Search PubMed⌕ Search

Biomedical subjects

A A Rizzo

Publications and source records attributed to A A Rizzo.

At least 19 recordsLinked to original sources
PubMed2001

Performance-driven facial animation: basic research on human judgments of emotional state in facial avatars.

Virtual reality is rapidly evolving into a pragmatically usable technology for mental health (MH) applications. As the underlying enabling technologies continue to evolve and allow us to design more useful and usable structural virtual environments (VEs), the next important challenge will involve populating these environments with virtual representations of humans (avatars). This will be vital to create mental health VEs that leverage the use of avatars for applications that require human-human interaction and communication. As Alessi et al.1 pointed out at the 8th Annual Medicine Meets Virtual Reality Conference (MMVR8), virtual humans have mainly appeared in MH applications to "serve the role of props, rather than humans." More believable avatars inhabiting VEs would open up possibilities for MH applications that address social interaction, communication, instruction, assessment, and rehabilitation issues. They could also serve to enhance realism that might in turn promote the experience of presence in VR. Additionally, it will soon be possible to use computer-generated avatars that serve to provide believable dynamic facial and bodily representations of individuals communicating from a distance in real time. This could support the delivery, in shared virtual environments, of more natural human interaction styles, similar to what is used in real life between people. These techniques could enhance communication and interaction by leveraging our natural sensing and perceiving capabilities and offer the potential to model human-computer-human interaction after human-human interaction. To enhance the authenticity of virtual human representations, advances in the rendering of facial and gestural behaviors that support implicit communication will be needed. In this regard, the current paper presents data from a study that compared human raters' judgments of emotional expression between actual video clips of facial expressions and identical expressions rendered on a three-dimensional avatar using a performance-driven facial animation (PDFA) system developed at the University of Southern California Integrated Media Systems Center. PDFA offers a means for creating high-fidelity visual representations of human faces and bodies. This effort explores the feasibility of sensing and reproducing a range of facial expressions with a PDFA system. In order to test concordance of human ratings of emotional expression between video and avatar facial delivery, we first had facial model subjects observe stimuli that were designed to elicit naturalistic facial expressions. The emotional stimulus induction involved presenting text-based, still image, and video clips to subjects that were previously rated to induce facial expressions for the six universals2 of facial expression (happy, sad, fear, anger, disgust, and surprise), in addition to attentiveness, puzzlement and frustration. Videotapes of these induced facial expressions that best represented prototypic examples of the above emotional states and three-dimensional avatar animations of the same facial expressions were randomly presented to 38 human raters. The raters used open-end, forced choice and seven-point Likert-type scales to rate expression in terms of identification. The forced choice and seven-point ratings provided the most usable data to determine video/animation concordance and these data are presented. To support a clear understanding of this data, a website has been set up that will allow readers to view the video and facial animation clips to illustrate the assets and limitations of these types of facial expression-rendering methods (www. USCAvatars.com/MMVR). This methodological first step in our research program has served to provide valuable human user-centered feedback to support the iterative design and development of facial avatar characteristics for expression of emotional communication.

Adolescent↗
PubMed2001

Psychological factors and hyperemesis gravidarum.

Hyperemesis gravidarum (HG) is a condition of severe, intractable nausea and vomiting during pregnancy. It has long been held that HG is a psychosomatic illness reflective of a long-term psychological trait, that is, conversion disorder. We investigated this possibility by conducting a two-phase study: (1) a comparison of women with (n = 9) and without (n = 10) HG during pregnancy and (2) a comparison of nonpregnant women who did (n = 10) and did not (n = 12) have HG during their most recent pregnancies. The pattern of findings differed between experiments 1 and 2. During pregnancy, women with HG scored significantly higher on three scales associated with conversion disorder (all p values <0.01) than did women without HG. There were no significant differences between HG subjects and controls after pregnancy. We find no support for the theory that HG is a psychosomatic condition. Rather, it appears to be a complex interaction of biological, psychological, and sociocultural factors.

Adult↗
PubMed2000

Associations between circulating sex steroid hormones and cognition in normal elderly women.

