COMD News

Events and Research in Speech, Language, and Hearing Disorders

Mixed feelings about living with tinnitus: A qualitative study

from Audiological Medicine

The aim of this qualitative study was to interview a group of tinnitus patients (n = 7) who were or had been involved in psychological treatment for their tinnitus. Following semi-structured interviews all conversations were transcribed and later categorized using methods inspired by grounded theory. Results revealed a higher order concept labelled ‘Mixed feelings about living with tinnitus’. Three descriptive categories were derived: 1) Consequences; 2) Treatment experiences; and 3) Tinnitus identity. Results are discussed in relation to the literature on tinnitus, and the future application of qualitative methods in tinnitus research is encouraged.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Can Intratympanic Dexamethasone Added to Systemic Steroids Improve Hearing Outcome in Patients With Sudden Deafness?

from Laryngoscope

Objective: To evaluate the therapeutic efficacy of intratympanic dexamethasone (ITD) injections added to systemic steroids in patients with idiopathic sudden sensorineural hearing loss (HL).

Materials and Methods: A total of 120 patients diagnosed with sudden HL were treated with ITD injections (0.3 mL on days 1, 3, and 5) plus 48 mg methylprednisolone (ITD group) or methylprednisolone alone (control group).

Results: The total recovery rate after the treatment was 73.3% in the ITD group and 70.0% in the control group. Although improvements in pure-tone average were the same in the two groups, the ITD group showed significantly better hearing improvement at 250 Hz than the control group.

Conclusion: The addition of ITD to systemic steroids did not result in significant improvements in the treatment of idiopathic sudden HL.

January 31, 2008 Posted by Callier Library | Uncategorized | , , , | No Comments

Outcomes of Treatment of Partial Deafness With Cochlear Implantation: A DUET Study

from Laryngoscope

Objectives: To compare speech test performance of adults with partial deafness cochlear implantation (PDCI) with that of adults with cochlear implant (CI). Based on the results, our objective is to determine the efficacy of the two applications of cochlear implantation, the first characterized by a shallow electrode insertion and preservation of low-frequency natural hearing for partial deafness, and the second characterized by a very deep electrode insertion used in subjects with severe to profound deafness. All the PDCI participants in this study were fitted with a recently upgraded DUET Hearing System from Med-El Corporation, Innsbruck, Austria.

Study Design: This is a two-group comparison study. Eleven experienced PDCI adults and 22 postlingually deafened CI adults participated in this study. Subjects were implanted with either COMBI 40+ or PULSAR cochlear implant.

Methods: Subjects were tested with monosyllable and sentence tests in Polish in quiet and under various signal-to-noise ratio (SNR) in the conditions of DUET only, CI only, DUET hearing aid (HA) only, and best aided (DUET plus contralateral hearing). CI subjects were tested with their CI.

Results: PDCI subjects performed significantly better than CI subjects did. Speech tests demonstrated the best results in the conditions of best aided and DUET only. The poorest results were obtained in the condition DUET HA only. Results show a greater benefit for the PDCI group of subjects fitted with the DUET, compared to the CI alone group.

Conclusions: The shallow electrode array insertion with preserved low-frequency hearing is a highly effective method for the treatment of partial deafness. The combination of HA and CI processor, i.e., the DUET, is beneficial in noise and in quiet.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Study Shows Variety of Approaches Help Children Overcome Auditory Processing and Language Problems

from NIH News.gov

For children who struggle to learn language, the choice between various interventions may matter less than the intensity and format of the intervention, a new study sponsored by the National Institute on Deafness and Other Communication Disorders (NIDCD) suggests. The study, led by Ronald B. Gillam, Ph.D., of Utah State University is online in the February 2008 Journal of Speech, Language, and Hearing Research. NIDCD is one of the National Institutes of Health.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Receptive and Productive Vocabulary Sizes of L2 Learners

