Tulane University

About: Tulane University is a education organization based out in New Orleans, Louisiana, United States. It is known for research contribution in the topics: Population & Blood pressure. The organization has 24478 authors who have published 47205 publications receiving 1944993 citations. The organization is also known as: University of Louisiana.

Behavioral and anatomical correlates of chronic episodic hypoxia during sleep in the rat

Abstract: The role played by chronic episodic hypoxia (EHYP) in the neurocognitive morbidity of obstructive sleep apnea (OSA) is unknown. Sleep recordings, Morris water maze experiments, and immunohistochemistry for NMDA NR1 glutamate receptor, c-fos protein, and apoptosis [nuclear immunoreactivity for single-stranded DNA and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling assay] were conducted in EHYP-exposed Sprague Dawley male rats. Exposures consisted of up to14 d in an environmental chamber in which O(2) concentrations were cycled between 10 and 21% every 90 sec or 30 min during 12 hr of daylight. For the remaining 12 hr, EHYP rats breathed room air, while controls spent 14 d in room air. Although EHYP induced significant disruption of sleep architecture during the initial day of exposure, sleep patterns normalized thereafter. Marked increases in apoptosis occurred in the CA1 hippocampal region (sevenfold) and cortex (Cx; eightfold) after 1-2 d of EHYP but not in CA3 and were followed by decreases toward normoxic levels by 14 d. Double labeling for NMDA NR1 and c-fos revealed marked architectural disorganization in CA1 and Cx with increases in c-fos over time. Rats exposed to EHYP displayed significantly longer escape latencies and swim path lengths to escape a hidden platform during 12 training trials given over 2 d. Differences in the performances of EHYP and control rats, although reduced, persisted after 14 d of recovery. We conclude that EHYP is associated with marked cellular changes over time within neural regions associated with cognitive functions. Furthermore, EHYP impaired performance during acquisition of a cognitive spatial task without affecting sensorimotor function. Such changes may underlie components of the learning and memory impairments found in OSA.

Spatial-temporal structures of human alpha rhythms: theory, microcurrent sources, multiscale measurements, and global binding of local networks

Abstract: A theoretical framework supporting experimental measures of dynamic properties of human EEG is proposed with emphasis on distinct alpha rhythms. Robust relationships between measured dynamics and cognitive or behavioral conditions are reviewed, and proposed physiological bases for EEG at cellular levels are considered. Classical EEG data are interpreted in the context of a conceptual framework that distinguishes between locally and globally dominated dynamic processes, as estimated with coherence or other measures of phase synchronization. Macroscopic (scalp) potentials generated by cortical current sources are described at three spatial scales, taking advantage of the columnar structure of neocortex. New EEG data demonstrate that both globally coherent and locally dominated behavior can occur within the alpha band, depending on narrow band frequency, spatial measurement scale, and brain state. Quasi-stable alpha phase structures consistent with global standing waves are observed. At the same time, alpha and theta phase locking between cortical regions during mental calculations is demonstrated, consistent with neural network formation. The brain-binding problem is considered in the context of EEG dynamic behavior that generally exhibits both of these local and global aspects. But specific experimental designs and data analysis methods may severely bias physiological interpretations in either local or global directions.

Workhorse semilocal density functional for condensed matter physics and quantum chemistry.

Abstract: Semilocal density functionals for the exchange-correlation energy are needed for large electronic systems. The Tao-Perdew-Staroverov-Scuseria (TPSS) meta-generalized gradient approximation (meta-GGA) is semilocal and usefully accurate, but predicts too-long lattice constants. Recent "GGA's for solids" yield good lattice constants but poor atomization energies of molecules. We show that the construction principle for one of them (restoring the density gradient expansion for exchange over a wide range of densities) can be used to construct a "revised TPSS" meta-GGA with accurate lattice constants, surface energies, and atomization energies for ordinary matter.