Browsing by Author "Davalos, Deana, advisor"

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Open Access
A multidisciplinary analytical approach to the identification of both modifiable and non-modifiable risk factors of dementia
(Colorado State University. Libraries, 2021) Willoughby, Kathleen Angela, author; Davalos, Deana, advisor; Rojas, Don, committee member; Malinin, Laura, committee member; Cleveland, Jeanette, committee member
In recent decades, dementia has become a growing global epidemic. As people are living longer, the number of individuals diagnosed with dementia has risen exponentially. Alzheimer's disease, the most common form of dementia, presently afflicts more that 5.4 million Americans (Thies et al., 2011). Though great strides have been made in dementia research, there is still much to be done to better pin-point disease risk and ameliorate decline and related symptom progression. This dissertation will focus on the efficacy of early intervention and risk factor identification as a first line of defense in staving off dementia progression. Within the B Sharp community-arts engagement program, we will evaluate domain-specific changes in older adult cognition over an acute and extended-duration timespan. Within the Alzheimer's Disease Neuroimaging Initiative, we will identify relevant risk factors associated with the consistent acceleration of cognitive decline as well as the slowing of such decline. As these proactive treatment approaches are more fully understood, better strategies for healthy aging can be implemented at both a generalized and individual level.
Open Access
Decreasing problematic alcohol use with behavioral strategies: a cognitive model
(Colorado State University. Libraries, 2020) Darwin, Marielle L., author; Davalos, Deana, advisor; Prince, Mark, committee member; Malcolm, Matthew, committee member
Problematic alcohol use is a pattern of hazardous consumption that commonly leads to negative outcomes that affect college students' ability to complete day-to-day responsibilities. Behavioral strategies such as ensuring a safe ride home or avoiding drinking games is linked to a reduction of alcohol-related consequences by providing concrete tactics to enable a change in patterns of consumption. Thus, improving an individual’s ability to utilize these strategies before or during alcohol consumption is targeted in contemporary interventions and preventative approaches. In spite of this practice, much is unknown regarding the underlying cognitive facilities needed to: retain awareness of these strategies, choose approaches in accordance with the situation at hand and update these tactics as needed. If the ability to productively utilize these methods is dependent on cognitive abilities, then individuals with poor cognitive function may be at a disadvantage. The aim of the current study was to investigate the roles of executive cognitive functioning and metacognition as they relate to behavioral strategy usage and adverse alcohol-related outcomes. Results indicate that executive cognitive functioning is inversely related to the number of experienced alcohol-related consequences. Furthermore, low executive function and metacognitive beliefs about alcohol pertaining to the cognitive harm of drinking interacted to significantly affect the use of behavioral strategies, which in turn was inversely related to consequences. The findings of the current study offered a cognitive-based model in support of the practice of employing strategies to decrease alcohol-related consequences, and determined whether implementation of these tactics can successfully take place in those with poor cognitive and metacognitive function.
Open Access
Duration mismatch negativity in high-risk populations for schizophrenia
(Colorado State University. Libraries, 2016) Pantlin, Lara N., author; Davalos, Deana, advisor; Malcolm, Matthew, committee member; Volbrecht, Vicki, committee member
Schizophrenia is a potentially disabling and intractable disorder that is categorized by disturbances in sensory information processing and a psychotic episode. Recent research has targeted clinically high-risk populations and used mismatch negativity (MMN) as an identification tool to provide information regarding the onset of psychosis. Patients with schizophrenia have smaller MMNs compared to controls; thus reduced amplitudes may reflect physiological deficits in temporal perception. The present study evaluated differences in duration MMN (dMMN) amplitudes between healthy and potentially high-risk participants. The hypothesis was that the participants who met the criteria for high-risk according to the 16-item Prodromal Questionnaire (PQ) (score > 6) would have attenuated dMMN amplitudes compared to controls. Participants completed the PQ. Brain activity was recorded using EEG while participants were presented with 2880 samples (120 cycles of 24 samples) of randomized tones that differed in duration (Standard = 500 ms; Deviant 1 = 425 ms; Deviant 2 = 250 ms). Three analyses were applied (Analysis 1: Controls = 0; Analysis 2: Traditional cut-off score Controls < 6; Analysis 3: Simple linear regressions). T-tests at each electrode location did not yield significance for Deviant 1. Deviant 2 demonstrated significant trends in Analysis 2 (Fz: t(115) = -2.26, p = .01; Cz: t(115) = -2.11, p = .02). Analysis 3 demonstrated a significant negative, linear relationship between survey scores and MMN amplitudes (Fz: R2= .034, p = .047). Findings may provide a tool for identifying those who are considered high-functioning, but could develop psychosis or cognitive and psychological difficulties associated with psychosis.