from Studies in Second Language Acquisition

This study investigated the relationship between receptive and productive vocabulary size. The experimental design expanded upon earlier methodologies by using equivalent receptive and productive test formats with different receptive and productive target words to provide more accurate results. Translation tests were scored at two levels of sensitivity to measure receptive and productive knowledge of meaning and form. The results showed that total receptive vocabulary size was larger than productive vocabulary. When responses were scored for fuller knowledge, receptive vocabulary size was also found to be greater than productive vocabulary size in each of three word frequency bands, with the difference between receptive and productive knowledge increasing as the frequency of the words decreased. However, when responses were scored for partial knowledge, there was little difference among vocabulary sizes at each frequency band. The findings also indicated that receptive vocabulary size might give some indication of productive vocabulary size. Learners who have a larger receptive vocabulary are likely to know more of those words productively than learners who have a smaller receptive vocabulary.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Syntactic Priming and ESL Question Development

from Studies in Second Language Acquisition

Interaction research that has investigated the relationship between language production and second language (L2) development has largely focused on learners’ immediate responses to interactional feedback. However, other speech production processes might help account for the beneficial relationship between interaction and L2 development. The current study examines whether syntactic priming—the tendency to produce a syntactic structure encountered in the recent discourse—is associated with English as a second language (ESL) question development. The participants were intermediate-level Thai learners of English (N = 46) at a large public university in northern Thailand. In two 20-min sessions, the participants carried out communicative activities with a more advanced L2 English interlocutor who had been scripted with developmentally advanced question forms. They also completed an oral pretest and two posttests that consisted of activities similar to those carried out during the treatment sessions. The results indicated that participants who evidenced high levels of syntactic priming were likely to advance to a higher stage in the developmental sequence of ESL question formation.

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

Audiology in Brazil

from the International Journal of Audiology

The profession of audiology took root in Brazil nearly a half a century ago and has since blossomed into a flourishing, well-developed field. Currently, audiologists in Brazil work at private institutions, including private medical practices and dedicated speech and hearing clinics. They are also employed in a wide array of public institutions, including community clinics, elementary schools, colleges, and universities. In both the private sector and health clinics, audiologists perform diagnostic evaluations of auditory and vestibular disorders, select and fit hearing aids, and provide aural rehabilitation. At the public level, they assist with workers’ health programs, dispense hearing aids, and aural rehabilitation. There is always room to grow, however, and the future of audiology in Brazil holds both challenges and opportunity. The following article will sketch the development of audiology training and practice in Brazil, provide a picture of how the field stands today, and summarize the unique challenges which the profession faces in this large and diverse nation.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Auditory rehabilitation for interaural asymmetry: Preliminary evidence of improved dichotic listening performance following intensive training

from the International Journal of Audiology

Children with dichotic left ear deficits received intensive training in phase I and phase II clinical trials designed to establish the efficacy of directly training dichotic listening. Dichotic verbal material was presented in the sound field with intensity adjusted separately for each speaker. Output from the right-sided speaker was initially 20-30 db HL lower than for the left-sided speaker, resulting in excellent performance in the left ear. Intensities were adaptively adjusted throughout training in 1, 2, and 5-dB steps in order to keep performance high across dichotic tasks. In both phase I (n= 8) and phase II (n=13) trials, children demonstrated significant gains in dichotic left ear performance after training. In phase II, children also demonstrated significant gains in right ear performance. Overall results from the two trials support the feasibility of this training approach for improving a larger than normal interaural asymmetry on dichotic listening tasks. Significant improvements in language comprehension and word recognition in phase II suggest that this type of training may also facilitate language skills in some children.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

from the International Journal of Audiology

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière’s disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9-22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR -0.6 to 5.3% at 0.25 kHz; IQR -1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

Simulated real-ear measurements of benefit from digital feedback suppression

from the International Journal of Audiology

Digital feedback suppression (DFS) enables users of hearing instruments (HI) to benefit from amplification levels that normally would provoke whistling or poor sound quality. A standardized test for the measurement of DFS benefit is not available. This paper proposes and evaluates an objective method for assessment of extra feedback-free amplification (headroom) provided by a given DFS. It is shown that the whistle-free loop gain can be calculated from data obtained with simulated real-ear measurements with the modified pressure method. Test-retest trials were carried out to assess the reliability of the proposed method. Also, a method was developed for defining an appropriate gain level at which the proposed measurement should be carried out. It is concluded that the proposed method needs to be modified to provide useful information.

