Master of Science

thesisThis thesis discusses the development of an olfactory display for the University of Utah TreadPort Virtual Environment (UUTVE). The goal of the UUTVE is to create a virtual environment that is as life like as possible by communicating to the user as many of the sensations felt in moving around in real the world as possible, while staying within the confines of the virtual environment's workspace. The UUTVE has a visual display, auditory display, a locomotion interface and wind display. With the wind display, it is possible to create an effective olfactory display that does not have some of the limitations associated with many of the current olfactory displays. The inclusion of olfactory information in virtual environments is becoming increasingly common as the effects of including an olfactory display show an increase in user presence. The development of the olfactory display for the UUTVE includes the following components: the physical apparatus for injecting scent particles into the air stream, the development of a Computational Fluid Dynamics (CFD) model with which to control the concentration of scent being sensed by the user, and user studies to verify the model and show as proof of concept that the wind tunnel can be used to create an olfactory display. The physical apparatus of the display consists of air atomizing nozzles, solenoids for controlling when the scents are released, containers for holding the scents and a pressurized air tank used to provide the required air to make the nozzles work. CFD is used model the wind flow through the TPAWT. The model of the wind flow is used to simulate how particles advect in the wind tunnel. These particle dispersion simulations are then used to create a piecewise model that is able to predict the scent's concentration behavior as the odor flows through the wind tunnel. The user studies show that the scent delivery system is able to display an odor to a person standing in the TPAWT. The studies also provided a way to measure the time it takes for a person to recognize an odor after it has been released into the air stream, and also the time it takes for a user to recognize that the odor is no longer present

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 127, April 1974

This special bibliography lists 279 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1974

Behavioral biology of mammalian reproduction and development for a space station

Space Station research includes two kinds of adaption to space: somatic (the adjustments made by an organism, within its lifetime, in response to local conditions), and transgenerational adaption (continuous exposure across sequential life cycles of genetic descendents). Transgenerational effects are akin to evolutionary process. Areas of a life Sciences Program in a space station address the questions of the behavioral biology of mammalian reproduction and development, using the Norway rat as the focus of experimentation

Aerospace Medicine and Biology: A cumulative index to the 1974 issues of a continuing bibliography

This publication is a cumulative index to the abstracts contained in supplements 125 through 136 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes three indexes--subject, personal author, and corporate source

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 119, September 1973

This special bibliography lists 213 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1973

Descending control of locomotion in the lamprey

Locomotion underlies a dynamic interplay of a basic motor pattern that is generated by spinal neural networks, descending control originating from supraspinal structures, and sensory feedback from the periphery. Locomotion usually occurs intermittently and thus, it must be initiated, maintained, and eventually stopped. Over the past decades, the lamprey has been used as an experimental model to define the cellular mechanisms controlling locomotion in vertebrates. In this model, spinal central pattern generators (CPGs) have been characterized and shown to generate rhythmic muscle contractions needed for body propulsion. The spinal CPGs are controlled by brainstem reticulospinal (RS) neurons, which are activated by upstream brain structures, such as the mesencephalic locomotor region (MLR). The MLR initiates and controls locomotion in a graded fashion and plays a role in goal-directed locomotion. Its activity is in turn controlled by forebrain structures, such as the basal ganglia. The focus of my thesis was to examine descending projections from forebrain structures to the MLR as well as MLR projections to different RS cell populations in the lamprey lower brainstem. For this, electrophysiological, neuroanatomical, Ca2+ - imaging, and behavioral experiments were performed. In vertebrates, forebrain dopaminergic neurons of the substantia nigra pars compacta (SNc) are classically described to send ascending projections to the striatum, the input structure of the basal ganglia. In a first study (Ryczko et al., 2013), we identified in the lamprey a previously unknown descending dopaminergic pathway from the posterior tuberculum (PT; the homologue structure to the mammalian SNc) that directly innervates the MLR. Experiments were performed in semi-intact preparations, in which cellular activity can be correlated to active swimming movements of the intact body. It was demonstrated that electrical PT stimulation elicits RS cell activity as well as motor behavior. Both RS cell activity and locomotor output were significantly increased when dopamine was injected locally into the MLR. On the other hand, local injections of a D1 receptor antagonist in the MLR dramatically decreased RS cell activity and locomotor activity. It was concluded that this descending dopaminergic pathway provides extra excitation to the MLR and consequently increases the locomotor output. It was thought that this newly identified dopaminergic pathway acts in parallel with a descending glutamatergic pathway from the PT to the MLR. In a second study (Ryczko et al., 2017), the glutamatergic projection was examined in detail. One important finding was that the PT controls MLR activity and consequently the locomotor speed in a graded fashion: increasing stimulation intensity of the PT leads to increasing MLR cell activity and locomotor speed. Local blockade of glutamate receptors in the MLR dramatically diminishes locomotor activity elicited by PT stimulation. Local injections of a D1 receptor antagonist in the MLR also decreases locomotor frequency but surprisingly, the graded control of locomotor speed was still present. It was concluded that the PT controls the locomotor speed in a graded fashion through direct descending glutamatergic projections to the MLR. In a third study (Juvin*, Grätsch* et al., 2016), it was demonstrated that RS cells do not respond to MLR stimulation uniformly, but with three distinct activity patterns. One RS cell population responds with a transient burst of activity at the beginning of a MLR stimulation, a second group displays a sustained response throughout the MLR stimulation, and a third group of RS cells was shown to display two transient bursts of activity: a first burst of activity is generated at the beginning and a second burst occurs at the end of a MLR stimulation. These RS cells were recorded in semi-intact preparations, and it was demonstrated that the second burst of activity is strongly correlated to the end of a locomotor bout (‘termination burst’). Local application of glutamate on these RS cells was shown to stop ongoing swimming movements, whereas inactivation of glutamate receptors elicits a slower termination. As they contribute to the termination of locomotion, these RS cells are referred to as stop cells. It was shown that the ‘termination burst’ does not underlie specific membrane properties of stop cells but rather synaptic inputs to those cells. The aim of a fourth study (Grätsch et al., under review) was to define the origin of these synaptic inputs. An important finding was that ongoing locomotion can be stopped by electrical and pharmacological MLR activation. When the animal is at rest, MLR stimulation elicits locomotion, but it produces very different effects if stimulated during locomotion. It stops swimming if it is stimulated at low intensity and prolongs swimming if stimulated at a higher intensity. Furthermore it was shown that MLR stimulation at low intensity also triggers the ‘termination burst’ in stop cells. Electrophysiological and anatomical experiments revealed that at least some connections between MLR and stop cells are monosynaptic. Parts of this work are published in peer-reviewed journals (Ryczko et al., 2013; Ryczko et al., 2017; Juvin*, Grätsch* et al., 2016) or are under review (Grätsch et al.)

