Matching Items (7)
Filtering by
- All Subjects: Rats
- Creators: Sanabria, Federico
Description
The unpleasant bitter taste found in many nutritious vegetables may deter their consumption. While bitterness suppression by prototypical tastants is well-studied in the chemical and pharmacological fields, mechanisms to reduce the bitterness of foods such as vegetables remain to be elucidated. Here tastants representing the taste primaries of salty and sweet were investigated as potential bitterness suppressors of three types of Brassicaceae vegetables. The secondary aim of these studies was to determine whether the bitter masking agents were differentially effective for bitter-sensitive and bitter-insensitive individuals. In all experiments, participants rated vegetables plain and with the addition of tastants. In Experiments 1-3, sucrose and NNS suppressed the bitterness of broccoli, Brussels sprouts, and cauliflower, whereas NaCl did not. Varying concentrations of NaCl and sucrose were introduced in Experiment 4 to assess the dose-dependency of the effects. While sucrose was a robust bitterness suppressor, NaCl suppressed bitterness only for participants who perceived the plain Brussels sprouts as highly bitter. Experiment 5, through the implementation of a rigorous control condition, determined that some but not all of this effect can be accounted for by regression to the mean. Individual variability in taste perception as determined by sampling of aqueous bitter, salty, and sweet solutions did not influence the degree of suppression by NaCl or sucrose. Consumption of vegetables is deterred by their bitter taste. Utilizing tastants to mask bitterness, a technique that preserves endogenous nutrients, can circumvent this issue. Sucrose is a robust bitter suppressor whereas the efficacy of NaCl is dependent upon bitterness perception of the plain vegetables.
ContributorsWilkie, Lynn Melissa (Author) / Capaldi Phillips, Elizabeth D (Thesis advisor) / Cohen, Adam (Committee member) / Johnston, Carol (Committee member) / Sanabria, Federico (Committee member) / Arizona State University (Publisher)
Created2014
Description
Smoking remains the leading cause of preventable death in the United States, and early initiation is associated with greater difficulty quitting. Among adolescent smokers, those with attention-deficit hyperactivity disorder (ADHD), characterized by difficulties associated with impulsivity, hyperactivity, and inattention, smoke at nearly twice the rate of their peers. Although cigarette smoking is highly addictive, nicotine is a relatively weak primary reinforcer, spurring research on other potential targets that may maintain smoking, including the potential benefits of nicotine on attention, inhibition, and reinforcer efficacy. The present study employs the most prevalent rodent model of ADHD, the spontaneously hypertensive rat (SHR) and its control comparison Wistar Kyoto (WKY) to examine the effects of acute and chronic subcutaneous nicotine injections on performance in three operant response inhibition paradigms. Functional activation in select regions of the prefrontal cortex and striatum was also explored. Acute (0.1, 0.3, 0.6 mg/kg) and chronic (0.3 mg/kg) nicotine increased impulsive responding regardless of strain, dose, or operant schedule. Dose-dependent decreases in latency to initiate the task were also observed. SHR receiving daily nicotine injections showed less activation in the nucleus accumbens shell compared to saline controls. Despite close similarities, one of the three operant tasks did not detect response inhibition deficits in SHR relative to WKY. A closer examination of these tasks may highlight critical components involved in the amelioration of response inhibition deficits.
ContributorsMazur, Gabriel Joseph (Author) / Sanabria, Federico (Thesis advisor) / Killeen, Peter R (Committee member) / Neisewander, Janet L (Committee member) / Wynne, Clive DL (Committee member) / Arizona State University (Publisher)
Created2014
Description
The failure to withhold inappropriate behavior is a central component of most impulse control disorders, including Attention Deficit Hyperactivity Disorder (ADHD). The present study examined the effects of housing environment and methylphenidate (a drug often prescribed for ADHD) on the performance of rats in two response inhibition tasks: differential reinforcement of low rate (DRL) and fixed minimum interval (FMI). Both tasks required rats to wait a fixed amount of time (6 s) before emitting a reinforced response. The capacity to withhold the target response (volitional inhibition) and timing precision were estimated on the basis of performance in each of the tasks. Paradoxically, rats housed in a mildly enriched environment that included a conspecific displayed less volitional inhibition in both tasks compared to rats housed in an isolated environment. Enriched housing, however, increased timing precision. Acute administration of methylphenidate partially reversed the effects of enriched housing. Implications of these results in the assessment and treatment of ADHD-related impulsivity are discussed.
