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Psychophysical and electrophysiological assessment of early visual processing and emotion recognition deficits in schizophrenia
Year of Dissertation:
Previous data suggest that patients with schizophrenia have preferential magnocellular (M) versus parvocellular (P) visual dysfunction. The goal of Experiment 1 was to characterize M–stream impairment in the patient population using a novel approach. Contrast thresholds at varying luminance levels were investigated. M– and P–biased responses were examined by using scotopic and photopic luminance conditions, respectively. Patients exhibited contrast threshold deficits during scotopic conditions, indicative of M–stream dysfunction. Further, the pattern of contrast threshold responses at photopic levels indicated relatively preserved patient P–pathway functionality. Experiment 2 used separate behavioral and electrophysiological paradigms to investigate contributions of low level visual pathway dysfunction in patients to emotion perceptual processing deficits. Contrast response curves for the dorsal (P1) and ventral (N170) pathways were elicited in response to contrast manipulated emotional faces. Results showed that the dorsal P1's pattern of response was impaired in patients while their N170 contrast response curves remained intact. Contributions of visual pathway dysfunction to impaired emotion recognition and affect–related processing, as indexed by the P250 amplitude, were then assessed. P250 activity in patients was reduced at all contrasts. Overall, across groups, the P1 component predicted both P250 amplitude and emotion recognition ability. Taken together, these data support the hypothesis that emotion recognition deficits in patients result from M/dorsal stream dysfunction. Experiment 3 examined the spatial–temporal oscillatory dynamics of schizophrenia patients during processing of complex visual stimuli. FFT spectrum activity and underlying generators of the delta, theta and alpha oscillatory frequencies were first assessed. Activity in the pre and post–stimulus intervals, and the ratio between them (event-related de/synchronization: ERD/ERS) were also evaluated. FFT data revealed controls had significantly greater alpha band activation in posterior electrodes as compared to patients. Conversely, patients exhibited greater theta–band activation over anterior electrodes versus controls. Topographical analysis suggested patients had abnormal underlying neural generators that gave rise to impaired theta and alpha–band activity. Further, instantaneous delta–band activity was significantly greater in patients during pre and post–stimulus intervals, possibly reflecting an overall generalized deficit. Finally, the data revealed that patients had a substantially reduced alpha ERD, highlighting their impairment in low level visual cortical gating mechanisms during processing of visual sensory inputs.
The effects of estrogen on carrageenan-induced nociceptive behaviors and inflammatory mediators in ovariectomized female mice
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Epidemiological studies have shown that pain perception is sexually dimorphic; females tend to experience greater sensitivity to painful stimuli and more chronic pain compared to males. Researchers believe that this dichotomy is caused by the distinct endocrinological profile of females. 17beta -estradiol has been shown to attenuate inflammatory behaviors in both the formalin and carrageenan (Cg) models of inflammation. Research also shows that estrogen affects many inflammatory mediators, including proinflammatory cytokines and prostaglandins (PG). Estrogen plays an important, yet complicated role, in inflammation, and little is known about the specific biochemical mechanisms involved. The objective of this study is to determine if, similar to rats, estrogen attenuates Cg-induced thermal hyperalgesia by altering cytokine or PG release. To that end, female OVX mice were pretreated with various doses of estradiol and injected with 1% Cg. Paw withdrawal latency was recorded prior to, 1 hour, and 5 hours after Cg-treatment in response to a low, medium, and high heat stimuli. Additional animals were treated with indomethacin, a COX blocker. High doses of estradiol caused an increase in nociceptive responses prior to and subsequent to Cg administration. This increase in these pain behaviors was not directly caused by an increase in proinflammatory cytokine levels or a decrease in anti-inflammatory cytokines levels. However, estradiol caused increases in cytokine levels in the untreated paw. Furthermore, treatment with indomethacin caused an attenuation of hyperalgesia. Additionally, indomethacin negated the difference between estradiol- and vehicle-treated mice, indicating that estrogen may interact with prostanoid synthesis. This effect, however, was not seen in the Cg-treated paw, suggesting that estradiol may be increasing hyperalgesia via another pathway as well. Taken together, our results suggest that estrogen's hyperalgesic effects are partly mediated through cytokine up-regulation and prostanoid synthesis, but the main mechanism of action still needs further investigation.
"I Shall not Fear:" Secure Attachment to G-d as a Buffer against Anxiety.
