Primary progressive aphasia is a degenerative disease affecting language while leaving other cognitive facilities relatively unscathed. The agrammatic subtype of PPA is characterized by agrammatic language production with impaired comprehension of noncanonical filler-gap syntactic structures, such as object-relatives [e.g., The sandwich that the girl ate was tasty], in which the filler is displaced from the object position within the relative clause to a position preceding both the verb and the agent and is replaced by a gap linked with the filler. (...) One hypothesis suggests that the observed deficits of these structures reflect impaired thematic integration, including impaired prediction of the thematic role of the filler and impaired thematic integration at the gap, but spared structure building. In the current study, we examined the on-line comprehension of object-relative and subject-relative clauses in healthy controls and individuals with agrammatic and logopenic PPA using eye-tracking. Eye-movement patterns in canonical subject-relative clause structures were essentially spared in both PPA groups. In contrast, eye-movement patterns in noncanonical object-relative clauses revealed delayed thematic prediction in both agrammatic and logopenic PPA, on-time structure building in both groups, and abnormal thematic integration in agrammatic, but not logopenic, PPA. We argue that these results are consistent with the hypothesis that agrammatic comprehension deficits reflect impaired thematic integration. (shrink)

LET ME BEGIN this inquiry with the simple but fundamental fact that the flow of time, or passage, as it is also known, is given in experience, that it is as indubitable an aspect of our perception of the world as the sights and sounds that come in upon us, even though it is not the peculiar property of a special sense. Consider, by way of illustration, that I am now sitting at the desk in my study. This particular event (...) was not present at any earlier time, nor will it be present shortly as I become involved in other activities. The present, as I experience it, is regularly associated with later and later events. It does not hop about capriciously from here to a later time, to a previous time, and then to a much later time, or trace out some other such indiscriminate pattern; instead I find it always in association with the next moment, and as I look backward and inward, so to speak, I find that the prior moment was present and that this next-later moment is present. Quite often this condition is expressed by means of imagery. We are asked to envision either a moving present racing along a fixed track of moments or events from earlier to later, or alternatively a fixed present through which stream a series of moments or events, first the earlier and then the later ones. One is in truth hard-pressed to find references to passage which do not employ quasi-poetical tropes and metaphors, and while these do help in some sense to say what we mean, great caution is required when handling them because of their ready tendency to draw us away from the actual phenomenon requiring explanation. (shrink)