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Item Exploring associations between proactive and reactive control(Montana State University - Bozeman, College of Letters & Science, 2016) Begnoche, John Patrick; Chairperson, Graduate Committee: Rebecca BrookerCognitive control is the act of regulating, coordinating, and sequencing mental processes in accordance with internally maintained behavioral goals (Braver, 2012; Norman & Shallice, 1986). The Dual Mechanisms of Control (DMC) theory argues that variations in cognitive control are driven by two distinct operating modes, proactive control and reactive control (Braver et al., 2007). Proactive control is defined as an anticipatory and effortful attentional strategy that actively sustains task-relevant information before the occurrence of a cognitively demanding event (Miller & Cohen, 2001). In contrast, reactive control is an automatic process that is passively maintained and relies upon high-conflict, or trigger, events to reactivate task-relevant information after the occurrence of a cognitively demanding event (Jacoby, Kelley, & McElree, 1999). Traditional models of cognitive control focus on reactive control initiating proactive control (Botvinick, Nystrom, Fissell, Carter, & Cohen, 1999). Yet, recent research suggests the possibility of shifting to a predominantly proactive strategy with less reliance on reactive processing (Braver, Paxton, Locke, & Barch, 2009; Schmid, Kleiman, Amodio, 2015). However, little work has analyzed a direct relation between continuously sustained proactive control and reduced input from reactive control. In addition, affective variables might impact the ability to shift between proactive and reactive modes of control (Braver, Gray, & Burgess, 2007). Individuals high in trait levels of worry exhibit heightened reactive control and reduced proactive control compared to controls (Moser, Moran, Schroder, Donnellan, & Yeung, 2013). In the current study, participants performed a cognitively-demanding task while neural correlates of proactive and reactive control were measured. Self-reported levels of trait worry were also collected. In agreement with a proactive model of cognitive control, the results of this experiment indicated that greater levels of sustained proactive control predicted decreased reactive processing. However, this relation was moderated by trait-worry such that enhanced proactive control only predicted decreased reactive control when levels of trait worry were low.Item Inducing proactive control using a Stroop cueing paradigm(Montana State University - Bozeman, College of Letters & Science, 2014) Olsen, Mariana Rachel; Chairperson, Graduate Committee: Keith A. HutchisonCognitive control refers to the relative ability to attend to relevant stimuli while ignoring irrelevant stimuli in service of a goal. Braver, Gray, and Burgess (2007) have proposed two complementary forms of control: proactive, which is preparatory in nature, and reactive, which is engaged after a stimulus or imperative event. The ability to use proactive control is often tested using the Stroop task; however, what is usually thought of as evidence for proactive control can be confounded with item-specific effects, sequential effects, and speed-accuracy trade-offs. To remedy this issue, the current study utilized a modified version of the Stroop task to examine the use of proactive control on a trial-by-trial basis. Two experiments tested participants' ability to flexibly engage proactive control in which participants were given 80% predictive EASY or HARD cues indicating whether an upcoming stimulus would be congruent or incongruent, respectively. I hypothesized that participants, especially those high in working memory capacity, would use the HARD cues to engage top-down control to suppress word-reading, leading to a) reduced Stroop interference following HARD cues, b) impaired recall and recognition for neutral words following HARD cues, and c) greater pupil dilation following HARD than EASY cues. In Experiment 1, participants showed reduced Stroop interference for stimuli following HARD relative to EASY cues. This effect was replicated in Experiment 2, with reduced Stroop interference in both reaction times and errors following HARD cues. However, neither recall or pupil dilation differed reliably as a function of cue or WMC. Together, these experiments demonstrate the utility of using a cueing procedure when examining proactive control in the Stroop task. Limitations and future directions in cueing research are discussed.Item Expectancy generation and utilization(Montana State University - Bozeman, College of Letters & Science, 2007) Shipstead, Zachary Martin; Chairperson, Graduate Committee: Keith A. HutchisonAlthough the research of Balota, Black and Cheney (1992) has shown attentional deficits in older adults to be detrimental to performance in semantic priming tasks which require a shift of attention away from a presented category, no attempt has been made to link performance to measures of attentional control. The current study utilizes the same paradigm as Balota, Black and Cheney with participants' attentional control measured using the battery of Hutchison (in press). Results show ability not only to generate expectancy for the target category, but to override automatic processes initiated by the prime word is tied to attentional control. Unfortunately, the attempt of Balota, Black and Cheney to estimate expectancy generation when no shift of attention is required may require revision.Item Spacing and lag effects in recognition memory : time versus intervening items(Montana State University - Bozeman, College of Letters & Science, 2007) Shively, Matthew David; Chairperson, Graduate Committee: Richard BlockSpacing and lag effects both refer to abundant findings that memory is enhanced when repeated items are spaced. Several researchers have realized the difficulty of explaining these effects using only one theory, and, therefore posited varying dual-process models. It is also unclear if there is a limit to the increase in memory performance due to increased lag. This study sought to understand how stimulus type influences spacing and lag effects, limits of the lag effect, and the importance of time and items in creating these effects. Experiment 1 found a unique spacing effect and lag effect. Experiment 2 found no spacing effect, yet a lag effect was found. Both time and items are important in generating spacing and lag effects.Item Hippocampal damage and novelty preference in the ischemic gerbil : dissociating object and arrangement memory(Montana State University - Bozeman, College of Letters & Science, 2007) McNeill, Damon Lee; Chairperson, Graduate Committee: A. Michael BabcockThe most insidious consequences of transient ischemia are its effect on the hippocampus and the memory systems it serves. The novelty preference test is a direct measure of memory function and has been used in the rat and primate animal models. The gerbil animal model has been used extensively to study the mechanism of ischemic brain damage; however, the novelty preference paradigm has not been used to study memory impairment in this species. In addition, the novelty preference paradigm has not been tested with models of ischemia. In the present experiment, Mongolian gerbils were tested in two different types of novelty-preference tasks (Object and Arrangement) following either ischemic insult or a sham control surgery.Item Behavioral consequences following AAV mediated hippocampal EAAC1 knockdown(Montana State University - Bozeman, College of Letters & Science, 2007) Coombs, Katie Marie; Chairperson, Graduate Committee: Michael BabcockThe neuronal glutamate transporter EAAC1 (EAAT3) is present in hippocampal neurons to prevent excessive glutamate accumulation. Glutamate receptor-dependent synaptic plasticity is important for learning and memory. The present study investigates behavior associated with blocking the glutamate transporter EAAC1. To manipulate EAAC1 function, rats were intrahippocampally injected with a adeno-associated viral (AAV) vector encoding an EAAC1 antisense mRNA sequence or an AAV empty cassette. Twenty-eight days following surgery, rats were tested in a delayed matching-to-place (DMTP) watermaze task to examine spatial memory, which is hippocampaldependent. Rats treated with EAAC1 antisense exhibited shorter latencies to locate the target platform relative to controls (p < 0.05). These data indicate that microinfusion of AAV encoding EAAC1 antisense significantly altered performance on task involving glutamate transmission and the hippocampus.