Priming sentence comprehension in aphasia: effects of lexically independent and specific structural priming

Background & Aims: Impaired message-structure mapping results in deficits in both sentence production and comprehension in aphasia. Structural priming has been shown to facilitate syntactic production for persons with aphasia (PWA). However, it remains unknown if structural priming is also effective in sentence comprehension. We examined if PWA show preserved and lasting structural priming effects during interpretation of syntactically ambiguous sentences and if the priming effects occur independently of or in conjunction with lexical (verb) information.

Methods & Procedures: Eighteen PWA and 20 healthy older adults (HOA) completed a written sentence-picture matching task involving the interpretation of prepositional phrases (PP; the chef is poking the solider with an umbrella) that were ambiguous between high (verb modifier) and low attachment (object noun modifier). Only one interpretation was possible for prime sentences, while both interpretations were possible for target sentences. In Experiment 1, the target was presented immediately after the prime (0-lag). In Experiment 2, two filler items intervened between the prime and the target (2-lag). Within each experiment, the verb was repeated for half of the prime-target pairs, while different verbs were used for the other half. Participants’ off-line picture matching choices and response times were measured.

Results: After reading a prime sentence with a particular interpretation, HOA and PWA tended to interpret an ambiguous PP in a target sentence in the same way and with faster response times. Importantly, both groups continued to show this priming effect over a lag (Experiment 2), although the effect was not as reliable in response times. However, neither group showed lexical (verb-specific) boost on priming, deviating from robust lexical boost seen in the young adults of prior studies.

Conclusions: PWA demonstrate abstract (lexically-independent) structural priming in the absence of a lexically-specific boost. Abstract priming is preserved in aphasia, effectively facilitating not only immediate but also longer-lasting structure-message mapping during sentence comprehension.     

Morphologic characterization of osteoblast-like cell cultures isolated from newborn rat calvaria

Summary Two methods for harvesting osteoblast-like cell populations from newborn (10 days) rat calvaria were compared. The first one consisted in culturing the periosteum-free bones and then trypsinizing the cells on the bone surface. The second one involved the migration of the osteoblasts on glass fragments before trypsinization. Since the plating efficiency, the proportion of alkaline phosphatase-positive cells, the population doubling time, and the calcium deposition were more adequate, the second method was used to further characterize the behavior of the cultures. During the first week of culture, the cells featured shapes similar to those observedin vivo on the surface of periosteum-free calvaria. They formed multilayers and, in the presence of ascorbic acid, synthetized an organic matrix containing exclusively type I collagen. Later, small amounts of type III collagen appeared. The cells were embedded in the matrix and progressively acquired the morphologic phenotype of osteocyte-like cells. The matrix mineralized in the presence of β-glycerophosphate. The technique of dropinoculation (high concentration of cells in a small volume of medium) promoted the multilayer formation and the achievement of large mineralized plates (about 1 cm²) in 3 weeks of culture.     

Diagnostic ultrasound of acute colonic diverticulitis by surgical residents

Background: Recent studies have documented the feasibility of ultrasonography (US) to diagnose acute colonic diverticulitis (ACD). This prospective observational trial determined the sonomorphology of ACD and evaluated the diagnostic accuracy of routine US performed on admission by surgeons in training. Methods: Fifty-seven consecutive patients with a confirmed episode of ACD were entered into this study, and the sonomorphology of the involved colon was assessed. US findings were compared to the results of the clinical evaluation and correlated to the clinicopathological outcome. Results: The sonomorphology of ACD was characterized by segmental inflammatory transformation of the colon averaging 9.9 ± 3.2 cm (range, 6–20) in length and visualized as target phenomena of a mean 3.5 ± 0.8 cm (range, 2.4–4.8) width. Targets were caused by hypoechogenic thickening of the colonic wall of an average 7.7 ± 2.6 mm (range, 4–18). In 40% of cases, a hyperechogenic halo representing peridiverticulitis (average width, 2.3 ± 0.6; range, 1.2–3 cm) was noted. Diverticula were seen in almost half of the cases. Of the 57 cases with confirmed ACD, the diagnosis was made by US in 48, for a global accuracy of 84.2%. US was false negative in nine patients, suggesting perforated appendicitis in five cases and acute appendicitis in one (the final diagnoses were perforated sigmoid diverticulitis in five cases and cecal diverticulitis in one case). In three patients, US was nondiagnostic. Conclusion: In the hands of sonographically trained surgeons, ultrasound is a useful modality to image acute colonic diverticulitis. US reveals diagnostic sonomorphology in most cases of ACD and therefore facilitates early confirmation of the diagnosis and assessment of severity. Received: 3 October 1996/Accepted: 9 May 1997