The human relationship with mortality has been widely studied in psychology research, with an extensive record suggesting that death-related stimuli impact behavior, even without conscious awareness. Yet, little is known about the underlying brain activity. In this systematic review, we aimed to examine whether there is something distinctive about the neural processing of death-related stimuli. We conducted a literature search to find studies where participants had been presented with death-related vs. other negatively valenced stimuli while undergoing functional brain imaging scanning. Seven functional magnetic resonance imaging (fMRI) studies with a total of 204 participants adhered to our criteria. Five of six studies that used whole-brain analysis found that unpleasant stimuli consistently elicited increased insular activity, but only when it was unrelated to mortality. This suggests a difference between the neural processing of death and other threats. We discuss possible interpretations and speculate that it is related to the insula’s role in sense of self and assessment of threat. Further research is needed to determine whether this marker is robust and what its function and consequences may be. A better understanding of how individuals process death-related information promises deeper insight into the human relationship with mortality. Bringing to light the nature of this relationship has significant implications for individuals and society, not least for mental health interventions and end-of-life care.

The contrasting infection strategy of herpes simplex virus (HSV) consists of an initial primary lytic infection in epithelial cells, followed by establishment of lifelong latency in sensory and autonomic neurons of the peripheral nervous system that innervate the site of infection. Any cellular stress trigger, ranging from external stimuli such as UV radiation or nerve injury to psychological and physiological stress, can reactivate HSV from latency in the neurons, resulting in recurrent disease episodes. Stress hormones and deprivation of neurotrophic factor (NTF) both have a strong correlation with HSV reactivation from neurons. However, neuronal signaling pathways cardinal to HSV latency and reactivation are still not clear. This dissertation provides new understanding of HSV latency and reactivation in response to two orthogonal stress stimuli, viz. stress hormones epinephrine (EPI) and corticosterone (CORT), as well as NTF deprivation that simulates a nerve injury in primary neuronal cultures. In this dissertation, we demonstrate that physiological stress hormones EPI and CORT differentially regulate HSV-1 and HSV-2 reactivation in adult neurons. Both EPI and CORT treatment reactivated only HSV-1 in sympathetic superior cervical ganglia (SCG) neurons, while HSV-2 was reactivated only by CORT in both sensory trigeminal ganglia (TG) neurons and sympathetic superior cervical (SCG) neurons. EPI utilized the combination of α and β adrenergic receptor complex, while CORT signaled through glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) to reactivate HSV in the neurons. NTFs are tissue-target derived growth factors required for neuronal protection and survival. Neurotrophins are also required for maintaining HSV latency, as NTF deprivation reactivates both HSV-1 and HSV-2 in adult sensory TG and sympathetic SCG neurons. In addition, assessing the temporal kinetics of HSV gene expression showed differential expression profiles of viral immediate-early (IE) genes ICP0, ICP4, ICP27 and trans-activator VP16 following treatment with stress hormones and NTF deprivation in HSV-1 and HSV-2 infected neurons. We also show that different molecular mechanisms are involved in HSV latency and reactivation, which are dependent on the stimuli and the type of neurons. Tyrosine kinase receptor-mediated PI3K-Akt-mTORC signaling cascades have been studied for their role in maintaining HSV latency. Activation of β-catenin signalosome expression has also been implicated during HSV latency and following reactivation. GSK3β is a key effector molecule that inter-connects Akt and β-catenin mediated pathways, forming an Akt-GSK3β-β-catenin signaling axis. Analyzing the Akt-GSK3β-β-catenin signaling in response to stress hormone and NTF deprivation revealed significant differences in protein expression levels between HSV-1 and HSV-2 infected sensory and sympathetic neurons. In HSV-1 infected neurons, the Akt-GSK3β-β-catenin maintains the signal transmission in order to keep the neurons alive, but HSV-2 infections obliterated the entire axis in the adult neurons, particularly in sympathetic neurons. In summary, we demonstrate that HSV-1 and HSV-2 do not have a 'one for all' infection mechanism. Establishment of latency and reactivation by HSV is virus specific, stimulus specific and neuron specific. / Doctor of Philosophy / Herpes simplex viruses (HSVs) are common global viral pathogens that are responsible for causing lifelong painful infections and debilitating disease. The two serotypes of HSV include HSV-1, which is associated with oral or ocular disease but can also cause genital disease, and HSV-2, which is predominantly associated with genital herpes. Once infected, both HSV-1 and HSV-2 are present as lifelong reservoirs in our peripheral neurons. Stress stimuli mediated by our stress hormones or external triggers, such as nerve trauma or an axonal injury, can periodically reactivate the latent virus to cause recurrent disease. Clinical manifestation of HSV recurrences range from asymptomatic viral shedding to painful blisters, cold sores, or herpetic keratitis. In some cases, the virus can spread to the central nervous system, causing encephalitis or recurrent meningitis. No vaccines have been approved yet, and the current treatment utilizes nucleoside analogs, such as acyclovir and its prodrug valacyclovir, to ameliorate the symptoms of HSV infection by halting viral replication and if taken as a daily prophylaxis, reduces the chances of clinical recurrence. Given the route and transmission efficiency of HSV, it is practically impossible to prevent herpes infection. To develop strategic therapeutic interventions to lock the virus in its latent phase in the neurons and prevent it from reactivation, a better understanding of neuronal signaling pathways cardinal to HSV latency and reactivation is necessary. However, neuronal signaling pathways cardinal to HSV latency and reactivation are still not clear. In this dissertation, we make contributions to better understand HSV latency and reactivation in response to stress stimuli. We show that different stress stimuli exert preferential reactivation between HSV-1 and HSV-2, and are further dependent upon the neurons where they establish latency. Our study specifically focuses on three neuronal stressors that have been associated with HSV recurrences: two stress hormones, epinephrine (EPI) and corticosterone (CORT), as well as deprivation of neurotrophic factors (NTF) that simulates nerve injury. We also focused on a neuronal signaling cascade involved in the response to all of these stimuli, Akt-GSK3β-β-catenin, and viral gene transcripts that respond to these stimuli during reactivation. Comprehensive understanding of the neuronal processes and viral gene transcripts involved during HSV-1 and HSV-2 reactivation in neurons will help the herpes virology field towards development of targeted therapies and vaccines to prevent reactivation and recurrent disease.