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

Transient evoked otoacoustic emissions (TEOAEs) in Caucasian and Chinese young adults

from the International Journal of Audiology

The goal of this study was to examine the effect of race and gender on transient evoked otoacoustic emission (TEOAE) characteristics. TEOAE amplitude, noise levels, and hearing thresholds were compared in 81 Caucasian (mean age: 27.8 years) and 81 Chinese (mean age: 24.7 years) young adults with normal hearing. TEOAE amplitude was significantly higher in females than males and in the Chinese group than the Caucasian group. Females had better hearing sensitivity than males consistent with TEOAE results. Hearing sensitivity was not statistically different between the two racial groups; however, the interaction between race and hearing thresholds was significant. As the noise levels between the two racial groups were not statistically different, the observed differences are most likely related to differences in middle-ear transmission properties or to differences in cochlear mechanisms. Documentation of gender and racial differences and understanding the underlying mechanism of these differences will not only assist us in understanding how TEOAE will be affected by middle-ear transmission properties but also will help us in establishing normative data in clinical settings.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Unlocking the Potential for Newborn Screening Research

from Newswise.com

In an article now online and set to be published in the Feb. 15 issue of the American Journal of Medical Genetics, University of Michigan C.S. Mott Children’s Hospital researcher and lead author Beth A. Tarini, M.D., says waiving informed consent for population-based newborn screening research would allow for a more complete evaluation of the safety and effectiveness of these tests before broad implementation.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Frequency discrimination in children: Perception, learning and attention

from Hearing Research

It is generally believed that both sensory immaturity and inattention contribute to the poor listening of some children. However, the relative contribution of each factor, within and between individuals, and the nature of the inattention are poorly understood. In three experiments we examined the threshold and response variability of 6–11 y.o. children on pure tone frequency discrimination (FD) tasks. We first confirmed that younger children had both higher thresholds and greater within- and between-listener variability than older children and adults. Higher thresholds were mostly attributed to high response variability due to poor sustained attention. We next compared performance on the auditory FD task with that on visual spatial FD. No correlation was found between the thresholds or variability of individuals on the two tasks, suggesting involvement of modality-specific attention. Finally, we found lower thresholds for 8–9 y.o. children performing auditory FD training in a classroom than in the laboratory, possibly due to training session length or to a more familiar, motivating and focussed training environment. The adult-like performance of many younger children at times during their testing or training, together with the high response variability of immature performers, suggested that most elevated FD thresholds in children are due to inattention.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Long-term outcome of speech and language in children after corrective surgery for cyanotic or acyanotic cardiac defects in infancy

from the European Journal of Paediatric Neurology

The purpose of this prospective study was to assess whether outcome of speech and language in children 5–10 years after corrective surgery for tetralogy of Fallot (TOF) or ventricular septal defect (VSD) in infancy was influenced by the preoperative condition of hypoxemia or cardiac insufficiency and whether it was associated with perioperative risk factors and neurodevelopmental outcome.

A total of 35 unselected children, 19 with TOF and hypoxemia and 16 with VSD and cardiac insufficiency, operated with combined deep hypothermic circulatory arrest and low-flow cardiopulmonary bypass at mean age 0.7±0.3 (mean±standard deviation) years, underwent, at mean age 7.4±1.6 years, standardized evaluation of speech and language functions. Results were compared between subgroups and related to perioperative factors, sociodemographic and neurodevelopmental status.

Age at testing, socioeconomic status and history of speech and language development were not different between the subgroups. In contrast, total scores on oral and speech motor control functions (TFS) as well as on oral and speech apraxia (Mayo Test) were significantly reduced (p<0.02 to <0.05), and scores on anatomical oral structures tended to be lower (p<0.09) in the TOF group as compared to the VSD group. No differences were found for auditory word recognition and phonological awareness as assessed by the Auditory Closure subtest of the Illinois Test of Psycholinguistic Abilities and the test of auditory analysis skills, respectively. In all children, higher age at testing and better socioeconomic status were associated with better results in all domains of assessment (p<0.001 to <0.04). Consistent impairments of all oral and speech motor control functions (TFS and Mayo Test) were present in 29% of all children with a mean age of 6.5 years in contrast to 43% with normal performance and a mean age of 8.3 years. On the receptive speech tasks, only 6% scored below the normal range of their age group. TFS subscores were significantly correlated with age, bypass duration and motor function, but not correlated with socioeconomic status, duration of cardiac arrest, intelligence and academic achievement.

