This study investigated whether veterans with post-traumatic stress disorder (PTSD) would display a bias to interpret ambiguous faces in a more threatening way than veterans without the disorder. While there are a number of studies showing that high levels of anxiety are associated with a negative interpretive bias, there is only one published study investigating interpretive style in PTSD. Furthermore, all but one of these studies has relied on ambiguous words or sentences as the evocative stimuli. The current proposal extended extant studies by investigating how PTSD and control subjects responded to ambiguous emotional faces. Specifically, using morphing software, a set of faces were developed that were ambiguous with regard to their emotional expression. Participants were asked to categorize the emotional expression of both the newly created set of ambiguous facial images as well as the easily discernible, threatening and non-threatening faces that were used to create the ambiguous stimuli. All stimuli were presented optimally (2500 ms) to allow for full conscious awareness of the stimuli as well as suboptimally (30 ms followed by mask). The participants' behavioral categorizations of the faces as well as their facial physiological responses were the primary outcome variables. The results from the behavioral data suggest that there was weak evidence for a negative interpretive style in individuals with PTSD, but stronger evidence for a lack of a positive interpretive bias as compared to controls. In other words, PTSD subjects made significantly fewer non-threatening interpretations of ambiguous facial expressions than control subjects. Signal detection analysis suggested that controls, but not participants with PTSD, exhibited a positive response bias when evaluating ambiguous stimuli. Psychophysiological data revealed that participants with PTSD showed higher levels of baseline tension in the zygomaticus major facial muscle region, possibly due to paradigm response demands. Additionally, an exploratory analysis of the corrugator supercilii muscle region response to suboptimally presented faces suggested confirmatory support for the results from the behavioral data that PTSD participants are characterized by the absence of a positivity bias / acase@tulane.edu

Previous research has identified the medial preoptic area (MPOA) as being critically involved in the mediation of masculine copulatory behavior in mammals. Other research has shown that fetal brain tissue can be transplanted successfully into the brains of adult mammals. The present study sought to determine whether copulatory behavior could be restored in males bearing MPOA lesions by fetal MPOA tissue transplanted into the midbrain. Of 5 rats receiving total MPOA lesions and fetal MPOA transplants, 3 recovered copulatory behavior. Of 3 rats receiving total MPOA lesions and fetal cerebral cortical transplants, one recovered copulatory behavior. Behavioral differences between the two groups were not statistically significant. However, the mean intromission frequency for MPOA-transplanted animals (M = 6.8, SD = 5.25) was greater than that for cerebral cortical-transplanted animals (M = 2.22, SD = 5.25). Yohimbine significantly increased mean intromission frequencies for both groups compared with pre- and post-yohimbine saline tests. However, baseline responding on control test days may have been unusually low. Thermoregulatory adaptation to a cold environment (5(DEGREES)C) by these animals was in the normal range, in marked contrast to what is commonly reported for animals bearing MPOA lesions. This discrepancy may be due to recovery of function mediated by a nonspecific transplant action, or to sparing of function due to dorsal placement of lesions. Some MPOA- and cerebral cortical-transplanted animals displayed motor symptoms following transplantation which could not be accounted for by encroachment of the transplant on the substantia nigra. The transplants may have innervated motor areas abnormally, thus producing motor symptoms. In any case, this is the first report of detrimental effects of transplanted fetal brain tissue. One hundred percent of the transplants survived the 8-week duration of the experiment and contained healthy neurons. Numerous LHRH-immunoreactive axons (but few perikarya) were detected in MPOA but not cerebral cortical transplants. It is concluded that the MPOA transplants displayed the characteristics of transplants which have been shown to modify brain function, but that the small sample sizes may have prevented the detection of any such effects / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

