex; IL, infralimbic cortex; PrL, prelimbic cortex; SI/MI, primary and sensory motor cortices; VTA, ventral tegmental area; SNPc, substantia nigra pars compacta.