The superior cervical ganglion (SCG) is the largest of the sympathetic chain ganglia which control a number of autonomic cardiovascular reflexes via neural activity in the postganglionic nerve trunk. In addition to the large principal neurons, these ganglia contain a minority population of smaller cells, the small intensely fluorescent or SIF cells, so named because of their intense fluorescence following treatments which reveal the presence of endogenous catecholamines (mainly dopamine in the rat). The physiological functions of the SIF cells are largely unknown and various roles have been proposed including (i) dopaminergic interneuron, which modulates ganglionic transmission, (ii) endocrine function, since many of them have a close association with the vasculature and (iii) chemosensory function, similar to that of the arterial chemoreceptors which sense blood gases and pH. Understanding the physiological role of SIF cells has been hampered by their small size, sparse distribution and relative inaccessibility, all of which render microelectrode electrophysiological studies difficult. In this thesis these limitations were overcome by use of (i) dissociated cell cultures of the rat SCG, in which growth conditions favoured SIF cell survival but not that of the principal neurons, and (ii) the novel high resolution patch clamp/whole cell recording technique which is ideal for the study of the electrophysiology of small cells. The ionic currents, which underlie many basic electrophysiological processes, were characterized in 5-16 day old cultures of SIF cells obtained from the SCG of neonatal rats. The main methodology consisted of whole cell recording under voltage clamp conditions, which permit the study of membrane ionic currents. Five main ionic currents were identified in all of the SIF cells ( > 100) studied: (i) a fast transient inward Na+ current, sensitive to the well-known blocker of voltage-gated Na+ channels i.e. tetrodotoxin or TTX; (ii) the delayed rectifier outward K+ current that is found in a variety of cell types; (iii) a Ca2+- activated outward K+ current, sensitive to Ca2+ channel blockers; (iv) a transient inward Ca2+ current which appears to be carried by N-type Ca2+ channels and (v) a slower, sustained inward Ca2+ current which appears to be carried by L-type Ca2+ channels. In addition a third type of outward K+ current, the fast transient K+ current or lA, was found in SIF cells obtained from 3-7 day old rats, but not from 1 day old rats. It therefore appears that this lA current, which is known to modulate firing frequency in neurons develops rapidly in vivo during the first postnatal week. This broad repertoire of ion channels in SIF cells suggests several possible sites for modulation by various agents including neurotransmitters, neuromodulators, or other chemosensitive agents. Since SIF cells were recently proposed to have arterial chemoreceptor function similar to glomus cells, the effect of one such stimulus, i.e. an acidic (intracellular) pH, was tested. It has recently been suggested that a decrease in intracellular pH is part of the pathway responding to extracellular stimuli in the glomus cell (Stea, Alexander and Nurse, in press). Acidification of the SIF cell's cytoplasm with the K+/H+ ionophore nigericin resulted in a suppression of both the fast inward Na+ current as well as the outward K+ current. However, these effects do not appear to beunique to SIF cells and therefore the possibility of a chemoreceptor role m the cardiovascular system requires further study. In summary, the characterization of the various ionic currents in SIF cells resulting from this thesis provides the necessary background which should eventually resolve not only the question of the physiological role of SIF cells in autonomic ganglia, but also help to understand the underlying mechanisms responsible for SIF cell function. / Thesis / Master of Science (MS)

The present study investigated the effects of meditative practices on the regulation of autonomic function. 74 subjects (38 women; 36 men) comprised from a range of experienced and non-experienced meditators, engaged in a series of psychophysiological tasks designed to generate specific autonomic states. Regression analyses revealed that experienced meditators, as predicted, displayed greater suppression of myocardial reactivity during a highly reflexive and stressful task. Meditative practice also predicted a rise in electrodermal activity during a relaxation task, contrary to expectations. These results support the concept that meditative practices may alter aspects of autonomic function. Further, these results inform an emerging mind-body paradigm and illustrate the potential consequences of meditative practices in specific disease states and prevention. / Ph. D.

Anxiety and its cognitive component of worry have been related to exaggerated cardiovascular reactivity and delayed recovery to laboratory stressors, and to increased risk of cardiovascular disease. Previous research on the anxiety-cardiovascular system relationship, including data from Knepp and Friedman (2008), are included to support this project. Two experiments were completed during the course of this study. The first consisted of two peripheral-based body positioning tasks. The second experiment used an active versus passive sympathetic stress task paradigm (mental arithmetic, hand cold pressor). Subjects were nonsmokers free of cardiovascular and neurological disease. Trait worry was examined through the Penn State Worry Questionnaire (PSWQ). Blood pressure recordings and cardiac recordings through ECG and ICG were done in each experiment during seven epochs: an anticipatory baseline with three baselines preceding and three recovery periods following each task. Repeated measures analysis was run on all cardiovascular measures. In the first experiment, high worriers had worsened blood pressure reactivity to task. The second experiment found that high worriers had increased stroke volume across all epochs. There were mixed findings in the studies relating to subjects acclimated to the laboratory experience. Future directions of research relating anxiety, worry, and cardiovascular risk factors are discussed. / Ph. D.