The development of controllable drug delivery systems is crucial for reducing toxicity and minimizing off-target drug effects for patients undergoing chemotherapy. Metal–organic frameworks (MOFs) are a class of hybrid materials that have become of interest in the field of drug delivery. MOFs are composed of metal nodes and organic bridging ligands. MOFs have a wide range of desirable properties including chemical stability, high porosity, and structural tunability which have positioned them as successful drug carriers. Through judicious choice of linker, stimuli-responsive MOFs can be synthesized to achieve precise control over cargo release. Previously, our lab developed a novel light-responsive drug delivery system using a framework known as UiO-AZB (UiO= University of Oslo, AZB=4,4ʹ-azobenzenedicarboxylic acid). This MOF contains a photoswitchable azobenzene linker. Upon irradiation with ultraviolet light, the compound undergoes a structural change known as photoisomerization, resulting in degradation of the MOF structure and simultaneous release of encapsulated cargo. To improve the clinical relevance of our framework, we focus on developing synthetic methods for production of visible light-responsive azobenzene photoswitches. A green light-responsive MOF (UiO-AZB-F) containing a 4,4ʹ-(diazene-1,2- diyl)bis(3,5-difluorobenzoic acid) linker was developed as a drug delivery system for the treatment of colorectal cancer. Our work also focuses on optimizing various aspects of MOF design to maximize and diversify cargo loading and precisely control cargo release rates. A combined computational and experimental investigation of drug adsorption process reveals that the presence of solvent can significantly impact the adsorption of drug molecules within MOF pores. To address these concerns, a variety of drug loading procedures were screened to determine conditions for maximizing the loading of diverse drug cargoes. Conditions for the loading of single agents as well as chemotherapy cocktails were explored to expand the application of our delivery platform to other cancer types including lung, pancreatic, bladder and cervical. To modulate the release of cargo, a series of MOFs containing precise ratios of green light-responsive linker were synthesized to create a platform for sustained release. Remarkably, several MOF derivatives showed enhancement in drug adsorption, highlighting the important role of host–guest interactions in nanocarrier development. Holistically, this work highlights the promise of stimuli-responsive MOFs as drug delivery platforms. / Doctor of Philosophy / Cancer is one of the leading causes of death worldwide. In 2021, nearly 2 million people in the U.S. were diagnosed with cancer. For patients undergoing chemotherapy treatment, the side effects of potent chemotherapeutics are often debilitating. Drug- delivery systems serve as a promising platform for localizing the delivery of chemotherapeutic drugs within a diseased area. When chemotherapeutics are delivered precisely to tumor regions via drug delivery systems, systemic side effects are significantly diminished. In this work, a series of materials known as metal–organic frameworks (MOFs) are developed as carriers for chemotherapeutic cargo. Due to the incorporation of photoactivated compounds within the backbone, these MOFs can be degraded on-demand through green light irradiation. As the framework degrades into small molecule components, drug cargo is simultaneously released. Methods for maximizing MOF drug loadings, diversifying the types of cargo that can be incorporated, and modifying cargo release rates are also investigated. This work establishes stimuli-responsive MOFs as promising materials for on-demand drug delivery.

