The mixing time of the fifteen puzzle

We show that there are universal positive constants c and C such that the mixing time T_{mix} for the fifteen puzzle in an n by n torus satisfies cn^4 log n < T_{mix} < Cn^4 log^2 n.Comment: 30 pages, 9 figure

Word-Retrieval Treatment in Aphasia: Effects of Sentence Context

Word-retrieval treatment studies in aphasia have reported the greatest influences on picture naming for trained words. To increase treatment effects to untrained words and sentence contexts, we investigated a sentence-reading treatment hierarchy that moves from errorless to generative production of sentences incorporating target nouns and verbs. In an individual with nonfluent aphasia, treatment resulted in improved picture naming for nouns and verbs and generalized increases in numbers of grammatical sentences and content words following noun therapy. A second individual with fluent aphasia improved little in picture-naming and sentence-generation tasks for both nouns and verbs. This sentence-based word-retrieval training, in which semantic and syntactic processes are engaged, led to improvements in word-retrieval measures during spontaneous sentence generation, but only for the participant with nonfluent aphasia. Contrary to expectations, these changes were greater following noun therapy than they were following verb therapy

A comparison of intention and pantomime gesture treatments for word retrieval in people with aphasia

Intention and pantomime gesture treatments for noun retrieval secondary to aphasia have not been compared. In a single-participant design, we investigated the effects of training on verbal and gestural productions following both gesture treatments in four individuals with aphasia. P1 improved verbal productions post intention treatment for trained words only. P2 and P3 improved usage of pantomime gestures to communicate in lieu of verbal gains. P4 improved verbal productions post intention and usage of gestures post pantomime treatment. The most effective type of gesture treatment for remediation of noun retrieval depends on the nature of word retrieval deficit

Constraint-induced Language Treatment: Time to Rethink?

Constraint-induced Language Treatment (CILT, CIAT) first emerged into clinical practice in aphasia treatment following publication of the Pulvermüller et al., paper in 2001. Since then CILT has engendered clinical research application (e.g. Kirmess & Maher, 2010) and a systematic review (Cherney et al., 2008, 2010) and in clinical practice has appeared as the featured treatment program in several aphasia treatment programs and garnered attention from third party payors. The history of CILT is relatively well known by now, having derived from Constraint-Induced Movement Therapy which has a rich literature base that includes literature on neuroplasticity and motor skill learning. Equally well known are the treatment principles of CILT: constraining the response format, treating in an intensive schedule, and shaping verbal responses

MossTalk Training for Word Retrieval: Generalization Across Semantic Categories

Little is known about the independent usefulness of MossTalk Words, a computerized training program for word retrieval, nor how training effects generalize to other untrained words. In a single-participant design, we investigated effects of independent training with MossTalk multi-mode matching exercises in four individuals with stroke-induced aphasia. Three of four participants improved in picture naming for trained words. One showed limited generalization to words in untrained semantic categories. Three improved in standardized testing, particularly for auditory comprehension, which is addressed in the matching exercises. Improvements are possible with independent training programs such as MossTalk Words

Word Retrieval Treatments for Aphasia: Connected Speech Outcomes

We examined changes in connected speech in individuals with aphasia following errorless naming treatment and gestural facilitation of naming administered in a single-participant crossover design. In addition to picture naming, participants completed two connected speech tasks during baseline and after each training phase. Positive training effect sizes in picture naming were associated with increased use of Correct Information Units and substantive nouns in connected speech. Greater use of CIUs and substantive nouns were evident for a questions task over a picture description task. Open-ended questions tended to be more effective than picture description for documenting speech changes associated with treatment

Communication Partner Training in Aphasia: A Critical Review

This presentation describes the procedures and results of a systematic review of the literature on communication partner training in aphasia. A search of thirteen databases resulted in 28 relevant articles published in English between 1975 and April, 2008. These included 8 group studies varying from randomized controlled trials to uncontrolled pre-post studies, 7 single-subject experimental designs, 5 qualitative research designs and 8 case studies. Studies were independently reviewed by two reviewers. Results revealed a wide range of quality scores. Most studies fell in the weaker AAN evidence strength classes. However, 3 studies met the criteria for Class I research

Computerized Training for Impairments of Word Comprehension and Retrieval in Aphasia

Semantic comprehension training paired with verbal production leads to improved word retrieval in individuals with aphasia. In a single-participant design, we investigated effects of semantic+phonologic training provided via computer with Moss Talk multi-mode matching exercises. Five individuals with moderate to severe word retrieval impairments participated; two also had significant impairments of lexical comprehension. Those two participants demonstrated increases in comprehension for trained and untrained words. All five participants improved in picture naming, particularly for trained words. We argue that lexical-semantic changes mediated training effects in both tasks along with alterations in attentional capabilities that influenced word comprehension more generally

Effects of Verbal plus Gestural Treatment in a Patient with Aphasia and Severe Apraxia of Speech

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Anomia Treatment Platform as Behavioral Engine for Use in Research on Physiological Adjuvants to Neurorehabilitation

The purpose of this study was to create a behavioral treatment engine for future use in research on physiological adjuvants in aphasia rehabilitation. We chose the behavioral target anomia, which is a feature displayed by many persons who have aphasia. Further, we wished to saturate the treatment approach with many strategies and cues that have been empirically reported to have a positive influence on aphasia outcome, with the goal being to optimize the potential for positive response in most participants. A single-subject multiple baseline design with replication across eight participants was employed. Four men and four women, with an average age of 62 yr and an average of 63.13 mo poststroke onset, served as participants. Word-retrieval treatment was administered 3 d/wk, 1 h/d for a total of 20 treatment hours (6-7 wk). Positive acquisition effects were evident in all eight participants (d effect size [ES] = 5.40). Treatment effects were maintained 3 mo after treatment termination for five participants (d ES = 2.94). Within and across semantic category, generalization was minimal (d ES = 0.43 within and 1.09 across). This study demonstrates that this behavioral treatment engine provides a solid platform on which to base future studies whereby various treatment conditions are manipulated and pharmacologic support is added