Research on the autonomic specificity of emotion has spanned several decades. Even though considerable evidence exists for supporting autonomic specificity for discrete emotion states (Kreibig, 2010), there is still an active debate, and conflicting explanations, for these findings (Quigley and Barrett, 2014). There have been several studies employing multivariate pattern classification analytic techniques and calls for those types of studies are still prevalent (Kragel and LaBar, 2014). Although many studies have explored the autonomic specificity of emotions, few have explored what effects the induction methods, themselves, have had in inducing the autonomic change. Autonomic specificity of induction methods might be a meaningful, and confounding, phenomenon in this literature. Based on this unknown variable, the current experiment was designed to see if methods for emotion elicitation could be meaningfully captured by these same pattern classification techniques. This was accomplished using three separate emotion-elicitation methods to elicit five separate emotions. A sample of 64 college-aged students watched film clips, read imagery scripts, and recalled personal memories for five discrete emotions. Using discriminant analysis, the evidence from the current study lent less support for autonomic specificity of emotion than past experiments, and lends some support for providing future exploration into autonomic change that is related to methods for induction. Potential confounds and task fatigue effects are discussed. / Ph. D.

Autism Spectrum Disorders (ASD) are an urgent health concern as new reports indicate approximately 1 in 110 children are affected by ASD (Centers for Disease Control and Prevention, 2009). Although children with ASD struggle with social interactions, quantitative meta-analyses have revealed that traditional social skill interventions only produce minimal effects (Bellini, Peters, Benner, & Hopf, 2007). Due to these minimal effects, this study diverged from the common understanding of social skill deficits and introduced an autonomic nervous system circuit as one root of social behavior problems. Children with ASD show a "fight-flight" (i.e., sympathetic) state at baseline and to unfamiliar individuals (e.g., Bal et al., 2010). Research indicates, however, that music has the ability to calm cardiovascular functioning (Iwanaga, Kobayashi, & Kawasaki, 2005) and improve social behaviors in children with ASD (Whipple, 2004). This study recruited participants (N = 23) between 4-7 years old with a previously diagnosed ASD. Each participant was assigned to a Music group, n = 11, or an Audiobook group, n = 12. The 90-minute experimental session consisted of a receptive vocabulary assessment and psychophysiological monitoring during a baseline video, social engagement task, listening period, and a recovery video. A soothed autonomic state was measured by increased high frequency heart rate variability and decreased heart rate. Results indicated a significant soothing effect for the Music group. Moreover, the Music group evidenced a significant increase in social attention (e.g., joint attention and sharing emotions) relative to the Audiobook group. Mediation analyses may reveal partial mediation for the soothed autonomic state on the relationship between group and social attention improvements. Thus, these results suggest that social skill interventions may not be targeting a core element of social deficits (i.e., over-aroused autonomic state). / Master of Science

The autonomic specificity of emotion is intrinsic for many major theories of emotion. One of the goals of this study was to validate a standardized set of music clips to be used in studies of emotion and affect. This was accomplished using self-reported affective responses to 40 music pieces, noise, and silence clips in a sample of 71 college-aged individuals. Following the music selection phase of the study; the validated music clips as well as film clips previously shown to induce a wide array of emotional responses were presented to 50 college-aged subjects while a montage of autonomic variables were measured. Evidence for autonomic discrimination of emotion was found via pattern classification analysis replicating findings from previous research. It was theorized that groups of individuals could be identified based upon individual response specificity using cluster analytic techniques. Single cluster solutions for all emotion conditions indicated that stimulus response stereotypy of emotions was more powerful than individual patterns. Results from pattern classification analysis and cluster analysis support the concept of autonomic specificity of emotion. / Master of Science / [Appendix B: Beck Depression Inventory, p. 61-64, was removed Oct. 4, 2011 GMc]