Nanoparticle-based delivery vehicles have received substantial interest in the field of drug delivery particularly pertaining to chemotherapeutics. By virtue of their size, nanoscale drug delivery vehicles overcome many obstacles encountered by traditional systems. Moreover, nanocarriers can be fabricated to be ‘smart’, meaning they can be responsive to internal stimuli relating to the microenvironment of the tumor and/or external stimuli that can be delivered non-invasively from outside of the body. One such external trigger is ultrasound, well-known for its role in biomedical imaging based on its wide availability, non-invasiveness, and safety but increasingly being applied for drug delivery. This thesis proposes solutions to two key challenges associated with locally-targeted polymer-based drug delivery: enhanced tumor accumulation and externally-triggered control over release kinetics. In the former case, brush polymer PLA-PEG analogues are synthesized and explored to correlate how the architecture of these brush blocks affects the resulting self-assembled nanoparticle size, zeta potential, cytotoxicity in vitro, circulation time, and accumulation profiles in vivo. Indeed, brush copolymer analogues allow for copolymerization with additional monomers while conserving ‘stealth properties of linear copolymers, as well as exhibit superior circulation times and longer-term tumor accumulation. In the latter case, a new ultrasound-triggered drug delivery platform is designed consisting of a hollow polymeric shell in which silica “corks” are entrapped; the application of ultrasound can exploit the high difference in the compressibility between the polymeric shell and the silica corks to pop out or otherwise perturb the cork particles, allowing for both on-demand drug release as well as a pulsatile release profiles to be achieved. Overall, by manipulating the surface properties and/or morphologies of polymer-based micro/nanoparticles, the results of this thesis show that key challenges in local drug delivery can be addressed and applied specifically to applications in cancer therapy. / Dissertation / Doctor of Philosophy (PhD) / Drug delivery vehicles attempt to address many of the shortcomings of traditional therapeutics, in particular their low solubility and a lack of tissue targeting, which result in poor efficacy and unwanted side-effects. Polymers specifically have been commonly employed in biomedical applications as there are a wide range of biodegradable polymers that do not cause adverse effects during intended application and can be removed from the body through normal biological function. More recently, more advanced, ‘smart’ materials have been developed that can respond to internal or external stimuli to better address treatment needs. This thesis presents novel polymer-based drug delivery vehicles with new structures useful to passively target particular sites in the body and/or alter drug release profiles, enabling improved drug efficacy and reduced side-effects.

Several studies have shown that the strength of classically conditioned fear varies inversely with the length of the CS-UCS interval (McAllister & McAllister, 1971). If fear conditioning is important in the vicious-circle (VC) phenomenon (Brown, 1969; Melvin, 1971; Mowrer, 1947), then the interstimulus interval between brightness cues (CS) and shock (UCS) may similarly affect VC behavior. Experiment 1 examined effects of brightness cue change on VC responding. Forty male hooded rats were assigned to four groups in a 2 x 2 design, using the presence or absence of shock in the third segment during extinction and the presence or absence of cue change as independent variables. Experiment 2 examined the effects of pre-shock brightness cue changes on VC behavior, and varied the interval between the cue change location and shock. Eighty male hooded rats were assigned to eight groups in a 2 x 4 design, using the presence or absence of shock in the third segment and cue change placement as independent variables. The results indicated that brightness cue changes can reduce VC behavior. Experiment 2 also demonstrated that a cue change in the first alley segment reduced vc·responding as effectively as a total alley cue change. Changing the lower startbox cues was less effective and changing Segment 2 cues had little effect on VC behavior. The results were consistent with the ISI effects found in conditioned-fear research, since there was a relationship between the strength of VC responding and the spatio-temporal interval between changed cues and shock. / Master of Science

