The human microbiome and its role in the ‘brain-gut’ bi-directional axis are becoming increasingly relevant to our understanding of the effects of gastro-intestinal microbiota on brain development ...and on various neurological diseases. One protein that may mediate the effects of this brain-gut axis is brain-derived neurotrophic factor (BDNF). BDNF is found not only in the brain but also in peripheral tissues. BDNF is essential in learning and memory through stabilization of long-term potentiation (LTP). Research has shown that its expression levels have been found to be greatly affected by diet and exercise. In events such as aging, decreased levels of BDNF has been associated with cognitive decline and increased susceptibility to neurodegenerative diseases such as Alzheimer’s disease (AD). This study aims to explore how the human microbiome maintained in a Western diet (high protein, high fat, high carbohydrate), affects BDNF expression and its levels in the ‘brain-gut’ bi-directional axis. Understanding BDNF and its relation to the brain-gut axis may prove invaluable towards further research to prevent the cognitive decline that comes with decreased BDNF expression.In this project, we compared BDNF and its precursor, proBDNF, levels in the brain, jejunum, and distal colon of mice. The mice used were necropsied at either three or six months and were either on a normal or high fat diet. Protein levels were stained and analyzed using MANOVAs, correlations, and regressions to observe any statistically significant relationship between the two proteins in their tissue location of origin. The results confirmed the hypothesized: proBDNF increased with age and was higher in a high fat diet versus a normal diet, while BDNF decreased with age. There was also a strong, positive correlation found between brain proBDNF and brain BDNF.These results suggest an intricate, yet complex relationship between proBDNF and BDNF and that proBDNF may play a significant role in gut dysbiosis. On this basis, future studies need to be done to further understand this relationship in the brain-gut axis. An important focus looking at the vagus nerve and these proteins and their high-affinity receptors, TrkB and p75, will uncover key information that will aid in preventative medicine for cognitive decline and neurodegenerative diseases.
Severe Weather Phobia is the excessive and unreasonable fear or anxiety regarding severe weather events. Literature on this topic is largely limited to case studies and no study has aimed to document ...potential maintenance factors. Utilizing models from other anxiety disorders, worry and attention biases may be investigated as potential maintenance factors. The current investigation aimed to determine whether attention biases towards pictorial (Study 1) and written (Study 2) stimuli are present within severe weather anxiety. Study 1 also aimed to evaluate whether engaging in worry regarding an upcoming severe weather event modulates attention biases using event related potentials. Results of Study 1 indicated that engaging in worry did result in increased anxiety regarding an upcoming severe weather threat; however, this increase in anxiety was present in those with and without elevations in trait severe weather anxiety. This study failed to observe any attentional biases within severe weather anxiety. Similarly, no attention biases were observed in Study 2. Overall, results of Study 1 and 2, generally, failed to support hypothesized attention biases to both pictorial and written stimuli. These results could suggest that those with severe weather anxiety do not present attentional biases similar to those observed in other anxiety disorders; however, a potentially more likely explanation is that the valance, arousal, and intensity of the stimuli presented in the paradigms were not robust enough to elicit an anxious response or bias in attention. A wider variety of severe weather stimuli should be investigated to determine which stimuli and at what intensity results in attention biases, increases in state anxiety, and psychological arousal. Once stimuli are developed, investigations into their impact on executive function and psychophysiology can be pursued.
