Monthly Archives: January 2011
Processing-speed deficits affect reading efficiency, even among individuals who recognize and decode words accurately. Children with ADHD who decode words accurately can still have inefficient reading fluency, leading to a bottleneck in other cognitive processes. This “slowing” in ADHD is associated with deficits in fundamental components of executive function underlying processing speed, including response selection. The purpose of the present study was to deconstruct processing speed in order to determine which components of executive control best explain the “processing” speed deficits related to reading fluency in ADHD. Participants (41 ADHD, 21 controls), ages 9-14 years, screened for language disorders, word reading deficits, and psychiatric disorders, were administered measures of copying speed, processing speed, reading fluency, working memory, reaction time, inhibition, and auditory attention span. Compared to controls, children with ADHD showed reduced oral and silent reading fluency and reduced processing speed—driven primarily by deficits on WISC-IV Coding. In contrast, groups did not differ on copying speed. After controlling for copying speed, sex, severity of ADHD-related symptomatology, and GAI, slowed “processing” speed (i.e., Coding) was significantly associated with verbal span and measures of working memory but not with measures of response control/inhibition, lexical retrieval speed, reaction time, or intrasubject variability. Further, “processing” speed (i.e., Coding, residualized for copying speed) and working memory were significant predictors of oral reading fluency. Abnormalities in working memory and response selection (which are frontally mediated and enter into the output side of processing speed) may play an important role in deficits in reading fluency in ADHD, potentially more than posteriorally mediated problems with orienting of attention or perceiving the stimulus.
Background: Extrapyramidal signs (EPS) may vary across 3 major subtypes of primary progressive aphasia (PPA): progressive nonfluent aphasia (PNFA), semantic dementia (SD), and progressive logopenic aphasia (PLA). Methods: We reviewed initial neurological examinations from a clinical PPA cohort (PNFA = 49, SD = 26, PLA = 28) to determine the prevalence of specific categories of EPS. Results: The presence of any EPS was more common in PNFA (38.8%) and PLA (35.7%) than in SD (3.8%). The PNFA group exhibited the highest prevalence of bradykinesia (PNFA: 22.4%, SD: 3.8%, PLA: 0.0%) and rigidity (PNFA: 30.6%, SD: 0.0%, PLA: 10.7%). Calculated positive likelihood ratios indicated bradykinesia (12.1) or rigidity (5.5) was more strongly associated with PNFA than other PPAs. Conclusion: These findings suggest that on initial presentation, specific EPS may help distinguish PPA subtypes when linguistic and/or neuroimaging profiles are indistinct. Moreover, EPS could represent a marker of underlying tauopathy, linking clinical presentation to neuropathology in PPA.
Validation of the language component of the Addenbrooke’s Cognitive Examination – Revised (ACE-R) as a screening tool for aphasia in stroke patients
Our results suggest that the language component of ACE-R has a satisfactory sensitivity and specificity compared with other screening tests used in strokes. It is easy to administer and free to use.
from the Australian Journal of Ageing
A number of physiological changes occur during pregnancy and amongst them, audiological and nasal changes are quite significant. These are mainly due to the changing levels of sex hormones and return to normal once the pregnancy is over. This study was conducted to document these changes. Forty (pregnant 40 and non-pregnant 40) consenting subjects in age group of 20–35 years were assigned to test and control groups. They underwent complete ENT and Obstetric examination. In test group Pure Tone Audiometry was performed in all trimesters of pregnancy and within 3 months of delivery. The subjects in the control group underwent pure tone audiometry only once. The nasal patency was measured by Gertner’s plate method. Results from each trimester and postpartum period were compared. A highly significant difference in pure tone thresholds was observed at frequencies ranging from 125 to 1000 Hz (P < 0.001). However frequencies higher than 1000 Hz demonstrated no significant correlation. Nasal patency as measured by mean area of vapour condensation in all trimesters and control groups was highly significant (P < 0.001). The results of this study confirm that these changes occur in the first trimester and gradually improve during the subsequent trimesters returning to normal in post partum period. However number of pregnancies bear no relationship with these changes
from the Indian Journal of Otolaryngology
Previous studies have found a significant correlation between spectral-ripple discrimination and speech and music perception in cochlear implant (CI) users. This relationship could be of use to clinicians and scientists who are interested in using spectral-ripple stimuli in the assessment and habilitation of CI users. However, previous psychoacoustic tasks used to assess spectral discrimination are not suitable for all populations, and it would be beneficial to develop methods that could be used to test all age ranges, including pediatric implant users. Additionally, it is important to understand how ripple stimuli are processed in the central auditory system and how their neural representation contributes to behavioral performance. For this reason, we developed a single-interval, yes/no paradigm that could potentially be used both behaviorally and electrophysiologically to estimate spectral-ripple threshold. In experiment 1, behavioral thresholds obtained using the single-interval method were compared to thresholds obtained using a previously established three-alternative forced-choice method. A significant correlation was found (r = 0.84, p = 0.0002) in 14 adult CI users. The spectral-ripple threshold obtained using the new method also correlated with speech perception in quiet and noise. In experiment 2, the effect of the number of vocoder-processing channels on the behavioral and physiological threshold in normal-hearing listeners was determined. Behavioral thresholds, using the new single-interval method, as well as cortical P1-N1-P2 responses changed as a function of the number of channels. Better behavioral and physiological performance (i.e., better discrimination ability at higher ripple densities) was observed as more channels added. In experiment 3, the relationship between behavioral and physiological data was examined. Amplitudes of the P1-N1-P2 “change” responses were significantly correlated with d′ values from the single-interval behavioral procedure. Results suggest that the single-interval procedure with spectral-ripple phase inversion in ongoing stimuli is a valid approach for measuring behavioral or physiological spectral resolution.
