Aging is influenced by genetic and lifestyle factors, which manifest differently in each individual. While genetic predispositions and structural brain changes occur throughout the aging process, interventions such as mindfulness meditation are promising in preventing cognitive decline and promoting healthy aging. Findings from various studies explore the impacts of various lifestyle factors, including diet, exercise, and mindfulness interventions on cognitive function and overall health as people age. Furthermore, mindfulness interventions have been shown to enhance cognitive performance, emotion regulation, and cardiovascular health. Addressing the psychological and physiological aspects of aging and the benefits of non-pharmaceutical interventions offers a holistic approach to healthy aging that is often overlooked. In this thesis, I examined various literature reviews, exploring the intersections between individual differences and mindfulness interventions in promoting healthy aging.

The ability to preferentially encode and later retrieve valuable information amidst a plethora of miscellaneous information is an essential aspect of human memory. Several hypotheses have been suggested to explain the enhanced ability to successfully encode high value items. These include the hypothesis that the prefrontal executive control processes are engaged for valuable information, producing elaborative rehearsal strategy. Another hypothesis is that greater attentional resources are allocated to higher value items via the reward driven mid-brain dopamine systems interacting with hippocampal and cortical areas to produce enhanced memory. To further understand the neural mechanisms of value on memory, electroencephalogram data under a value-directed remembering paradigm (VDR) was analyzed for oscillatory activity. During the task, participants encoded words assigned a different point value with the instruction to maximize the point value of recognized words during test. To analyze frequency activity during encoding, conditions of subsequent memory as subjective responses of either recollection (i.e., “remember”) and familiarity (i.e., “know”) were assessed. A possible way to observe the allocation of attention resources in the brain are alpha oscillations (8-15 Hz) which are thought to underlie this process. Participants demonstrated superior memory for high versus low value point items. Following the hypothesis that there is a greater recruitment of attentional resources for high value information, alpha oscillatory power in the occipital/temporal cortex displayed significantly more desynchronization for high value compared to low value conditions during encoding. As well, successful retrieval compared with unsuccessful retrieval and subsequent “remember” or “know” conditions resulted in a qualitatively different, more sustained desynchronization of alpha and other unanticipated frequency band oscillations during encoding that are discussed. Taken together, these findings support previous research for alpha-band desynchronization during encoding items of value into memory and potentially open paths to decouple value and memory driven processes.

Dopamine neurons are essential for several aspects of cognition. Several decades of Parkinson’s Disease (PD) research have revealed that the deterioration of these neurons is associated with a wide range of cognitive deficits such as attention, motor coordination, and memory. The diversity of these deficits is a demonstration of the structural and functional heterogeneity within the dopaminergic system; projections from the substantia nigra and the ventral tegmental area to striatum have targets in the frontal and medial temporal cortices. It is known that prospective memory is negatively affected by PD, but whether the deficits originate from pathways that support attention, retrospective memory, working memory, and/or motor control has not yet been determined. For the current study, the goal is to estimate the structural integrity of these pathways by using diffusion-imaging analysis to then correlate these estimates with prospective memory performance within a standard event-based task. Two participant data sets were reported in the current study and compared with the global and target fractional anisotropy as well as seed connectivity. All the results reported here are preliminary.

The capacity to track time in the seconds-to-minutes range, or interval timing, appears to be at least partially dependent on intact hippocampal (HPC) function. The current dissertation sought to dissociate timed responses, non-timed responses, and motivational aspects of behavior in order to propose a role of the HPC in specific timing sub-processes. In Chapter 2, effects of dorsal HPC (dHPC) lesions on temporal responding in a switch-timing task revealed a critical role of dHPC in the acquisition of interval timing criteria. Following dHPC lesions, the start time of responding was systemically shortened, in a manner that was enhanced and sustained when encoding a novel long interval, consistent with a memory-based account of dHPC function in timed responding. Chapter 3 investigated effects of chronic stress, which has been shown to reliably induce HPC dendritic retraction, on interval timing, utilizing response-initiated schedules of reinforcement, which facilitate deconvolution of timing and motivation. This revealed task-dependent effects on interval timing and motivation, where stress induced transient effects on motivation in a prospective timing task, but transient effects on the variability of timed responding in a retrospective timing task, consistent with an effect on memory function in interval timing. Chapter 4 sought to bring timed responding, motivation, and non-timed behaviors under stronger procedural control, through the implementation of a response-initiated timing-with-opportunity-cost task, in which a cost is imposed on temporal food-seeking by the presence of a concurrent source of probabilistic reinforcement. This arrangement garnered strong schedule control of behavior, and revealed individual-subject differences in the effects of reward devaluation, such that it affected motivation in some rats, but temporal responding in others. Using this methodology, Chapter 5 investigated initial temporal entrainment of behavior under pharmacological deactivation of dHPC and revealed its critical involvement in updating memory to new temporal contingencies. Together, data from this dissertation contrast with prior conclusions that the HPC is not involved in learning temporal criteria, and instead suggest that its function is indeed critical to encoding temporal intervals in memory.

