The neural representation of plural discourse entities.

Little is known about the underlying neural structures that mediate the generation and tracking of discourse referents. In two functional magnetic resonance imaging experiments, we examined the neural structures involved in generating and maintaining the representations of multiple referents. Experiment 1 used two-sentence discourses with singular and plural conditions linking back to single or conjoined subjects. In Experiment 2, conjunction type was manipulated in order to keep the number of discourse entities constant across the discourse. Both experiments found greater activation in the superior parietal lobule bilaterally for plural entities relative to singular entities in Experiment 1 and for unconjoined plural entities relative to conjoined plural entities in Experiment 2. This parietal activation suggests that referring to multiple entities evokes multiple representations that need to be integrated and tracked. We discuss these findings in terms of psycholinguistic theories of multiple referent representations.

Digenean larvae parasitizing Cerastoderma edule (Bivalvia) and Nassarius reticulatus (Gastropoda) from Ria de Aveiro, Portugal.

This work reviews the significant community of digenean trematodes observed infecting the edible cockle, Cerastoderma edule, and the snail Nassarius reticulatus in the channel of S. Jacinto, Ria de Aveiro Estuary, Portugal. The Digenea observed comprise 15 species, belonging to the families Bucephallidae (1), Echinostomatidae (4), Gymnophallidae (3), Lepocreadiidae (1), Microphallidae (1), Monorchiidae (1), Renicolidae (1), Strigeidae, (1), and Zoogonidae (2). The species were studied by light microscopy and scanning electron microscopy. Information is included for hosts, sites of infection, prevalence, and a brief description of parasite surface morphology. The significance of these observations is compared with the presence of these digeneans from other regions, mainly the Atlantic Ocean and Mediterranean Sea. The Ria de Aveiro is a geographical location conducive to extensive species co-occurrence resulting from the overlap between southern (Mediterranean) and northern definitive hosts of the parasites. Differences in life cycle strategies were observed and discussed.