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The primary goal of the proposed research is to identify how stress is internalized to affect cognitive functioning and increase the risk for Major Depressive Disorder (MDD). Dysfunctional stress reactivity has been proposed to be a risk factor for ongoing affective distress, yet mechanisms underlying this process remain unexplained. The medial prefrontal cortex (mPFC) has been implicated in the etiology of MDD, in the reactivity to stress, as well as in the adaptation of behavior to reinforcement. The combined activities of this particular neural system identify it as a focal node by which stress may be internalized to affect cognitive, emotional, and behavioral functioning. The experiments detailed here examined electroencephalographic (EEG) features that reflect cognitive control functions in the mPFC. Participants underwent EEG assessment as they completed a reinforcement (reward and punishment) learning task sensitive to mPFC-basal ganglia functioning, both with and without a laboratory stress manipulation. This experiment assessed how stress reactivity altered neural systems of reinforcement, and it contrasted these same factors with currently depressed individuals. In this series of investigations, we have identified a measure of how, and a possible mechanism by which, punishment information is internalized in stress reactivity and in the expression of MDD: error and punishment signals are increasingly coupled with the salience of "bad" outcomes. Stress-related alteration of reward and punishment learning systems - particularly in the mPFC - is a viable candidate for how dysfunctional stress reactive responses are translated into ongoing cognitive and affective distress in depression.

This research examines the summation characteristics of the neural network subserving self-stimulation reward. The data show that the neural network has two integrators that sum the signals produced by brain stimulation. The time constant of the first integrator is approximately 450 msec, whereas that of the second integrator is approximately 6.5 sec. Furthermore, these integrators are sensitive to the spatiotemporal arrival of the signals. / When prolonged stimulation is delivered at a high pulse frequency, the initial pulses contribute the most to the rewarding effect. Later pulses are affected by the reduced ability of the neurons or synapses to transmit signals along the neural network due to fatigue. / A fatigue effect may be dissipated by splitting a pulse train into two parts by an interval of no stimulation. This should increase the rewarding effectiveness of the pulse train. However, the rewarding effectiveness is dependent upon the duration of the interval of no stimulation and the magnitude of the two pulse-train halves. A long interval of no stimulation combined with a low stimulation magnitude may cause a frustration response and a decay in memory of the associations between the response, first pulse-train half, and second pulse-train half. These would make the rewarding effectiveness of the two pulse-train halves lower than that of a continuous pulse train. / Previous models of summation are unable to predict the present results. The data are explained in terms of a newly developed model of summation involving two central integrators and fatigue.

Despite growing recognition that impulsivity is associated with pathological gambling (PG), three methodological concerns continue to prevent a meaningful examination of how impulsivity is specifically associated with PG. First, the lack of studies specifically comparing PGs to less severe gamblers leaves the question of whether impulsivity was not also associated with less severe gamblers unexamined. Second, the inadequate control of confounding variables in most studies raises concerns about whether findings that impulsivity is associated with PG may be spurious. Third, many findings that impulsivity is associated with PG are based on unrelated definitions of impulsivity, and are therefore relatively uninformative. / The present series of studies is the first attempt to address all of these concerns at the same time. In terms of appropriate comparison groups, study 1 compared PGs to at-risk gamblers and social gamblers, and study 2 compared severe PGs to moderately severe PGs and social gamblers. In terms of adequate controls, both studies examined PGs who were not in treatment and representative in terms of comorbid drug use. In addition, both studies controlled for age, gender, education, socioeconomic status, psychiatric comorbidity, and general cognitive function. Study 2 furthermore controlled for depression, trait anxiety, aggression, and criminality. In terms of improving how impulsivity is examined, study 1 elaborated a neuroanatomically-based definition of impulsivity and examined how three hypothesized neuroanatomical components of impulsivity were associated with PG. In study 2, different operationalizations of impulsivity, based on the same definition of impulsivity, were examined regarding their association with PG. / Every measure that was directly related to the present definition of impulsivity was significantly associated with severe PGs, and only severe PGs, suggesting that severe PGs may comprise a distinct group of gamblers. Measures which were not directly related to this definition of impulsivity were not significantly different between severe PGs (or PGs in study 1) and less severe gamblers. Severe PGs performed as well or better than social gamblers on retention capacity and attention control measures of working memory. / In conclusion, the inability to inhibit inappropriate reward-seeking is argued to be a primary deficit of severe PGs in our sample.

