The Role of Alpha-Band Brain Oscillations as a Sensory Suppression Mechanism during Selective Attention

Evidence has amassed from both animal intracranial recordings and human electrophysiology that neural oscillatory mechanisms play a critical role in a number of cognitive functions such as learning, memory, feature binding and sensory gating. The wide availability of high-density electrical and magnetic recordings (64–256 channels) over the past two decades has allowed for renewed efforts in the characterization and localization of these rhythms. A variety of cognitive effects that are associated with specific brain oscillations have been reported, which range in spectral, temporal, and spatial characteristics depending on the context. Our laboratory has focused on investigating the role of alpha-band oscillatory activity (8–14 Hz) as a potential attentional suppression mechanism, and this particular oscillatory attention mechanism will be the focus of the current review. We discuss findings in the context of intersensory selective attention as well as intrasensory spatial and feature-based attention in the visual, auditory, and tactile domains. The weight of evidence suggests that alpha-band oscillations can be actively invoked within cortical regions across multiple sensory systems, particularly when these regions are involved in processing irrelevant or distracting information. That is, a central role for alpha seems to be as an attentional suppression mechanism when objects or features need to be specifically ignored or selected against

Second Intermediate Host-Specificity of \u3ci\u3eHaematoloechus complexus\u3c/i\u3e and \u3ci\u3eHaematoloechus medioplexus\u3c/i\u3e (Digenea: Haematoloechidae)

Second intermediate host-specificity was examined for two species of the frog lung fluke genus Haematoloechus. Nine species of freshwater arthropods were exposed to cercariae of H. complexus and H. medioplexus. Metacercariae of H. complexus developed in all arthropod species used. Metacercariae of H. medioplexus developed only in anisopteran odonate naiads. This difference in host utilization may have epizootiological implications. The potential development of H. complexus in a greater number of arthropods than H. medioplexus may increase the chances of ingestion of H. complexus by an anuran host. The range of arthropods parasitized by H. complexus indicates that host-specificity of the metacercarial stage of this fluke is not restricted by the phylogeny of aquatic arthropods

Gallium(III)-Promoted Halocyclizations of 1,6-Diynes

Adrian Landreth was an REU student, summer 2014Cyclization of 1,6-diynes promoted by stoichiometric Ga(III) halides produces vinyl halides in good to excellent yields. Under acidic conditions, initially formed iodocyclization products undergo in situ Friedel-Crafts cyclizations, giving access to iodo-indenopyridines. The application of the vinyl halides in cross-coupling reactions has been explored, and mechanistic aspects of the cyclization are discussed.HIGMS CMLD Initiative (P50 GM067041) NSF REU - Adrian Landreth support (CHE 1156666) NSF - NMR purchase (CHE 0619339) NSF - HRMS purchase (CHE0443618

Orbital-free Bond Breaking via Machine Learning

Machine learning is used to approximate the kinetic energy of one dimensional diatomics as a functional of the electron density. The functional can accurately dissociate a diatomic, and can be systematically improved with training. Highly accurate self-consistent densities and molecular forces are found, indicating the possibility for ab-initio molecular dynamics simulations

Recent Decisions

Comments on recent decisions by Harry D. Snyder, John A. Vuono, Leonard J. Kamer, John A. Young, Allan C. Schmid, William B. McFadden, David N. McBride, and Thomas J. Griffin

Redescription of the Frog Bladder Fluke \u3ci\u3eGorgoderina attenuata\u3c/i\u3e from the Northern Leopard Frog, \u3ci\u3eRana pipiens\u3c/i\u3e

Morphological characters used to differentiate North American bladder flukes, Gorgoderina spp., are problematic and different authors use different morphological characteristics for distinguishing species. More importantly, no type specimens exist for four of the 12 North American species infecting anuran and caudatan hosts. A redescription of Gorgoderina attenuata (Stafford, 1902) Stafford, 1905 is based on new collections from 6 species of anurans from Arkansas, Nebraska, New York, and Wisconsin. Morphological comparisons between gravid G. attenuata recovered from bullfrogs and northern leopard frogs indicated statistically significant differences in 11 of 28 morphological characters examined. However, there was overlap among all of these characters, and it is unclear whether these morphological types represent host-induced morphological changes in worm morphology or cryptic species. Based on our findings, we suggest that morphological and molecular data from G. attenuata-like worms recovered from the other 23 definitive hosts reported for G. attenuata need to be collected to resolve this issue

Evolutionary Constraints on Population Structure: The Parasites of \u3ci\u3eFundulus zebrinus\u3c/i\u3e (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long- term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water