Time perception and delay discounting in the FMR1 knockout rat.

There is substantial evidence for timing (time perception) abnormalities related to developmental disabilities, particularly autism spectrum disorder. These findings have been reported in humans and nonhuman preclinical models. Our research objective was to extend that work to a genetic knockout (KO) model of fragile X/developmental disability, the FMR1 KO rat.

Exercise recovers weight gain, but not increased impulsive choice, caused by a high-fat diet.

A high-fat diet has negative effects on physical, neurological, and behavioral outcomes. One consistent finding is that a diet high in fat increases impulsive choice behavior-behavior that is linked to a wide range of other negative health behaviors. While the mechanism for this increase in impulsive choice is not well understood, exercise, with its well-known and many benefits, may serve as an effective and accessible way to combat increased impulsive choice associated with a high-fat diet.

Timing and delay discounting in attention-deficit/hyperactivity disorder: A translational approach.

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that often presents with abnormal time perception and increased impulsive choice behavior. The spontaneously hypertensive rat (SHR) is the most widely used preclinical model of the ADHD-Combined and ADHD-Hyperactive/Impulsive subtypes of the disorder. However, when testing the spontaneously hypertensive rat from Charles River (SHR/NCrl) on timing and impulsive choice tasks, the appropriate control strain is not clear, and it is possible that one of the possible control strains, the Wistar Kyoto from Charles River (WKY/NCrl), is an appropriate model for ADHD-Predominately Inattentive.

Effects of immediate-reinforcement training on delay discounting behavior in rats.

Chronic exposure to delayed reinforcement has been shown to increase choice for larger, later reinforcement in a subsequent delay discounting task. In the three experiments presented in this paper, the opposite was tested: effects of chronic exposure to immediate reinforcement on choice in a subsequent delay discounting task. In Experiment 1, larger, later reinforcement choice was significantly reduced as a result of exposure to immediate reinforcement, compared to a maturation/handle control group, in experienced, male Lewis rats.

Preliminary evidence for timing abnormalities in the CNTNAP2 knockout rat.

The CNTNAP2 gene has been implicated in several neuropsychological disorders, including autism spectrum disorder (ASD) and schizophrenia. The CNTNAP2 knockout (KO) rat model, rats without the CNTNAP2 gene, exhibits deficits in social interaction and increases in both repetitive and anxiety-like behaviors. However, deficits in time perception that may underlie several of the neuropsychological disorders implicated have not been investigated.

Timing and Intertemporal Choice Behavior in the Valproic Acid Rat Model of Autism Spectrum Disorder.

Recently it has been proposed that impairments related to autism spectrum disorder (ASD) may reflect a more fundamental disruption in time perception. Here, we examined whether in utero exposure to valproic acid (VPA) can generate specific behavioral deficits related to ASD and time perception. Pups from control and VPA groups were tested using fixed-interval (FI) temporal bisection, peak interval, and intertemporal choice tasks.

Interventions aimed at changing impulsive choice in rats: Effects of immediate and relatively long delay to reward training.

A relatively strong preference for smaller-sooner rewards (SSR) over larger-later rewards (LLR) is associated with a host of maladaptive behavioral patterns. As such, the clinical implications for increasing preference for LLR are profound. There is a growing body of literature that suggests extended exposure to delayed reward may increase preference for LLR in rats.

Searching for the variables that control human rule-governed "insensitivity".

Verbal rules or instructions often exert obvious and meaningful control over human behavior. Sometimes instructions benefit the individual by enabling faster acquisition of a skill or by obviating an aversive consequence. However, research has also suggested a clear disadvantage: "insensitivity" to changing underlying contingencies.

Effects of signaling on temporal control of behavior in response-initiated fixed intervals.

Behavior and events distributed in time can serve as markers that signal delays to future events. The majority of timing research has focused on how behavior changes as the time to some event, usually food availability, decreases. The primary objective of the two experiments presented here was to assess how behavior changes as time passes between two time markers when the first time marker was manipulated but the second, food delivery, was held constant.

Stimulus control in two rodent models of attention-deficit/hyperactivity disorder.

The spontaneously hypertensive (SHR/NCrl) rat from Charles River is one of the most widely used models of the combined subtype of Attention-Deficit/Hyperactivity Disorder (ADHD-C). Although often used as its control strain, the Wistar Kyoto (WKY/NCrl) from Charles River has been proposed as a model of the predominately inattentive subtype of ADHD (ADHD-PI). In Experiment 1 SHR/NCrl, WKY/NCrl, and Wistar (WI; the progenitor strain for the two models) rats were trained on a left→right lever-press sequence in the presence of light discriminative stimuli that signaled the active lever in the sequence.

What is timed in a fixed-interval temporal bisection procedure?

Recent research on interval timing in the behavioral and neurological sciences has employed a concurrent fixed-interval (FI) procedure first reported by Platt and Davis (Journal of Experimental Psychology: Animal Behavior Processes, 9, 160-170, 1983). Studies employing the task typically assess just 1 dependent variable, the switch/bisection point; however, multiple measures of timing are available in the procedure and it is unclear (a) what is timed (i.e.

Reducing pawing in horses using positive reinforcement.

Aversive control is a common method to reduce undesirable behavior in horses. However, it often results in unintended negative side effects, including potential abuse of the animal. Procedures based on positive reinforcement, such as differential reinforcement of other behavior (DRO), may reduce undesirable behaviors with fewer negative consequences.

Timing in response-initiated fixed intervals.

Different events can serve as time markers that initiate intervals in schedules of reinforcement. Pigeons were exposed to fixed-interval (FI) schedules in which the onset of the interval was signaled by the illumination of a key light or initiated by a peck to a lighted key. Food was delivered following the first response after the interval elapsed.

Choice and timing in pigeons under differing levels of food deprivation.

State-dependent valuation learning (SDVL) is a preference for stimuli associated with relative food deprivation over stimuli associated with relative satiety. Pigeons were exposed to experimental conditions designed to investigate SDVL and to test the hypothesis that obtained relative immediacy during training predicts choice during test probes. Energy states were manipulated using a procedure that has previously revealed SDVL in starlings and pigeons.

Pigeon responding in fixed-interval and response-initiated fixed-interval schedules.

In fixed-interval (FI) and response-initiated fixed-interval (RIFI) schedules of reinforcement, a response is required after an interval has elapsed for delivery of reinforcement. In RIFI schedules, a response is required to initiate each interval as well. The objective of this experiment was a systematic comparison of performance in the two schedule types over a range of interval durations.

The effects of response-cost punishment on instructional control during a choice task.

The present study investigated the effects of punishing responses inconsistent with rules on instructional control during a choice task. In a procedure modeled after Hackenberg and Joker (1994), 7 adults were presented with repeated choices between progressive- and fixed-time schedules of reinforcement and were given instructions (rules) for how to respond to maximize earnings. Across sessions, the progressive-time schedule step size was manipulated so that the instructions became increasingly inaccurate, and deviating from the instructions produced greater earnings.

Reduction of biting and chewing of horses using differential reinforcement of other behavior.

Biting and chewing by horses on crossties can result in injury to the handler and damage to equipment. Operant-conditioning techniques have been used to train horses and could be used to reduce or eliminate undesirable biting and chewing. Presently, a differential-reinforcement-of-other-behavior (DRO) schedule, in the context of a reversal design, was effective in reducing biting and chewing in two horses.