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- Genre: Academic theses
Description
Theories of interval timing have largely focused on accounting for the aggregate properties of behavior engendered by periodic reinforcement, such as sigmoidal psychophysical functions and their scalar property. Many theories of timing also stipulate that timing and motivation are inseparable processes. Such a claim is challenged by fluctuations in and out of states of schedule control, making it unclear whether motivation directly affects states related to timing. The present paper seeks to advance our understanding of timing performance by analyzing and comparing the distribution of latencies and inter-response times (IRTs) of rats in two fixed-interval (FI) schedules of food reinforcement (FI 30-s and FI 90-s), and in two levels of food deprivation. Computational modeling revealed that each component was well described by mixture probability distributions embodying two-state Markov chains. Analysis of these models revealed that only a subset of latencies are sensitive to the periodicity of reinforcement, and pre-feeding only reduces the size of this subset. The distribution of IRTs suggests that behavior in FI schedules is organized in bouts that lengthen and ramp up in frequency with proximity to reinforcement. Pre-feeding slowed down the lengthening of bouts and increased the time between bouts. When concatenated, these models adequately reproduced sigmoidal FI response functions. These findings suggest that behavior in FI fluctuates in and out of schedule control; an account of such fluctuation suggests that timing and motivation are dissociable components of FI performance. These mixture-distribution models also provide novel insights on the motivational, associative, and timing processes expressed in FI performance, which need to be accounted for by causal theories of interval timing.
ContributorsDaniels, Carter W (Author) / Sanabria, Federico (Thesis advisor) / Brewer, Gene (Committee member) / Wynne, Clive (Committee member) / Arizona State University (Publisher)
Created2015
Description
Temporal bisection is a common procedure for the study of interval timing in humans and non-human animals, in which participants are trained to discriminate between a “short” and a “long” interval of time. Following stable and accurate discrimination, unreinforced probe intervals between the two values are tested. In temporal bisection studies, intermediate non-reinforced probe intervals are typically arithmetically- or geometrically- spaced, yielding point of subjective equality at the arithmetic and geometric mean of the trained anchor intervals. Brown et al. (2005) suggest that judgement of the length of an interval, even when not reinforced, is influenced by its subjective length in comparison to that of other intervals. This hypothesis predicts that skewing the distribution of probe intervals shifts the psychophysical function relating interval length to the probability of reporting that interval as “long.” Data from the present temporal bisection study, using rats, suggest that there may be a within-session shift in temporal bisection responding which accounts for observed shifts in the psychophysical functions, and that this may also influence how rats categorize ambiguous intervals.
ContributorsGupta, Tanya A. (Author) / Sanabria, Federico (Thesis advisor) / Wynne, Clive (Committee member) / McBeath, Michael (Committee member) / Arizona State University (Publisher)
Created2019
Description
The present series of studies examined whether a novel implementation of an
intermittent restraint (IR) chronic stress paradigm could be used to investigate hippocampal-dependent spatial ability in both sexes. In experiments 1 and 2, Sprague- Dawley male rats were used to identify the optimal IR parameters to assess spatial ability. For IR, rats were restrained for 2 or 6hrs/day (IR2, IR6, respectively) for five days and then given two days off, a process that was repeated for three weeks and compared to rats restrained for 6hrs/d for each day (DR6) and non-stressed controls (CON). Spatial memory was tested on the radial arm water maze (RAWM), object placement (OP), novel object recognition (NOR) and Y-maze. The results for the first two experiments revealed that IR6, but not IR2, was effective in impairing spatial memory in male rats and that task order impacted performance. In experiment 3, an extended IR paradigm for six weeks was implemented before spatial memory testing commenced in male and female rats (IR- M, IR-F). Unexpectedly, an extended IR paradigm failed to impair spatial memory in either males or females, suggesting that when extended, the IR paradigm may have become predictable. In experiment 4, an unpredictable IR (UIR) paradigm was implemented, in which restraint duration (30 or 60-min) combined with orbital shaking, time of day, and the days off from UIR were varied. UIR impaired spatial memory in males, but not females. Together with other reports, these findings support the interpretation that chronic stress negatively impairs hippocampal-dependent function in males, but not females, and that females appear to be resilient to spatial memory deficits in the face of chronic stress.
intermittent restraint (IR) chronic stress paradigm could be used to investigate hippocampal-dependent spatial ability in both sexes. In experiments 1 and 2, Sprague- Dawley male rats were used to identify the optimal IR parameters to assess spatial ability. For IR, rats were restrained for 2 or 6hrs/day (IR2, IR6, respectively) for five days and then given two days off, a process that was repeated for three weeks and compared to rats restrained for 6hrs/d for each day (DR6) and non-stressed controls (CON). Spatial memory was tested on the radial arm water maze (RAWM), object placement (OP), novel object recognition (NOR) and Y-maze. The results for the first two experiments revealed that IR6, but not IR2, was effective in impairing spatial memory in male rats and that task order impacted performance. In experiment 3, an extended IR paradigm for six weeks was implemented before spatial memory testing commenced in male and female rats (IR- M, IR-F). Unexpectedly, an extended IR paradigm failed to impair spatial memory in either males or females, suggesting that when extended, the IR paradigm may have become predictable. In experiment 4, an unpredictable IR (UIR) paradigm was implemented, in which restraint duration (30 or 60-min) combined with orbital shaking, time of day, and the days off from UIR were varied. UIR impaired spatial memory in males, but not females. Together with other reports, these findings support the interpretation that chronic stress negatively impairs hippocampal-dependent function in males, but not females, and that females appear to be resilient to spatial memory deficits in the face of chronic stress.