Depth perception is essential for safe and effective mobility. When an observer moves through an environment, the retinal images of surrounding objects shift in the field of view, creating motion ...parallax, which can be used to infer the depths of the objects. When an observer walks forward to approach an object, the image of the object expands in the field of view, inducing expansive motion parallax; when the motion direction of the observer contains a lateral component, the object image shifts laterally to the left or right, which is termed lateral motion parallax. This thesis investigates three questions regarding the effect of motion parallax on depth perception for people with intact and artificially reduced acuity: whether motion parallax increases depth perception accuracy compared to static viewing with pictorial depth cues present; whether expansive and lateral motion parallax differs from each other in assisting depth perception; and whether continuous motion provides more benefit to accurate depth perception than object image displacement. To control the level of acuity loss, the participants included in this thesis were normally sighted, and the acuity reduction was simulated with digital filters or blur goggles.Chapter 1 provides an overview of the three experiments described in the thesis. In all three experiments, the participants looked at two objects in a virtual or physical scene and estimated the depth separation between the objects either by moving a slider on the screen or by verbal report. Chapters 2 and 3 focus on the effect of visual signals from motion parallax. The results show that when estimating object depth in a virtual scene on a computer screen, for participants with both intact acuity and artificially reduced acuity, the accuracy in the static viewing condition was low, lateral motion parallax yielded higher accuracy than expansive motion parallax, and the continuous motion was more beneficial than discrete object image displacement. Chapter 4 examines the effect of motion parallax for observers who walked in a physical space. The accuracy of depth estimation for static viewing in the physical space was higher than that in the virtual space, and the effect of observer motion was weaker. Lateral motion parallax only increased the accuracy of depth estimation when the acuity reduction was severe and the pictorial cues in the scene were manipulated to be misleading.While motion parallax is an important source of depth information in a scene presented on a screen, in the physical world, pictorial cues may often be sufficient for estimating the depth of objects, reducing the importance of motion parallax. Further investigations are needed to evaluate the importance of motion parallax for people with impaired vision.
This clinical case study centers on integrating self-guided MDMA experiences in addressing treatment-resistant post-traumatic stress disorder (PTSD). The subject-client of the study was a clinical ...psychologist who experienced complex trauma within her family throughout her early childhood.The literature review describes the evolution of the PTSD diagnosis and the various approaches taken to address the unexperienced experience at the heart of PTSD. The final section reviews the literature on MDMA-assisted protocols and their huge leap forward in efficacy over previous treatments for PTSD.The psychotherapy with the case subject-client lasted for just over a year, during which time she prepared for and integrated three experiences with MDMA. She self- organized these, without therapist presence, within the first six months of the work. After these experiences, the therapy continued so that she could help further integrate the insights and breakthroughs of those self-organized sessions.With the assistance of MDMA and reviewing these experiences, she expanded her capacity to be connected to and process the overwhelming experiences of her childhood. She was able to shift her identity from a pathological view (where she saw herself as broken) to a mythological one (where she saw how the healing of her trauma had enabled her authentic power).A key learning in this clinical case study was that the intersubjective element of the therapeutic process was vital in supporting the client to connect with walled-off parts of herself; and that this element, at the time of writing, was not substantially developed in current protocols for integrating experiences with MDMA.The client’s work in therapy has been interpreted in this clinical case study through the lens of the Parsifal myth. Like Parsifal, her single-minded goal for many years was an escape from pain and a quest for longing. By the end, she understood that the sensitivity that had been a source of such pain for her as a child was a gift that she had honed during her quest. With the frame of post-traumatic growth, it was possible for her to see her recovery from trauma as a meaningful process.
Communicating our experiences to others relies on complex shared social, cultural, and psychological mechanisms. Research increasingly shows that shared neural mechanisms also play a role in the ...success of interpersonal communication. Synchronous activity in shared or complementary regions of the brain promotes emotional connections, cooperation, and memory between communicators. Regions of the brain involved in social and self-relevant information processes – (1) mentalizing, or thinking about the thoughts of others, and (2) self-relevance, or prospecting about the importance of information to the self – show synchrony in ways that correlate with communication outcomes. Synchrony can occur between two individuals, like speakers and their listeners, but it can also occur among a group of listeners, the audience. We use a form of neuroimaging called functional near-infrared spectroscopy to study neural activity as people tell and hear stories. First, we measure synchrony between storytellers and listeners. Chapter 2 shows that synchrony in mentalizing brain regions between a storyteller and her listeners predicts effective communication of emotional states. Next, we consider how synchrony across larger groups of audience members relates to successful communication. Chapter 3 demonstrates that an individual listener's similarity to the average brain response in other audience members, in self-relevance processing regions, predicts the listener's ability to authentically re-tell a story. Finally, extending this work, we also examine whether shared preferences predict neural synchrony in audience members. Chapter 4 integrates information about audience members’ individual preferences for content with audience-level neural synchrony. Within audiences of sports fans and theater lovers, self-reported content preferences predict behavioral liking for entertainment, but neural synchrony does not predict similar preferences in this case. Together these studies explore how synchrony between individuals predicts understanding and ability to transmit stories.
