Lateralization of speech processing in the brain as indicated by mismatch negativity and dichotic listening

The goal of the present study was to evaluate the differences between dichotic listening and mismatch negativity as measures of speech lateralization in the human brain. For this purpose, we recorded the magnetic equivalent of the mismatch negativity, elicited by consonant-vowel syllable change, and tested the same subjects in the dichotic listening procedure. The results showed that both methods indicated left-hemisphere dominance in speech processing. However, the mismatch negativity, as compared to the right-ear advantage, suggested slightly stronger left-hemisphere dominance in speech processing. No clear correlation was found between the laterality indexes of mismatch negativity and right-ear advantage calculated from dichotic listening results. The possible explanation for this finding would be that these two measures reflect different stages of speech processing in the human brain.     

Optimizing treatment in social phobia: a review of treatment resistance

Over the last 25 years, there has been a rapid expansion of our knowledge base of social phobia (SP). Although there are a number of well-validated treatment modalities, including pharmacotherapy and cognitive-behavioral therapy, significant gaps remain in our ability to achieve full remission in most patients. Despite advances in the neurobiology of SP, the etiology has yet to be determined. Investigations examining potential predictors of response have provided little guidance in selecting an appropriate treatment modality. These gaps in our knowledge have pushed us to examine issues related to treatment resistance. This paper presents a review of the current literature and issues related to treatment-resistant SP, including a discussion of the functional impairment associated with SP, definitions of treatment response and remission, as well as outcome measures that have been used in clinical investigations of SP. In addition, criteria for a standard treatment trial, predictors of treatment response, a review of treatment resistance studies, and potential directions for future research are examined. The most promising strategies to attain remission, will likely involve augmenting selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors with agents such as anticonvulsants, benzodiazepines, and antipsychotics as well as combining pharmacotherapy with cognitive-behavioral therapy. Our current treatment target of simply attaining a response needs to be refocused, so that an asymptomatic state and high end state functioning become the final goal of treatment.     

CBT对社交焦虑障碍有效干预的神经预测因子及机器学习应用

认知行为疗法（CBT）是社交焦虑障碍的标准疗法,对其疗效的神经预测因子研究有利于个性化诊疗方案选择。初步证据表明,干预前高级视皮层、背侧前扣带回、背内/外侧前额叶及眶额皮层的功能激活,杏仁核与情绪调节相关脑区的结构与功能连接,情绪性刺激诱发的晚期正成分与治疗后症状的改善有关,因而是潜在的预测因子。基于机器学习的个体化预测存在样本量小的突出问题。未来研究应考虑跨研究机构合作共享大数据,在多模态、多任务条件下收集数据,并在独立样本中验证预测的有效性。     

An experiential avoidance conceptualization of depressive rumination: Three tests of the model

This study examined an experiential avoidance conceptualization of depressive rumination in 3 ways: 1) associations among questionnaire measures of rumination, experiential avoidance, and fear of emotions; 2) performance on a dichotic listening task that highlights preferences for non-depressive material; and 3) psychophysiological reactivity in an avoidance paradigm modeled after the one used by Borkovec, Lyonfields, Wiser, and Deihl (1993) in their examination of worry. One hundred and thirty-eight undergraduates completed questionnaire measures and participated in a clinical interview to diagnose current and past episodes of depression. Of those, 100 were randomly assigned to a rumination or relaxation induction condition and participated in a dichotic listening task, rumination/relaxation induction, and depression induction. Questionnaire measures confirmed a relationship between rumination status and avoidance; however, no significant effects were found in the dichotic listening task. Psychophysiological measures indicated no difference in physiological response to a depression induction among high ruminators (HR). However, low ruminators (LR) in the relaxation condition exhibited a larger IBI response than LR in the rumination condition. Overall, these results provide partial support for an avoidance conceptualization of depressive rumination. Implications of these findings are discussed.     

