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Current models of spoken word recognition have been predominantly based on studies of Indo-European languages. As a result, less is known about the recognition processes involved in the perception of tonal languages (e.g., Mandarin Chinese), and the role of lexical tone in speech perception. One view is that words in tonal languages are processed phonologically through individual segments, while another view is that they are processed lexically as a whole. Moreover, a recent study claimed to be the first to discover an early phonological processing stage in Mandarin (Huang et al., 2014). There seems to be a lack of investigations concerning tonal languages, as no clear conclusions have been reached about the nature of tonal processes, or a model of spoken word recognition that best incorporates lexical tone. The current study addressed these issues by presenting 18 native Mandarin speakers with aural sentences with medial target words. These either matched or mismatched the preceding visually presented sentences with medial target words (e.g, 家 /jia1/home). Violation conditions involved target words that differed in the following ways: tone violation, where only the tone was different (e.g., 价 /jia4/“price”), onset violation, where only the onset was different (e.g., 虾 /xia1/“shrimp”), and syllable violation, where both the tone and the onset were different (e.g., 糖 /tang2/“candy”). We did not find evidence for an early phonological processing stage in Mandarin. Instead, our findings indicate that Mandarin syllables are processed incrementally through phonological segments and that tone is strongly associated with lexical access. These results are discussed with respect to modifications for existing models in spoken word recognition to incorporate the processes involved with tonal language recognition.

There has been increased effort to understand the neurophysiological effects of concussion aimed to move diagnosis and identification beyond current subjective behavioral assessments that suffer from poor sensitivity. Recent evidence suggests that event-related potentials (ERPs) measured with electroencephalography (EEG) are persistent neurophysiological markers of past concussions. However, as such evidence is limited to group-level analyzes, the extent to which they enable concussion detection at the individual-level is unclear. One promising avenue of research is the use of machine learning to create quantitative predictive models that can detect prior concussions in individuals. In this paper, we translate the recent group-level findings from ERP studies of concussed individuals into a machine learning framework for performing single-subject prediction of past concussion. We found that a combination of statistics of single-subject ERPs and wavelet features yielded a classification accuracy of 81% with a sensitivity of 82% and a specificity of 80%, improving on current practice. Notably, the model was able to detect concussion effects in individuals who sustained their last injury as much as 30 years earlier. However, failure to detect past concussions in a subset of individuals suggests that the clear effects found in group-level analyses may not provide us with a full picture of the neurophysiological effects of concussion.

Mismatch negativity (MMN) is a component of the event-related potential (ERP) that is elicited through an odd-ball paradigm. The existence of the MMN in a coma patient has a good correlation with coma emergence; however, this component can be difficult to detect. Previously, MMN detection was based on visual inspection of the averaged ERPs by a skilled clinician, a process that is expensive and not always feasible in practice. In this paper, we propose a practical machine learning (ML) based approach for detection of MMN component, thus, improving the accuracy of prediction of emergence from coma. Furthermore, the method can operate on an automatic and continuous basis thus alleviating the need for clinician involvement. The proposed method is capable of the MMN detection over intervals as short as two minutes. This finer time resolution enables identification of waxing and waning cycles of a conscious state. An auditory odd-ball paradigm was applied to 22 healthy subjects and 2 coma patients. A coma patient is tested by measuring the similarity of the patient's ERP responses with the aggregate healthy responses. Because the training process for measuring similarity requires only healthy subjects, the complexity and practicality of training procedure of the proposed method are greatly improved relative to training on coma patients directly. Since there are only two coma patients involved with this study, the results are reported on a very preliminary basis. Preliminary results indicate we can detect the MMN component with an accuracy of 92.7% on healthy subjects. The method successfully predicted emergence in both coma patients when conventional methods failed. The proposed method for collecting training data using exclusively healthy subjects is a novel approach that may prove useful in future, unrelated studies where ML methods are used.

A consistent limitation when designing event-related potential paradigms and interpreting results is a lack of consideration of the multivariate factors that affect their elicitation and detection in behaviorally unresponsive individuals. This paper provides a retrospective commentary on three factors that influence the presence and morphology of long-latency event-related potentials—the P3b and N400. We analyze event-related potentials derived from electroencephalographic (EEG) data collected from small groups of healthy youth and healthy elderly to illustrate the effect of paradigm strength and subject age, we analyze ERPs collected from an individual with severe traumatic brain injury to illustrate the effect of stimulus presentation speed. Based on these critical factors, we support that: (1) the strongest paradigms should be used to elicit event-related potentials in unresponsive populations, (2) interpretation of event-related potential results should account for participant age, and (3) speed of stimulus presentation should be slower in unresponsive individuals. The application of these practices when eliciting and recording event-related potentials in unresponsive individuals will help to minimize result interpretation ambiguity, increase confidence in conclusions, and advance the understanding of the relationship between long-latency event-related potentials and states of consciousness.