OBJECTIVE: To provide exploratory analyses of associations between levels of several sex hormones and cognitive performance in elderly women. BACKGROUND: Sex steroid hormones are implicated in the cognitive processes of the adult brain. Comparing cognitive performance across or between conditions associated with different hormone levels, such as phases of the menstrual cycle, surgical menopause, and estrogen replacement therapy suggests conditions with higher levels of estrogen are associated with better verbal memory and possibly worse visuospatial ability. METHOD: The authors measured circulating sex hormone levels in 39 highly educated, nondemented, predominantly white elderly women. Levels were correlated with neuropsychological performance, controlling for age, education, frequency of prior testing, use of estrogen replacement, and depression. RESULTS: High estradiol levels were associated with better delayed verbal memory and retrieval efficiency, whereas low levels were associated with better immediate and delayed visual memory. Levels of testosterone were related positively to verbal fluency. Levels of progesterone and androstenedione were unrelated to cognitive performance. CONCLUSIONS: Both estrogen and testosterone showed associations with cognitive performance. Estrogen may enhance, and depress, specific cognitive skills.

Aged↗
PubMed1998

Basic issues in the use of virtual environments for mental health applications.

In order for Virtual Environments (VE) to be efficiently developed in the areas of clinical psychology and neuropsychology, a number of basic theoretical and pragmatic issues need to be considered. The current status of VE's in these fields, while provocative, is limited by the small number of controlled studies that have been reported which apply this technology to clinical populations. This is to be expected considering it's relatively recent development, expense, and the lack of familiarity with the technology by mainstream researchers in these fields. In spite of this, some work has emerged which can begin to provide a basic foundation of knowledge which could be useful for guiding future research efforts. Although much of the work does not involve the use of fully immersive head mounted displays (HMD's), studies reporting PC-based flatscreen approaches are providing valuable information on issues necessary for the reasonable and measured development of VE/mental health applications. In light of this, the following review will focus on basic issues that we see as important for the development of both HMD and non-HMD VE applications for clinical psychology, neuropsychological assessment, and cognitive rehabilitation. These basic issues are discussed in terms of decision-making for choosing to develop and apply a VE for a mental health application. The chapter covers the issues involved with choosing a VE approach over already existing methods, deciding on the "fit" between a VE approach and the clinical population, level of presence, navigation factors, side effects, generalization, and general methodological and data analysis concerns.

Adult↗
PubMed1997

Virtual reality and cognitive assessment and rehabilitation: the state of the art.

VR offers the potential to develop human testing and training environments that allow for the precise control of complex stimulus presentations in which human cognitive and functional performance can be accurately assessed and rehabilitated. However, basic feasibility issues need to be addressed in order for this technology to be reasonably and efficiently applied to the neuropsychological assessment (NA) and cognitive rehabilitation (CR) of persons with acquired brain injury and neurological disorders. This chapter will provide an introduction to the basic concepts of neuropsychological assessment and cognitive rehabilitation along with rationales for virtual reality's applicability in these complimentary fields. We review the relevant literature regarding theoretical and pragmatic issues for these applications, and provide a description of our ongoing work developing a mental rotation/spatial skills cognitive assessment and training system. References are provided in each section for further reading in each area reviewed.

Computer Graphics↗
PubMed1996

Gender comparisons of cognitive performances among vascular dementia, Alzheimer disease, and older adults without dementia.

BACKGROUND: We hypothesized that women with Alzheimer disease (AD) would perform worse on a test of semantic memory but not on tests of other cognitive domains. We did not expect that women without dementia would perform more poorly than men without dementia on the same task. OBJECTIVE: To explore the specificity of a semantic memory deficit among women with AD by exploring gender differences among a group of subjects with vascular dementia (VD). DESIGN: A case-control study in which differences between men and women were explored using regression models to control for the potentially confounding effects of age, education, duration of dementia, and severity of dementia. SETTING: Alzheimer's Disease Research Center Consortium of Los Angeles and Orange Counties, California. SUBJECTS: Volunteers, recruited from the community or clinic referrals, who met clinical criteria for AD (n = 159) or VD (n = 117) or met criteria for control status without dementia (n = 134). MAIN OUTCOME MEASURES: Five neuropsychological measures, commonly used in the diagnosis and assessment of dementia. RESULTS: Women with VD scored lower than men with VD on 3 tests. However, when controlling for potential confounds, the gender difference was maintained only for the semantic memory task. Women with AD showed a strong trend to perform worse than men with AD on the test of semantic memory only. No gender differences were found among subjects without dementia. CONCLUSIONS: Findings support the existence of a semantic memory deficit for women with AD and suggest that a similar deficit may exist among women with VD.

Aged↗
PubMed1988

Effects of caffeine withdrawal on motor performance and heart rate changes.