Children with preoperative hypoxemia due to cyanotic cardiac defects in infancy are at higher risk for dysfunction in speech and language than those with cardiac insufficiency due to acyanotic heart defects. Age at testing, socioeconomic status, and duration of cardiopulmonary bypass influenced test results. Long-term outcome in speech and language functions can be considered as a sensitive indicator of overall child development after cardiac surgery.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Hearing Loss Prevents the Maturation of GABAergic Transmission in the Auditory Cortex

from Cerebral Cortex

Inhibitory neurotransmission is a critical determinant of neuronal network gain and dynamic range, suggesting that network properties are shaped by activity during development. A previous study demonstrated that sensorineural hearing loss (SNHL) in gerbils leads to smaller inhibitory potentials in L2/3 pyramidal neurons in the thalamorecipient auditory cortex, ACx. Here, we explored the mechanisms that account for proper maturation of -amino butyric acid (GABA)ergic transmission. SNHL was induced at postnatal day (P) 10, and whole-cell voltage-clamp recordings were obtained from layer 2/3 pyramidal neurons in thalamocortical slices at P16–19. SNHL led to an increase in the frequency of GABAzine-sensitive (antagonist) spontaneous (s) and miniature (m) inhibitory postsynaptic currents (IPSCs), accompanied by diminished amplitudes and longer durations. Consistent with this, the amplitudes of minimum-evoked IPSCs were also reduced while their durations were longer. The 1- and β2/3 subunit–specific agonists zolpidem and loreclezole increased control but not SNHL sIPSC durations. To test whether SNHL affected the maturation of GABAergic transmission, sIPSCs were recorded at P10. These sIPSCs resembled the long SNHL sIPSCs. Furthermore, zolpidem and loreclezole were ineffective in increasing their durations. Together, these data strongly suggest that the presynaptic release properties and expression of key postsynaptic GABAA receptor subunits are coregulated by hearing.

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

Suprameatal approach for cochlear implantation in 45 Chinese children

from the International Journal of Pediatric Otorhinolaryngology

Objective
To investigate the feasibility of applying the suprameatal approach (SMA) for cochlear implantation in Chinese children with profound sensory hearing loss, and to demonstrate a technical modification incorporated in the procedure due to an observed racial difference.

Study design
Retrospective study.

Setting
University hospital.

Patients
Forty-five Chinese children (total 47 ears) with profound sensory hearing loss were surgically treated from May 2005 to May 2006. The patients were followed anywhere from 1 month to 20 months post-surgery, with 30 patients being followed for more than 6 months.

Interventions
All patients received cochlear implantation through the suprameatal approach. In this procedure, the cochleostomy was performed in one stage after the suprameatal tunnel was finished, rather than the two-stage approach described by Kronenberg (who firstly introduced the suprameatal approach). Three patients with low-lying dura (which is considered to be the contraindication for cochlear implantation with SMA) were treated with a further modified surgical approach.

Results
Among the 47 ears, full electrode pairs were completely inserted in 45 ears without surgical difficulties, but 1 ear was only fitted with 9 pairs of electrodes because of an ossified cochlea, and another with just 8 pairs of electrodes due to serious cochlear dysplasia. An intraoperative “gusher” occurred in the dysplasia case, and a small piece of temporalis muscle was used, along with biology glue, to seal the cochleostomy and prevent further leakage. In 1 case, the electrode was inserted into the cochlea through the tunnel lateral to the chorda tympani because adhesion had occurred between the incus and chorda tympani. There were no postoperative complications in any case. Thirty cases exhibited better hearing or speech development from cochlear implantation after more than 6 months of follow-up.