The paramount importance of research design and research methodologies within the shared space of neurology, clinical neurophysiology, and cognitive neuroscience serves as the theme around which a range of topics is presented. After a tour of historical figures of human electrophysiology and electroencephalography (EEG), the discussion turns to event-related potential (ERP). Emphasizing the lengthy history of these manifestations of cognition, the chapter outlines the extensive research literature that has demonstrated the sensitivity of ERPs to a range cognitive functions, including attention, language processing, and memory. There follows a series of examples of ERP applications in the clinical domain, including disorders of consciousness, stroke, autism, coma, and concussion. These examples not merely demonstrate the general utility of these electrophysiological responses but stress that their independence from behavioral responses provides a much needed clinical method to assess individuals who are literally or virtually impossible to assess using traditional behaviorally based clinical tools. The chapter concludes with the suggestion that is time that the incontrovertible utility of ERPs be employed more fully within clinical contexts to assist the clinical community in providing objective assessments of a range of neurologic conditions.

The paramount importance of research design and research methodologies within the shared space of neurology, clinical neurophysiology, and cognitive neuroscience serves as the theme around which a range of topics is presented. After a tour of historical figures of human electrophysiology and electroencephalography (EEG), the discussion turns to event-related potential (ERP). Emphasizing the lengthy history of these manifestations of cognition, the chapter outlines the extensive research literature that has demonstrated the sensitivity of ERPs to a range cognitive functions, including attention, language processing, and memory. There follows a series of examples of ERP applications in the clinical domain, including disorders of consciousness, stroke, autism, coma, and concussion. These examples not merely demonstrate the general utility of these electrophysiological responses but stress that their independence from behavioral responses provides a much needed clinical method to assess individuals who are literally or virtually impossible to assess using traditional behaviorally based clinical tools. The chapter concludes with the suggestion that is time that the incontrovertible utility of ERPs be employed more fully within clinical contexts to assist the clinical community in providing objective assessments of a range of neurologic conditions.

fMRI and EEG during mental imagery provide alternative methods of detecting awareness in patients with disorders of consciousness (DOC) without reliance on behaviour. Because using fMRI in patients with DOC is difficult, studies increasingly employ EEG. However, there has been no verification that these modalities provide converging information at the individual subject level. The present study examined simultaneous EEG and fMRI in healthy volunteers during six mental imagery tasks to determine whether one mental imagery task generates more robust activation across subjects; whether activation can be predicted from familiarity with the imagined activity; and whether EEG and fMRI converge upon the same conclusions about individual imagery performance. Mental arithmetic generated the most robust activation in the majority of subjects for both EEG and fMRI, and level of activation could not be predicted from familiarity, with either modality. We conclude that overall, EEG and fMRI agree regarding individual mental imagery performance.

The current literature presents a discordant view of mild traumatic brain injury and its effects on the human brain. This dissonance has often been attributed to heterogeneities in study populations, aetiology, acuteness, experimental paradigms and/or testing modalities. To investigate the progression of mild traumatic brain injury in the human brain, the present study employed data from 93 subjects (48 healthy controls) representing both acute and chronic stages of mild traumatic brain injury. The effects of concussion across different stages of injury were measured using two metrics of functional connectivity in segments of electroencephalography time-locked to an active oddball task. Coherence and weighted phase-lag index were calculated separately for individual frequency bands (delta, theta, alpha and beta) to measure the functional connectivity between six electrode clusters distributed from frontal to parietal regions across both hemispheres. Results show an increase in functional connectivity in the acute stage after mild traumatic brain injury, contrasted with significantly reduced functional connectivity in chronic stages of injury. This finding indicates a non-linear time-dependent effect of injury. To understand this pattern of changing functional connectivity in relation to prior evidence, we propose a new model of the time-course of the effects of mild traumatic brain injury on the brain that brings together research from multiple neuroimaging modalities and unifies the various lines of evidence that at first appear to be in conflict., We investigate concussion’s effects on the human brain directly after impact and decades post-injury. Functional connectivity between a set of brain areas was heightened in recently concussed subjects and was diminished in subjects who sustained their injuries years prior (compared to age-matched controls). The study highlights the dynamic nature of concussion., Graphical Abstract Graphical Abstract

