Conflict Test Battery for Studying the Act of Facing Threats in Pursuit of Rewards

Abstract

Survival depends on the ability of animals to avoid threats and approach rewards. Traditionally, these two opposing motivational systems have been studied separately. In nature, however, they regularly compete for the control of behavior. When threat- and reward-eliciting stimuli (learned or unlearned) occur simultaneously, a motivational conflict emerges that challenges individuals to weigh available options and execute a single behavioral response (avoid or approach). Most previous animal models using approach/avoidance conflicts have often focused on the ability to avoid threats by forgoing or delaying the opportunity to obtain rewards. In contrast, behavioral tasks designed to capitalize on the ability to actively choose to execute approach behaviors despite threats are scarce. Thus, we developed a behavioral test battery composed of three conflict tasks to directly study rats confronting threats to obtain rewards guided by innate and conditioned cues. One conflict task involves crossing a potentially electrified grid to obtain food on the opposite end of a straight alley, the second task is based on the step-down threat avoidance paradigm, and the third one is a modified version of the open field test. We used diazepam to pharmacologically validate conflict behaviors in our tasks. We found that, regardless of whether competing stimuli were conditioned or innate, a low diazepam dose decreased risk assessment and facilitated taking action to obtain rewards in the face of threats during conflict, without affecting choice behavior when there was no conflict involved. Using this pharmacologically validated test battery of ethologically designed innate/learned conflict tasks could help understand the fundamental brain mechanisms underlying the ability to confront threats to achieve goals.

Ventral Pallidum and Amygdala Cooperate to Restrain Reward Approach from Overriding Defensive Behaviors

“…Additionally, rats with BLA inactivation exhibited an extended duration of time spent in the goal zone, but a shorter time to press for food (goal zone, factorial ANOVA, group: F(1,22)= 29.46, p= 0.000; trials: F(1,22)= 14.03, p= 0.001; interaction: F(1,22)= 5.61, p= 0.02; conflict trials VEH: 13.06%; conflict trials INACT: 42.21%, post hoc comparison p=0.000; latency to press in the goal zone, factorial ANOVA, group: F(1,22) = 17.82, p= 0.000; trials: F(1,22)= 19.91, p= 0.001; interaction: F(1,22)= 18.11, p= 0.000; conflict trials VEH: 43.07 s; conflict trials INACT: 17.68 s, post hoc comparison p= 0.000). After inactivation of the BLA, the decrease in latency to cross was comparable to that previously observed using the anxiolytic drug diazepam (Illescas-Huerta et al, 2021). Overall, these findings suggest that BLA not only plays a critical role in the cautious decision-making process when confronting threats for food but also signals urgency, promoting the immediate compromise of potential harm to achieve a goal.…”

“…Moreover, VP inactivation led to a substantial increase in the time required by rats to obtain food, regardless of whether the task involved confronting a threat (as in conflict trials) or not (as in non-conflict trials) (factorial ANOVA, group: F(1,24)= 27.38, p= 0.000; trials: F(1,24)= 6.18, p= 0.02; interaction: F(1,24)= 1.28, p= 0.26; non-conflict trials VEH: 17.04 s, non-conflict trials INACT: 131.58 s, post hoc comparison p= 0.000; conflict trials VEH: 82.17 s, conflict trials INACT: 155.94, post hoc comparison p= 0.03). This VP inactivation effect is comparable to providing free access to food (satiety) one day before the CMC test (Illescas-Huerta et al, 2021), indicating that the task involves goal-directed behavior guided by incentive motivation. Nearly half of the rats subjected to VP inactivation (three out of seven) failed to cross within the allotted time (180s), suggesting a compromised incentive motivation to obtain food, regardless of the trial type.…”

“…For example, rats exhibit increased risk-taking behavior in response to food deprivation, social competition, and predator cues (Davis et al, 2009; Choi and Kim, 2010; Dent et al, 2014; Engelke et al, 2021; Zoratto et al, 2022). The CMC task provides a realistic and ecologically relevant scenario for studying risk-taking behavior in rodents, involving calculated effortful actions that require suppressing defensive responses to threats (Illescas-Huerta et al, 2021). Prior research has shown that administering diazepam, a commonly used anxiolytic, before the CMC test encourages rats to cross more readily in pursuit of food when potential danger is involved, without impacting non-conflict situations (Illescas-Huerta et al, 2021).…”

“…Rats underwent training for the crossing-mediated conflict task as previously described (Illescas-Huerta et al, 2021). Briefly, this training encompassed three stages: reward training, threat training, and discrimination training to differentiate between non-conflict and conflict trials.…”

“…When searching for food, foraging animals often face dangers in nature, which illustrates their ability to suppress their fear to achieve their goal. A novel behavioral tool, the crossing-mediated conflict (CMC) task, was recently developed to investigate this choice strategy in rats (Illescas-Huerta et al, 2021). This naturalistic task allows for the assessment of foraging choices that involve rapid transitions from effortful safe food acquisition to food seeking, despite threats within dynamic and unpredictable conditions.…”