Conclusions
The SMA was found to be a simple and safe technique for cochlear implantation in Chinese children. It enables wide exposure of the middle ear, and is especially suitable for cases with a narrow facial recess, an anteriorly located facial nerve, or an ossified cochlea. It is almost impossible to injure the facial nerve or the chorda tympani nerve. The cochleostomy can be performed in one stage in those patients with a normal cochlea. With some modifications, a low-lying dura will not be the absolute contraindication of SMA.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Speech Error Elicitation and Co-occurrence Restrictions in Two Ethiopian Semitic Languages

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

CSHL scientists make progress in determining how the brain selectively interprets sound

from EurekAlert.org

The researchers used a new technique called “in vivo cell-attached patch clamp recording” which measures the reaction of individual neurons. This recording technique samples neurons in a fair and unbiased way, unlike traditional approaches, which favored the largest and most active neurons. Using this technique, the team found that only 5% of neurons in the auditory cortex had a “high firing rate” when receiving a range of sounds of varying length, frequency, and volume. The experiment included white noise and natural animal sounds.

January 31, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

Sparse Representation Of Sounds In The Unanesthetized Auditory Cortex

from Medical News Today.com

How do neuronal populations in the auditory cortex represent sounds? Although sound-evoked neural responses in the anesthetized auditory cortex are mainly transient, recent experiments in the unanesthetized preparation have emphasized subpopulations with other response properties.

Published this week in the open-access journal PLoS Biology, Tomas Hromadka, Anthony Zador, and colleagues show how they quantified the relative contributions of these different subpopulations in the auditory cortex of awake head-fixed rats.

January 31, 2008 Posted by Callier Library | Uncategorized | , | No Comments

How far can clinical trial data be generalised?

from the National electronic Library for Medicines (NeLM)

Abstract A research study and Commentary in the Archives of Internal Medicine look at the differences between clinical trial populations and patients in practice.

The research study was carried out on behalf of the US Centers for Medicare and Medicaid Services (CMS), which determines coverage for services provided to Medicare and Medicaid patients using published evidence. Its authors carried out a meta-analysis of patient characteristics for all the clinical trials used to produce cardiovascular technology assessments by CMS, and compared them with the known demographics of Medicare patients. Cardiovascular technology was chosen because this is the largest area of expenditure for Medicare.

They evaluated a total of 141 trials involving 40,009 individuals, and found significant differences between the population groups. Compared to the Medicare population, trial participants were younger (mean 60.1 vs. 74.7 years), more likely to be male (75.4% vs. 41.8%), and a majority were non-US residents (60% vs. 0%). When age and gender distribution were analysed by year of publication, there was a clear change between the oldest study analysed (1982) to the newest (2006): using 2000 as a centre point, there was a significant increase per year of publication in mean age (0.38 years per year, P < 0.001) and decrease in the number of males (0.6% per year, P = 0.02). The distribution of participant nationality was related to the trial locations: a majority were carried out in Europe (51.1%), with just over a third (37.0%) taking place wholly or partly in the US. Most trials did not report results stratified by demographic variables.

The authors of the study conclude that in clinical trials relied on by the CMS to decide on coverage for Medicare participants, the participants differed substantially from the Medicare population.

In the Commentary, the authors expand on the results of this study. They point out that even when a trial is internally valid (i.e. its results accurately reflect the true outcomes in the study participants), its results are externally completely valid for individuals who are similar to the trial participants and receive the same intervention. Once patients and interventions start to differ from those in the trial, it becomes more and more difficult to generalise the original results to the real patient. As it would be impossible to carry out controlled trials reflecting all possible patients and circumstances, it is necessary to use clinical judgement to decide how far the trial results apply to a specific individual.

To illustrate the difficulties, they present a number of examples. They compare the rates of hyperkalaemia in patients receiving a potassium-sparing diuretic and an ACE-inhibitor between randomised and non-randomised studies: in a non-randomised case-control study, patients receiving a potassium-sparing diuretic had about 20x the risk of hyperkalaemia as those who did not; however in a controlled trial of patients with heart failure and receiving an ACE-inhibitor, there was no significant difference in the incidence of hyperkalaemia between those receiving and those not receiving a potassium-sparing diuretic (spironolactone). While there are a number of explanations for the difference, it is likely that different treatment protocols account for a significant proportion: in the controlled trial, spironolactone was administered cautiously with a low starting dose and frequent monitoring - this is as much part of the intervention as the study drugs used.