IntroductionComa is a deep state of unconsciousness that can be caused by a variety of clinical conditions. Traditional tests for coma outcome prediction are based mainly on a set of clinical observations. Recently, certain event-related potentials (ERPs), which are transient electroencephalogram (EEG) responses to auditory, visual or tactile stimuli, have been introduced as useful predictors of a positive coma outcome (ie, emergence). However, such tests require the skills of clinical neurophysiologists, who are not commonly available in many clinical settings. Additionally, none of the current standard clinical approaches have sufficient predictive accuracies to provide definitive prognoses.ObjectiveThe objective of this study is to develop improved machine learning procedures based on EEG/ERP for determining emergence from coma.Methods and analysisData will be collected from 50 participants in coma. EEG/ERP data will be recorded for 24 consecutive hours at a maximum of five time points spanning 30 days from the date of recruitment to track participants’ progression. The study employs paradigms designed to elicit brainstem potentials, middle-latency responses, N100, mismatch negativity, P300 and N400. In the case of patient emergence, data are recorded on that occasion to form an additional basis for comparison. A relevant data set will be developed from the testing of 20 healthy controls, each spanning a 15-hour recording period in order to formulate a baseline. Collected data will be used to develop an automated procedure for analysis and detection of various ERP components that are salient to prognosis. Salient features extracted from the ERP and resting-state EEG will be identified and combined to give an accurate indicator of prognosis.Ethics and disseminationThis study is approved by the Hamilton Integrated Research Ethics Board (project number 4840). Results will be disseminated through peer-reviewed journal articles and presentations at scientific conferences.Trial registration numberNCT03826407.

Concussion has been shown to leave the afflicted with significant cognitive and neurobehavioural deficits. The persistence of these deficits and their link to neurophysiological indices of cognition, as measured by event-related potentials (ERP) using electroencephalography (EEG), remains restricted to population level analyses that limit their utility in the clinical setting. In the present paper, a convolutional neural network is extended to capitalize on characteristics specific to EEG/ERP data in order to assess for post-concussive effects. An aggregated measure of single-trial performance was able to classify accurately (85%) between 26 acutely to post-acutely concussed participants and 28 healthy controls in a stratified 10-fold cross-validation design. Additionally, the model was evaluated in a longitudinal subsample of the concussed group to indicate a dissociation between the progression of EEG/ERP and that of self-reported inventories. Concordant with a number of previous studies, symptomatology was found to be uncorrelated to EEG/ERP results as assessed with the proposed models. Our results form a first-step towards the clinical integration of neurophysiological results in concussion management and motivate a multi-site validation study for a concussion assessment tool in acute and post-acute cases.

Objective The present study sought to determine: 1) whether concussed adolescents exhibited deficits in neurocognitive functioning as reflected by neurophysiological alterations; 2) if neurophysiological alterations could be linked to supplementary data such as the number of previous concussions and days since injury; and 3) if deficits in psychological health and behavioural tests increased during diagnosis duration. Methods Twenty-six concussed adolescents were compared to twenty-eight healthy controls with no prior concussions. Self-report inventories evaluated depressive and concussive symptomatology, while behavioral tests evaluated cognitive ability qualitatively. To assess neurophysiological markers of cognitive function, two separate auditory oddball tasks were employed: 1) an active oddball task measuring executive control and attention as reflected by the N2b and P300, respectively; and 2) a passive oddball task assessing the early, automatic pre-conscious awareness processes as reflected by the MMN. Results Concussed adolescents displayed delayed N2b and attenuated P300 responses relative to controls; showed elevated levels of depressive and concussive symptomatology; scored average-to- low-average in behavioral tests; and exhibited N2b response latencies that correlated with number of days since injury. Conclusion These findings demonstrate that concussed adolescents exhibit clear deficiencies in neurocognitive function, and that N2b response latency may be a marker of concussion recovery.

Objective Recent studies demonstrate that sports-related concussions can have negative consequences on long-term brain health. The goal of the present study was to determine whether retired Canadian Football League (CFL) athletes with a history of concussions exhibit alterations in neurocognitive functioning, along with changes in physical, social, and psychological health. Methods Our study compared nineteen retired CFL athletes’ concussion histories to eighteen healthy age-matched controls with no history of concussion. Self-report inventories were used to assess depression, memory, attention, and general health. Neurophysiological markers of cognitive function were evaluated with event-related brain potentials (ERPs) as measured in two protocols: (1) A Mismatch Negativity (MMN) protocol for assessing the automatic early attentional brain mechanism; and, (2) a P300 auditory oddball task for assessing consciously controlled attention. Results Relative to controls, CFL players exhibited: response delays and reduced amplitudes in neurophysiological responses; overall decreases in cognitive function; and poorer scores on self-reports of physical, social, and psychological health; reflecting problems in all three categories. Conclusion Our findings demonstrate that multiple concussions sustained over several years can lead to altered cognitive and psychosocial function. Significance Neurophysiological markers of conscious and pre-conscious attention provide an objective assessment for evaluating long-term cognitive consequences of concussion.

