Anatomy and Neuroscience - Research Publications
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ItemNo Preview AvailableDetecting Subtle Changes in Visuospatial Executive Function and Learning in the Amnestic Variant of Mild Cognitive Impairment(PUBLIC LIBRARY SCIENCE, 2011-07-14)BACKGROUND AND PURPOSE: Amnestic mild cognitive impairment (aMCI) is a putative prodromal stage of Alzheimer's disease (AD) characterized by deficits in episodic verbal memory. Our goal in the present study was to determine whether executive dysfunction may also be detectable in individuals diagnosed with aMCI. METHODS: This study used a hidden maze learning test to characterize component processes of visuospatial executive function and learning in a sample of 62 individuals with aMCI compared with 94 healthy controls. RESULTS: Relative to controls, individuals with aMCI made more exploratory/learning errors (Cohen's d = .41). Comparison of learning curves revealed that the slope between the first two of five learning trials was four times as steep for controls than for individuals with aMCI (Cohen's d = .64). Individuals with aMCI also made a significantly greater number of rule-break/error monitoring errors across learning trials (Cohen's d = .21). CONCLUSIONS: These results suggest that performance on a task of complex visuospatial executive function is compromised in individuals with aMCI, and likely explained by reductions in initial strategy formulation during early visual learning and "on-line" maintenance of task rules.
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ItemCriterion and Construct Validity of the CogState Schizophrenia Battery in Japanese Patients with Schizophrenia(PUBLIC LIBRARY SCIENCE, 2011-05-26)BACKGROUND: The CogState Schizophrenia Battery (CSB), a computerized cognitive battery, covers all the same cognitive domains as the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery but is briefer to conduct. The aim of the present study was to evaluate the criterion and construct validity of the Japanese language version of the CSB (CSB-J) in Japanese patients with schizophrenia. METHODOLOGY/PRINCIPAL FINDINGS: Forty Japanese patients with schizophrenia and 40 Japanese healthy controls with matching age, gender, and premorbid intelligence quotient were enrolled. The CSB-J and the Brief Assessment of Cognition in Schizophrenia, Japanese-language version (BACS-J) were performed once. The structure of the CSB-J was also evaluated by a factor analysis. Similar to the BACS-J, the CSB-J was sensitive to cognitive impairment in Japanese patients with schizophrenia. Furthermore, there was a significant positive correlation between the CSB-J composite score and the BACS-J composite score. A factor analysis showed a three-factor model consisting of memory, speed, and social cognition factors. CONCLUSIONS/SIGNIFICANCE: This study suggests that the CSB-J is a useful and rapid automatically administered computerized battery for assessing broad cognitive domains in Japanese patients with schizophrenia.
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ItemAcoustic analysis of the effects of 24 hours of sustained wakefulness(Australasian Speech Science and Technology Association, 2010)The effect of 24 hours of sustained wakefulness on the speech of healthy adults is poorly documented. Therefore, speech samples were systematically acquired (e.g., every four hours) from 18 healthy adults over 24 hours. Stimuli included automated and extemporaneous tasks, sustained vowel and a read passage. Measures of timing and frequency were derived acoustically using Praat and significant changes were observed on all tasks. The effect of fatigue on speech was found to be strongest just before dawn (after 22 hours). Key features of timing (e.g., mean pause length), frequency (e.g., F4 variation) and power (alpha ratio) changed as a function of increasing levels of fatigue. Index Terms: fatigue, voice, tiredness, clinical marker
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ItemNo Preview AvailableAcoustic analysis of the effects of sustained wakefulness on speech(ACOUSTICAL SOC AMER AMER INST PHYSICS, 2010-12)Exposing healthy adults to extended periods of wakefulness is known to induce changes in psychomotor functioning [Maruff et al. (2005). J. Sleep Res. 14, 21-27]. The effect of fatigue on speech is less well understood. To date, no studies have examined the pitch and timing of neurologically healthy individuals over 24 h of sustained wakefulness. Therefore, speech samples were systematically acquired (e.g., every 4 h) from 18 healthy adults over 24 h. Stimuli included automated and extemporaneous speech tasks, sustained vowel, and a read passage. Measures of timing, frequency and spectral energy were derived acoustically using PRAAT and significant changes were observed on all tasks. The effect of fatigue on speech was found to be strongest just before dawn (after 22 h). Specifically, total speech time, mean pause length, and total signal time all increased as a function of increasing levels of fatigue on the reading tasks; percentage pause and mean pause length decreased on the counting task; F4 variation decreased on the sustained vowel tasks /a:/; and alpha ratio increased on the extemporaneous speech tasks. These findings suggest that acoustic methodologies provide objective data on central nervous system functioning and that changes in speech production occur in healthy adults after just 24 h of sustained wakefulness.
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ItemNo Preview AvailableEvaluation of communication assessment practices during the acute stages post stroke(WILEY-BLACKWELL PUBLISHING, INC, 2010-12)RATIONALE, AIMS AND OBJECTIVES: Early detection of communication impairment post stroke is an important prognostic indicator and promotes the use of individualized treatment protocols. Therefore, the methods for speech and language assessment used by communication experts in acute settings following stroke were investigated. METHODS: A survey was conducted among 254 speech and language pathologists providing acute care for patients following stroke in all states and territories across Australia and New Zealand. Respondent attitudes and practices in speech and language assessment post stroke were recorded with a standardized questionnaire collected online. RESULTS: A total of 174 (68.5%) speech and language pathologists responded. Over 70% of participants assessed language and 80% assessed speech using their own clinical assessments. Respondents identified limited test repeatability and poor sensitivity to change over acute periods as key areas of concern for currently available standardized assessments. CONCLUSIONS: Subjective and/or un-standardized assessments were the most commonly used measures of communication during the acute phases post stroke. These results highlight a critical need for the development of population-specific communication assessments that build on existing clinician derived techniques and expertise while considering the acute time demands and transient nature of patient's communicative functioning.
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ItemNo Preview AvailableReliability, stability, and sensitivity to change and impairment in acoustic measures of timing and frequency(Elsevier Inc., 2011)Assessment of the voice for supporting classifications of central nervous system (CNS) impairment requires a different practical, methodological, and statistical framework compared with assessment of the voice to guide decisions about change in the CNS. In experimental terms, an understanding of the stability and sensitivity to change of an assessment protocol is required to guide decisions about CNS change. Five experiments (N=70) were conducted using a set of commonly used stimuli (eg, sustained vowel, reading, extemporaneous speech) and easily acquired measures (eg, f0–f4, percent pause). Stability of these measures was examined through their repeated application in healthy adults over brief and intermediate retest intervals (ie, 30 seconds, 2 hours, and 1 week). Those measures found to be stable were then challenged using an experimental model that reliably changes voice acoustic properties (ie, the Lombard effect). Finally, adults with an established CNS-related motor speech disorder (dysarthria) were compared with healthy controls. Of the 61 acoustic variables studied, 36 showed good stability over all three stability experiments (eg, number of pauses, total speech time, speech rate, f0–f4). Of the measures with good stability, a number of frequency measures showed a change in response to increased vocal effort resulting from the Lombard effect challenge. Furthermore, several timing measures significantly separated the control and motor speech impairment groups. Measures with high levels of stability within healthy adults, and those that show sensitivity to change and impairment may prove effective for monitoring changes in CNS functioning.