A First Examination of Aphasia Using Pupillometry

We use pupillometry to examine the time-course of sentence processing in aphasia, perhaps the first study to do so.  By time-locking pupillary responses to stimulus presentation, we are able to collect a continuous measure of processing load in a participant-friendly and efficient manner.  In this first proof-of-concept effort, we manipulate the thematic fit that occurs between a verb and its arguments. We find that aphasic patients’ pupillary responses are similar to those of their age matched controls as well as healthy college age students, whereby pupil size increases when thematic fit is violated

The Auditory Comprehension of Unaccusative Verbs in Aphasia

Some persons with aphasia, particularly those diagnosed with a Broca’s aphasia, exhibit a delayed time course of lexical activation in canonically ordered S-V-O sentences (Ferrill et al., 2012) and delayed re-activation of displaced arguments in sentences that contain syntactic dependencies (Love et al., 2008). These patterns support the Delayed Lexical Activation (DLA) hypothesis: Lexical activation is delayed relative to the normal case, and thus lexical activation and syntactic operations are de-synchronized; that is, lexical access is too slow for normally fast-acting syntactic operations. This delay in lexical access leads to what appear to be syntactic comprehension deficits in aphasia. In the current study we further examined lexical activation during sentence comprehension in persons with aphasia by using unaccusative verbs. Unaccusative verbs are a type of intransitive verb with a single argument that is base generated in object position and displaced to the surface subject position, leaving behind a copy or trace (‘gap’) of the movement (see, for example, Burzio, 1986), as in: 1. The girl vanished Thus there is a syntactic dependency between the two positions. When encountering sentences that contain syntactic dependencies (e.g., object relatives, Wh-questions) neurologically unimpaired individuals immediately reactivate the displaced argument at the gap (Shapiro et al., 1999; Love et al., 2008). In contrast to this immediate reactivation, prior findings indicate that neurologically unimpaired individuals do not reactivate the displaced argument in similar sentences with unaccusative verbs until 750ms downstream from the gap (Friedmann et al., 2008). This built-in delay observed with unaccusative verbs in neurologically healthy participants provides a unique opportunity to further examine lexical delays in individuals with Broca’s aphasia. Importantly, individuals with Broca’s aphasia may have unaccusative verb deficits. Previous research has found that persons with aphasia have difficulty producing unaccusative verbs. Offline truth-value judgment tasks with intransitive sentences containing unaccusative verbs do not reveal comprehension deficits (Lee & Thompson, 2004). However, in a sentence-picture matching task, McAllister et al. (2009) found lower accuracy for intransitive sentences that contained unaccusative verbs than transitive sentences. We entertain the following hypothesis: The delayed lexical access routines better synchronize with the delay of reactivating the argument of unaccusatives, suggesting that individuals with Broca’s aphasia should evince a pattern like that of unimpaired individuals. Alternatively, participants with Broca’s aphasia might show activation even further downstream from the gap, given that in other sentence constructions containing syntactic dependencies they exhibit a delayed pattern of reactivation compared to neurologically unimpaired individuals

Superclasses and supercharacters of normal pattern subgroups of the unipotent upper triangular matrix group

Let $U_n$ denote the group of $n\times n$ unipotent upper-triangular matrices over a fixed finite field \FF_q, and let U_\cP denote the pattern subgroup of $U_n$ corresponding to the poset \cP. This work examines the superclasses and supercharacters, as defined by Diaconis and Isaacs, of the family of normal pattern subgroups of $U_n$. After classifying all such subgroups, we describe an indexing set for their superclasses and supercharacters given by set partitions with some auxiliary data. We go on to establish a canonical bijection between the supercharacters of U_\cP and certain \FF_q-labeled subposets of \cP. This bijection generalizes the correspondence identified by Andr\'e and Yan between the supercharacters of $U_n$ and the \FF_q-labeled set partitions of $\{1,2,...,n\}$. At present, few explicit descriptions appear in the literature of the superclasses and supercharacters of infinite families of algebra groups other than \{U_n : n \in \NN\}. This work signficantly expands the known set of examples in this regard.Comment: 28 page

A Linguistic-Specific Approach to Treatment of Sentence Production Deficits in Aphasia

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Real-time Sentence Processing in Aphasia

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The Use of Linguistic Theory as a Framework for Treatment Studies in Aphasia

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The time-course of lexical activation during sentence comprehension in aphasia

We present a cross-modal priming study using simple active sentence constructions to map out the time-course of lexical activation throughout a sentence. Preliminary findings suggest that in contrast to our unimpaired listeners who demonstrated immediate initial activation of a lexical item and a linear, relatively gradual decay, our participants with agrammatic aphasia demonstrated a pattern of late initial activation, and then immediate decay.  We surmise that this delayed lexical access coupled with the accelerated time-course of decay contributes to what appears to be a disrupted integration process

Verb preference effects in the sentence comprehension of fluent aphasic individuals

This investigation examined sentence processing of fluent aphasic subjects with varying severity levels. Subjects performed a cross-modal lexical decision task for transitive and intransitive verbs in preferred and non-preferred frameworks. Verb processing was measured by reaction times during on-line sentence comprehension. Reaction times to the cross-modal lexical decision (CMLD) task indicated that the subjects with aphasia were insensitive to preference information associated with the processing of verbs in sentences. Severity level did not alter the pattern observed regarding verb type and preferences

Modal Ω-Logic: Automata, Neo-Logicism, and Set-Theoretic Realism

This essay examines the philosophical significance of $\Omega$-logic in Zermelo-Fraenkel set theory with choice (ZFC). The duality between coalgebra and algebra permits Boolean-valued algebraic models of ZFC to be interpreted as coalgebras. The modal profile of $\Omega$-logical validity can then be countenanced within a coalgebraic logic, and $\Omega$-logical validity can be defined via deterministic automata. I argue that the philosophical significance of the foregoing is two-fold. First, because the epistemic and modal profiles of $\Omega$-logical validity correspond to those of second-order logical consequence, $\Omega$-logical validity is genuinely logical, and thus vindicates a neo-logicist conception of mathematical truth in the set-theoretic multiverse. Second, the foregoing provides a modal-computational account of the interpretation of mathematical vocabulary, adducing in favor of a realist conception of the cumulative hierarchy of sets

Analysis of Verbs and Verb-Argument Structure: A Method for Quantification of Aphasic Language Production

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