ContributorsPeay, Dylan (Author) / Conrad, Cheryl D. (Thesis advisor) / Bimonte-Nelson, Heather A. (Committee member) / Wynne, Clive (Committee member) / Arizona State University (Publisher)
Created2019
Description
Opioid use rates and related deaths continue to be a public health crisis; while there are many contributing factors to opioid use disorders, criteria for diagnosis include problems related to social functioning. Previous research indicates that laboratory rats, which are frequently used as animal models of addiction-related behaviors, are capable of prosocial behavior. The following collection of studies were performed to determine the effects of heroin on prosocial behavior in rats, as well as the role of the insula in both self-administration of heroin and prosocial behaviors. All of the experiments were conducted utilizing an established model of prosocial behavior in rats in which a performing rat releases a cagemate from a restrainer. The occurrence of and latency to free the confined rat was recorded. After baseline rescuing behavior was established, rats were allowed to self-administer heroin (0.06 mg/kg/infusion i.v.), and subsequent experimental conditions were imposed.
Experimental conditions, in a series of different studies, included comparing heroin reinforcers with sucrose, chemogenetically modulating the insular cortex (both stimulatory and inhibitory processes) and administering excitotoxic lesions in the insula. There were significant differences in saving behaviors between heroin and sucrose groups demonstrating an opioid induced loss of prosocial behavior. Modulating the insula chemogenetically resulted in some restoration of these opioid related deficits, and insular lesions did not significantly impact prosocial behaviors, however, there were significant differences between rates of heroin intake in lesioned animals versus non-lesioned controls. Taken together, these results demonstrate the deleterious effects of heroin on prosocial behaviors and offer further support for the role of the insula in both addiction and social constructs.
Experimental conditions, in a series of different studies, included comparing heroin reinforcers with sucrose, chemogenetically modulating the insular cortex (both stimulatory and inhibitory processes) and administering excitotoxic lesions in the insula. There were significant differences in saving behaviors between heroin and sucrose groups demonstrating an opioid induced loss of prosocial behavior. Modulating the insula chemogenetically resulted in some restoration of these opioid related deficits, and insular lesions did not significantly impact prosocial behaviors, however, there were significant differences between rates of heroin intake in lesioned animals versus non-lesioned controls. Taken together, these results demonstrate the deleterious effects of heroin on prosocial behaviors and offer further support for the role of the insula in both addiction and social constructs.
ContributorsTomek, Seven Eli (Author) / Olive, Michael F (Thesis advisor) / Neisewander, Janet (Committee member) / Wynne, Clive (Committee member) / Comer, Sandra (Committee member) / Arizona State University (Publisher)
Created2020
Description
A handheld metal noisemaker known as a “clicker” is widely used to train new behaviors in dogs; however, evidence for the superior efficacy of clickers as opposed to providing solely primary reinforcement or other secondary reinforcers in the acquisition of novel behavior in dogs is almost entirely anecdotal. Three experiments were conducted to determine under what circumstances a clicker may result in acquisition of a novel behavior more rapidly or to a higher level compared to other readily available reinforcement methods. In Experiment 1, three groups of 30 dogs each were trained to emit a novel sit and stay behavior of increasing duration with either the delivery of food alone, a verbal stimulus paired with food, or a clicker with food. The group that received only a primary reinforcer reached a significantly higher criterion of training success than the group trained with a verbal secondary reinforcer. Performance of the group experiencing a clicker secondary reinforcer was intermediate between the other two groups, but not significantly different from either. In Experiment 2, three different groups of 25 dogs each were shaped to emit a nose targeting behavior and then perform that behavior at increasing distances from the experimenter using the same three methods of positive reinforcement as in Experiment 1. No statistically significant differences between the groups were found. In Experiment 3, three groups of 30 dogs each were shaped to emit a nose-targeting behavior upon an array of wooden blocks with task difficulty increasing throughout testing using the same three methods of positive reinforcement as previously. No statistically significant differences between the groups were found. Overall, the findings suggest that both clickers and other forms of positive reinforcement can be used successfully in training a dog to perform a novel behavior, but that no positive reinforcement method has significantly greater efficacy than any other.
ContributorsGilchrist, Rachel (Author) / Wynne, Clive (Thesis advisor) / Hahs, Adam (Committee member) / Anderson, Samantha (Committee member) / Arizona State University (Publisher)
Created2020