Heavy caffeine Users and Non-users were tested twice using a signalled reaction time paradigm, while heart rate was recorded. During the 7-day interval between the two sessions, the User group maintained normal caffeine intake for the first 5 days and abstained from caffeine during the last 2 days, which constituted a withdrawal period. The Non-users abstained from caffeine (as they usually do) during the entire 7-day period. The analyses of the reaction time (RT) data indicated no differences during Session 1 and a significant group difference during Session 2, with the Non-users exhibiting faster RT's. The Users exhibited no change between Sessions 1 and 2, while the Non-users showed a decrease in RT's (increased speed) across Sessions, which may be indicative of a practice effect. The analysis of the heart rate data from the 5-s period prior to the imperative stimulus yielded no differences during Session 1, and a significant group difference in Session 2, with the Non-users exhibiting larger decelerations. Across the two Sessions, the Non-users showed an increase in the magnitude of the heart rate deceleration, while the Users exhibited a decline in the size of the deceleration. Since the magnitude of heart rate deceleration has been interpreted as an index of attention, it appears that the Users were exhibiting less efficient attention during withdrawal from caffeine (Session 2) than were the Non-users. This conclusion is supported by the RT data, showing slower response times for the Users during Session 2, as compared to Non-users.

Adult↗
PubMed1986

The saliva thiocyanate analysis: a methodological extension and its relationship to CO and self-report in moderate smokers.

Parameters for the storage and analysis of saliva samples used to measure thiocyanate (SCN) levels among moderate smokers were systematically studied. The variables targeted for study were the temperature of storage (0 to 20 degrees F) and the size of the container (5 ml or 10 ml). Additionally, these same variables were examined, independently under three different temporal delays to laboratory analysis: immediate, 3 days, and 7 days. Results within each of the delay conditions revealed no significant differences in SCN levels and provided support for the reliability of measurement when using these procedures in the study of thiocyanate levels. Self-reported smoking rate and alveolar carbon monoxide (COa) readings of a week prior were found to correlate relatively highly with thiocyanate readings. These findings broaden the support for SCN as a corroborative measure of smoking.

Carbon Monoxide↗
PubMed1984

Crab lung.

Explore the source record for details and available documents.

Adult↗
PubMed1983

[H2 histamine antagonists and the hypothalamo-hypophyseal-gonadal axis: effect of short-term treatment on serum levels of prolactin, FSH, LH and testosterone in male ulcer patients].

Serum prolactin (PRL ng/ml) was measured in 7 male patients on cimetidine (CMT) and in 13 on ranitidine (RNT) before therapy and 5, 10, 15 and 30 days after; at the same intervals FSH (ng/ml), LH (ng/ml) and testosterone (ng/ml) were measured in 5 patients too, in order to ascertain hypothalamic, pituitary, gonadal dysfunction caused by H2 histamine blockers. In agreement with other authors, FSH, LH and testosterone were not affected: no statistical difference was found between basal values and the times of follow-up. In RNT-treated patients PRL showed a little, but not significant increase; in CMT-treated group PRL increased with a peak on 10th day (19.41 +/- 2.14 ng/ml vs. 9.50 +/- 1.72 ng/ml; P less than 0.01); on 30th day PRL levels were still higher than basal ones (15.85 +/- 2.38 ng/ml vs. 9.50 +/- 1.72 ng/ml; P less than 0.05). Unlike other trials we observed that PRL rises very early in oral treatment with CMT, perhaps for resetting of inhibiting factors, it trends to decrease and reach basal values shortly after 30th day notwithstanding therapy. It is now widely accepted that H2 blocker's action is on central histaminergic pathways modulating PRL secretion; in our opinion, the measured differences of PRL secretion with CMT and RNT in short term observations, are produced by different crossing of blood-brain barreer.

Adult↗
PubMed1982

Long-term follow-up (3-4 years) of treatment for smoking reduction.

The present paper reports the 3- and 4-year follow-ups of two smoking reduction clinics (n = 103) employing a comprehensive, non-aversive, behavioral treatment using stimulus control and self-control techniques. Most of the data were gathered via phone contact, while some clients were interviewed in person with corroborative carbon monoxide measurements taken at that time. While the general findings were similar to those reported for other long-term follow-ups of smoking programs, unlike earlier reports, the overwhelming majority of subjects were contacted (an average of 90% for all follow-up periods). The average percentage of baseline for smoking subjects was equal to 56% and average percentage abstinent equal to 24% at final follow-up. Data are also presented which suggest greater attention be paid to the potential efficacy of controlled smoking when assessing the effectiveness of smoking reduction programs.

Adult↗