New synthetic advances in the control of nanoparticle size and shape along with the development of new surface modifications facilitates the growing use of nanomaterials in biomedical applications. Of particular interest are functional and biocompatible nanomaterials for sensing, imaging, and drug delivery. The goal of this research is to tailor the function of nanomaterials for biomedical applications by improving the biocompatibility of the systems. Our work demonstrates both a bottom up and a post synthetic approach for incorporating stability, stealth, and biocompatibility to metal based nanoparticle systems. Two main nanomaterial projects are the focus of this dissertation. We first investigated the development of a green synthetic procedure to produce gold nanoparticles for biological imaging and sensing. The size and morphology of gold nanoparticles directly impact their optical properties, which are important for their function as imaging agents or their use in sensor systems. In this project, a synthetic route based on the natural process of biomineralization was developed, where a designed protein scaffold initiates the nucleation and subsequent growth of gold ions. To gain insight into controlling the size and morphology of the synthesized nanoparticles, interactions between the gold ions and the protein surface were studied along with the effect of ionic strength on interactions and then subsequent crystal growth. We are able to control the size and morphology of the gold nanoparticles by altering the concentration or identity of protein scaffold, salt, or reducing agent. The second project involves the design and optimization of metal organic framework nanoparticles for an external stimulus triggered drug delivery system. This work demonstrates the advantages of using surface coatings for improved stability and functionalization. We show that the addition of a polyethylene glycol surface coating improved the colloidal stability and biocompatibility of the system. The nanoparticle was shown to successfully encapsulate a variety of small molecule cargo. This is the first report of photo-triggered degradation and subsequent release of the loaded cargo as a mechanism of stimuli-controlled drug delivery. Each of the aforementioned projects demonstrates the design, synthesis, and optimization of metal-based systems for use in biomedical applications. / Ph. D.

When something is not attended to by a person, even when it is right before them, they won't perceive it. This is known as inattentional blindness (Mack & Rock, 1998). Sometimes information missed due to inattentional blindness is trivial but inattentional blindness can become a problem when it hinders people from responding to something appropriately when a response is needed. When a visual cue is missed there can be an impact on decision-making. Variations in color luminance may also be a factor in one's ability to attend to something. For example, if a person is attending to a number of objects that are one color shade (for instance, dark green), it may be possible that this person might not see an additional object appear in their field of view (FOV) if it is the same color and shade. Conversely, the opposite might be true that a person is more likely to attend to the additional object if it is the same dark green color, opposed to an object that is colored a lighter green. This research investigated whether some variations of luminance of the same color (for example, dark green to light green) can affect one's ability to attend an additional object entering one's FOV. A scenario was presented to tank gunners that required them to observe objects of one color (dark green) while an additional object was briefly presented to them colored either dark green or light green. In this between-subjects study, 48 participants observed four dark green and four light green enemy tanks moving about the battlefield. Each was given a task that involved monitoring the dark green tanks only. During their monitoring, an additional vehicle (M981A3 FIST-V) briefly entered and exited their FOV. The additional vehicle was presented to 24 participants colored dark green. For the other 24, it was presented colored light green. This research addressed whether there was an association between color luminance, FOV, or focused attention and detection of the FIST-V. The results did not indicate an association between FOV and detection of the FIST-V [÷2(1, N = 48) = 0.08, p = 1.0]. Nor was there an association between focused attention and detection of the FIST-V using the following self-reporting questionnaires for determining levels of focused attention: ETAS [÷2(1, N = 48) = 2.06, p = 0.20], the CFQ [÷2(1, N = 48) = 0.75, p = 0.56], and the DAPI [÷2(1, N = 47) = 1.39, p = 0.75]. In the same manner, there was also no association between field dependence and detection of the FIST-V [÷2(1, N = 43) = 0.34, p = 0.75]. There was, however, an association between color luminance and detection of the FIST-V [÷2(1, N = 48) = 36.80, p < 1.0e-8]. / Master of Science