This thesis project examines neuropsychological disorders with regards to facial recognition. It looks at the research significance as well as the regions of the brain involved in facial recognition. It reviews what these regions look like when they are healthy, and what they look like when they are impaired and their resulting function. In addition, the project looks at autism and schizophrenia which have as one their symptoms facial recognition disorder. As a result, the project dives into what goes on these patients which results in impaired facial recognition. The project also looks at the own-race bias, and how that relates to facial recognition. Finally, the project proposes an experimental proposal to identify the neural centers involved in facial recognition in patients with Alzheimer’s, drawing upon previous research on the subject. An actual experiment was not conducted due to the pandemic, but there is a section of expected results in the event that the experiment is run. The expected results are that patients with Alzheimer’s should have deficits in the N170 component, the N400 component, the hippocampus and a smaller region of the cortex involved with processing faces compared to healthy controls.

Self-control has been shown to be an important influence behind a variety of risk and protective behaviors, such as substance abuse. Although prior research points to the existence of multiple dimensions of self-control, this concept is not consistently defined and frequently only studied as a conglomerate in clinical research. The current study sought to examine how two experimental manipulations of subcomponents of self-control (motivation and self-efficacy) affect real-world consumptive behavior after accounting for executive function. Additionally, the validity and reliability of a brief state survey measure of perceived self-control capacity, internal motivation, and external motivation was tested. The goal was to examine how basic scientific principles involved in self-control translate into clinically relevant behaviors, which may inform understanding of momentary lapses in self-control behavior, potentially leading to novel prevention and intervention efforts. 94 college students completed a 1-2 hour laboratory protocol during which they completed survey and laboratory-based tasks of self-control and related behaviors, executive function, and ad libitum alcohol consumption. Results showed that the self-efficacy manipulation successfully increased perceived self-control capacity, although this did not lead to a significant reduction in consumption. The motivation manipulation neither increased motivation nor reduced consumption in this sample. However, the brief state survey measure of self-control subcomponents demonstrated strong test-retest reliability and distinction from trait self-control, demonstrating its viability for use in future research. By elucidating the relationships between specific mechanisms of self-control, laboratory-based tasks and manipulations, and real-world consumptive behaviors, prevention and intervention efforts for problems such as alcohol abuse may be tailored to the needs of the individual and made more impactful and cost-effective.

The use of functional magnetic resonance imaging (fMRI) has been increasing in popularity due to its ability to measure brain activity during presentation of stimuli. Blood flow responses in the brain occur when a stimulus is presented and can be measured using fMRI. The delay of onset of this blood flow response can vary due to distances from the heart to the brain blood vessels. This variability causes differences in onset and time to peak blood flow response across the brain that is not currently predictable. To account for this, statistical analyses add the response's temporal derivative to regression models. Derived from the Taylor series expansion, the temporal derivative corrects for small variations in the time delay for the blood flow response (i.e. less than 1 second or so). However, I show that inclusion of the temporal derivative in analyses increases false positive rates. I conducted fMRI analyses on data collected as participants complete motor responses and on resting state data. Analyses were repeated both with and without inclusion of the temporal derivative. More significant responses were found with inclusion of the temporal derivative in both cases, suggesting possible increases in false positive rates. The goal of the present study is to increase awareness of the current fMRI data analysis practices and their potential flaws.

Working memory capacity and fluid intelligence are important predictors of performance in educational settings. Thus, understanding the processes underlying the relation between working memory capacity and fluid intelligence is important. Three large scale individual differences experiments were conducted to determine the mechanisms underlying the relation between working memory capacity and fluid intelligence. Experiments 1 and 2 were designed to assess whether individual differences in strategic behavior contribute to the variance shared between working memory capacity and fluid intelligence. In Experiment 3, competing theories for describing the underlying processes (cognitive vs. strategy) were evaluated in a comprehensive examination of potential underlying mechanisms. These data help inform existing theories about the mechanisms underlying the relation between WMC and gF. However, these data also indicate that the current theoretical model of the shared variance between WMC and gF would need to be revised to account for the data in Experiment 3. Possible sources of misfit are considered in the discussion along with a consideration of the theoretical implications of observing those relations in the Experiment 3 data.

Properly deciding to engage in or to withhold an action is a critical ability for goal-oriented movement control. Such decision may be driven by expected value from the choice of action but associating physical effort may discount such value. A novel anticipatory stopping task was developed to investigate effort discounted decision process potentially present in proactive inhibitory control. Subjects performed or abstained from target reach if they believed it was a Go or Stop trial respectively. Reward was awarded to a reach, correctly timed to hit a target at the same time as the moving bar in Go trials. During the Stop trials, correctly judging to not engage in a reach from the color of the moving bar that linked to the bar’s probability of stopping before the target resulted in gaining a reward. Resistive force field incurred additional physical effort for choosing to reach. Introducing effort expectedly decreased the tendency to respond at trials with higher stop probability. Surprisingly, tendency to respond increased and corresponding reaction time decreased in the trials with lower stop probability. Such asymmetric effect suggests that the value of context ineffective response is discounted, and the value of context effective response is flexibly enhanced by its associated effort cost to drive decision-process in goal-oriented manner. Medial frontal event related potential (ERP) locked to the onset of moving bar appearance reflected such effort discounted decision process. Theta band observed in Stop trials accounted for evaluation of effort and context possibly reinforcing such decision-making.