Ego-resiliency (ER) is a trait that describes the ability to cope with stress, while effortful control (EC) is an individual difference related to the ability to optimally inhibit negative emotion through attentional mechanisms. ER has been linked to flexible cardiovascular responding without accounting for autonomic nervous system origins of physiological responses. Similarly, EC tends to be associated with increased cardiac vagal control. However, differences in the autonomic characteristics of these constructs remain unclear. In the current study, it was hypothesized that compared to low-scorers, individuals who score high on ER and EC will each have greater vagal control and less sympathetic control over interbeat intervals (IBI) changes during laboratory stressors. Subjects engaged in a mental arithmetic, speech preparation, and verbal fluency task to elicit cardiovascular activation along a continuum of threat. Electrocardiography and impedance cardiography were collected before, during, and after these tasks to assess changes in autonomic functioning. Results from multiple regression analyses indicated that high levels of EC predicted increased vagal control over IBI recovery and less sympathetic reactivity of IBI reactivity. Contrary to predictions, ER showed an opposite pattern of autonomic regulation across stressors. / Master of Science

Interoception, the perception of the body's physiological state, is often studied in relation to emotion processing. Particularly, cardioception has been largely implicated in anxiety. Three related but distinct dimensions of interoception have recently emerged in the literature: sensibility (IS), accuracy (IAC), and awareness (IAW). Divergent findings regarding interoception and anxiety may result from lacking appreciation for interoceptive dimensions. Additionally, the role of cardiovascular afferent feedback in anxiety and interoception is largely unknown. Baroreflex sensitivity (BRS) has been implicated in interoceptive processes yet no known research directly measures this in relation to multidimensional cardioception. The present study aimed to assess the degree to which IS, IAC, IAW, and BRS predict trait anxiety at rest and during anticipatory anxiety. Results partially suggest increased IAC and BRS, but more variable IS and IAW in relation to trait anxiety. Overall, results show complex associations among factors, suggesting increased specificity among the constructs. Results highlight the importance of attention to construct validity and method variance in the study of interoceptive subdomains. Finally, the present study helps to pave the way for continued investigations concerning cardioception in enduring anxiety and the related role of the baroreflex in cardiac afferent processes. / PHD / Interoception, the perception of the body’s physiological state, is often studied in relation to emotion processing. Particularly, cardioception (the sense of cardiac activity, such as the perception of a racing heart) has been largely implicated in anxiety. Three related but distinct dimensions of interoception have recently emerged in the literature: sensibility (IS), accuracy (IAC), and awareness (IAW). Divergent findings regarding interoception and anxiety may result from lacking appreciation for interoceptive dimensions. Additionally, the role of cardiovascular feedback to the brain in anxiety and interoception is largely unknown. The baroreflex system rapidly modulates activity of the heart in accordance with short-term blood pressure changes. The sensitivity of this homeostatic baroreflex system (BRS) also plays a role in interoceptive processes, yet no known research directly measures this in relation to multidimensional cardioception. The present study aimed to assess the degree to which IS, IAC, IAW, and BRS predict dispositional anxiety at rest and during anticipatory anxiety. Results partially suggest increased IAC and BRS, but more variable IS and IAW in relation to dispositional anxiety. Overall, results show complex associations among factors, suggesting increased specificity among the variables. Results highlight the importance of attention to measurement precision and various ways to assess the dimensions of interoception. Finally, the present study helps to pave the way for continued research concerning perception of the heart’s activity in enduring anxiety and the related role of cardiovascular activity at various levels of conscious awareness. Ultimately, research on this topic is highly important for the eventual improvement of existing therapeutics for individuals regularly experiencing severe anxiety.

The dynamic behaviors of a complex organism are explained via voluntary and involuntary action. One underpinning of this system is organized and facilitated by the autonomic nervous system, integrating information from conscious and non-conscious centers in a seemingly hierarchical fashion. As a result, voluntary actions have the ability to inhibit reflexive actions via an inhibitory circuit. 111 subjects performed four diverse autonomic tasks consisting of voluntary and involuntary combinations. Analysis supports the proposed hierarchical model. Each task evoked specific autonomic states. Voluntary tasks influenced autonomic actions more than involuntary tasks. And working memory capacity mediated voluntary control. / Master of Science

The present study investigated autonomic nervous system (ANS) patterning during experimentally manipulated emotion. Film clips previously shown to induce amusement, anger, contentment, disgust, fear, and sadness, in addition to a neutral control, were presented to 34 college-aged subjects while electrodermal activity, blood pressure and electrocardiogram (ECG) were recorded as was self-reported affect. Mean and mean successive difference of inter-beat interval were derived from the ECG. Pattern classification analysis revealed emotion-specific patterning for all emotion conditions except disgust. Discriminant function analysis was used to describe the location of discrete emotions within a dimensional affective state space, for both self-report and ANS activity. Findings suggest traditional dimensional emotion models accurately describe the state space for self-reported emotion, but may require modification in order to accurately describe the state space for ANS activity during discrete emotions. Proposed modifications are consistent with the adoption of a discrete-dimensional hybrid model as well as current trends in emotion theory. / Master of Science