Evaluating Adaptation and Olivocochlear Efferent Feedback as Potential Explanations of Psychophysical Overshoot
Masked detection threshold for a short tone in noise improves as the tone’s onset is delayed from the masker’s onset. This improvement, known as “overshoot,” is maximal at mid-masker levels and is reduced by temporary and permanent cochlear hearing loss. Computational modeling was used in the present study to evaluate proposed physiological mechanisms of overshoot, including classic firing rate adaptation and medial olivocochlear (MOC) feedback, for both normal hearing and cochlear hearing loss conditions. These theories were tested using an established model of the auditory periphery and signal detection theory techniques. The influence of several analysis variables on predicted tone-pip detection in broadband noise was evaluated, including: auditory nerve fiber spontaneous-rate (SR) pooling, range of characteristic frequencies, number of synapses per characteristic frequency, analysis window duration, and detection rule. The results revealed that overshoot similar to perceptual data in terms of both magnitude and level dependence could be predicted when the effects of MOC efferent feedback were included in the auditory nerve model. Conversely, simulations without MOC feedback effects never produced overshoot despite the model’s ability to account for classic firing rate adaptation and dynamic range adaptation in auditory nerve responses. Cochlear hearing loss was predicted to reduce the size of overshoot only for model versions that included the effects of MOC efferent feedback. These findings suggest that overshoot in normal and hearing-impaired listeners is mediated by some form of dynamic range adaptation other than what is observed in the auditory nerve of anesthetized animals. Mechanisms for this adaptation may occur at several levels along the auditory pathway. Among these mechanisms, the MOC reflex may play a leading role.
Recovery from aphasia is a dynamic, ongoing process
Mark your calendars for Saturday, February 5th at 2 p.m EDT.
from SLP Chat
Auditory cortical N100 in pre- and post-synaptic auditory neuropathy to frequency or intensity changes of continuous tones
Abnormalities of auditory cortical N100 in AN reflect disorders of both temporal processing (low frequency) and neural adaptation (high frequency). Auditory N100 latency to the low frequency provides an objective measure of the degree of impaired speech perception in AN.
We previously reported that foetal valproate exposure impairs intelligence quotient. In this follow-up investigation, we examined dose-related effects of foetal antiepileptic drug exposure on verbal and non-verbal cognitive measures. This investigation is an ongoing prospective observational multi-centre study in the USA and UK, which has enrolled pregnant females with epilepsy on monotherapy from 1999 to 2004. The study seeks to determine if differential long-term neurodevelopmental effects exist across four commonly used drugs (carbamazepine, lamotrigine, phenytoin and valproate). This report compares verbal versus non-verbal cognitive outcomes in 216 children who completed testing at the age of three years. Verbal and non-verbal index scores were calculated from the Differential Ability Scales, Preschool Language Scale, Peabody Picture Vocabulary Test and Developmental Test of Visual-Motor Integration. Verbal abilities were lower than non-verbal in children exposed in utero to each drug. Preconceptional folate use was associated with higher verbal outcomes. Valproate was associated with poorer cognitive outcomes. Performance was negatively associated with valproate dose for both verbal and non-verbal domains and negatively associated with carbamazepine dose for verbal performance. No dose effects were seen for lamotrigine and phenytoin. Since foetal antiepileptic drug exposure is associated with lower verbal than non-verbal abilities, language may be particularly susceptible to foetal exposure. We hypothesize that foetal drug exposure may alter normal cerebral lateralization. Further, a dose-dependent relationship is present for both lower verbal and non-verbal abilities with valproate and for lower verbal abilities with carbamazepine. Preconceptional folate may improve cognitive outcomes. Additional research is needed to confirm these findings, extend the study to other drugs, define the risks associated with drug treatment for seizures in the neonates, and understand the underlying mechanisms.