Open Access
Event-related potentials for the implicit and explicit processing of emotional facial expressions as basic level- and subordinate level-stimulus categories
(Colorado State University. Libraries, 2014) Nomi, Jason S., author; Troup, Lucy J., advisor; Davalos, Deana, advisor; Kraiger, Kurt, committee member; Draper, Bruce A., committee member
The two dominant models in face perception propose independent mechanisms are responsible for initial face perception (discriminating a face from an object), identity recognition (recognizing a specific face) and emotional expression perception (processing of an expression). However, Bruce and Young (1986) propose a linear model where identity recognition and expression perception operate in a parallel manner after initial face perception while Haxby, Hoffman and Gobbini (2000) propose an interactive model where all three mechanisms interact with each other within a non-linear core system. Event related potentials (ERPs) demonstrate that initial face perception is reflected by the temporal occipital P1 and N170 while identity recognition is reflected by the anterior N250. Some studies have found an expression influence on the P1 and N170 while other studies have not, providing mixed support for either model. The current study examined how facilitation of basic level and subordinate level category processing of emotional expressions may have influenced the results of previous studies. Research in stimulus category processing demonstrates that faces are typically processed at the subordinate level (e.g. my friend "Joe" as opposed to the basic level of "face") while objects are processed at the basic level (e.g. car but not the subordinate level of "Nissan Sentra"). However, there has been little research exploring how the processing of expressions may be influenced by category processing. Happy, neutral and sad expressions were presented in isolation for Experiment 1 to facilitate processing of expressions on the basic level (faces are all unfamiliar with the most basic changes being only in expression) while the same expressions were presented alongside cars, houses and butterflies in Experiment 2 to facilitate subordinate processing (basic level: faces vs. objects; subordinate level: happy, neutral and sad expressions and cars, houses and butterflies). Experiment 1 found P1 and N170 modulations by happy, neutral and sad expressions that were not influenced by implicit or explicit processing condition with no such modulations in Experiment 2. Additionally, there were early modulations of ERPs related to expression in both experiments in the 30-80ms range with explicit processing mediating face and object differences found in the 30-80ms range for Experiment 2. The results of the current study support the Haxby, Hoffman, and Gobbini model where expression perception mechanisms can modulate early ERP components reflecting initial face perception and also show that this modulation depends on the presence or absence of comparison object stimuli. When comparison stimuli were not present (Experiment 1), expressions processed as a basic level stimulus category mainly influenced ERPs in the 140-400ms time range reflecting enhanced processing of the specific expression. When comparison object stimuli were present (Experiment 2), expressions processed as a subordinate stimulus category mainly influenced ERPs in the 30-140ms time range reflecting quicker categorization due to the presence of object stimuli rather than processing of the specific emotional expression.