Alcohol use disorder (AUD) is a disease in which a person consumes copious amounts of alcohol even without the desire to do so. This disorder’s severity on decision-making tasks has been studied with ...majority male subjects. To examine the impact on flexible decision-making skills, probabilistic reversal learning tasks are often used to test cognitive flexibility. Although existing studies have studied effects on reversal learning in rodents as well as using other types of debilitating substances/lesions, this study has been adapted to probabilistic measures using mice models for chronic alcohol consumption and to evaluate sex differences. Using a Med Associates operant box, 36 male and 36 female mice were food-deprived and tested using a multiple reversal (MR) behavioral task in which they must respond to a nose port with the highest probability of reinforcement. After a round of initial testing, half of the mice were administered 10% alcohol + 0.1% saccharin, while the other half (control group) received only 0.1% saccharin for 24 days and then tested once more. The male and female mice were analyzed separately to account for sex differences in alcohol effects. The number of reversals and the probability of choosing the nose port with the highest reinforcement (p(Correct)) were found to be significantly diminished in the male mice that received alcohol and found there to be no significant effect in the female mice. This study has concluded that there is a significant effect of sex in decision-making skills which amplifies the notion that both male and female subjects should be included in future research studies.
Heightened reactivity to uncertain threats (U-threats) has emerged as a transdiagnostic marker of internalizing psychopathologies (IPs) as evidenced by increased startle responses. A developing ...theory and recent research also suggest that heightened reactivity to U-threats may be an important individual difference factor that facilitates excessive drinking as a means of avoidance-based coping and characterizes individuals with current and past alcohol use disorder (AUD). Previous studies have used fMRI to identify the neural correlates of heightened responses to U-threat and consistently observed increased activation in the anterior insula (AIC), anteromedial (AM) thalamus and dorsal anterior cingulate cortex (dACC); however, no study to date that we are aware of has examined directional information flow between these regions, which was the primary aim of our study. Specifically, the current study aimed to understand how these three regions function as a network during anticipation of U-threat (and predictable threat/P-threat) in IP and AUD. Towards this goal, functional magnetic resonance imaging (fMRI) and dynamic causal modeling (DCM) were used to study inter-regional effective connectivities (ECs) and U- (and P-) threat-related modulations thereof within this network in two study samples. The first included a heterogeneous, transdiagnostic IP sample and a group of healthy controls (without any psychopathology). The second included groups of individuals with and without AUD diagnosis within the past two years who were otherwise matched on the rates of IPs. Within each study sample, parametric empirical Bayesian (PEB) modeling was used to conduct between-group differences in modulatory changes of ECs during U-threat and P-threat trials. In addition, we conducted exploratory analyses to determine whether any of the observed modulatory changes of ECs were associated with individual differences in anxiety and depressive symptoms (Study 1) or average weekly alcohol consumption in the past month (Study 2). Two main findings emerged: (Study 1) During U-threat trials, the right AM thalamus was more inhibited by the right AIC in individuals with IP relative to healthy controls; this directional influence was more prominent among participants who endorsed greater depressive, but not anxiety, symptoms; (Study 2) During U-threat trials, compared to the control group, the right AIC was more excited by the right AM thalamus in the AUD group; this directional influence was stronger among individuals who on average consumed more drinks per week. As expected, we found no group differences in modulatory changes of ECs during P-threat trials in either study sample. To our knowledge, this is the first study to examine directional interactions between key frontolimbic regions during anticipation of U-threat (and P-threat) and demonstrate the importance of top-down and bottom-up thalamic-insular projections during U-threat processing in IP and AUD, respectively. Prospective studies are warranted to examine causal pathways and establish temporal precedence.