Fifty years of dichotic listening research - still going and going and…

This year celebrates 50 years of research in auditory laterality and hemispheric asymmetry, using a dichotic listening approach. The discovery of the "right ear advantage" in 1961 by Doreen Kimura to dichotic presentations of phonetic stimuli paved the way for new studies of how speech perception and related language processes are lateralized in the human brain. The articles in this special issue, celebrating the first 50 years of dichotic listening research, reveal both the breadth and depth of current research, with contributions spanning from basic research to clinical applications, from behavioral studies to studies using advanced neuroimaging techniques, and with contributions from all over the world. It is my hope as Guest Editor that the next 50 years will be as productive as the first 50 years.     

Autism clinical trials: biological and medical issues in patient selection and treatment response

Biomedical measures are critical in the initial patient-screening and -selection phases of a clinical trial in autism and related disorders. These measures can also play an important role in the assessment and characterization of response and can provide an opportunity to study underlying etiologic and pathophysiologic processes. Thus, biomedical measures, including clinical laboratory analyses, metabolic screening, and chromosomal analysis, are used to screen for potential safety-related problems, to decrease biological and genetic heterogeneity, and to define subgroups. Neurobiological measures can be examined as possible predictors, modifiers or surrogates of therapeutic response, and adverse effects. Neurobiological research measures can also be used to study mechanisms and extent of drug action and to perform baseline and longitudinal investigations of possible pathophysiologic alterations. The potential utility and desirability of specific measures are considered and the general approach to choosing measures for incorporation is discussed.     

Structural Imaging Measures of Brain Aging

During the course of normal aging, biological changes occur in the brain that are associated with changes in cognitive ability. This review presents data from neuroimaging studies of primarily “normal” or healthy brain aging. As such, we focus on research in unimpaired or nondemented older adults, but also include findings from lifespan studies that include younger and middle aged individuals as well as from populations with prodromal or clinically symptomatic disease such as cerebrovascular or Alzheimer’s disease. This review predominantly addresses structural MRI biomarkers, such as volumetric or thickness measures from anatomical images, and measures of white matter injury and integrity respectively from FLAIR or DTI, and includes complementary data from PET and cognitive or clinical testing as appropriate. The findings reveal highly consistent age-related differences in brain structure, particularly frontal lobe and medial temporal regions that are also accompanied by age-related differences in frontal and medial temporal lobe mediated cognitive abilities. Newer findings also suggest that degeneration of specific white matter tracts such as those passing through the genu and splenium of the corpus callosum may also be related to age-related differences in cognitive performance. Interpretation of these findings, however, must be tempered by the fact that comorbid diseases such as cerebrovascular and Alzheimer’s disease also increase in prevalence with advancing age. As such, this review discusses challenges related to interpretation of current theories of cognitive aging in light of the common occurrence of these later-life diseases. Understanding the differences between “Normal” and “Healthy” brain aging and identifying potential modifiable risk factors for brain aging is critical to inform potential treatments to stall or reverse the effects of brain aging and possibly extend cognitive health for our aging society.     

Socioeconomic status, a forgotten variable in lateralization development

Socioeconomic status (SES), a variable combining income, education, and occupation, is correlated with a variety of social health outcomes including school dropout rates, early parenthood, delinquency, and mental illness. Several studies conducted in the 1970s and 1980s largely failed to report a relationship between SES and hemispheric asymmetry as measured by lateral differences in dichotic listening, tactile dot enumeration, and visual emotion and word recognition. However, none of the studies used asymmetry measures correcting for both ceiling and floor effects in accuracy, raising the question of whether lower and higher SES groups were comparable. Here the published data are reanalyzed using a laterality coefficient that corrects for such effects. The results are consistent across studies in revealing reduced lateralization in lower SES groups. Developmentally, this finding is consistent with either maturation delay or reduced functional specialization, or both. Suggestions are made for further research that include the use of behavioral asymmetry measures to screen tasks for structural and functional brain imaging.     

Effects of varied response modes upon dichotic consonant-vowel identification latency

Reaction times for two right-handed subjects who received 6000 trials of dichotic stop-vowels were obtained under response conditions involving the left hand, right hand, and neck muscles. Results indicated latencies were shorter (150+ msec) when targets were presented to the right rather than the left ear. Large and stable differences in latencies remained invariant with the mode of response. Reaction times did not vary as a function of the target's place or manner of articulation. The relationship between obtained measures of latency and percentage correct ruled out speed-accuracy trade-offs as a source of the obtained differences in latencies.     