A contingent aftereffect involves the pairing of two levels of one stimulus attribute with two levels of another during a given exposure period. Following this exposure, changes in the perception of a test stimulus in which one level of one attribute is shared with the adapting stimulus is contingent upon the presence of the appropriately paired level of the other. When this occurs, it is assumed that the perceptual channels which process each attribute must interact. The term 'aftereffect' applies to suprathreshold stimuli. When threshold is used as the dependent variable, the term 'adaptation effect' is more appropriate The present investigation was designed to demonstrate two new contingent auditory adaptation effects. It was predicted that periodicity-specific adaptation effects on modulation sensitivity would be contingent on carrier frequency for amplitude and frequency modulated signals. Two separate experiments were thus conducted, one using amplitude modulated (AM) stimuli and one using frequency modulated (FM) stimuli. Two levels of carrier frequency (1009 Hz and 200 Hz) were paired with 2 levels of modulation rate (2 Hz and 8 Hz) and presented alternately during a 20 minute exposure period. It was expected that greater elevations in modulation threshold would occur when test stimuli shared the same level on both attributes as the adapting stimulus. For example, if a subject adapted to a 1009 Hz tone frequency modulated at 2 Hz alternating with a 2000 Hz tone frequency modulated at 8 Hz, it would be expected that threshold elevations in response to an FM test stimulus with a carrier frequency of 2000 Hz and a modulation rate of 8 Hz would be greater than threshold elevations in response to an FM test stimulus with a carrier frequency of 2000 Hz and a modulation rate of 2 Hz Rate-specific adaptation effects contingent on carrier frequency were demonstrated for frequency modulated signals. There was some evidence for carrier frequency contingent adaptation to amplitude modulated signals, however, the effect failed to reach significance. Pure tone detection thresholds were not affected by adaptation / acase@tulane.edu

This study examined the physiological and cognitve ability effects of a 16 week aerobic exercise program on a sample of older (60-72) men (n = 7) and women (n = 37). The effect of hopefulness as described by Seligman (1990) was also analyzed. Subjects were randomly assigned to either a walking program of constant intensity (heart rate $>$ 70%) and progressive duration (20 minutes to 40+ minutes), a strength and flexibility program (heart rate $<$ 70%), or a no exercise control. Subjects were expected to participate three times a week. Pretest data suggested no significant differences in the variables of concern: physiological (max VO$\sp2$, mean arterial pressure $\{MAP\},$ resting heart rate, and weight) or cognitive ability; flexibility of closure (Hidden Patterns), speed of closure (Gestalt Completion), vocabulary (Verbal Comprehension), and creativity (Alternate Uses). The walking group improved aerobic capacity significantly over both the strength and flexibility and control groups. There were no other significant physiological gains. The aerobic group also showed significant increases in percent increase of creativity compared to either the strength and flexibility or control. Exercising subjects reported perceived improvement in performance of cognitive ability, but while they did improve it was not significant. There was a significant relationship between estimated max VO$\sp2$ and hopefulness, however there were no significant relationships between cognitive ability and hopefulness. / Source: Dissertation Abstracts International, Volume: 56-05, Section: B, page: 2928. / Thesis (Ph.D.)--The Florida State University, 1995.

This study was designed to characterize the effects of PCP and PCP derivatives on dopamine systems using electrophysiological and behavioral methods. TCP, a high affinity PCP/NMDA receptor ligand only increased A10 firing while BTCP, a high affinity DA reuptake ligand only decreased activity. PCP with similar affinity for the NMDA and reuptake sites, produced a dose dependent bimodal change in the activity of A10 neurons. Lesions of the nucleus accumbens or treatment with picrotoxin, a GABA antagonist attenuated the BTCP and high dose PCP inhibitory effects thus supporting the existence of a GABAergic accumbal-VTA feedback pathway. Furthermore, BTCP and PCP produced significant increases in locomotor activity which were attenuated by accumbens lesions. The present data provide an explanation for PCP's bimodal effects and possibly for its psychotomimetic properties as well as abuse liability which may reside with its blockade of dopamine reuptake in the mesolimbic system.