Open Access
Heart rate variability as a biomarker of self-control and its relationship with depression
(Colorado State University. Libraries, 2021) Darwin, Marielle L., author; Davalos, Deana, advisor; Thomas, Michael, committee member; Rickard, Kathryn, committee member; Tracy, Brian, committee member
Human behavior is guided by a desire to attain certain goals. Individuals must manipulate the pursuit of multiple goals simultaneously and decide how to navigate their environments to support the desires they most value. Failures of self-control are common and present as psychopathologies characterized by emotional and cognitive dysregulation, namely depression. The relationship between poor self-control and the manifestation of depression is critical to target in order to better predict, understand, diagnose, and treat symptomologies, yet the precise nature of the relationship between self-control and depression is insufficiently understood. The current study employed a novel approach to investigate the relationship between self-control and depression and whether our understanding of that relationship could be improved with the incorporation of heart rate variability (HRV), a robust neurocardiac biomarker of self-control-related abilities. Findings supported the merit of HRV as a biomarker of self-control and revealed that self-control fully mediated the relationship between HRV and depression, although effect sizes indicate that the relationships were weak. It was expected that age played a role in this relationship due to the changing lifespan trajectories of neurocardiac networks interconnected with self-control and depression, although this premise was found to be unsupported. These discoveries deepen our understanding of the neurocognitive and autonomic dynamics of depression and supplicate clinical researchers aiming to decrease dysfunction to entertain approaches supported by a biopsychological perspective.
Open Access
Mechanisms of prospective memory performance: exploring depression-related impairments in metamemory, cue detection, and intention retrieval
(Colorado State University. Libraries, 2025) Rice, Micheala S., author; Davalos, Deana, advisor; Thomas, Michael, committee member; Faw, Meara, committee member; Karoly, Hollis, committee member
Prospective memory (PM) is a critical cognitive skill describing our ability to create and perform future-intentioned goals. College students require a high level of PM abilities to complete their assignments for school, attend work and class regularly, and balance their social life with studying and personal care. PM can be divided into its two subcomponents: cue detection and intention retrieval, which can be measured using electroencephalogram/event-related potentials (EEG/ERPs). Impairments in PM may be explained or predicted by variations in these specific neurophysiological components. Metamemory, or how an individual thinks of their own memory abilities, may predict overall PM performance; metamemory guides how an individual encodes their intended future goal, monitors the environment for the cue, and sets reminders to complete their goal. Since the components of PM are necessary to successfully perform a PM goal, and metamemory may interact with the neurocognitive underpinnings of PM, metamemory beliefs may also predict cue detection and intention retrieval. Further, metamemory beliefs and the neurocognitive components of PM may be sensitive to psychological disorders, such as depression, which could impact overall PM performance. Depression is a particularly prevalent and debilitating disorder, especially among college students, and could play a role in these various factors involved in PM. This dissertation is made up of three papers that examine the neural and cognitive mechanisms involved in the relationship between depression and PM. The first paper characterizes how metamemory beliefs predict the neural and behavioral components of PM. The second paper assesses how depression levels predict the neural components of PM and metamemory beliefs. Further, Study 2 assesses how the relationship between depression and the neural components of PM varies based on metamemory beliefs. Finally, the third paper builds on Studies 1 and 2 by examining how depression levels relate to behavioral PM performance, and if metamemory beliefs or the neural components of PM may explain or contribute to this relationship. Altogether, this dissertation clarifies the cognitive, neural, and psychological factors that may support or harm PM skills, which could help inform intervention strategies to strengthen and protect future-oriented goal setting abilities.