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Religion has a long and mixed history in the field of psychology. Historically, some leading figures in the field viewed religion as a source of neuroses and poor mental health; others saw a more positive spiritual resource. Recently, empirical data on religion and mental health has proliferated. There is now consensus that religion is associated with lower depression. However, the link between religion and anxiety is less clear-cut. This paper proposes that a) religion can have exacerbating or alleviating effects on anxiety depending on which aspect of religion is being studied and b) the primary religious variable that affects anxiety levels is attachment to G-d. Utilizing the `safe haven' attachment function, people with a secure attachment to G-d seek Him when they are stressed. The anxiolytic benefit of seeking an omnipresent secure attachment figure should lead to lower general levels of anxiety. Hypotheses were explored in a series of three studies. Study One examined which aspects of religion are related to anxiety using correlational self-report methods. Hierarchical multiple regressions supported the hypothesis that attachment to G-d was of primary importance in predicting anxiety levels. In addition, positive and negative aspects of religion were differentially correlated with anxiety, as predicted. The process through which G-d attachment relates to anxiety was experimentally explored in Study Two. Participants were exposed to a stressful situation (electric shock threat), and their implicit tendency to seek G-d was measured. Results were surprising: explicitly, those with secure G-d attachment reported a greater tendency to seek G-d when stressed, but those with highly avoidant G-d attachment were the only ones to demonstrate an implicit tendency to seek G-d. Study Three further probed this association by measuring the calming effects of a G-d prime. Stress was induced in all participants while anxiety was measured (physiologically and via self-report). ANOVAs demonstrated that securely G-d attached participants primed with religious as opposed to neutral sentences experienced greater reductions in anxiety over time. Overall, this research clarified the different ways in which religion might relate to anxiety and elucidated some exact mechanisms through which religion buffers against anxiety.
Of home and other figments: The passage of exile in the Tibetan diaspora
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This dissertation used a study of lives approach to understand the stories told by four Tibetans who came to New York following the passage of the Immigration Act of 1990 when Tibetans first came to the United States in mass. Not unlike other diasporas in the world today, the transfer of the events, the stories, and in many cases, the wounds, of exile formatively shape the narrative hereafter of younger generations, though this phenomenon has been given little attention in the social sciences. This work asked: 1) What stories of exile are passed from one generation to another and what are the mechanisms of transmission within that passage? (2) How is home understood generationally? (3) And within the experience of exile, what are the possibilities for action in daily life? Looking across four life historical accounts, my analysis revealed that the stories my informants heard as they grew up can be grouped into the themes of death, survival, and hope. The stories they passed on to younger people in their lives took the form of bodily care, solitude, and discrimination. These stories moved through the narrative mechanisms of translation, silence, and interlocutory slippage with attention to a story's didactic, shaping features. Home was understood as an impossibility for those younger Tibetans with whom I spoke, whereas it was associated with death and decay for older Tibetans. However, generational differences were downplayed by considering exile as a noun (a status) and verb (the ongoing result of an event), which was rife with socio-economic implications. Action took the form of community involvement and its gesture, a commitment to education, and a cursory knowledge of politics. These forms of action were narrated through bearing witness, employing the subjunctive, and calling attention to the body to narrate what escaped words. This inquiry highlights the importance of stories in the experience of exile, as well as the mechanisms through which exile is narrated. Additionally, my analysis emphasizes a consideration of death and natality as central to the experience of exile, and explores the literal and metaphorical ways through which death and natality become narrative forces.
Jealousy Comprehension during Middle Childhood: The Roles of Perspective Taking, Gender, and Maternal Reminiscing within Narrative Construction
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The aim of the current study was to provide an extensive assessment of the socio-cognitive development of children's jealousy understanding during middle childhood within the context of narrative construction. In doing so, influences of perspective-taking ability, gender, and maternal reminiscing on children's ability to understand -and talk about- jealousy (a complex emotion) between the ages of 5 and 11 were examined. In total, 40 girls (M age = 8y;2m, SD = 2y;1m), 40 boys (M age = 8y;7m, SD = 2y;0m), and their mothers participated. Children completed a series of narrative tasks that were coded for emotion understanding: a fictional narrative about a frog experiencing jealousy, post-story probe questions, an individual autobiographical narrative about their own experience of jealousy, and a co-constructed personal narrative in which children and their mothers were asked to talk about a time their child experienced jealousy. Additionally, mothers completed the fictional narrative task for an adult comparison to children's abilities. Children were also administered measures of socio-cognitive development (Test of Emotion Comprehension, Test of Perspective-Taking Ability) and intellectual development (Verbal Intelligence - PPVT, Nonverbal Intelligence - TONI), and mothers were administered a measure of Verbal Intelligence (PPVT). Overall, findings from the current study provide evidence that (1) children exhibit an increased understanding of jealousy across multiple measures of emotion understanding between the ages of 5 and 11, (2) there is considerable overlap in the feelings of jealousy and envy during middle childhood, (3) perspective taking is linked to children's abilities to talk about another's feelings during middle childhood, and (4) girls' emotion understanding is displayed and acquired in a more interpersonal context than boys'. Furthermore, the present study extends the literature on maternal-guided reminiscing to include assessment during middle childhood, examining the roles of both style and content, and through evaluating both parties' discourse. In doing so, maternal elaboration was found to be beneficial for children's autobiographical narrative abilities during middle childhood. Results are discussed in relation to socialization practices behind children's expression of jealousy -a negative emotion associated with interpersonal rivalry- that is frequently experienced, but that American culture says should not be expressed.