Increased impulsivity and alterations in reward sensitivity co-occur in many psychiatric disorders. Moreover, individuals reporting more impulsive traits are less efficient in learning stimulus-reward associations. This suggests that impulsivity and reward sensitivity may be linked, consistent with evidence that the orbital frontal cortex (OFC) is implicated in both processes. This study examined the relationship between impulsive traits, assessed by the Barratt Impulsiveness Scale (BIS) and the Eysenck (EIQ), and performance on three behavioral tasks that measure impulsivity and reward sensitivity. The tasks included a Conditioned Pattern Preference (CPP) task, which measures the preference for abstract visual cues as an index of implicit emotional learning, a Probabilistic Reversal Learning (PRL) task that assessed the ability to alter behaviour when reward contingencies change and an Emotional Stroop task which assessed attentional control in response to emotionally salient stimuli. This study provided novel information on the relationship between processes that mediate impulsivity and reward sensitivity. In brief, subjects that were considered to have some explicit knowledge of experimental conditions showed a higher preference formation for the pattern paired with the reward on 90% of the conditioning trials. Although there was no overall effect of impulsivity, the medium impulsive group displayed the strongest preference formation (highest score for the 90% pattern and lowest score for the 10% pattern) compared to the low and high groups. Furthermore, there was an overall effect of Word Category in that participants made more errors for the emotional words (positive and negative) than the neutral words. There was no overall effect of Impulsivity on Stroop performance in this sample. Finally, for the PRL task more participants in the high impulsive group did not meet criterion for the Acquisition stage while more low impulsive subjects did not meet reversal criterion. Furthermore, high impulsive subjects made more overall errors in the Acquisition stage but not Reversal stage. In brief, low and high impulsive subjects performed sub-optimally on the CPP and PRL tasks but not on the Stroop task. This pattern reflects an inverted-U shaped relationship of the effects of impulsivity on associative learning. / Thesis (Master, Psychology) -- Queen's University, 2010-02-05 13:33:27.076

Decisions are based on multiple sources of information. For example, sensory information encoding environmental features may be combined with prior experience to bias judgements in visual behaviour. With the goal of characterizing the rules by which sensory and non-sensory variables combine to direct saccade selection processes monkeys were trained in a visual search task where the discriminability of a visual target and reward outcome for correct foveation varied systematically. Target discriminability was manipulated across three levels of luminance contrast while reward was manipulated by 'tagging' a spatial location such that target foveation at the tagged location yielded one, two or four times the liquid reward available at all other locations. The location and discriminability of the search target amongst seven distractor stimuli varied randomly from trial-to-trial while the magnitude of reward at the tagged location was fixed for each experimental block. Reward was found to have a large effect on search behaviour when target discriminability was low, but as discriminability increased, the effect of reward diminished. More specifically, reward increased choice probability and reduced the latency of saccades to target and distractor stimuli appearing in the tagged location. Together, the results suggested the effects of reward and luminance on saccade selection were dependent on one another. To characterize the nature of this interaction search psychophysics were couched in saccade selection processes using signal detection theory. Signals carrying target and distractor related information were modelled and taken to capture an actual discrimination process implemented by the brain. It was found that a response bias in saccade selection processes could largely reproduce monkey choice behaviour for both correct and incorrect trials. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2010-08-03 22:22:15.825