Open Access
Mechanisms of timing: an integrative theoretical approach
(Colorado State University. Libraries, 2019) Pantlin, Lara N., author; Davalos, Deana, advisor; Prince, Mark, advisor; Malcolm, Matthew, committee member; Rojas, Don, committee member
Accurate timing allows individuals to perform essential tasks to meet societal demands, such as scheduling, responding to warning signals and planning. Since timing impacts various functions, understanding the meaning of a timing deficit is necessary. Poor performance in neurophysiological measures of timing has been related to psychopathology but has not specifically been related to one's ability to plan or maintain a schedule. Inability to track elapsed time as done in behavioral tasks is often related to poor performance in academic settings, but the intricacies of how inaccurate timing in one task manifests in other timing tasks has not been examined. The present study proposes a comprehensive examination of timing by dividing the field into three sub-domains: neurophysiological, behavioral, and applied temporal processing. These sub-domains are organized based on the tasks traditionally used to assess timing. Neurophysiological timing (Level I) was assessed using a duration-based mismatch negativity paradigm (dMMN), which fundamentally requires minimal cognitive resources. Behavioral timing (Level II) introduces the role of attention and working memory to accurately determine the amount of elapsed time (verbal estimation) or the generation of a pause, which reflects a specified amount of time (interval production). These tasks do not require the higher-order cognitive functions such as decision making and planning which are needed to accurately perform applied temporal processing tasks (e.g., time management and scheduling) (Level III). Hypothesis I proposed a hierarchical relationship among the three subdomains in which each succeeding level in the mediation is informed by the previous one and is distinct from the others based on the amount of cognition required to perform the task. Hypothesis II not only offered an extension of Hypothesis I, but also sought to examine the ways timing can be systematically improved through intervention methods. Across two time-points, participants were screened for select psychopathologies often associated with timing deficits (e.g., psychosis, traumatic brain injury, and substance use), underwent EEG recordings of dMMN to measure neurophysiology (Level I), performed two behavioral timing tasks (verbal estimation and interval production) (Level II), and completed three measures of applied temporal processing (letter-number sequencing and two time management surveys) (Level III). Hypothesis I was analyzed using a mediation model where neurophysiology (Level I) is expected to inform behavioral performance (Level II), which would subsequently influence accuracy on applied tasks (Level III). Hypothesis II was analyzed using repeated-measures ANOVAs to assess which intervention increases accuracy between time-points. Although Hypothesis I yielded nonsignificant results, interesting trends in the expected direction existed. Higher responses on the neurophysiological tasks were related to higher accuracy on behavioral and applied temporal processing measures. Hypothesis II yielded significant interactions between session and intervention and overall, suggested that using feedback to calibrate individuals to their abilities is the most appropriate intervention technique for increasing behavioral and applied accuracy. However, inclusion of tasks evaluating intermediate stages of timing is required if a full scale time continuum is to be modeled. Yet, this work provided the initial groundwork to further investigate the way time-related information is handled in the healthy brain.
Open Access
Neural correlates of prospective memory in college students with anxiety
(Colorado State University. Libraries, 2023) Rice, Michaela S., author; Davalos, Deana, advisor; Thomas, Michael, committee member; Faw, Meara, committee member; Tompkins, Sara Anne, committee member
Prospective memory is the ability to create and execute future tasks. It is comprised of two components: cue detection and intention retrieval. Prospective memory is essential for successfully performing high-level goals, a proficiency that is of extreme importance in college populations. Previous research has shown that prospective memory is vulnerable to deterioration in individuals with psychological disorders. Anxiety is a psychological disorder that has been associated with various cognitive deficits, including prospective memory impairment, and it is highly prevalent among undergraduate students. To date, no studies have investigated the relationship between prospective memory and anxiety using neurophysiology. The purpose of the present study is to fill this gap in the literature by examining prospective memory performance in college students with anxiety using an electroencephalogram (EEG). After recording anxiety levels via self-reported measures, participants completed a computerized prospective memory task while two types of event-related potentials were recorded from an EEG: the N300 to assess cue detection, and the prospective positivity to assess intention retrieval. The findings indicate that anxiety was not significantly related to prospective memory performance, although the data patterns suggest that accuracy decreased as anxiety increased. Intention retrieval was weakly positively correlated with accuracy, and weakly negatively correlated with state anxiety. Taken together, these results suggest intention retrieval could be a key component in supporting prospective memory for college students with high state anxiety.