Other areas of difficulty for which examples are presented include differences in patient characteristics (not just in terms of demographics, but also study exclusion criteria), treatment adherence, and duration of treatment and follow-up. Overall, they conclude that although the results of randomised trials can often be applied to patients and situations dissimilar to those of the trial, such extrapolation should not be a reflex.

January 31, 2008 Posted by Callier Library | Uncategorized | | No Comments

Safe Removal Of Gliomas To Preserve Language Requires Less Extensive Brain Exposure Than Previously Thought

from Medical News Today.com

A more limited approach to craniotomy—the procedure through which a patient’s skull is opened up to expose the brain—than has traditionally been used by neurosurgeons can maximize resection and minimize lasting side effects when tumours within or near language pathways are removed, according to the results of a prospective study published in the New England Journal of Medicine.

January 30, 2008 Posted by Callier Library | Uncategorized | | 1 Comment

Role of computed tomography and bronchoscopy in speech prosthesis aspiration

from Annals of Otology, Rhinology, and Laryngology

Tracheoesophageal puncture prostheses (TEPPs) are an integral aspect of speech rehabilitation for many patients who have undergone total laryngectomy. Because one flange of the prosthesis sits in the trachea and the other in the esophagus, these devices can be aspirated or swallowed if dislodged. Five cases of prosthesis aspiration that occurred in 4 veterans within a 16-month period are described. The 5 aspirated TEPPs resulted in highly variable clinical presentations ranging from complaints of “lost” TEPPs in asymptomatic patients to near-asphyxiation. Furthermore, the aspirated TEPPs were not reliably demonstrated on chest radiographs, often leading to delayed diagnosis. Aspiration of TEPPs may be more common than formerly recognized, and chest computed tomography or bronchoscopy is indicated in cases of missing TEPPs not demonstrated on plain films.

January 30, 2008 Posted by Callier Library | Uncategorized | , | No Comments

The N3 potential compared to sound and galvanic vestibular evoked myogenic potential in healthy subjects and in multiple sclerosis patients

from the Journal of Vestibular Research

Both sound (s-) and galvanic (g-) vestibular-evoked myogenic potential (VEMP) enable us to study the saccular pathways. However, the VEMP can be abnormal for non-vestibular factors, such as insufficient activation of the sterno-cleido-mastoid (SCM) muscle or a lesion that involves the accessory nucleus and/or nerve or the SCM muscle. These drawbacks do not affect another technique that evaluates the saccular function: the N3 potential.

We recorded both the s- and the g-VEMP and the N3 potential in a group of 31 healthy subjects to establish a reference range. The N3 potential and the s-VEMP were recordable bilaterally from all the subjects, whereas the g-VEMP was undetectable uni- or bilaterally in 7 subjects. The latency and amplitude values of the s-VEMP did not differ from those of the g-VEMP. For all three techniques, the latency and amplitude values from the right and from the left recording and/or stimulation side were the same. We suggest using normative latency and amplitude values based on the mean and ratio of the right- and left-side values.

The s-VEMP, the N3 potential and the auditory evoked response (ABR) were compared in 15 subjects suffering from multiple sclerosis. The three techniques detected a similar number of abnormalities, but these abnormalities were not correlated. This suggests that these different techniques should be regarded as complementary in evaluating saccular function.

January 30, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Silence Is Golden: Transient Neural Deactivation in the Prefrontal Cortex during Attentive Reading

