Vowels and diphthongs

This study compares the acoustic and articulatory properties of the Romanian mid diphthong /ea/ to the hiatus sequence /e.a/, and the high diphthong /ja/ to the hiatus sequence /i.a/. Both acoustic and articulatory (EMA) data support the analysis of the mid diphthong as forming a complex nucleus, consistent with its phonotactic behavior. This diphthong exhibits the greatest temporal overlap between the two vowels and the largest coarticulation/blend between its vocalic targets. The hiatus sequence /i.a/, which spans two syllables, shows the least overlap and coarticulation. The high diphthong /ja/ is a tautosyllabic sequence, displaying an intermediate degree of overlap, more similar to /ea/ than to hiatus sequences in its timing properties.

The variable prosodic parsings of Nivaĉle glottal stop

This paper establishes the featural and prosodic representations of the Nivaĉle (Mataguayan) glottal stop. On the one hand, it is proposed that the Nivaĉle glottal stop is unspecified for place features, but specified for constricted glottis ([c.g]). On the other hand, it is advanced that /ʔ/ is an independent consonantal phoneme in the language that has multiple prosodic parsings. First, a glottal stop can occur (contrastively) in syllable onset position. Second, a postvocalic glottal stop can be variably parsed to the vocalic Nucleus of the syllable and hence form part of a Complex Nucleus or to the coda position. As a result, two different manifestations of phonetic glottalized vowels are realized: creaky/rearticulated and vowelglottal coda, respectively. It is argued that these diverse glottal realizations are rooted in a set of prosodic constraints.

Bilateral lesions of nucleus subpretectalis/interstitio-pretecto-subpretectalis (SP/IPS) selectively impair figure–ground discrimination in pigeons

Earlier, we reported that nucleus rotundus (Rt) together with its inhibitory complex, nucleus subpretectalis/interstitio-pretecto-subpretectalis (SP/IPS), had significantly higher activity in pigeons performing figure–ground discrimination than in the control group that did not perform any visual discriminations. In contrast, color discrimination produced significantly higher activity than control in the Rt but not in the SP/IPS. Finally, shape discrimination produced significantly lower activity than control in both the Rt and the SP/IPS. In this study, we trained pigeons to simultaneously perform three visual discriminations (figure–ground, color, and shape) using the same stimulus displays. When birds learned to perform all three tasks concurrently at high levels of accuracy, we conducted bilateral chemical lesions of the SP/IPS. After a period of recovery, the birds were retrained on the same tasks to evaluate the effect of lesions on maintenance of these discriminations. We found that the lesions of the SP/IPS had no effect on color or shape discrimination and that they significantly impaired figure–ground discrimination. Together with our earlier data, these results suggest that the nucleus Rt and the SP/IPS are the key structures involved in figure–ground discrimination. These results also imply that thalamic processing is critical for figure–ground segregation in avian brain.