No / Z. W. Pylyshyn and R. W. Storm (1988) have shown that human observers can accurately track four to five items at a time. However, when a threshold paradigm is used, observers are unable to track more than a single trajectory accurately (S. P. Tripathy & B. T. Barrett, 2004). This difference between the two studies is examined systematically using substantially suprathreshold stimuli. The stimuli consisted of one (Experiment 1) or more (Experiments 2 and 3) bilinear target trajectories embedded among several linear distractor trajectories. The target trajectories deviated clockwise (CW) or counterclockwise (CCW) (by 19°, 38°, or 76° in Experiments 1 and 2 and by 19°, 38°, or 57° in Experiment 3), and observers reported the direction of deviation. From the percentage of correct responses, the ¿effective¿ number of tracked trajectories was estimated for each experimental condition. The total number of trajectories in the stimulus and the number of deviating trajectories had only a small effect on the effective number of tracked trajectories; the effective number tracked was primarily influenced by the angle of deviation of the targets and ranged from four to five trajectories for a ±76° deviation to only one to two trajectories for a ±19° deviation, regardless of whether the different magnitudes of deviation were blocked (Experiment 2) or interleaved (Experiment 3). Simple hypotheses based on ¿averaging of orientations,¿ ¿preallocation of resources,¿ or pop-out, crowding, or masking of the target trajectories are unlikely to explain the relationship between the effective number tracked and the angle of deviation of the target trajectories. This study reconciles the difference between the studies cited above in terms of the number of trajectories that can be tracked at a time.

No / We have previously shown (Bloj et al., 2008; Abstracts Materials & Sensations 2008) that under particular conditions colour memory is independent of presentation media, and of the illuminants under which colours are viewed. In the present study we investigate whether colour naming is also unaffected by these two factors. Forty-eight colour samples from the Natural Colour System (NCS) collection were presented as real paper samples or as accurate computer simulations displayed on a calibrated monitor. The colour swatches could be presented under a daylight illuminant ¿ two intensities, 85 ( D1 ) or 60 cd m)2 ( D2 ) ¿ or a purple illuminant, 45 cd m)2 ( Lily ). The colour samples were shown in arrays of 16 (4 · 4 layout) and the observer s task was to assign one of the eleven basic colour terms to each of the samples. Six observers repeated this colour naming task five times for each presentation medium and illuminant. On average, in 73% of the cases the same colour term was assigned to surface and display colours. This level of agreement was highest for colour samples under daylight (D1-82%, D2-73%) and poor for Lily (65%). Although colour memory is unaffected by the nature of the colour stimulus, here we show that there are limitations to cross-media agreement in colour naming.

Yes / Purpose: To demonstrate that silent substitution stimuli can be used to generate electroretinograms (ERGs) that effectively isolate rod photoreceptor function in humans without the need for dark adaptation, and that this approach constitutes a viable alternative to current clinical standard testing protocols. Methods: Rod-isolating and non-isolating sinusoidal flicker stimuli were generated on a 4 primary light-emitting diode (LED) Ganzfeld stimulator to elicit ERGs from participants with normal and compromised rod function who had not undergone dark-adaptation. Responses were subjected to Fourier analysis, and the amplitude and phase of the fundamental were used to examine temporal frequency and retinal illuminance response characteristics. Results: Electroretinograms elicited by rod-isolating silent substitution stimuli exhibit low-pass temporal frequency response characteristics with an upper response limit of 30 Hz. Responses are optimal between 5 and 8 Hz and between 10 and 100 photopic trolands (Td). There is a significant correlation between the response amplitudes obtained with the silent substitution method and current standard clinical protocols. Analysis of signal-to-noise ratios reveals significant differences between subjects with normal and compromised rod function. Conclusions: Silent substitution provides an effective method for the isolation of human rod photoreceptor function in subjects with normal as well as compromised rod function when stimuli are used within appropriate parameter ranges. Translational Relevance: This method of generating rod-mediated ERGs can be achieved without time-consuming periods of dark adaptation, provides improved isolation of rod- from cone-based activity, and will lead to the development of faster clinical electrophysiologic testing protocols with improved selectivity.