RESUMEN
Crime scene investigations are highly complex environments that require the CSI to engage in complex decision-making. CSIs must rely on personal experience, context information, and scientific knowledge about the fundamental principles of forensic science to both find and correctly interpret ambiguous traces and accurately reconstruct a scene. Differences in CSI decision making can arise in multiple stages of a crime scene investigation. Given its crucial role in forensic investigation, CSI decision-making must be further studied to understand how differences may arise during the stages of a crime scene investigation. The following exploratory research project is a first step at comparing how crime scene investigations of violent robberies are conducted between 25 crime scene investigators from nine countries across the world. Through a mock crime scene and semi-structured interview, we observed that CSIs have adopted a variety of investigation approaches. The results show that CSIs have different working strategies and make different decisions when it comes to the construction of relevant hypotheses, their search strategy, and the collection of traces. These different decisions may, amongst other factors, be due to the use of prior information, a CSI's knowledge and experience, and the perceived goal of their investigation. We suggest the development of more practical guidelines to aid CSIs through a hypothetico-deductive reasoning process, where (a) CSIs are supported in the correct use of contextual information, (b) outside knowledge and expertise are integrated into this process, and (c) CSIs are guided in the evaluation of the utility of their traces.
Asunto(s)
Crimen , Ciencias Forenses , Humanos , Solución de Problemas , Proyectos de InvestigaciónRESUMEN
Optogenetics allows for the targeted temporary inhibition or stimulation of specific brain regions in vivo with precise temporal resolution. Here, we describe the steps to perform intracranial optogenetic surgery in rodents as well as instructions to build an optogenetic headcap and set up an optogenetic testing environment to conduct experiments. Behavioral studies have implemented these methods to stimulate the central amygdala (CeA) to create an addictive-like preference for reward.
Asunto(s)
Encéfalo/fisiología , Núcleo Amigdalino Central/fisiología , Channelrhodopsins/genética , Optogenética/métodos , Animales , Conducta Adictiva/genética , Núcleo Amigdalino Central/metabolismo , Ratones , Motivación/genética , Ratas , RecompensaRESUMEN
Slot-machine gambling incorporates numerous audiovisual cues prior to and during reward delivery (e.g. spinning wheels, flashing lights, celebratory sounds). Over time, these cues may motivate playing and even elicit cravings and relapse in those affected by gambling disorder. Animal studies suggest a heightened attraction to these cues despite diminished predictive ability under reward uncertainty, as evidenced by sign-tracking behavior in rats. Repeated amphetamine administration may also enhance the incentive value attributed to cues. Here, we explored the impact of reward uncertainty and prior amphetamine sensitization on the relative attractiveness and conditioned reinforcing properties of serial Pavlovian cues with different degrees of predictive and incentive value in rats. Animals were sensitized through repeated injections of amphetamine (1-4â¯mg/kg) or saline and then trained in a Pavlovian autoshaping task involving two sequential lever-auditory cue combinations (CS1, CS2) under Certain (100%-1) or Uncertain (50%-1-2-3) reward conditions. Subsequently, we evaluated the impact of acute amphetamine exposure on cue attraction. Our results suggest that Uncertainty alone enhanced attraction towards the reward-proximal CS2. However, combined sensitization and Uncertainty reversed cue preference relative to Uncertainty alone, enhancing attraction towards the more predictive reward-distal CS1. Both cues acquired conditioned reinforcing properties, despite the CS2 being otherwise ignored in all groups besides Uncertainty. However, combined sensitization and Uncertainty increased the reinforcing value of both cues and doubled the amount of interaction with the CS1 lever per presentation. Our results imply competitive mechanisms for attributing incentive value to gambling-related cues between reward uncertainty, prior amphetamine sensitization, and acute amphetamine administration.
Asunto(s)
Anfetamina/farmacología , Sensibilización del Sistema Nervioso Central/fisiología , Señales (Psicología) , Motivación , Recompensa , Incertidumbre , Animales , Condicionamiento Clásico , Masculino , RatasRESUMEN
The flashing lights and celebratory sounds that dominate slot-machine gambling are believed to promote engagement and motivation to keep playing. However, these cues are often presented in the absence of reward, and previous research suggests that this reward uncertainty, which degrades their predictive value, also increases their incentive value. Here, we used autoshaping to tease apart the impact of reward uncertainty on the predictive and incentive value of a conditioned stimulus (CS) using serial cues. Each CS trial began with the presentation of a predictive CS1, followed by a CS2, holding primarily incentive value, because of its proximity to sucrose reward delivery, under Certain (100%-1) or Uncertain (50%-1- 2-3) reward conditions. Subsequently, we tested the impact of amphetamine and nicotine on cue attraction, and the ability of these cues to either serve as a conditioned reinforcer, or promote motivation for sucrose during a progressive ratio task. Finally, we measured anxiety behavior, and examined its interaction with each cue and uncertainty. Our results suggest that reward uncertainty increases attraction to the incentive CS2 and its ability to trigger motivation and reward-seeking. However, although the CS2 is largely ignored under Certain conditions, both CS1 and CS2 become conditioned reinforcers for both groups. Finally, amphetamine reduced the attraction of the CS1 for both groups but had no effect on the attraction of the CS2. These results suggest that reward uncertainty recruits and increases the incentive value of cues with limited predictive value and highlights the distinction between cue attraction, reward-seeking and conditioned reinforcer properties.