Dichotic perception and laterality in neonates

Groups of 4-day-old neonates were tested for dichotic discrimination and ear differences with the High-Amplitude-Sucking procedure. In the first experiment, dichotic speech discrimination was attested by comparison with a control group. Furthermore, among those subjects who showed a substantial recovery of sucking response at least after one of the two syllable changes, it was observed that significantly more subjects manifested a stronger reaction to a right-ear change than to a left-ear change. In the second experiment, 4-day-old neonates were tested on syllable and music timbre discrimination. The significant Stimulus Type x Ear interaction observed suggests perceptual asymmetries indicative of very precocious brain specialization.     

Predicting Treatment Response in Older Adults with Insomnia

This study examined potential predictors of treatment outcome in late-life insomnia. Fifty-four older adults with chronic insomnia were treated with cognitive–behavior therapy (CBT), pharmacotherapy (PCT), or combined CBT plus PCT. Pretreatment characteristics such as demographic, clinical, psychometric, and sleep variables were examined as correlates or potential predictors of treatment response. Treatment response was defined by posttreatment sleep efficiency as measured subjectively by daily sleep diary and objectively by polysomnography. The results indicate that age, insomnia duration, medical illness, and previous use of sleep medications can moderate subjective or objective treatment outcome or both of these in late-life insomnia. However, there are no reliable predictors of outcome across all treatment and assessment modalities. The implications of these findings for the treatment of insomnia in older adults seen in primary care settings are discussed.     

Identifying predictors of treatment response

This article provides a rationale for considering predictors of growth in a treatment group as inadequate to identifying predictors of treatment response. When we interpret predictors of growth in a treatment group as synonymous with predictors of treatment response, we implicitly attribute all of the treated children's growth to the treatment, an untenable assumption under most conditions. We also contend that the use of standard scores in predictors of growth studies does not allow us to differentiate growth from treatment, from growth from other factors. We present two research methodologies that are appropriate methods of identifying predictors of treatment response: (a) single-subject experimental logic utilized to identify the specific participants in which treatment responses (not just growth) were found, combined with follow-up group comparison logic to identify the characteristics on which responders and nonresponders differ, and (b) statistical interactions among child/family/context characteristics and randomly assigned group membership. Principles for selecting potential predictors of treatment response are provided.     

汉语普通话声调加工的右耳优势及其机理：一项双耳分听的研究

采用双耳分听的任务探讨了汉语普通话声调加工的右耳优势问题,并引进反应手的因素,探讨了汉语声调加工的右耳优势的机制。结果表明,汉语母语被试对普通话声调的加工存在右耳、左脑优势,但这种优势是相对的,右脑也具备加工声调信息的能力,结果支持了直接通达模型。     

The role of distinctive features in the dichotic perception of vowels

A dichotic listening experiment was conducted to determine if vowel perception is based on phonetic feature extraction as is consonant perception. Twenty normal right-handed subjects were given dichotic CV syllables contrasting in final vowels. It was found that, unlike consonants, the perception of dichotic vowels was not significantly lateralized, that the dichotic perception of vowels was not significantly enhanced by the number of phonetic features shared, and that the occurrence of double-blend errors was not greater than chance. However, there was strong evidence for the use of phonetic features at the level of response organization. It is suggested that the differences between vowel and consonant perception reflect the differential availability of the underlying acoustic information from auditory store, rather than differences in processing mechanisms.     