Objective The need to have a pediatric-specific concussion management protocol on Return to School (RTS) and Return to Activity (RTA) after concussion has been recognized internationally. The first step to evaluate the protocol effectiveness is to establish whether children and youth are adhering to these recommendations. The objective of this study was to explore the prevalence and predictors of adherence to RTS and RTA concussion management protocols for children/youth. Design A prospective cohort of children/youth with concussion. Setting Childhood Disability Research Centre. Participants One hundred thirty-nine children/youth aged 5 to 18 years, diagnosed with concussion and symptomatic upon enrollment, were followed for up to 6 months. Primary recruitment occurred from a Children's Hospital Emergency Department. Intervention Provision of RTS/RTA guidelines. Main outcome measures Measurement of adherence came from multiple sources, including the child's and parent's knowledge of protocols, research personnel evaluations, and self-reported stages of RTS/RTA and Post-Concussion Symptom Scale (PCSS) scores. Results Spearman correlations and logistic regression were used, investigating the relationship between PCSS and progression of protocols and determining predictors of adherence. Significant negative associations between total PCSS score and stage of RTS/RTA protocols were found. Fifty-three percent and 56% of the participants adhered to the RTS and RTA protocols, respectively. Conclusions Children's knowledge of protocols and total PCSS scores significantly predicted adherence to RTS/RTA and may be the most important factors in predicting adherence during recovery from concussion.

Although routinely used, control group criteria vary considerably in research. Drawing from aspects in our normative study on musical emotion perception, we show how a group of participants who would normally be considered a control group in most studies, display clear event-related potential (ERP) differences when grouped by affective assessment scores that are rarely administered to presumed “control” group candidates. This preliminary finding demonstrates the importance of careful screening of control group membership. Failure in this process can produce misleading observations, undermining the validity of results.

Electroencephalography data recorded during functional magnetic resonance imaging acquisition are subject to large cardiac-related artifacts that must be corrected during postprocessing. This study compared two widely used ballistocardiogram (BCG) correction algorithms as implemented in two software programs. Reduction of BCG amplitude, correlation of corrected data with electrocardiogram traces, correlation of independent components with electrocardiogram traces, and event-related potential signal-to-noise ratio from each algorithm were compared. Both algorithms effectively reduced the BCG artifact, with a slight advantage of average artifact subtraction over the optimal basis set method (0.1-2.2%) when the quality of the correction was examined at the individual subject level. This study provides users of these software tools with an important, practical, and previously unavailable comparison of the performance of these two methods.

The N400 component is commonly associated with the detection of linguistic incongruity. A few studies have shown that the N400 can also be elicited by non-linguistic stimuli. Different spatiotemporal patterns were observed between the typical Linguistic N400 and the Non-linguistic N400, suggesting distinct brain generators. The aim of this study was to investigate the presence of an N400 in response to linguistic and non-linguistic stimuli, and to specify anatomical sources of both N400s using a novel analysis method: the Bayesian Model Averaging (BMA) distributed source model. Picture-word and environmental soundpicture associations, either congruent or incongruent, were presented to ten young healthy adults while highdensity ERP recordings were made. Standard electrophysiological analyses confirmed that the N400 was not specific to linguistic incongruity but was also elicited by environmental sound-picture incongruities. Different topographic distributions were obtained for the Linguistic N400 and Non-linguistic N400. BMA analysis showed that the Linguistic N400 generators were mostly located in the left superior temporal gyrus, whereas the sources of the Non-linguistic N400 were identified mostly in the right middle and superior temporal gyri. Detection of linguistic incongruities recruited cerebral areas commonly associated with language processing, whereas non-linguistic incongruities recruited right cerebral regions usually associated with auditory processing of non-linguistic stimuli. The Linguistic and Non-linguistic N400s appear to be elicited by similar cognitive mechanisms assumed by different cerebral areas depending on the type of material to be processed. The present findings support the existence of parallel pathways for the processing of linguistic and non-linguistic incongruities.

Diagnoses and assessments of cognitive function in disorders of consciousness (DOC) are notoriously prone to error due to their reliance on behavioural measures. As a result, researchers have turned to functional neuroimaging and electrophysiological techniques with the goal of developing more effective methods of detecting awareness and assessing cognition in these patients. This article reviews functional magnetic resonance imaging (fMRI) and electroenchphalography (EEG)-based studies of cognition and consciousness in DOC, including assessment of basic sensory, perceptual, language, and emotional processing; studies for detection of conscious awareness; paradigms for the establishment of communication in the absence of behaviour; and functional connectivity studies. The advantages and limitations of fMRI and EEG-based measures are examined as research and clinical tools in this population and an explanation offered for the rediscovery of the unique advantages of EEG in the study of DOC.

Accurate and fast detection of event related potential (ERP) components is an unresolved issue in neuroscience and critical health care. Mismatch negativity (MMN) is a component of the ERP to an odd stimulus in a sequence of identical stimuli which has good correlation with coma awakening. All of the previous studies for MMN detection are based on visual inspection of the averaged ERPs (over a long recording time) by a skilled neurophysiologist. However, in practical situations, such an expert may not be available or familiar with all aspects of evoked potential methods. Further, we may miss important clinically essential events due to the implicit averaging process used to acquire the ERPs. In this paper we propose a practical machine learning approach for automatic and continuous assessment of the ERPs for detecting the presence of the MMN component. The proposed method is realized in a classification framework. Performance of the proposed method is demonstrated on 22 healthy subjects through a leave-one subject-out strategy where the MMN components are identified with about 93% accuracy.

