In this thesis, I will explore the idea that choices between present, smaller value options and future, larger value options depend on how much individuals trust the future to deliver the reward. Due to this aspect of trust, the individual must build their estimate of trust based on information for their present environment and their future expectations. This estimate of future trust can change across different time points in the same environment (i.e., before and after a national election) and between environments in the same time point (i.e., between two countries experiencing different economic rates of change). In this set of presented experiments, I will explore the link between decision environment and delay discounting, as well as the relationship between the contents of future perception and delay discounting. These two experiments will test differences in delay discounting (a) across two economic systems (China and the U.S.), as well as (b) before and after a national election (2018 U.S. Midterms). The results of the different decision environments study show that the delay discounting rates are significantly different across the two countries, specifically within the framing of present and future. These differences are not explained by differences in culture effects or individual differences in personality traits, suggesting that difference in environment is driving the effect. The results from the Midterm election experiments show evidence for differences in delay discounting between political identities and income groups. There are also differences in how these two groups perceive the contents of their future before and after the election. Specifically with evidence that negative future projection corresponds with increased delay discounting. Overall, these experiments show that delay discounting can be affected by the way information is framed within an environment and how we expect our environments to change over time.

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Song production in songbirds is controlled by parts of the brain known as the song control regions (SCRs). During spring, gonads increase in size, males sing to attract mates, and SCRs become larger. This neuroplasticity is controlled by the change in day length and increased plasma testosterone (T) levels. Plasma T can be reduced by stress through the production of corticosterone (CORT), through the production of beta-endorphin, or through direct effects on the testes via the nervous system. We determined the T, estradiol, and CORT hormonal profiles of wild House Finches by capturing and sampling blood from the finches every season for two years. To track SCR neuroplasticity in the wild, we also measured the volume of two specific SCRs, the HVC and RA, every season. We then examined the effects of stress on the finch endocrine system in the wild by performing a 30-minute restraint stress protocol once every season and took blood samples before and after the restraint. To determine whether stress and/or CORT affect neuroplasticity in SCRs, we captured male house finches during winter and brought them into captivity. They were allowed to acclimate to captivity for one month on short days (8L:16D) before we transferred them to long days (16L:8D) and restraint stressed half the birds. We measured their gonads, plasma T and CORT levels, volumes of the HVC and RA, and the number of new neurons in the HVC. HVC volumes were smaller in stressed than non-stressed birds, while RA volumes did not differ. There was no difference in number of new neurons or estimated total number of neurons in the HVC between control and restrained birds. Because the HVC is involved in song production, it is possible that stress negatively impacts singing behavior and reproductive success in House Finches. Future work should address how natural stressors may affect neuroplasticity in birds.

There are two distinct communication systems in the brain, term wiring and volume transmission (Agnati et al., 2010). Volume transmission refers to a way of communication lacking any wire-like channel connecting the source of signal and its target. This way of signaling is the focus of the current thesis. Portal systems are one aspect of volume transmission in which they provide a pathway for diffusible signaling between bodily fluids (blood and cerebrospinal fluid) and the nervous system. A portal system entails two capillary beds linked by connecting veins. This connection allows signals from one capillary bed to be transported to a target in high concentrations without being diluted in the systemic circulation (Dorland, 2020). For the past decades, the only identified portal system in the brain is pituitary portal system (Popa, 1930; Popa & Fielding, 1933). Here, hypothalamic neurosecretions are released into the fenestrated capillaries of median eminence, a circumventricular organ, and transported to the capillaries of anterior pituitary via portal veins. The median eminence, due to its location on the surface of the ventricle and its contact to the cerebrospinal fluid, is categorized as a circumventricular organ. According to the classification (Oldfield & McKinley, 2015), there are three sensory circumventricular organs in the brain, all are characterized by fenestrated capillaries allowing contact between brain parenchyma and blood. For this reason, the circumventricular organs are known as “windows to the brain” (Gross et al., 1987). Whether other circumventricular organs also form portal systems is unknown. This thesis examines whether sensory circumventricular organs, specifically the organum vascular organ of the lamina terminals, the subfornical organ and the area postrema, bear portal systems. Although there have been prior studies of the vascularity of these CVOs in many species (reviewed in Duvernoy and Risold (2007)), the tissue preparation methods available limited the possibility of tracking small vessels over relatively large volumes in these structures. In the present work, to preserve the blood vessel structure, brain clearing and light sheet microscopy were combined to acquire volumetric images of the regions containing the circumventricular organs. In vivo two-photon microscopy was used to study the blood flow of the sensory circumventricular organs and the adjacent neuropil. The results indicate that organum vasculosum of the lamina terminalis is connected to the brain’s clock located in the suprachiasmatic nucleus by portal vessels. The direction of blood flow is from the suprachiasmatic nucleus to the organum vasculosum of the lamina terminalis, and speed of blood flow is faster during the night compared to the day. Volumetric imaging of the suprachiasmatic nucleus also shows portal veins emerging from the rostral shell region of this nucleus. Also, the subfornical organ connects to the septofimbrial nucleus and the triangular nucleus of the septum via portal veins. The arrangement of the vasculature of the area postrema differs from the other sensory CVOs: the AP and the nucleus of the solitary tract share a common capillary bed directly joining the vasculature of these morphologically distinct nuclei. In summary, there are multiple portal systems connecting the circumventricular organs. These newly discovered portal systems represent new pathways for diffusible signaling, bridging the systemic circulation, cerebrospinal fluid, circumventricular organs and the portal veins connected regions.