The present program of research explored the impact of performance-contingent rewards on perceived autonomy and intrinsic motivation. Four studies sought to clarify the debate between behaviorist (Eisenberger and Cameron, 1996; Eisenberger, Pierce, and Cameron, 1999; Eisenberger, Rhoades, and Cameron, 1999) and the social cognitive researchers (Deci & Ryan, 1980, 1985; Deci, Koestner, & Ryan, 1999) regarding the impact of such incentives on perceived autonomy. Two experimental studies (Studies 1 and 2) examined this relationship among college students and elementary school children. Results revealed an undermining effect of performance-contingent rewards on participants' affective experience of autonomy (enhanced feelings of pressure and tension). No significant results were found on intrinsic motivation for college students, whereas for elementary school children, rewards increased enjoyment for the target activity. / Two field-based quasi-experimental studies (Studies 3 and 4) were designed to explore the impact of performance-contingent rewards in an organizational setting. Both studies differentiated between private sector workers, who received a merit-based salary (performance-reward expectancy) and workers from the public sector who received a salary based on seniority (no performance-reward expectancy). Study 3 replicated the previous findings by demonstrating that that performance-reward expectancy undermined workers perceived autonomy. Study 4 extended these results by revealing that the presence of performance contingent reward programs in organizations undermined employees' work satisfaction and relatedness. Such incentives also had a tendency to reduce workers' adjustment to retirement.

Följande studie avser att undersöka relationen mellan engagemang, belöning och välbefinnande på arbetsplatsen. Siegrist (1996) förklarar sambandet genom Effort-Reward Imbalance model (ERI), något som denna studie kombinerar med Dieners (1986) teori om subjektivt välbefinnande. 156 personer deltog i enkätstudien, där 97 var kvinnor. Enkäterna var utformade med påståenden där deltagarna fick skatta sina svar. Datan analyserades genom en multipel regressionsanalys, korrelationer och t-test. I den multipla regressionen framkom det att hög insats/ låg belöning och överengagemang inte var signifikanta prediktorer utav variansen i subjektivt välbefinnande. Genom korrelationer kunde man utläsa att tre hypoteser visade signifikanta resultat, medan en hypotes inte visade något signifikant resultat genom stora t-test i avseende på huruvida kvinnor skattar högre nivå av överengagemang än män. Studien bidrog till en ökad förståelse för obalansen mellan hög insats/ låg belöning och överengagemang och dess betydelse för individens subjektiva välbefinnande.

<p>In comparison to Mark and Luke, Matthew's Gospel contains a striking preponderance of economic imagery, especially in passages dealing with sin, righteousness, and divine recompense. This cluster of economic terms is found in every strand of tradition in Matthew's Gospel, and frequently appears to be the result of Matthean redaction. A good chunk of this language occurs in five uniquely Matthean parables dealing either with the pricelessness of the kingdom or judgment and reward (the hidden treasure in 13:44; the pearl in 13:45-46; the parable of the unforgiving servant in 18:23-35; the parable of the workers in the vineyard 20:1-16; the sheep and the goats in 25:31-46). Matthean additions to the triple tradition also tend to contain economic language. </p><p> In this dissertation I begin by analyzing Matthew's economic language against the backdrop of similar language in other early Jewish and Christian literature. I then go on to examine the import of this language for the narrative as a whole, arguing that some of the Gospel's central claims about Jesus emerge from this conceptual matrix. To be more specific, the narrative provides a coherent description of how Jesus saves his people from their sins and comes to be enthroned as Son of Man. Matthew draws on images of exile and debt-bondage to depict the people Jesus came to save as captives because of the debt of their sins. Jesus is introduced as the one born to save his people from their sins (1:21), and throughout the Gospel he does this by teaching them how to find debt forgiveness and store up treasure in the heavens in order to acquire eternal life. From the time Jesus begins predicting his death and resurrection he also teaches his disciples to follow him in giving their lives and being repaid with resurrection (16:24-28; 19:29), participation in the rule of the Son of Man (19:27-28), and the price of release for others who are in captivity. The passion narrative portrays the very repayment Jesus told the disciples that both he and they would receive: Jesus is raised from the dead, given all authority as Son of Man, and earns the ransom-price for the many. The end of the age remains in the future, and so suffering and doubt persist. Nevertheless, God's repayment of Jesus' self-giving is a foretaste of the coming settling of accounts.</p> / Dissertation