Up to 40% of individuals with unresponsive wakefulness syndrome (UWS) actually might be conscious. Recent attempts to detect covert consciousness in behaviorally unresponsive patients via neurophysiological patterns are limited by the need to compare data from brain-­injured patients to healthy controls. In this report, we pilot an alternative within-­subject approach by using propofol to perturb the brain state of a patient diagnosed with UWS. An auditory stimulation series was presented to the patient before, during, and after exposure to propofol while high-­density electroencephalograph (EEG) was recorded. Baseline analysis revealed residual markers in the continuous EEG and event-­related potentials (ERPs) that have been associated with conscious processing. However, these markers were significantly distorted by the patient’s pathology, challenging the interpretation of their functional significance. Upon exposure to propofol, changes in EEG characteristics were similar to what is seen in healthy individuals and ERPs associated with conscious processing disappeared. At the 1-­month follow up, the patient had regained consciousness. We offer three alternative explanations for these results: (1) the patient was covertly consciousness, and was anesthetized by propofol administration; (2) the patient was unconscious, and the observed EEG changes were a propofol-­specific phenomenon; and (3) the patient was unconscious, but his brain networks responded normally in a way that heralded the possibility of recovery. These alternatives will be tested in a larger study, and raise the intriguing possibility of using a general anesthetic as a probe of brain states in behaviorally unresponsive patients.

The field of neuroimaging has experienced a tremendous boom due to technological advances in the last ten years and this is also reflected in the electroencephalography / event-related potentials (EEG/ERP) method. This contribution provides an overview of the main EEG/ERP hardware systems and software development currently on the market and the benefits of such technology for the study of language issues. We discuss the “added-value” such technology brings to the research of language and the possibilities of combining various neuroimaging technique with emphasis on the integration of EEG/ERP and functional magnetic resonance imaging (fMRI). Our contribution ends with a look at what we think may be the methodologies that drive the field forward in the not too distant future.

This study investigated eyewitness identification using ERPs. Twenty participants completed two eyewitness lineup tasks (standard and deception conditions). For the standard condition, participants tried to accurately identify the culprit, whereas in the deception condition, they were asked to deceptively conceal their recognition of the culprit. Identification rates based on P300 patterns were calculated using two different individual analysis procedures (A and B) that varied in stringency. Correct identification rates for the standard condition were 100% for both procedures A and B. For the deception condition, correct identification rates of the concealed culprit were 90%, and 70% respectively for procedures A and B. Data from a prior study [the culprit-absent condition from Lefebvre, C.D., Marchand, Y., Smith, S.M. & Connolly, J.F., 2007. Determining eyewitness identification accuracy using event-related brain potentials (ERPs). Psychophysiology, 44, 894-904.] was reanalysed to investigate differences in false identification rates based on procedures A and B. False identifications were substantially higher when using procedure A (29%) versus procedure B (0%). Overall, superiority was found for procedure B compared to procedure A based on Grier's A'.

PurposeThe purpose of this paper is to identify key themes within the blended learning literature and to develop a series of practical recommendations to facilitate the successful adaptation and implementation of a “blended approach to learning delivery”.Design/methodology/approachThe literature was reviewed and informed a series of recommendations for organisations considering adopting or implementing blended approaches to teaching and training.FindingsSeveral key themes centering on the importance of evaluation, skills training, pedagogy, human factors, technology and implementation were identified. The emerging themes informed a series of practical recommendations to assist organisations considering blended learning approaches. Findings highlight the current limitations in the evidence base.Practical implicationsThe identified key themes and practical recommendations provide a useful assist to organisations considering adopting and implementing blended approaches to teaching and training.Originality/valueThe paper highlights key areas for development in the blended learning literature and at the organisational level.

Event-related brain potentials (ERPs) were recorded during a computerized and modified version of the Digit Span Backwards (DB) task from the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III). The modified DB version (ERP-DB task) was divided into two sections of 2, 4, 6 and 8 digits in length (Group 1) and 3, 5 and 7 digits in length (Group 2). Each trial had a study phase and a test phase. For the study phase, a series of digits was presented sequentially and aurally to 20 participants (10 for each group). For the test phase, a second series of digits was also presented sequentially and aurally that either corresponded to the reverse order of the digits in the study phase (correct condition) or had one digit in the sequence replaced by an incorrect digit (incorrect condition). The traditional DB task of the WAIS-III was also administered for comparison purposes. A prolonged positive slow wave (PSW) peaking between 450 and 750 ms was elicited to incorrect condition trials. For each participant, a derived measure was calculated from the ERP differentiation between correct and incorrect conditions. The derived measure was defined as the mean of the t-values obtained from the correct and incorrect waveform comparison, within the temporal interval that encompassed this component. The strongest statistical correlations between the derived measure and the traditional DB test scores were found at the Pz site (Group 1: r=0.79; Group 2: r=0.59). This statistical approach shows that it is possible to adequately relate an individual's performance on a traditional measure of working memory and ERP patterns. Overall, we believe that this kind of ERP approach holds promise as a technique for assessing quantitatively non-communicative patients.