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 308)

This bibliography lists 175 reports, articles, and other documents introduced into the NASA scientific and technical information system in February, 1988

Aerospace Medicine and Biology: A cumulative index to a continuing bibliography

This publication is a cumulative index to the abstracts contained in Supplements 138 through 149 of AEROSPACE MEDICINE AND BIOLOGY: A CONTINUING BIBLIOGRAPHY. It includes three indexes -- subject, personal author, and corporate source

Exploring local neuronal circuitry with controlled iontophoresis

Understanding how neurochemical messengers propagate neuronal signals and ensure delivery of nutrients to fuel this process is the first step to proper treatment and prevention of disorders involving neurological dysregulation. Here, the technique of controlled iontophoresis is coupled to electrochemical detection of dopamine, serotonin, and molecular oxygen (O2) and concurrent monitoring of cell firing to begin to probe the mechanics of local neural circuits. Iontophoresis is a drug delivery technique where application of current causes charged molecules to migrate through a glass capillary. In controlled iontophoresis these capillaries are coupled to a carbon-fiber microelectrode and ejections are monitored electrochemically. The ability to control and modify iontophoretic ejections in real-time makes controlled iontophoresis a significant advancement over previous iterations of iontophoresis as explained and demonstrated herein. Use of this technique first established that we can in fact selectively modulate electrically evoked dopamine release in the striatum of anesthetized rats with local application of an autoreceptor antagonist. Then, the technique was used to examine functional hyperemia, the link between cerebral blood flow and neurochemical release, by monitoring local changes in O2. Direct glutamate application, known to cause vasodilation, increased local O2 concentration linking these O2 changes to blood flow. Additionally, with controlled iontophoresis the relative concentrations of glutamate applied could be compared. This led to the discovery that application of high concentrations of glutamate induced ionic oscillations that are attributed to calcium. Next, the role of serotonin in functional hyperemia is examined in two regions with different serotonergic topography. Unlike glutamate, serotonin application is shown have a much more complex role in functional hyperemia, inducing increases, decreases, and no change in O2. Finally, in order to really understand neuronal signaling, it must be given a context. This work concludes with collection of concurrent electrochemical/electrophysiological data while controlled iontophoresis is used to selectively modulate dopamine release and cell firing in freely-moving animals engaged in behavioral tasks. Preliminary application of this technique has confirmed the existence of subpopulations of medium spiny neurons in the nucleus accumbens and shown that each of these subpopulations plays a unique role in intracranial self-stimulation.Doctor of Philosoph