In this dissertation, I examine the nature and structure of consciousness. Conscious experience is often said to be phenomenally unified, and subjects of consciousness are often self-conscious. I ask whether these features necessarily accompany conscious experience. Is it necessarily the case, for instance, that all of a conscious subject's experiences at a time are phenomenally unified? And is it necessarily the case that subjects of consciousness are self-conscious whenever they are conscious? I argue that the answer to the former is affirmative and the latter negative. In the first chapter, I set the stage by distinguishing phenomenal unity from other species of conscious unity. A pair of conscious states is phenomenally unified if they are experienced together as part of a single experience that encompasses them both. In this and the next two chapters I defend the thesis that, necessarily, for any subject (of conscious mental states) at any time, all of that subject's conscious mental states (at that time) are part of a single, maximal state of consciousness. I call this thesis the "Unity Thesis." I proceed by considering some preliminary questions that might be raised about the Unity Thesis. For instance, the thesis presupposes that it is coherent to talk about parts of mental states. I consider objections by Tye and Searle and argue that the notion of an experiential part is unproblematic. In the remaining pages of the chapter, I present the source of the biggest challenge to the Unity Thesis: the data gathered from split-brain subjects. The Unity Thesis is formulated using the notion of a maximal state of consciousness. In the second chapter, I attempt to precisify this notion in a way that does not pre-emptively decide the debate over the Unity Thesis. In informal terms, a maximal state of consciousness is a sum of conscious states that are i) simultaneous, ii) have the same subject, and iii) all have a conjoint phenomenology. I call this the Consensus View. I then consider two unorthodox views that the Consensus View does not take off the table: the views that a "collective consciousness" and a "spread consciousness" are possible. A collective subject is one that can enjoy the experiences of an indeterminate number of "lesser" subjects of consciousness by sharing them together with those subjects. A spread subject is one that can enjoy the experiences of an indeterminate number of lesser subjects of consciousness, but it does so, not by sharing those experiences with the lesser subjects, but by absorbing the lesser subjects of experience into itself, thereby erasing the traditional boundaries between the entities we intuitively think of as subjects of experience. I argue that, although the Consensus View does not decide against them, these views stretch the bounds of coherence and should not, therefore, be accepted. Having presented an account of what maximal state of consciousness is, I define a stream of consciousness in terms of a maximal states of consciousness. In the rest of chapter two, I consider and argue against a number of different ways of interpreting the split-brain data that are either inconsistent with the Unity Thesis or attribute more than one subject of consciousness to split-brain subjects. Among the views I consider are Lockwood's partial-unity view and the views, by theorists such as Sperry, Koch, Puccetti, Marks, and Tye, that split-brain subjects have two non-overlapping streams of consciousness. In chapter three, I consider a recent attempt by Bayne to account for the split-brain data in a way that does not attribute two streams of consciousness to them. According to Bayne's Switch Model, the consciousness of split-brain subjects can be likened to that of a ball that is passed back and forth between the two hemispheres of the upper-brain. The hemispheres take turns supporting a single stream of consciousness. I consider the empirical data in some detail and argue that the data is not as compatible with the Switch Model as Bayne claims. I close the chapter by presenting the rough outline of an interpretation of the split-brain data that is consistent with both the Unity Thesis and the split-brain data. In chapter four, I turn from defending the Unity Thesis to examining an attempt to account for conscious unity. Rosenthal has offered a theory of conscious unity as an extension of his higher-order theory of consciousness. I consider his account of conscious unity in light of a well-known objection to his theory: the (Representational) Mismatch Objection. It can be asked what it is like for a subject of experience when a higher-order state misrepresents its target first-order state. If what it is like for the subject corresponds to the content of the higher-order state, then it appears as though higher-order representation is unnecessary for conscious experience, for it would appear as though it is possible for a state to be conscious without being represented by a higher-order state. If what it is like corresponds to the content of the lower-order state, then it would again seem as though representation at the higher-order level is unnecessary for conscious experience, for the higher-order state would not seem to be doing any work in generating the experience. I consider and argue against two recent defences of Rosenthal's higher-order theory from the Mismatch Objection. Then I turn to Rosenthal's account of conscious unity. Rosenthal's account posits two mental mechanisms. I refer to the ways of accounting for conscious unity via these two mechanisms as the "gathering strategy" and the "common-ascription strategy" respectively. Both of these strategies, I argue, appear to locate the basis for certain phenomenal facts in higher-order representational facts. This raises a prima facie question: does Rosenthal's account of conscious unity land him square within the sights of the Mismatch Objection? Although the gathering strategy may ultimately be understood in a way that does not make it subject to the Mismatch Objection, Rosenthal has certain commitments that bar this strategy from serving as a complete account of conscious unity. This is problematic for Rosenthal, I argue, because his common-ascription strategy faces some difficult questions. This strategy makes conscious unity due to an implicit expectation a subject of consciousness has that, whenever he or she engages in introspection, an explicit sense of conscious unity will be generated. I argue that it is very difficult to see how such an implicit sense could both avoid the Mismatch Objection and do the work it needs to do in order to account for conscious unity. In chapter five, the discussion turns from the unity of consciousness to self-consciousness. The question that is considered in this and the last chapter is the question whether conscious experience is necessarily accompanied by self-consciousness. The affirmative answer to this question I call the Ubiquity Thesis. I spend some time distinguishing robust conceptions of self-consciousness from minimal conceptions of self-consciousness. The notion of self-consciousness invoked by the Ubiquity Thesis is a minimal one. In spite of the fact that the Ubiquity Thesis invokes only a minimal or thin conception of self-consciousness, I believe the thesis to be false and argue against it. In this chapter I take up the views of Husserl. Husserl is often regarded as the progenitor of the phenomenological tradition, a tradition in which many philosophers affirm the Ubiquity Thesis. I examine and argue against an interpretation of Husserl's work, one defended by Zahavi, according to which Husserl could be seen to defend the Ubiquity Thesis. One claim that Husserl makes is that, in order for an object to become the intentional target of a conscious state, it must be given to consciousness beforehand. It is possible, during acts of deliberate introspection, for consciousness to take itself as its object. On Husserl's view, this requires consciousness to be given to itself beforehand. This self-givenness of consciousness, argues Zahavi, can be seen as a kind of minimal self-consciousness. Husserl has also offered an account of this self-givenness of consciousness and it appears in his discussion of inner time-consciousness. I attempt to argue, using some of Husserl's other views regarding psychological stances (or standpoints), that consciousness is not given to itself outside of the adoption of a certain psychological standpoint. I also offer an alternative way of accounting for inner time-consciousness, one that does not have, as a built-in feature, that consciousness always has itself as a secondary object. In the sixth and final chapter, I take up a contemporary defence of the Ubiquity Thesis. Kriegel, a higher-order theorist like Rosenthal, has argued that every conscious state is conscious in virtue of the fact that it represents itself. This self-representation is understood as a kind of self-consciousness and, thus, his theory can be seen as affirming the Ubiquity Thesis. In the first part of the chapter, I take issue with the way in which Kriegel lays out the conceptual terrain. In particular, Kriegel countenances a property he calls "intransitive state self-consciousness." I argue that this way of speaking is confused. I then turn to considering Kriegel's account. Kriegel identifies the species of self-consciousness that pervades all of conscious experience with a peripheral awareness of one's own mental states. I argue that such a peripheral inner awareness does not accompany all of our mental states and, thus, that Kriegel's views do not give us reason to accept the Ubiquity Thesis.