Abstract: Previous research has found that pain can exert a disruptive effect on cognitive processing. This experiment was conducted to extend previous research with participants with chronic pain. This report examines pain's effects on early processing of auditory stimulus differences using the Mismatch Negativity (MMN) in healthy participants while they experienced experimentally induced pain. Event-related potentials (ERPs) were recorded using target and standard tones whose pitch differences were easy- or difficult-to-detect in conditions where participants attended to (active attention) or ignored (passive attention) the stimuli. Both attention manipulations were conducted in no pain and pain conditions. Experimentally induced ischemic pain did not disrupt the MMN. However, MMN amplitudes were larger to difficult-to-detect deviant tones during painful stimulation when they were attended than when they were ignored. Also, MMN amplitudes were larger to the difficult- than to the easy-to-detect tones in the active attention condition regardless of pain condition. It appears that rather than exerting a disruptive effect, the presence of experimentally induced pain enhanced early processing of small stimulus differences in these healthy participants.

Objective This study investigated the effectiveness of an ERP-compatible Digit Span Backward (ERP-DB) task to determine working memory abilities in healthy participants. Methods Participants were administered both the standard digit span backward and ERP-DB tasks. The ERP-DB task was divided into two sections, consisting of 2, 4, 6 and 8 (Group 1) and 3, 5, and 7 (Group 2) set sizes. A set of digits was aurally presented, followed by a second set that either corresponded to the reverse order of the first set (correct condition) or had one digit in the sequence replaced by an incorrect digit (incorrect condition). Results Two posterior positive components were found to distinguish the two conditions; an earlier positive component (P200/P300) was elicited in the correct condition, whereas a comparatively robust and prolonged positive slow wave (PSW) was elicited in the incorrect condition. Furthermore, the PSW and the difference in PSW amplitude between incorrect and correct conditions (dPSW) dissipated as working memory load increased and were related to working memory capacity. Conclusions The PSW, dPSW and P200/P300 components were found to be associated with working memory abilities and may have the potential to act as neurophysiological markers for the assessment of working memory capacity. Significance This research lends support for the utility of the ERP-DB task as a means of assessing working memory abilities, which may have implications for testing patients with expressive communication impairments.

The goal of the present study was to delineate phonology's role in silent reading using event-related brain potential (ERP) techniques. Terminal endings of high cloze sentences were manipulated in four conditions in which the terminal word was: (1) the high cloze ending and thus orthographically, phonologically and semantically congruent (e.g., The gambler had a streak of bad luck.); (2) a pseudohomophone that was orthographically incongruent, but was phonologically congruent to the anticipated ending (e.g., The ship disappeared into the thick phog [fog].); (3) a word that was orthographically, phonologically and semantically incongruent to expectations (e.g., The dog chased the cat up the Queen [tree].); or (4) a nonword and consequently orthographically, phonologically and semantically incongruent to expectations (e.g., The gas station is about two miles down the bole [road].). A N270 was elicited by orthographically incongruent words and nonwords (conditions 2, 3 and 4), likely reflecting violations of orthographic form expectations, while the presence of the N400 to semantically incongruent words and nonwords (conditions 3 and 4) reflected violations of semantic expectations. The relative absence of the N400 response to pseudohomophones (condition 3) indicates that integrating word meaning with sentential context is influenced by the phonological representation of the presented letter string. The implication of these results for theories of word recognition is discussed.

The spatio-temporal dynamics of cortical activation underlying auditory word recognition, particularly its phonological stage, was studied with whole-head magnetoencephalography (MEG). Subjects performed a visuo-auditory priming task known to evoke the phonological mismatch negativity (PMN) response that is elicited by violations of phonological expectancies. Words and non-words were presented in separate conditions. In each of the 318 trials, the subjects first saw a word/non-word (e.g., ‘cat’) that was soon followed by a prime letter (e.g., ‘h’). Their task was to replace mentally the sound of the first letter of the word/non-word with the prime letter, thus resulting in a new word/non-word (e.g., ‘hat’). Finally, an auditory word/non-word either matching or mismatching with the anticipated item was presented. In most subjects, a PMNm followed by a later, N400m-like negativity was obtained in the left hemisphere to the mismatching auditory stimuli. A similar response pattern was obtained in the right hemisphere only in a few subjects. Source localization of the N1m, an index of acoustic analysis, and the PMNm and N400m-like responses was performed using L1 minimum-norm estimation. In the left hemisphere, the PMNm source for the words was significantly more anterior than the source of the N400m-like response; for the non-words, the PMNm source was significantly more anterior than the sources of the N1m and the N400m-like response. These results suggest that the left-hemisphere neuronal networks involved in sub-lexical phonological analysis are at least partly different from those responsible for the earlier (acoustic) and later (whole item) processing of speech input.