Does Discovery-Based Instruction Enhance Learning?
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Since Bruner's (1961) call for research into discovery-based learning, controversy has surrounded the efficacy of such a constructivist approach to instruction (e.g., Tobias & Duffy, 2009). For decades, research has investigated to what extent discovery-based instruction enhances learning tasks or conversely, detracts from them. Research has included wide varieties of domains and discovery-based instructional approaches. Samples have included both children and adults and both novices and experts within their specific domains. It seems that what the field needs is a definition of discovery learning from a practical perspective because a review of the literature reveals that although there might be an implied sense of what discovery learning is, the methodologies employed vary greatly. Furthermore, the characteristics of effective discovery methodology(s) need to be examined with careful consideration of the domain involved, the age of the sample, the comparison condition, and the outcome assessments. Therefore, two meta-analyses were conducted using a sample of 164 studies: the first examined the effects of unassisted discovery learning versus explicit instruction and the second examined the effects of enhanced and/or assisted discovery versus other types of instruction (e.g., explicit, unassisted discovery, etc.). Random effects analyses of 580 comparisons revealed that outcomes were favorable for explicit instruction when compared to unassisted discovery under most conditions, d = -.38 (95% CI = -.44/-.31). In contrast, analyses of 360 comparisons revealed that outcomes were favorable for enhanced discovery when compared to other forms of instruction, d = .30 (95% CI = .23/.36). The findings suggest that unassisted discovery does not benefit learners, whereas feedback, worked examples, scaffolding, and elicited explanations do.
The Temporal Relationship between Daytime Napping and Memory Consolidation
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An extensive body of literature exists substantiating the idea that sleep facilitates the strengthening, stabilization, and protection of newly formed memories, aiding in consolidation from short-term to long-term stores. However, research as to the temporal boundaries of the benefit of sleep to declarative memory is deficient. It has been established that sleep benefits memory compared to equal time spent awake, but when sleep needs to occur relative to the learning period, as well as how much and what type of sleep is necessary, has been little explored. Additionally, researchers have focused on how the brain works on previously encoded information during sleep, but very few have addressed whether sleep prepares the brain to take on new information when it occurs prior to learning. Using efficient daytime naps, the present series of studies addressed these shortcomings and the results provided support exclusively to an active role for sleep in memory processing. Study I unexpectedly demonstrated superior performance for recognition memory with increased delay before sleep onset, resulting in increased slow wave sleep (SWS) in the later nap groups. Study II determined that sleep must progress into SWS, rather than merely Stages 1 and 2, for better short-term retention, subsequent protection from stimulus-related interference, and long-term consolidation, although even a brief nap provides temporary retention benefits over remaining awake. Examining sleep prior to learning in Study III, it was found that a 60-minute nap prepared the brain to more efficiently consolidate information, despite the fact that nap and wake groups encoded material equally. Overall, the present research provides clarification, although perhaps task-dependent, to the existing questions regarding the temporal relationship between sleep and learning. Additionally, the results proffer support for active processing during sleep potentially through standard consolidation and/or homeostatic downscaling of synaptic potentials, the major mechanistic theories ascribing a role for SWS in declarative memory processing.