A gene x environment interaction exists in the expression of anxiety for both human and nonhuman primates, such that individuals who are carriers of the (s) allele of the serotonin transporter genotype ( 5-HTT LPR) and exposed to early life stress are more at risk for exhibiting anxiety. The hypothalamic-pituitary-adrenal (HPA) axis has also been implicated in anxiety disorders but the relationship between early life/genotype, HPA activity, and anxiety is not well understood. Further, studies linking the HPA axis to anxiety have relied on "point" samples (blood and salivary cortisol) which reflect moments in time rather than long-term activity. The purpose of this dissertation was three fold: (1) to examine anxious behavior in monkeys with different 5-HTT LPR genotypes and rearing environments across the first two years of life, (2) to compare long-term HPA activity (as measured with hair cortisol) with acute HPA activity (as measured with salivary cortisol) in the same period, and (3) to determine which measure of HPA activity predicts anxiety and/or mediates the rearing/genotype influences on anxious behavior. Infant rhesus monkeys ( Macaca mulatta , N=61) were mother-peer-reared (MPR, n=21), peer-reared (PR, n=20), or surrogate-peer-reared (SPR, n=20) for 8 months, then all relocated into a large social housing situation for the next 18 months. Monkeys were genotyped for 5-HTT LPR and hair and saliva samples were collected for cortisol analysis at months 6, 12, 18, and 24. Behavior was recorded twice per week per subject from 2-24 months and analyzed for the duration of anxiety, social play, and grooming. Regression analysis established predictors of these behaviors. Rearing condition and sex were significant predictors of anxiety across the two years, and HPA activity added significant predictive power in the first six months only. Mediation of the rearing/anxiety relationship by the HPA axis was not evident. Interestingly, hair (but not salivary) cortisol early in life was positively correlated with later anxious behavior. These findings demonstrate the detrimental effects of adverse early life experience on behavioral development and shed light on the interplay between environment, adrenocortical activity, and anxiety. They further demonstrate the usefulness of a long-term measure of HPA activity in predicting later behavior.