Study design A retrospective comparison of three different types of bone grafts for posterior spinal fusion in adolescent idiopathic scoliosis. Objective To determine the efficacy of bone marrow and demineralized bone matrix as a bone graft substitute for spinal fusion. Summary of background data Several reports have documented a high morbidity associated with harvesting autologous iliac crest bone graft (ICBG) for spinal fusion. Composite bone graft consisting of demineralized bone matrix and aspirated bone marrow may reduce the morbidity and still retain the osteoinductive properties of iliac crest autograft. Methods Three different bone grafting techniques were used by a single surgeon in 88 consecutive patients who had posterior spinal fusion for adolescent idiopathic scoliosis. Segmental instrumentation with dual-rod fixation was used in all cases. Selection of type of graft was determined historically by the time when the operations were performed. Autologous ICBG was used in Group A, freeze-dried corticocancellous allograft in Group B, and composite graft of autologous bone marrow and demineralized bone matrix in Group C. Seventy-seven patients were reviewed, with a minimum of 2 years' follow-up (mean, 3 years 7 months; range, 2 years-9 years 5 months). Radiographs were assessed for pseudarthrosis and loss of correction of 10 degrees or more. Loss of 10 degrees of correction has been previously identified as an indicator of potential pseudarthrosis or fusion instability. Both of these criteria were used to compare success of fusion. Results Failure caused by pseudarthroses was seen in two patients (2.6%), one in Group A and one in Group B. Eleven patients lost greater than 10 degrees of correction, but only one demonstrated pseudarthroses. The 13 patients with pseudarthroses or loss of correction constitute the failure group for purposes of graft assessment. The failure rate was 12.5% in Group A (ICBG), 28% in Group B (freeze-dried corticocancellous allograft), and 11.1% in Group C (composite graft of autologous bone marrow and demineralized bone matrix). Eliminating patients with crankshaft phenomenon did not substantially change the results. There was no morbidity associated with bone marrow aspiration. Conclusions Fusion rates were comparable for GroupA (ICBG) and Group C (composite graft of autologous bone marrow and demineralized bone matrix). The composite graft is our preferred graft for fusions in adolescent idiopathic scoliosis.

Objective : Event-related brain potentials (ERPs) were used to assess language function after stroke and demonstrate that it is possible to adapt neuropsychological tests to evaluate neurocognitive function using ERPs. Prior ERP assessment work has focused on language in both healthy individuals and case studies of aphasic neurotrauma patients. The objective of the current study was to evaluate left-hemisphere stroke patients who had varying degrees of receptive language impairment. It was hypothesized that ERPs would assess receptive language function accurately and correlate highly with the neuropsychological data. Methods : Data were collected from 10 left-hemisphere stroke patients; all were undergoing rehabilitation at the time of testing. Each patient received a battery of neuropsychological tests including the Peabody Picture Vocabulary Test-Revised (PPVT-R; Minnesota: American Guidance Service, 1981). ERPs were recorded during a computerized PPVT-R, in which pictures are presented followed by digitized spoken words that are either congruent or incongruent with the pictures. Results and conclusion : Incongruent spoken words within an individual's vocabulary level elicited well-known ERP components. One of the components (the N400) could be utilized as a marker of intact semantic processing. The ERP results were subsequently quantified and N400 derivative scores correlated highly with the neuropsychological findings. The results provided a clear demonstration of the efficacy of ERP-based assessment in a neurological patient group. Significance : Language function in stroke patients can be evaluated, independent of behavior, using electrophysiological measures that correlate highly with traditional neuropsychological test scores.

Although most clavicular fractures in adults heal with no or minimal persistent symptoms, the rate of symptomatic malunion or nonunion of displaced fractures of the clavicle has ranged from 3% to 5% in a number of reports1-5. In a previous study of fifteen clavicular nonunions and malunions2, the senior one of us (J.F.C.) found that seven patients experienced intermittent or chronic symptoms associated with impingement on the thoracic outlet. These symptoms occurred most often when the patient abducted the shoulder or elevated the arm to an overhead position. Such patients are sometimes treated for cervical disc disease or, as in this case report, managed with resection of the first rib without relief of symptoms. We and others3,5-7 have observed that the diagnosis and the surgical correction of thoracic outlet syndrome secondary to clavicular malunion may be delayed. Because clavicular fractures usually heal without sequelae, patients who present with late symptoms may be considered malingerers or compensation seekers7-10. Also, some physicians may advise against surgical correction because of the long-standing tradition of nonoperative treatment of clavicular fractures11,12 and because of an appropriate concern that operative treatment of the malunited fracture is associated with a risk of damage to the underlying neurovascular structures12,13. Fatal subclavian vascular injuries from a fractured clavicle have been occasionally reported13-16. The purpose of this report is to present a case of thoracic outlet syndrome produced by a clavicular malunion and to illustrate our technique of clavicular osteotomy to correct the problem. A thirty-six-year-old man who operated heavy equipment sustained a fracture to the right clavicle and subsequently was diagnosed as having thoracic outlet syndrome. Because of persistent pain, numbness, and inability …