ContributorsHill, Jade C (Author) / Sanabria, Federico (Thesis advisor) / Killeen, Peter (Committee member) / Neisewander, Janet (Committee member) / Arizona State University (Publisher)
Created2011
Description
Nicotine is thought to underlie the reinforcing and dependence-producing effects of tobacco-containing products. Nicotine supports self-administration in rodents, although measures of its reinforcing effects are often confounded by procedures that are used to facilitate acquisition, such as food restriction, prior reinforcement training, or response-contingent co-delivery of a naturally reinforcing light. This study examined whether rats acquire nicotine self-administration in the absence of these facilitators. A new mathematical modeling procedure was used to define the criterion for acquisition and to determine dose-dependent differences in rate and asymptote levels of intake. Rats were trained across 20 daily 2-h sessions occurring 6 days/week in chambers equipped with active and inactive levers. Each active lever press resulted in nicotine reinforcement (0, 0.015, 0.03, 0.06 mg/kg, IV) and retraction of both levers for a 20-s time out, whereas inactive lever presses had no consequences. Acquisition was defined by the best fit of a logistic function (i.e., S-shaped) versus a constant function (i.e., flat line) for reinforcers obtained across sessions using a corrected Akaike information criterion (AICc) as a model selection tool. The results showed an inverted-U shaped function for dose in relation to the percentage of animals that acquired nicotine self-administration, with 46% acquiring at 0.015 mg/kg, 73% at 0.03 mg/kg, and 58% at 0.06 mg/kg. All saline rats failed to acquire as expected. For rats that acquired nicotine self-administration, multiple model comparisons demonstrated that the asymptote (highest number of reinforcers/session) and half learning point (h; session during which half the assymptote had been achieved) were justified as free parameters of the reinforcers/session function, indicating that these parameters vary with nicotine dose. Asymptote exhibited an inverted U-shaped function across doses and half learning point exhibited a negative relationship to dose (i.e., the higher the dose the fewer sessions to reach h). These findings suggest that some rats acquire nicotine self-administration without using procedures that confound measures of acquisition rate. Furthermore, the modeling approach provides a new way of defining acquisition of drug self-administration that takes advantage of using all data generated from individual subjects and is less arbitrary than some criteria that are currently used.
ContributorsCole, Natalie (Author) / Neisewander, Janet L (Thesis advisor) / Sanabria, Federico (Thesis advisor) / Bimonte-Nelson, Heather A. (Committee member) / Olive, Michael F (Committee member) / Arizona State University (Publisher)
Created2011
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
Many behaviors are organized into bouts – brief periods of responding punctuated by pauses. This dissertation examines the operant bouts of the lever pressing rat. Chapter 1 provides a brief history of operant response bout analyses. Chapters 2, 3, 5, and 6 develop new probabilistic models to identify changes in response bout parameters. The parameters of those models are demonstrated to be uniquely sensitive to different experimental manipulations, such as food deprivation (Chapters 2 and 4), response requirements (Chapters 2, 4, and 5), and reinforcer availability (Chapters 2 and 3). Chapter 6 reveals the response bout parameters that underlie the operant hyperactivity of a common rodent model of attention deficit hyperactivity disorder (ADHD), the spontaneously hypertensive rat (SHR). Chapter 6 then ameliorates the SHR’s operant hyperactivity using training procedures developed from findings in Chapters 2 and 4. Collectively, this dissertation provides new tools for the assessment of response bouts and demonstrates their utility for discerning differences between experimental preparations and animal strains that may be otherwise indistinguishable with more primitive methods.
ContributorsBrackney, Ryan J (Author) / Sanabria, Federico (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Neisewander, Janet (Committee member) / Killeen, Peter (Committee member) / Arizona State University (Publisher)
Created2015
Description
Incentive salience is a motivational-cognitive process that can transform an otherwise neutral stimulus into something that is wanted. The prolonged use of nicotine appears to enhance incentive salience; it has been suggested that the nicotinic enhancement of incentive salience contributes to the potential of relapse in individuals with tobacco addiction. In order to determine whether (a) nicotinic enhancement of incentive salience for non-nicotinic stimuli occurs when rats self-administer nicotine and (b) a history of nicotine use facilitates such enhancement, rats were trained in a morning self-administration paradigm (SA), in combination with an afternoon 4-CS Pavlovian conditioned approach task (PCA) for 24 days. SA was followed by extinction and cue reinstatement. Nicotine SA enhanced incentive salience in the PCA. Upon extinction, incentive salience quickly declined to saline levels, indicating that the nicotinic enhancement of incentive salience is transient. Experimenter-administered nicotine enhanced incentive salience similarly regardless of nicotine history, suggesting that a previous history of nicotine use does sensitize the nicotinic enhancement of incentive salience. Taken together, these results suggest that nicotine must be onboard for the expression of nicotinic enhancement of incentive salience. This suggests that the role of incentive salience in the development and relapse of tobacco addiction may need to be revisited.
ContributorsOverby, Paula F. (Author) / Sanabria, Federico (Thesis director) / Gipson-Reichardt, Cassandra (Committee member) / Beckmann, Joshua (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05