Left inferior frontal cortex and syntax: function, structure and behaviour in patients with left hemisphere damage
For the past 150 years, neurobiological models of language have debated the role of key brain regions in language function. One consistently debated set of issues concern the role of the left inferior frontal gyrus in syntactic processing. Here we combine measures of functional activity, grey matter integrity and performance in patients with left hemisphere damage and healthy participants to ask whether the left inferior frontal gyrus is essential for syntactic processing. In a functional neuroimaging study, participants listened to spoken sentences that either contained a syntactically ambiguous or matched unambiguous phrase. Behavioural data on three tests of syntactic processing were subsequently collected. In controls, syntactic processing co-activated left hemisphere Brodmann areas 45/47 and posterior middle temporal gyrus. Activity in a left parietal cluster was sensitive to working memory demands in both patients and controls. Exploiting the variability in lesion location and performance in the patients, voxel-based correlational analyses showed that tissue integrity and neural activity—primarily in left Brodmann area 45 and posterior middle temporal gyrus—were correlated with preserved syntactic performance, but unlike the controls, patients were insensitive to syntactic preferences, reflecting their syntactic deficit. These results argue for the essential contribution of the left inferior frontal gyrus in syntactic analysis and highlight the functional relationship between left Brodmann area 45 and the left posterior middle temporal gyrus, suggesting that when this relationship breaks down, through damage to either region or to the connections between them, syntactic processing is impaired. On this view, the left inferior frontal gyrus may not itself be specialized for syntactic processing, but plays an essential role in the neural network that carries out syntactic computations.
Using a novel surgical approach, it’s possible to rebuild the trachea and preserve a patient’s voice after removing an invasive throat tumor, according to a new report from Henry Ford Hospital in Detroit.
from The Medical News
Behavioural variant frontotemporal dementia is characterized by a change in comportment. It is associated with considerable functional decline over the course of the illness albeit with sometimes dramatic variability among patients. It is unknown whether any baseline features, or combination of features, could predict rate of functional decline in behavioural variant frontotemporal dementia. The aim of this study was to investigate the effects of different baseline clinical, neuropsychological, neuropsychiatric, genetic and anatomic predictors on the rate of functional decline as measured by the Clinical Dementia Rating Sum of Boxes scale. We identified 86 subjects with behavioural variant frontotemporal dementia that had multiple serial Clinical Dementia Rating Sum of Boxes assessments (mean 4, range 2–18). Atlas-based parcellation was used to generate volumes for specific regions of interest at baseline. Volumes were utilized to classify subjects into different anatomical subtypes using the advanced statistical technique of cluster analysis and were assessed as predictor variables. Composite scores were generated for the neuropsychological domains of executive, language, memory and visuospatial function. Behaviours from the brief questionnaire form of the Neuropsychiatric Inventory were assessed. Linear mixed-effects regression modelling was used to determine which baseline features predict rate of future functional decline. Rates of functional decline differed across the anatomical subtypes of behavioural variant frontotemporal dementia, with faster rates observed in the frontal dominant and frontotemporal subtypes. In addition, subjects with poorer performance on neuropsychological tests of executive, language and visuospatial function, less disinhibition, agitation/aggression and night-time behaviours at presentation, and smaller medial, lateral and orbital frontal lobe volumes showed faster rates of decline. In many instances, the effect of the predictor variables observed across all subjects was also preserved within anatomical subtypes. Furthermore, some of the predictor variables improved our prediction of rate of functional decline after anatomical subtype was taken into account. In particular, age at onset was a highly significant predictor but only after adjusting for subtype. We also found that although some predictor variables, for example gender, Mini-Mental State Examination score, and apathy/indifference, did not affect the rate of functional decline; these variables were associated with the actual Clinical Dementia Rating Sum of Boxes score estimated for any given time-point. These findings suggest that in behavioural variant frontotemporal dementia, rate of functional decline is driven by the combination of anatomical pattern of atrophy, age at onset, and neuropsychiatric characteristics of the subject at baseline.
Light therapy can help preserve vocal cord function for patients with early stage laryngeal cancer: Study
Light, or photodynamic, therapy can help preserve the voice and vocal cord function for patients with early stage laryngeal (voice box) cancer, according to a study from Henry Ford Hospital in Detroit.
from The Medical News
This study was designed to characterize the brain system that monitors speech in people who stutter and matched controls. We measured two electrophysiological peaks associated with action-monitoring: the error-related negativity (ERN) and the error positivity (Pe). Both the ERN and Pe were reliably observed after errors in a rhyming task and a nonverbal flanker task, replicating previous reports of a language-monitoring ERN and demonstrating that the Pe can also be elicited by phonological errors. In the rhyming task, stutterers showed a heightened ERN peak regardless of whether they actually committed an error. Similar results, though only marginally significant, were obtained from the flanker task. These results support the vicious cycle hypothesis, which posits that stuttering results from over-monitoring the speech plan. The elevation of the ERN in stutterers and the similarity of the results between the flanker and rhyming tasks implies that speech-monitoring may rely on the same neural substrate as action-monitoring.
from Brain and Language