Nicotinic acetylcholine receptors (nAChR) are neurotransmitter-gated ion channels that exist as a family of subtypes defined by unique subunit compositions. nAChR containing α6 subunits (α6*-nAChR) have attracted interest because α6 subunits are thought to be localized in brain regions implicated in reward, mood and drug dependence. To provide new information necessary toward a more complete understanding of roles of α6*-nAChR in neuropsychiatric health and disease, three lines of investigation were pursued. A set of stably transfected, human, immortalized cell lines were generated that heterologously express nAChR α6 subunits in combination with other nAChR subunits found in reward brain regions (nAChR subunit combinations α6β2, α6β4, α6β2β3, α6β4β3, α6β2β3α5, α6β4β3α5, α6α4β2β3 and α6α4β4β3). The α6α4β2β3 combination may have a functional response to epibatidine that differs from that of the α4β2 nAChR. A unique binding site was identified in cells transfected with the α6β4β3α5 nAChR subunit combination. Messenger RNA fluorescence in situ hybridization (mRNA FISH) studies established regional and celluar distribution of nAChR α6 subunit mRNA in the mouse brain. The third line of study extended this work to examine potential co-expression of nAChR α6 subunits and glutamic acid decarboxylase (GAD) or tyrosine hydroxylase (TH) as labels of GABAergic and dopaminergic/catecholaminergic neurons respectively, using tandem mRNA FISH and fluorescence immunohistochemistry. nAChR α6 subunit signal in the substantia nigra (SN) and ventral tegmental area (VTA) was congruent with previous studies. Message was also detected in the amydala, dentate gyrus, striatum, zona incerta, and cingulate, entorhinal, perirhinal, piriform, and prelimbic cortices. nAChR α6 mRNA was coexpressed with GAD in the amygdala, dentate gyrus, striatum, SN, VTA and cingulate, entorhinal, prelimbic and prelimbic cortices. TH was exclusively co-localized with nAChR α6 mRNA in the SN and VTA. Findings suggest extended roles for α6*-nAChR in the brain, particularly in the control of GABAergic neuronal activity and/or GABA release. These studies provide new insights into the composition of α6*-nAChR, the localization and cellular origins of nAChR α6 subunit expression. Data collected suggest roles for α6*-nAChR in many brain regions, including those involved in higher order processes involved in drug dependence and reward, and in modulation of inhibitory neurotransmission.

No description available.

Tailgating (maintaining an inadequate headway) is a major road safety concern that emerges because drivers tend to misperceive their following distance. Drivers seldom receive enough feedback to correct this error, leaving them vulnerable to rear-end collisions. While there have been attempts to address this issue through vehicle automation and warning systems, these approaches have not been sensitive to the needs of young drivers. The present investigation sought to implement a headway evaluation system: an in-vehicle display designed to provide motorists with real-time as well as aggregate headway feedback. This system was designed to teach drivers to recognize safe headways and to motivate adherence. Compared to drivers selecting their own headway or those attempting to count a two second headway, drivers using the headway evaluation system maintained longer headways that would be conducive to collision avoidance. This system may be beneficial as a training device for new drivers. / AUTO21, the Ontario Innovation Trust, the Canada Foundation for Innovation, and the Natural Sciences and Engineering Research Council of Canada