Previous research using violation-of-expectation paradigms suggests that very young infants have a good understanding of unobserved physical events. Yet toddlers appear to lack this knowledge when confronted with the door task, a visuospatial reasoning task which parallels ones used in the habituation/looking time studies. Many studies have been conducted in an effort to determine why toddlers perform poorly on the door task yet the answer remains unclear. The current study used a correlational approach to investigate door task performance from both psychological (executive function), and neuroscience (prefrontal cortex) perspectives. Children between the ages of 2 ½ - 3 years were tested on the standard door task as well as four other tasks. Three of the tasks were believed to activate prefrontal cortex: the three boxes-stationary, a spatial working memory task; the three boxes-scrambled, a non-spatial working memory task; and the three pegs task, an inhibitory control task. The fourth task was a recognition memory task which had been previously linked to the medial temporal lobe. Only a single task, the three pegs task, was found to correlate with door task performance (r = .510, p

Traumatic brain injury (TBI) is a leading cause of disability in the United States (Coronado et al., 2011). There is a recognized need for better motor assessments to help mitigate these disabilities. Advances in markerless motion capture and in magnetic resonance imaging (MRI) provide an opportunity to improve clinical assessments, and link them to damage measured in MRI scans. The primary aims of this research were to 1) develop a quantitative motor assessment (QMA), and seed a normative database to enable comparison of impaired behavior to unimpaired, 2) test the sensitivity of the QMA, and 3) link QMA results to underlying TBI damage.The QMA developed in Aim 1 consisted of five tests: finger oscillation, tremor, visually guided movement, reaction time, and balance. We administered the QMA and traditional analgous tests to 132 healthy 18-50 year olds. We later added a coginitive motor integration (CMI) test and a stength-dexterity pinch test, then administered them to 31 (16 male, mean age = 24.7) healthy individuals. We seeded a normative database for the QMA and CMI measures. (A normative database for the pinch test already exists.) Correlations between the QMA and traditional tests were weak but the QMA results followed expected trends.In the second aim, 31 (16 male, mean age = 24.7 years) individuals with TBI completed all of the motor tests, and age- and gender-matched controls completed the CMI and pinch tests. We tested the sensivity of the QMA, the CMI and pinch tests, and traditional tests by their ability to correctly identify TBI subjects based solely on test results. The QMA was more sensitive than the other test groups. In Aim 3, we performed a stepwise regression to evaluate the relationship between motor deficits and brain injury, using motor test results and MRI images from the TBI and control groups. We found significant relationships between deficits in precision and increases in superior lateral ventricular volumes, deficits in pointing tasks and decreases in fractional anisotropy (FA) in the corticospinal tract, deficits in rhythmicity during finger oscillation and decreased FA in the thalamocortical tract. There were also relationships between each of the motor deficit measures and the FA values in the corpus callosum. This was the first step in showing that a quantitative motor assessment using markerless motion capture is feasible. The QMA is sensitive and can be linked to underlying brain damage. Though the QMA is not yet ready for clinical use, this research provides insights that will help address gaps in TBI rehabilitation.

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