<p> The ability to flexibly control or inhibit unwanted actions is critical for everyday behavior. Lack of this capacity is characteristic of numerous psychiatric diseases including attention deficit hyperactivity disorder (ADHD). My project is designed to study the neural underpinnings of response inhibition and to what extent these mechanisms are disrupted in animals with impaired impulse control. I therefore recorded single neurons from dorsal striatum, orbitofrontal cortex, and medial prefrontal cortex from rats performing a novel rodent variant of the classic "stop signal" task used in clinical settings. This task asks motivated rats to repeatedly produce simple actions to obtain rewards while needing to semi-occasionally inhibit an already initiated response. To take this a step further, I compared normal rats to rats prenatally exposed to nicotine in order to better understand the mechanism underlying inhibitory control. Rats exposed to nicotine before birth show abnormal attention, poor inhibitory control, and brain deficits consistent with impairments seen in humans prenatally exposed to nicotine and those with ADHD.</p><p> I found that dorsal striatum neurons tend to encode the direction of a response and the motor refinement necessary to guide behaviors within the task rather than playing a causal role in response inhibition. However the orbitofrontal cortex, a direct afferent of dorsal striatum, possesses the capacity to inform the striatum of the correct action during response inhibition within the critical time window required to flexibly alter an initiated movement. On the other hand, medial prefrontal cortex functions as a conflict &ldquo;monitor&rdquo; to broadly increase preparedness for flexible response inhibition by aggregating current and past conflict history. Lastly, rat pups exposed to nicotine during gestation exhibit faster movement speeds and reduced capacity for inhibitory behavior. Physiologically, prenatal nicotine exposure manifests in a hypoactive prefrontal cortex, diminished encoding of task parameters, and reduced capacity to maintain conflict information.</p>

This study tested the sensitization model proposed by Bell, Miller & Schwartz (1992) to study multiple chemical sensitivity (MCS). The sensitization models indicates that a traumatic event which elicits a strong response can sensitize limbic and/or mesolimbic pathways and future less intense trauma or stimuli, in the same or different modality, can elicit an amplified response. Three groups of subjects were tested: (1) women who reported chemical sensitivity; (2) sexually abused women without chemical sensitivity; and (3) healthy woman without chemical sensitivity nor sexual abuse history. All subjects were exposed to odorant and nonodorant control stimuli once a week for three weeks. Electroencephalographic (EEG) activity was recorded while subjects sniffed the odorant and control stimuli. Based on the sensitization model, it was hypothesized that subjects who reported chemical sensitivity as well as subjects who reported a history of sexual abuse would show increases in the amplitude spectrum in the alpha frequency band across experimental sessions during exposure to odorant stimuli. Additionally, it was hypothesized that the healthy control subjects would show little or no changes over time. As predicted, the chemically sensitive and the sexually abused groups showed sensitization across experimental sessions. Additionally, the healthy control subjects showed habituation across experimental sessions. These findings indicate that individuals with chemical sensitivity show evidence of sensitization and that sensitization is not specific to MCS.

The purpose of this research was to test a theoretical model adapted from Jones (1998) of the impact of symptoms on Health-Related Quality of Life (HRQOL) in Chronic Obstructive Pulmonary Disease (COPD). The modified model proposed that breathlessness, physical impairment, diminished psychological well-being, negative outlook, and disability had effects on physical and mental components of HRQOL in COPD. A correlational descriptive design was used for a secondary analysis of data obtained from a longitudinal repeated measures design in COPD (Meek, 1995). The sample consisted of 58 individuals with COPD with moderate to severe impairment (FEV₁ = 40.49%) and a mean age of 70.2 ± 8.28 years. The subjects were tested using spirometry, Visual Analogue Scales, Baseline Dyspnea Index, selected subscales of the Bronchitis-Emphysema Symptom checklist (depression/anxiety), Positive and Negative Affect Scale (negative affect), the Pulmonary Functional Status and Dyspnea Scale (activity component), and Medical Outcome Study Short Form-36. Multiple regression analysis was used to examine the relationships in the model. Results of analysis of data in comparison of the over-identified model and an exploratory (just-identified) model demonstrated that parts of the model were not supported by the data and the exploratory model was able to explain more variance in the data than the overidentified model (W = 8.48, p̱ < .10). In this study, the exploratory (just-identified) model was accepted as the final model accounting for 52% of the variance in impaired physical component of HRQOL (Ṟ² = .52, p̱ < .001) and 58% of the variance in impaired mental component of HRQOL (Ṟ² = .58, p̱ < .001). Disability and physical impairment had direct effects on physical health component of HRQOL. Negative outlook and breathlessness had direct effects on mental health component of HRQOL. Breathlessness demonstrated a greater impact than the model would have proposed. Health providers should assess clients' perception of breathlessness and be aware of how that perception could influence HRQOL. Health care providers should plan interventions for individuals with COPD to decrease breathlessness through participating in educational, rehabilitation, or other programs, designated to decrease breathing effort and associated distress.