<p> When someone hears regular, periodic sounds, such as drum beats, footsteps, or stressed syllables in speech, these individual stimuli tend to be grouped into a perceived rhythm. One of the hallmarks of rhythm perception is that the listener generates expectations for the timing of upcoming stimuli, which theorists have described as endogenous periodic modulations of attention around the time of anticipated sounds. By constructing an internal representation of a rhythm, perceptual processes can be augmented by proactively deploying attention at the expected moment of an upcoming stressed syllable, the next step in an observed stride, or during the stroke of a co-speech hand gesture. A hypothetical benefit of this anticipatory allocation of attention is that it might facilitate temporal integration across the senses, binding multisensory aspects of our experiences into a unified &ldquo;now,&rdquo; anchored by temporally-precise auditory expectations. The current dissertation examines this hypothesis, exploring the effects of auditory singletons, and auditory rhythms, on electrophysiological indices of perception and attention to a visual stimulus, using the flash-lag paradigm. An electroencephalography study was conducted, where sounds, either isolated or presented rhythmically, occurred in alignment with a task-relevant visual flash. Results suggest a novel dissociation between the multisensory effects of discrete and rhythmic sounds on visual event perception, as assessed by the N1 component of the event-related potential, and by oscillatory power in the beta (15&ndash;20 Hz) frequency range. This dissociation is discussed in the context of classic and contemporary research on rhythm perception, temporal orienting, and temporal binding across the senses, and contributes to a more refined understanding of rhythmically-deployed attention. </p><p>

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Peripheral and central atrial natriuretic factor (ANF) concentrations were measured across the estrous cycles of rats. Sprague-Dawley female rats, approximately 180 days of age, were maintained under a controlled illumination cycle (L/D: 14/10, onset 0500 hr), and their estrous cycles were monitored on the basis of vaginal cytology. Females (n = 5-13) were decapitated during early proestrus (0900-1100 hr), late proestrus (1700-1900 hr), estrus (0900-1100 hr), early metestrus (0900-1100 hr), and late metestrus (1700-1900 hr). Plasma was obtained from trunk blood, and atria, brains, and pituitaries were quickly removed and frozen in dry ice. Uterine sizes were rated on a 5 point scale, with 1 indicating no uterine ballooning and 5 indicating maximum ballooning. Eight brain regions were dissected from frozen coronal sections (300 um) with a metal cannula (i.d. = 1 mm). Plasma and supernatants of atrial, pituitary, and brain regional homogenates were applied to Sep-Pak C18 cartridges, and extracted ANF concentrations were determined by specific radioimmunoassay. Plasma ANF concentration significantly increased (Newman-Keuls: p $<$.01) during early metestrus (mean = 37.0 pg/ml plasma) relative to early proestrus (14.8 pg/ml), late proestrus (12.8 pg/ml), estrus (19.8 pg/ml), and late metestrus (12.8 pg/ml) concentrations. Early metestrus atrial ANF concentration (mean = 1.79 ug/mg protein) significantly decreased (Newman-Keuls: p $<$.05) relative to early proestrus (2.73 ug/mg) and late proestrus (2.92 ug/mg) concentrations. Centrally, ANF concentration was lower (quadratic trend: p $<$.005) during estrus (mean =.725 ng/mg protein) and, to a lesser extent, during early metestrus (.842 ng/mg) compared to concentrations during early proestrus (.908 ng/mg), late proestrus (.933 ng/mg), and late metestrus (.954 ng/mg) in hypothalamic tissue bordering the third ventricle. Also, ANF levels significantly decreased (linear trend: p $<$.05) after proestrus in the midbrain dorsal raphe nucleus (early proestrus mean =.950, late proestrus =.943, estrus =.693, early metestrus =.663, and late metestrus =.758 ng/mg protein). These findings suggest an interaction between female reproductive hormones and both peripheral and central ANF. Also, a relationship between peripheral ANF activity and uterine ballooning is suggested / acase@tulane.edu

Both coping behaviors and physiological vulnerability to stress have been found to be associated with the development of psychopathology; however, less is known about the interrelations between coping and physiological stress responses. This study explored relations between late adolescents' styles of coping with distress and their physiological reactivity and recovery to negotiating conflict with their romantic partners. Partners' coping styles and the interaction between partners' coping styles were also examined as predictors of stress responses. One hundred and ninety couples were asked to discuss and attempt to resolve a conflictual issue that they had disagreed about in the previous month. Physiological reactivity was assessed using samples of salivary cortisol, a primary hormonal product of one of the major stress response systems. A salivary cortisol sample at entry, a pre-task anticipatory sample, and 5 post-task samples were collected. Growth modeling of the cortisol data indicated that dyadic coping was a better predictor of cortisol reactivity and recovery during relationship conflict than individual coping behaviors alone. In addition, relations among coping and physiological stress responses were found to be significantly different for males and females.

No description available.

No description available.

Changes associated with Alzheimer's Disease (AD) in the association cortices of temporal, occipital, and parietal lobes of the brain, result in significantly impaired performance of AD subjects on tests of semantic memory. The most prevalent theory regarding the deterioration of semantic memory is that it is a bottom-up process. That is, the knowledge of attributes becomes lost or inaccessible prior to the knowledge of categories. Previous research of this theory has resulted in conflicting results. The purpose of this study was to test further the theory, while taking into account task difficulty. Thirty probable AD and 28 normal elderly subjects were administered tasks of attribute and categorical knowledge. Results revealed significant differences in performance as a result of task difficulty. These results call into question the methodology previously used to assess the bottom-up theory, as well as the ability to use attribute and categorical knowledge separately.