Ethical and legal issues are complex—more complex than one person can be consciously aware of. To discuss such issues from only one perspective would be myopic. Therefore, this review article was written by authors from 12 countries/cultures: Australia, China, Cuba, Ireland, India, Japan, Lithuania, Russia., South Africa, The Netherlands, Turtle Island and United States. The following issues were addressed: Standards of reasonable and prudent care, responsibility for care, failure to diagnose properly, failure in care, liability and malpractice, and postvention. There is no one standard of care worldwide on these issues. It is concluded that standards are defined according, first to the standards of community practices, and second, to the resources available, and hence, what reasonably can be expected. Communities are encouraged to examine and discuss these matters as we embark on this millennium.

Background Conventional imaging techniques are unable to detect abnormalities in the brain following mild traumatic brain injury (mTBI). Yet patients with mTBI typically show delayed response on neuropsychological evaluation. Because fractal geometry represents complexity, we explored its utility in measuring temporal fluctuations of brain resting state blood oxygen level dependent (rs-BOLD) signal. We hypothesized that there could be a detectable difference in rs-BOLD signal complexity between healthy subjects and mTBI patients based on previous studies that associated reduction in signal complexity with disease. Methods Fifteen subjects (13.4 ± 2.3 y/o) and 56 age-matched (13.5 ± 2.34 y/o) healthy controls were scanned using a GE Discovery MR750 3T MRI and 32-channel RF-coil. Axial FSPGR-3D images were used to prescribe rs-BOLD (TE/TR = 35/2000ms), acquired over 6 minutes. Motion correction was performed and anatomical and functional images were aligned and spatially warped to the N27 standard atlas. Fractal analysis, performed on grey matter, was done by estimating the Hurst exponent using de-trended fluctuation analysis and signal summation conversion methods. Results and Conclusions Voxel-wise fractal dimension (FD) was calculated for every subject in the control group to generate mean and standard deviation maps for regional Z-score analysis. Voxel-wise validation of FD normality across controls was confirmed, and non-Gaussian voxels (3.05% over the brain) were eliminated from subsequent analysis. For each mTBI patient, regions where Z-score values were at least 2 standard deviations away from the mean (i.e. where |Z| > 2.0) were identified. In individual patients the frequently affected regions were amygdala (p = 0.02), vermis(p = 0.03), caudate head (p = 0.04), hippocampus(p = 0.03), and hypothalamus(p = 0.04), all previously reported as dysfunctional after mTBI, but based on group analysis. It is well known that the brain is best modeled as a complex system. Therefore a measure of complexity using rs-BOLD signal FD could provide an additional method to grade and monitor mTBI. Furthermore, this approach can be personalized thus providing unique patient specific assessment.

BACKGROUND: There is converging evidence for the notion that pain affects a broad range of attentional domains. This study investigated the influence of pain on the involuntary capture of attention as indexed by the P3a component in the event-related potential derived from the electroencephalogram. METHODS: Participants performed in an auditory oddball task in a pain-free and a pain condition during which they submerged a hand in cold water. Novel, infrequent and unexpected auditory stimuli were presented randomly in a series of frequent standard and infrequent target tones. P3a and P3b amplitudes were observed to novel, unexpected and target-related stimuli, respectively. RESULTS: Both electrophysiological components were characterized by reduced amplitudes in the pain compared with the pain-free condition. Hit rate and reaction time to target stimuli did not differ between the two conditions presumably because the experimental task was not difficult enough to exceed attentional capacities under pain conditions. CONCLUSIONS: These results indicate that voluntary attention serving the maintenance and control of ongoing information processing (reflected by the P3b amplitude) is impaired by pain. In addition, the involuntary capture of attention and orientation to novel, unexpected information (measured by the P3a) is also impaired by pain. Thus, neurophysiological measures examined in this study support the theoretical positions proposing that pain can reduce attentional processing capacity. These findings have potentially important implications at the theoretical level for our understanding of the interplay of pain and cognition, and at the therapeutic level for the clinical treatment of individuals experiencing ongoing pain.

There is a substantial body of basic research that has utilized ERPs to investigate the neurological basis of cognition. This research has, in turn, led to the development of practical applications of cognitive ERPs in patient populations. In particular, recent work has focused on the development of ERP-based assessment measures for the neuropsychological assessment of dyslexia and language impairments secondary to stroke. This review describes the innovative assessment methods program (IAMP), an initiative to utilize ERPs for a neuropsychological assessment of patients who cannot be evaluated by traditional methods. The success of this program has demonstrated that ERPs can be used to reliably evaluate an individual's reading and speech comprehension abilities, independent of behavioral and speech production impediments. In contrast to traditional neuropsychological assessment, these ERP methods can discern the cognitive strategies used by an individual to perform a task.