Open Access
Perceptual differences and perceptive fields in binocular and monocular color vision
(Colorado State University. Libraries, 2016) Opper, Jamie K., author; Volbrecht, Vicki, advisor; Davalos, Deana, advisor; Anderson, Chuck, committee member; DeLosh, Ed, committee member
This study investigated perceptual differences in stimuli viewed with one eye (monocular) or two eyes (binocular) in the central (fovea) and peripheral retina (10° retinal eccentricity). In particular, this study focused on changes in color perception for monochromatic stimuli (450 nm to 670 nm, in 20 nm steps) varying in size (1°, 1.7°, 2.25°, 2.7°, 3.7°). A hue-scaling procedure was utilized to ascertain hue perception. With this procedure, three binocular normal and one strabismic amblyope assigned percentages to each of the four elemental hues (i. e., blue, yellow, red, and green) as well as saturation. Only one to two hue terms were allowed to describe a single stimulus, and the percentages had to sum to 100. Members of opponent-color pairs (red/green and yellow/blue) could not be used simultaneously to describe the same stimulus. Hue-scaling results from normal observers showed that, in general, smaller stimuli (1°, 1.7°, 2.25°) in the peripheral retina resulted in weaker hue perception than a 1° stimulus presented to the fovea, although this reduction was less noticeable for the binocular peripheral conditions than for the monocular peripheral conditions, and more noticeable for the monocular nasal retinal condition than the monocular temporal retinal condition. Differences between peripheral and foveal hue perception abated as stimulus size increased. Additionally, the range of wavelengths where blue (yellow) was perceived was narrower (wider) in the periphery relative to the fovea for all stimulus sizes. No differences were observed between monocular and binocular foveal hue or saturation perception, where only one stimulus size was used (1°). Peripherally-presented binocular stimuli fell upon the nasal retina of one eye and the temporal retina of the other, and peripheral binocular hue and saturation perceptions for smaller stimuli were more similar to that of the monocular temporal retina, regardless of whether the stimulus fell on the temporal retina of the left or right eye. Since hue-scaling data were obtained for several stimulus sizes in the peripheral retina it was possible to derive the size of perceptive fields, which are perceptual analogues of receptive fields and indicate the stimulus size at which hue perception stabilizes; i.e., the size at which amount of perceived hue ceases to increase with further increase in stimulus size. Perceptive fields measured in the monocular nasal retina were larger than those measured in the monocular temporal retina for all elemental hues. Overall, monocular perceptive fields were larger than the binocular perceptive fields. Possible physiological reasons for the findings include suppression of chromatic signals by rod photoreceptors, differences in cone photoreceptor distribution and relative ratios of cone types over the surface of the retina, and changes in the nature of the connections of the cone photoreceptors to their associated ganglion cells with increasing retinal eccentricity. The amblyopic observer was found to have abnormal hue and saturation perception relative to the normal observers, particularly for stimuli perceived as red and green, which may be due to abnormalities in the parvocellular pathway, the neural pathway presumed to mediate the perception of red and green.
Open Access
The interaction of executive functioning and emotional processing, as measured electrophysiologically
(Colorado State University. Libraries, 2012) Campbell, Alana M., author; Davalos, Deana, advisor; Draper, Bruce, committee member; Henry, Kim, committee member; Troup, Lucy, committee member
The current study investigated the interaction between emotion and executive functions. To better understand this relationship, responses to emotional images were measured electrophysiologically while participants performed a delayed match to sample task using emotional images from the International Affective Picture System as the stimuli. Participants rated the emotionality of the second, target image after being exposed to a first, probe image. The electrophysiological responses were measured as a late positive potential (LPP) elicited from the second images. The LPPs varied based on the emotionality of both the first and second image. Negative images were susceptible to manipulation from the first images. Additionally, participants completed an n-back test to assess their overall executive functioning. No relationship was found between the n-back task and electrophysiological responses. These results fit with a valence hypothesis and provide support to the theory that executive functions for emotional information are served by different, or at least additional, factors than those for cognitive working memory.