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.     

Brain morphology in first-episode schizophrenic-like psychotic patients: a quantitative magnetic resonance imaging study

Brain morphology was examined using magnetic resonance imaging in 30 first-episode patients with a schizophreniclike psychosis, 15 chronic schizophrenics, and 20 neurological controls. Statistical analyses of computer-generated measurements of regions of interest were controlled for gender, age, social class, and total brain volume. Lateral ventricular size was increased in both first-episode and chronic schizophrenic patients, with greater significance on the left than on the right side. Only the chronic patients, however, had reduced temporal lobe size, which also was greater on the left side. No major correlations of regional brain morphological measurements with cognitive functioning were found, although some measurements of verbal memory were correlated with parahippocampal size. This is a report of a preliminary study that suggests that some morphological brain changes may be present at the time of first treatment for a psychotic illness, whereas others may occur later in the course of illness. Future prospective studies may determine the clinical significance of these changes and whether they progress with the development of illness chronicity.     

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.