Food restriction has been shown to affect responding for reward and has been manipulated to devalue reward. Reward density has been shown to alter responding in both first-order schedules and chain schedules. Devaluation has differential effects in first-order schedules and the links of chain schedules. The objective of the current study was to analyze the reward devaluation effect in a two-link chain schedule by manipulating food restriction and reward density in the proximal link; these variables had previously not been studied systematically. The chain schedule required rats to lever press according to a random interval 120-s schedule to turn on a light conditioned stimulus (CS). In the presence of the CS rats were rewarded for pulling a chain; the chain was active on a variable ratio (VR) 5 schedule of reinforcement for some rats, while the chain was on continuous reinforcement (CRF) for the other rats. Food restriction protocols were either 1-hr daily free feeding (1-hr feeding) or a daily ration to maintain weight at 80% of free feed controls (ration). Devaluing the CS while in the isolated proximal link was done by exposing trained rats to sessions of chain pulling in the presence of the CS but withholding reward. In subsequent lever press sessions without the CS, decreased responding was seen in rats that had undergone the devaluation procedure, but only in rats on the 1-hr feeding protocol. This devaluation effect was found in both the CRF and VR 5 schedules. Subsequent tests of lever pressing for the CS also revealed decreased responding. Post-test CS discrimination sessions demonstrated CS devaluation that has not been demonstrated previously. These results demonstrate that the isolated devaluation of the proximal link in a heterogeneous two-link chain schedule can result in decreased responding in the isolated first link. This effect is dependent on sufficient food restriction and demonstrates a measurable devaluation effect which is independent of the reward being present. This study also demonstrated that isolated devaluation of the second link can be subsequently measured in a post-test CS discrimination re-acquisition session regardless of food restriction, which had no significant effect in the session. The devaluation effect has not been demonstrated in a re-acquisition session before, rather responding in previous re-acquisition sessions were only affected by food restriction. / Thesis (Master, Psychology) -- Queen's University, 2007-09-11 11:49:20.814

Behavioural choices of animals as they acquire resources in the wild are well characterized by foraging theory; however, the neural mechanisms underlying these behaviours are not well understood. The goal of this thesis is to understand the brain mechanisms involved in selecting and executing such foraging behaviours. To do so, rhesus monkeys performed a novel visuosaccadic foraging task while we recorded the activity of single neurons in the intermediate layers of the superior colliculus (SCi). An important innovation of this task is that both target profitability – the measure of value in the simplest case of foraging theory – and saccade choice are measured separately. We hypothesized that target profitability is represented in the SCi in addition to its well characterized role in saccade planning and preparation. Visual Foraging Task: Monkeys harvested coloured dots representing prey items by fixating them for a pre-specified handling time. On each trial, multiple prey are presented, sharing identical physical attributes except that each was one of three colours. All prey of the same colour shared the same profitability [Profitability = reward magnitude (ml)/handling time (s)]. According to foraging theory, intake of reward is maximized if prey are selected in descending order of their profitability. Indeed, we found subjects gradually approached optimal efficiency. We computed an index of the relative subjective profitability of each prey colour, which compared the rank order with which monkeys chose prey of each colour. This subjective index of profitability was then compared to concomitant SC activity attributed to the prey item in the neuron’s response field (RF). First, we found that the amount of SC activity reflected the subjective profitability of the RF targets, and established that this effect was not simply a result of saccade goal planning. Second, profitability information remains dominant throughout the handling period until reward delivery, after which activity also became selective for upcoming saccades. Together, our results highlight the prominent role of target profitability in shaping SCi activity. We propose that profitability information in the SCi may play an important role in resolving competition between numerous target representations to choose the next saccade goal. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2011-02-21 15:37:43.468

No description available.

The pedunculopontine tegmental nucleus (PPTg) has been proposed to be critical in drug and food reward. It is a major source of cholinergic inputs to the substantia nigra and ventral tegmental area, areas important in reward, and is believed to modulate activity of dopamine neurons through a cholinergic mechanism. The firing rate of cholinergic PPTg cells is regulated by muscarinic autoreceptors that can be blocked to increase cell firing. If the PPTg modulates dopamine neurons involved in reward, then a muscarinic antagonist microinjected into the PPTg should be rewarding. To test this hypothesis, bilateral microinjections of scopolamine methyl bromide (5 $ mu$g or 20 $ mu$g) or 0.9% saline were used as reward treatments in the conditioned place preference test. On the test day, rats from both doses of drug avoided the drug-paired chamber, which suggests that cholinergic PPTg cells are not involved in reward.