THE EFFECTS OF ENRICHMENT ON COGNITION IN RATS (RATTUS NORVEGICUS)
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Abstract THE EFFECTS OF ENRICHMENT ON COGNITION IN RATS RATTUS NORVEGICUS by Amber A. Alliger Adviser: Dr. Peter Moller Animal models play an integral role in pharmaceutical research when developing drugs for human use. It is therefore imperative that animal models accurately represent human systems. In an attempt to reduce variability of test results, animals are often kept in barren, non-natural conditions. There is, however, a growing awareness that environmental enrichment will increase the validity of test results. The aim of the present study was to allow animals to control their environment using operant conditioning procedures, and to assess the effect of control on cognitive tasks. Four predictions were tested: 1. Rats (Rattus norvegicus) will control three stimuli (light, sound and a running wheel). 2. Animals will exhibit preferences for particular stimulus strengths. 3. Animals that exert control over the environmental stimuli will show increased performance in cognitive tasks compared to animals that lack control.4. Animals that can control environmental stimuli will have lower corticosterone levels than animals that lack such control, where corticosterone levels are used as an assessment of stress. Experimental subjects in both experiments did show control over a light stimulus, and performed significantly better in a discrimination task as compared with subjects that could not control their environment. There was no difference in corticosterone levels between control and experimental subjects. These results will contribute to an understanding how enrichment and control of environmental stimuli, in particular, affect the welfare of animals in captive environments, and aid in designing experimental conditions that will produce animal models that will increase validity and reliability in research.
FACIAL EMOTIONAL EXPRESSION FOLLOWING VOICE TREATMENTS IN INDIVIDUALS WITH PARKINSON'S DISEASE
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A growing body of work has documented impairments in emotional facial expression (i.e., masked facies) in individuals with Parkinson's disease (PD). These impairments negatively impact patients' social interactions and functioning in daily life. However, little attention has been given to remediating facial emotional expression deficits in PD. Preliminary research has demonstrated that the treatment of voice using the Lee Silverman Voice Treatment (LSVT®; Ramig et al., 1995) has beneficial effects on limited aspects of facial expression in PD (Spielman et al., 2003). The present study extends the literature by examining the effects of two voice treatments on facial expression in PD in a comprehensive way, including facial mobility (FM) and three aspects of facial emotional expressivity (i.e., frequency [EF], variability [EV] and intensity [EI]). Participants included 56 posers, individuals who produced emotional and non-emotional monologues, and 18 raters, individuals who rated posers' facial expressions from video-recorded monologues. Ratings were made on a 7-point Likert scale for the four aspects of facial expression. Raters were trained to criterion, and reliability was high for each emotional expression variable (Intraclass Correlation Coefficient range .85 to .90). The study included four poser groups: 3 PD groups whose posers were randomly assigned into an LSVT, Articulation Voice Treatment (ARTIC), or a no treatment control group, and a demographically matched healthy control group (NC). Findings revealed that PD male posers displayed impaired facial expression at baseline compared to NCs on all variables examined, although PD women did not differ from NCs for any aspect of facial expression. Treatment findings showed that patients who received LSVT were rated as having higher FM, EF, EV, and EI after treatment, four weeks later, than at baseline. This increase was not observed for the 3 other poser groups. It is speculated that LSVT improves facial expression because facial and vocal expression are emotional communication channels that exist within a larger network of emotional processing. Facial and vocal emotional expression are linked at several levels of neural organization: cortical, subcortical, and cranial nerve. The broader clinical implications of our findings are that masked facies can be remediated using LSVT.
The developmental trajectory of contour integration in autism spectrum disorders
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Sensory input is inherently ambiguous and complex, so perception is believed to be achieved by combining incoming sensory information with prior knowledge. One model envisions the grouping of sensory features (the local dimensions of stimuli) to be the outcome of a predictive process relying on prior experience (the global dimension of stimuli) to disambiguate possible configurations those elements could take. Contour integration, the linking of aligned but separate visual elements, is one example of perceptual grouping. Kanizsa-type illusory contour (IC) stimuli have been widely used to explore contour integration processing. Consisting of two conditions which differ only in the alignment of their inducing elements, one induces the experience of a shape apparently defined by a contour and the second does not. This contour has no counterpart in actual visual space - it is the visual system that fills-in the gap between inducing elements. A well-tested electrophysiological index associated with this process (the IC-effect) provided us with a metric of the visual system's contribution to contour integration. Using visually evoked potentials (VEP), we began by probing the limits of this metric to three manipulations of contour parameters previously shown to impact subjective experience of illusion strength. Next we detailed the developmental trajectory of contour integration processes over childhood and adolescence. Finally, because persons with autism spectrum disorders (ASDs) have demonstrated an altered balance of global and local processing, we hypothesized that contour integration may be atypical. We compared typical development to development in persons with ASDs to reveal possible mechanisms underlying this processing difference. Our manipulations resulted in no differences in the strength of the IC-effect in adults or children in either group. However, timing of the IC-effect was delayed in two instances: 1) peak latency was delayed by increasing the extent of contour to be filled-in relative to overall IC size and 2) onset latency was delayed in participants with ASDs relative to their neurotypical counterparts.