This project has two aims. The first is to draw attention and focus on a highly consequential assumption of recent cognitive science. Mental Sentence Corollary: Some mental processes of the ...cognizer’s cognitive-computational architecture operate uniformly over inputs that have a sentential structure: the content sentences of propositional attitudes sentences.I call this assumption the Mental Sentence Corollary. It underlies the core theoretical commitments of the Computational Theory of Mind. I will show how this unsuspected assumption generates what is known as the Problems of Relevance for our memorial processes: Belief projection, belief expansion, and belief revision. The second aim of this project is to provide a toy model of human semantic memory that eschews the Mental Sentence Corollary, especially as it applies to storing "sentences in the head". I call it the 'Graph Theoretical Model for Human Semantic Memory'. In sketching this model I remonstrate against the sentential account of information storage by propounding a theory of human semantic memory based on the idea that memory works by structuring and organizing information in a non-sentential, lexical, graph-theoretic manner. Moreover, I show how one can remain a proponent of the Computational Theory of Mind, even if one does not suppose a sentential account of information storage.
Bystanders of cyberbullying behavior committed by close friends have an array of circumstances to consider when deciding the most appropriate action to the conduct they are witnessing. The purpose of ...this study was to gain an understanding and in-depth knowledge about the experiences and perceptions of bystanders who witness cyberbullying behavior. The guiding research question was What are the experiences and perceptions of college bystanders who witness friends engaging in cyberbullying? The bystander effect theory (BET) was utilized to focus attention on the experiences of bystanders through which decisions to intervene or not were taken into consideration, given the magnitude of conduct occurring among peers. A generic qualitative research design was utilized to explore and understand this phenomenon. Research shows that qualitative approaches of more in-depth descriptions are necessary to understand the phenomenon and decide whether it is a significant issue among multiple locations and backgrounds. The participants of this study consisted of 18–25-year-old, English-speaking, active college students. The drawn sample was derived from a population that lived in the SouthAtlantic region of the United States. The data collected was derived from 11 participants who were of African American, European American, Middle Eastern, and Mixed descent. Participants engaged in semi-structured interviews with seven open-ended questions. That data obtained from interviewees was analyzed using the inductive, thematic analysis with the constant comparison,which produced common themes and patterns following the transcripts. The five themes that emerged from the study were: (a) decision making is a daunting process, (b) bystanders share victim responsibility, (c) bystanders are essential to minimizing cyberbullying, (d) social media is identity important, and (e) bystanders are unaware cyberbullying was occurring. The significant findings gathered from the study indicated that bystanders of friends who engage in cyberbullying have some correlation that perpetrator relationships drive bystander reaction.
Despite researchers’ best efforts, it still is unclear whether researchers and practitioners can feel comfortable randomizing survey items because of its inconsistent impact on psychometric ...properties. Using moderated non-linear factor analysis, the present study explored whether randomization, construct strength, and differences in conscientiousness and neuroticism affected respondents’ survey responding behavior to randomized and grouped versions of a communication anxiety measure. Randomization did not affect how respondents interpreted the measure’s content but did affect how they responded to matrix items that appeared next to repeated response scales. Construct strength positively predicted factor level differences, with respondents who reported feeling more certain in their answers and finding them more accessible reporting higher levels of communication anxiety and responding with greater variability. Lastly, respondents higher in conscientiousness and neuroticism were more susceptible to randomization than their counterparts, evidenced by more factor- and item-level differences. Taken together, these findings suggest researchers can randomize items without fear of affecting how respondents interpret the measure’s content. Nevertheless, randomization and grouping artificially inflated and attenuated respondent scores, respectively, calling into question the reliability of diagnoses for respondents who fall near clinically significant thresholds. Thus, I encourage researchers and practitioners to consider administering question formats besides matrices, especially those interested in using absolute scores. Ultimately, the present study emphasized the importance of considering how all survey design features can affect survey responding behavior.