Syftet med studien var att undersöka vilka stressreducerade ledarskapsbeteenden som chefer använder sig av gentemot sina medarbetare. Studien har en deduktiv ansats där två etablerade balansteorier; Karasek och Theorells (1990) krav och kontrollmodell samt Siegrits (1996) ansträngning och belöningsmodell, användes för att studera empirin. Ett målinriktat urval gjordes (n = 10) och av dessa var fem stycken kvinnor och fem stycken män. Semi-strukturerade intervjuer genomfördes med chefer på samma eller liknande position i en organisation. Det empiriska materialet analyserades genom en tematisk modell. Resultatet visade att cheferna använder sig av olika dimensioner av balansteorierna. Samtliga chefer använde sig av socialt stöd i olika former och majoriteten av cheferna gav medarbetarna kontroll över sin arbetssituation för att reducera stress. Ett fåtal av cheferna försökte få medarbetarna att uppleva yrkesstatus som belöning och slutligen lyfte cheferna fram vikten av att skapa en balans mellan arbetslivet och privatlivet för att främja medarbetarnas hälsa.

The study of feeding behavior, and in particular the study of subjective hedonic experience and objective measures of motivation, are central to understanding how appetite regulation can be compromised in certain individuals. Furthermore, with an integrated picture of physiological and behavioral changes that can occur as a result of energy deprivation what emerges is a better understanding of how palatable food can disrupt attempts at regulating body weight at lower levels of body energy stores. In Article I, the genetic association study examining a potential role for a dopamine-related polymorphism in weight loss, it was shown that contrary to the main hypothesis there was no association between TaqIA polymorphism and the amount of body weight loss. In Article II, it was shown that palatability and olfaction ratings increased as a result of a 24 hour fast and females demonstrated larger improvements in overall olfactory performance. Initial body weight was positively related to improved odor detection threshold and total odour score (TDI). Using the same population sample as Article II, Article III highlights that higher sensitivity to reward and disinhibition scores correlated with responding for palatable snack food stimuli in the relative-reinforcing value of food (RRV) task, further indicating that RRV has strong ties with impulsivity. There was a demonstrable lack of negative alliesthesia under the fasted condition where, after a 75% increase in ad libitum energy intake (EI) relative to the fed condition, this greater amount of food consumed was still rated as being more palatable than the lesser amounts consumed under the fed condition. In Article IV it was shown that an equicaloric (-25%) energy deficit by diet alone was a greater challenge to appetite regulation and resulted in greater compensatory increases in EI than deprivation by exercise alone. Independent of deprivation modality there were significant improvements in odour threshold scores. TDI score increased only under diet alone; furthermore, the noted increase in mean TDI score was positively related to increased ad libitum EI. The picture that emerges is that, acutely, a complete fast has more pronounced effects on appetite and ad libitum EI than dieting alone, which in turn had greater effects than exercise alone or controls. Also, TDI improved under all three methods of energy deprivation, but moreso under conditions of deprivation by diet alone.

<p>Few aspects of human cognition are more personal than the choices we make. Our decisions &mdash; from the mundane to the impossibly complex &mdash; continually shape the courses of our lives. In recent years, researchers have applied the tools of neuroscience to understand the mechanisms that underlie decision making, as part of the new discipline of decision neuroscience. A primary goal of this emerging field has been to identify the processes that underlie specific decision variables, including the value of rewards, the uncertainty associated with particular outcomes, and the consequences of social interactions. Here, across three independent studies, I focus on the neural circuitry supporting social valuation &mdash; which shapes our social interactions and interpersonal choices. In the first study (Chapter 2), I demonstrate that social valuation relies on the posterior ventromedial prefrontal cortex (pVMPFC). Extending these findings, I next show that idiosyncratic responses within pVMPFC predict individual differences in complex social decision scenarios (Chapter 3). In addition, I also demonstrate that decisions involving other people (e.g., donations to a charitable organization) produce increased activation in brain regions associated with social cognition, particularly the temporal-parietal junction (TPJ). Finally, in my last study (Chapter 4), I employ functional connectivity analyses and show that social cognition regions &mdash; including the TPJ &mdash; exhibit increased connectivity with pVMPFC during social valuation, an effect that depends upon individual differences in preferences for social stimuli. Collectively, these results demonstrate that the computation of social value relies on distributed neural circuitry, including both value regions and social cognition regions. Future research on social valuation and interpersonal choice must build upon this emerging theme by linking neural circuits and behavior.</p> / Dissertation