from Cerebral Cortex

It is becoming increasingly clear that attention-demanding tasks engage not only activation of specific cortical regions but also deactivation of other regions that could interfere with the task at hand. At the same time, electrophysiological studies in animals and humans have found that the participation of cortical regions to cognitive processes translates into local synchronization of rhythmic neural activity at frequencies above 40 Hz (so-called gamma-band synchronization). Such synchronization is seen as a potential facilitator of neural communication and synaptic plasticity. We found evidence that cognitive processes can also involve the disruption of gamma-band activity in high-order brain regions. Intracerebral electroencephalograms were recorded in 3 epileptic patients during 2 reading tasks. Visual presentation of words induced a strong deactivation in a broad (20–150 Hz) frequency range in the left ventral lateral prefrontal cortex, in parallel with gamma-band activations within the reading network, including Broca’s area. The observed energy decrease in neural signals was reproducible across patients. It peaked around 500 ms after stimulus onset and appeared subject to attention-modulated amplification. Our results suggest that cognition might be mediated by a coordinated interaction between regional gamma-band synchronizations and desynchronizations, possibly reflecting enhanced versus reduced local neural communication.

January 29, 2008 Posted by Callier Library | Uncategorized | | No Comments

Spatiotemporal Interaction between Sound Form and Meaning during Spoken Word Perception

from Cerebral Cortex

Cortical dynamics of spoken word perception is not well understood. The possible interplay between analysis of sound form and meaning, in particular, remains elusive. We used magnetoencephalography to study cortical manifestation of phonological and semantic priming. Ten subjects listened to lists of 4 words. The first 3 words set a semantic or phonological context, and the list-final word was congruent or incongruent with this context. Attenuation of activation by priming during the first 3 words and increase of activation to semantic or phonological mismatch in the list-final word provided converging evidence: The superior temporal cortex bilaterally was involved in both analysis of sound form and meaning but the role of each hemisphere varied over time. Sensitivity to sound form was observed at 100 ms after word onset, followed by sensitivity to semantic aspects from 250 ms onwards, in the left hemisphere. From 450 ms onwards, the picture was changed, with semantic effects now present bilaterally, accompanied by a subtle late effect of sound form in the right hemisphere. Present MEG data provide a detailed spatiotemporal account of neural mechanisms during speech perception that may underlie characterizations obtained with other neuroimaging methods less sensitive in temporal or spatial domain.

January 29, 2008 Posted by Callier Library | Uncategorized | , , | No Comments

The Neural Bases of the Lexical Effect: An fMRI Investigation

from Cerebral Cortex

The lexical effect is a phenomenon whereby lexical information influences the perception of the phonetic category boundary for stimuli from word–nonword continua. At issue is whether this effect is due to “top-down” influence of upper levels of processing on perceptual processing, or instead is due to decision-stage processes. In this study, brain activity was monitored using functional magnetic resonance imaging as subjects performed a phonetic categorization task on items taken from 2 continua in which one end of the continuum was a real word and the other was not (gift–kift and giss–kiss). If the lexical effect has a perceptual basis, modulation of activation should be seen as a function of the lexical effect in areas such as the superior temporal gyri (STG) which have previously been implicated in perceptual processing. In contrast, if the effect is purely due to decision-related factors, such modulation would be expected only in areas which have been linked to executive processes, such as frontal and midline structures. Modulation of activation as a function of the lexically biased shift in phonetic category boundary was observed in the STG bilaterally as well as in frontal and midline structures. This activation pattern suggests that the lexical effect has at minimum a perceptual component, in addition to an executive decision-related component. These results challenge the view that lexical effects on phonetic boundary placement are due solely to postperceptual, decision-stage processes, and support those models of language processing which allow for higher-level lexical information to directly influence the perception of incoming speech.

January 29, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Time Course of Neural Activity Correlated with Colored-Hearing Synesthesia

from Cerebral Cortex

Synesthesia is defined as the involuntary and automatic perception of a stimulus in 2 or more sensory modalities (i.e., cross-modal linkage). Colored-hearing synesthetes experience colors when hearing tones or spoken utterances. Based on event-related potentials we employed electric brain tomography with high temporal resolution in colored-hearing synesthetes and nonsynesthetic controls during auditory verbal stimulation. The auditory-evoked potentials to words and letters were different between synesthetes and controls at the N1 and P2 components, showing longer latencies and lower amplitudes in synesthetes. The intracerebral sources of these components were estimated with low-resolution brain electromagnetic tomography and revealed stronger activation in synesthetes in left posterior inferior temporal regions, within the color area in the fusiform gyrus (V4), and in orbitofrontal brain regions (ventromedial and lateral). The differences occurred as early as 122 ms after stimulus onset. Our findings replicate and extend earlier reports with functional magnetic resonance imaging and positron emission tomography in colored-hearing synesthesia and contribute new information on the time course in synesthesia demonstrating the fast and possibly automatic processing of this unusual and remarkable phenomenon.