Subjective improvement following treatment with carbamazepine (Tegretol) for a subpopulation of patients with traumatic brain injuries

Over a 3-yr period, 19 patients who had sustained brain traumas during motor vehicle incidents and who exhibited abnormal scores for a dichotic word-listening task and Roberts' Epileptic Spectrum Disorder Inventory more than one year after the injury were recommended for treatment with carbamazepine (Tegretol). The psychiatric profile of these patients, as defined by the Minnesota Multiphasic Personality Inventory, was similar to the profile of patients from other studies who had displayed more objective improvement following this treatment. Of the 14 patients 12 who followed the recommendation retrospectively reported that within a few weeks after treatment they experienced marked reductions in the incidence of sudden confusion and depression, increased attention and focus, and either elimination or attenuation of an aversive sensed presence. Such results suggest that many of the debilitating symptoms that persist for months to years after a traumatic brain injury may be electrical in nature rather than due to "psychological responses" and might be treatable by appropriate dosages of carbamazepine or other, e.g., Gabapentin (Neurontin) antiepileptic compounds.     

Dichotic listening in children: age-related changes in direction and magnitude of ear advantage

Children between the ages of 5 and 12 years were tested with dichotic listening tests utilizing single syllable words and random presentations of digits. They produced a higher prevalence of left ear dominance than expected, especially among right-handed children when tested with words. Whether more children demonstrate the LEA because of right hemisphere dominance for language or because there is less stability in ear advantage direction at younger ages cannot be fully resolved by this study. When ear advantages were measured by subtracting each child's lower score from the higher score without regard to right or left direction, an age-related trend toward lower measures of ear advantage was evident. This trend was greater for dichotic words than for dichotic digits. Structural factors that may be related to these results and possible influences of attention and verbal workload on the two kinds of dichotic stimuli are discussed.     

Clinical and treatment comparisons between adults with early- and late-onset obsessive-compulsive disorder

It is often suggested that early onset of disorders leads to higher severity and greater treatment refractoriness. Previous research has investigated whether there are clinical and demographic differences between groups of individuals who have experienced onset of obsessive-compulsive disorder (OCD) at an early or later age. Results suggest that individuals who report an early onset (EO) of the disorder report greater severity and persistence of symptoms. However, few studies have investigated whether there are differences in treatment response. The present study represents a preliminary investigation in the setting of a specialist OCD clinic. Analysis was undertaken using clinical records to investigate whether there were clinical differences and in response to cognitive-behavioural treatment (CBT) between individuals who developed OCD at an early (n = 22) or late (n = 23) age. No differences in treatment response between the groups were found. However, the EO group were rated as being more severe across a range of measures at start of treatment, and hence at end of treatment they remained more severe than the LO group. This has clinical implications, suggesting that more treatment sessions may be required for individuals who report an EO of symptoms.     

Corpus callosum size is linked to dichotic deafness and hemisphericity, not sex or handedness

Individuals differ in the number of corpus callosum (CC) nerve fibers interconnecting their cerebral hemispheres by about threefold. Early reports suggested that males had smaller CCs than females. This was often interpreted to support the concept that the male brain is more "lateralized" or "specialized," thus accounting for presumed male predominance in mathematics, as well as for aggressive behavior. Ultimately, meta-analyses of these many reports found no significant overall sex differences in inter-cerebral information carrying capacity. Here, using quantitative MRI, we found the midline CC area of 113 subjects was significantly correlated, not with handedness or sex, but with dichotic deafness, and even more so with redefined hemisphericity, the latter accounting for over 19% of CC variability. That is, both dichotic hearing and right brain-oriented individuals of either sex had significantly larger CCs than dichotically deaf or left brain-oriented persons. Thus, current traditions of brain laterality and gender may benefit from revisions that include redefined hemisphericity.     

Do dichotic listening procedures measure lateralization of information processing or retrieval strategy?

The data from two dichotic studies, both of which evaluated spontaneously generated response strategies under free recall and one of which also manipulated retrieval strategy by instruction, supported a conception that what dichotic procedures mostly measure are response strategies—mobile and readily deployed without loss of mnemonic capability. Consequently, competitional methods which are heavily influenced by output factors appear to be unreliable as a means of evaluating input processing dominance.     

Effect of directed attention on cerebral asymmetries in stuttering adults

9 stutterers and 9 nonstutterers were administered a dichotic digits test under conditions of free recall and directed attention. Analysis indicated right-ear preference for both groups and no differences between the free recall and directed listening conditions. Results are discussed in relation to previous studies in which dichotic digit-stimuli were presented to stutterers.