January 29, 2008 Posted by Callier Library | Uncategorized | | No Comments

Alexia and agraphia: Contrasting perspectives of J.-M. Charcot and J. Hughlings Jackson

from Neurology

Objective: To evaluate 19th-century concepts of cerebral localization for complex mental activities, focusing on alexia and agraphia in published writings of Jean-Martin Charcot (1825–1893) and John Hughlings Jackson (1835–1911).

Background: In the early 1860s, Broca’s reports on a special role for the left frontal lobe in articulate language ignited frenetic interest in cerebral localization. Disorders of written language (alexia and agraphia) were enmeshed in ensuing discussions of how the brain was organized for language and other complex behaviors.

Design/Methods: Focused review and analysis of Charcot’s and Hughlings Jackson’s publications on aphasia, alexia, and agraphia.

Results: In the wake of Broca’s observations, the extent to which language functions in general—or such specialized functions as reading and writing—might involve focal cerebral representation was controversial. Based on his clinical–pathologic approach to “regional diagnosis,” Charcot came to value insights provided by “partial isolated aphasias.” He described patients with isolated alexia and agraphia, and he proposed a functional–anatomic framework to accommodate these disorders. Adopting a hierarchical model of nervous system organization, Hughlings Jackson argued that reading and writing could not be dissociated from other aspects of “intellectual language.” Charcot’s reductionism was typical of his era, but Hughlings Jackson’s more holistic approach was to gain ascendancy in early decades of the 20th century.

Conclusions: Charcot’s and Hughlings Jackson’s positions on alexia and agraphia reflected contrasting philosophical approaches to the study of brain disorders. Their views informed the opinions of their contemporaries and neurologic heirs in important debates on cerebral organization.

January 29, 2008 Posted by Callier Library | Uncategorized | , | No Comments

Montreal researchers warn about over-the-counter eardrops for wax buildup

from Medbroadcast.com

Researchers who studied over-the-counter eardrops for softening wax buildup are warning about the possibility of hearing loss and other problems if the drops are used by someone with a perforated eardrum.

January 29, 2008 Posted by Callier Library | Uncategorized | | No Comments

The effect of vestibular rehabilitation supplemented by training of the breathing rhythm or proprioception exercises, in patients with chronic peripheral vestibular disease

from the Journal of Vestibular Research

Objective: To assess the effect of performing vestibular rehabilitation using the Cawthorne & Cooksey exercises supplemented by training of the breathing rhythm or proprioception exercises on self-reported disability and postural control, in patients with chronic, peripheral, vestibular disease.

Methods: Fifty one patients with peripheral vestibular disease and abnormal caloric test participated in the study (mean age 43 ± S.D. 9 years). They were assigned to one of 3 treatment groups: I. Cawthorne &} Cooksey exercises with training of the breathing rhythm (n=17); II. Cawthorne & Cooksey exercises with proprioception exercises (n=17) and III. Cawthorne & Cooksey exercises with no additional intervention (n=17). The Dizziness Handicap Inventory and static posturography were evaluated prior to treatment and at week 8 of follow-up.

Results: Prior to treatment, composite scores on the Dizziness Handicap Inventory and static posturography were similar in the 3 groups. After treatment, a decrease of the composite score of at least 18 points was observed more frequently in patients of the respiration group (94%), compared to the proprioception group (53%) and the Cawthorne & Cooksey group (70%) (p=0.03); while the proprioception group showed a significant decrease of oscillation during all sensory conditions of static posturography (p< 0.05).

Conclusion: The results suggest that regulation of the breathing pattern may have an influence on disability related to chronic vestibular disease, while proprioception exercises may improve postural control. However, further studies are needed to evaluate if training of the breathing rhythm could be an additional tool for vestibular rehabilitation.

January 29, 2008 Posted by Callier Library | Uncategorized | , | No Comments