Information Processing Deficits Research Articles

Brain lateralization and self-reported symptoms of ADHD in a population sample of adults: a dimensional approach.

Many clinical studies reported a compromised brain lateralization in patients with Attention-Deficit/Hyperactivity Disorder (ADHD) without being conclusive about whether the deficit existed in the left or right hemisphere. It is well-recognized that studying ADHD dimensionally is more controlled for comorbid problems and medication effects, and provides more accurate assessment of the symptoms. Therefore, the present study applied the dimensional approach to test the relationship between brain lateralization and self-reported ADHD symptoms in a population sample. Eighty-five right-handed university students filled in the Conners’ Adult ADHD Rating Scales and performed a lateralization reaction time task. The task consists of two matching conditions: one condition requires nominal identification for letters tapping left hemisphere specialization (Letter Name-Identity condition) and the other one requires physical and visuospatial identification for shapes tapping right hemisphere specialization (Shape Physical-Identity condition). The letters or shapes to be matched are presented in left or right visual field of a fixation cross. For both task conditions, brain lateralization was indexed as the difference in mean reaction time between left and right visual field. Linear regression analyses, controlled for mood symptoms reported by a depression, anxiety, and stress scale, showed no relationship between the variables. These findings from a population sample of adults do not support the dimensionality of lateralized information processing deficit in ADHD symptomatology. However, group comparison analyses showed that subjects with high level of inattention symptoms close to or above the clinical cut-off had a reduced right hemisphere processing in the Shape Physical-Identity condition.

Low to Moderate Average Alcohol Consumption and Binge Drinking in Early Pregnancy: Effects on Choice Reaction Time and Information Processing Time in Five-Year-Old Children.

BackgroundDeficits in information processing may be a core deficit after fetal alcohol exposure. This study was designed to investigate the possible effects of weekly low to moderate maternal alcohol consumption and binge drinking episodes in early pregnancy on choice reaction time (CRT) and information processing time (IPT) in young children.MethodParticipants were sampled based on maternal alcohol consumption during pregnancy. At the age of 60–64 months, 1,333 children were administered a modified version of the Sternberg paradigm to assess CRT and IPT. In addition, a test of general intelligence (WPPSI-R) was administered.ResultsAdjusted for a wide range of potential confounders, this study showed no significant effects of average weekly maternal alcohol consumption during pregnancy on CRT or IPT. There was, however, an indication of slower CRT associated with binge drinking episodes in gestational weeks 1–4.ConclusionThis study observed no significant effects of average weekly maternal alcohol consumption during pregnancy on CRT or IPT as assessed by the Sternberg paradigm. However, there were some indications of CRT being associated with binge drinking during very early pregnancy. Further large-scale studies are needed to investigate effects of different patterns of maternal alcohol consumption on basic cognitive processes in offspring.

Blockade of growth hormone secretagogue receptor 1A signaling by JMV 2959 attenuates the NMDAR antagonist, phencyclidine-induced impairments in prepulse inhibition.

RationaleSchizophrenic-spectrum patients commonly display deficits in preattentive information processing as evidenced, for example, by disrupted prepulse inhibition (PPI), a measure of sensorimotor gating. Similar disruptions in PPI can be induced in rodents and primates by the psychotomimetic drug phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor. Mounting evidence suggests that the hunger hormone ghrelin and its constitutively active receptor influences neuronal circuits involved in the regulation of mood and cognition.ObjectivesIn the present series of experiments, we investigated the effects of ghrelin and the growth hormone secretagogue receptor (GHS-R1A) neutral antagonist, JMV 2959, on acoustic startle responses (ASR), PPI, and PCP-induced alterations in PPI.ResultsIntraperitoneal (i.p.) administration of ghrelin (0.033, 0.1, and 0.33 mg/kg) did not alter the ASR or PPI in rats. Conversely, i.p. injection of JMV 2959 (1, 3, and 6 mg/kg), dose dependently decreased the ASR and increased PPI. Pretreatment with JMV 2959 at a dose with no effect on ASR or PPI per se, completely blocked PCP-induced (2 mg/kg) deficits in PPI while pretreatment with the highest dose of ghrelin did not potentiate or alter PPI responses of a sub-threshold dose of PCP (0.75 mg/kg).ConclusionThese findings indicate that the GHS-R1A is involved in specific behavioral effects of PCP and may have relevance for patients with schizophrenia.

Children With ADHD Show Impairments in Multiple Stages of Information Processing in a Stroop Task: An ERP Study

This study investigated the role of impaired inhibitory control as a factor underlying attention deficit hyperactivity disorder (ADHD). Children with ADHD and typically developing children completed an animal Stroop task while electroencephalogram (EEG) was recorded. The lateralized readiness potential and event-related brain potentials associated with perceptual and conflict processing were analyzed. Children with ADHD were slower to give correct responses irrespective of congruency, and slower to prepare correct responses in the incongruent condition. This delay could result from enhanced effort allocation at earlier processing stages, indicated by differences in P1, N1, and conflict sustained potential. Results suggest multiple deficits in information processing rather than a specific response inhibition impairment.

The Unique and Combined Effects of Reinforcement and Methylphenidate on Temporal Information Processing in Attention-Deficit/Hyperactivity Disorder.

Temporal information processing and reward sensitivity are neurocognitive impairments key to attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to examine the unique and combined impact of reinforcement and methylphenidate (MPH) on temporal information processing in children with ADHD. We predicted that both monetary reinforcement and MPH would ameliorate temporal information processing deficits in ADHD, and we expected that the combined effect of reinforcement and MPH would be most beneficial. Forty children (23 with ADHD and 27 typical controls, aged 8-12 y) performed a time production task under 3 conditions: reward, response cost, and feedback only. Children with ADHD also performed the task (in random order) with placebo, a low, a medium, and a high dose of MPH. Dependent variables were time production accuracy and variability. At baseline, children with ADHD displayed poor internal clock functioning compared with controls, as reflected by greater underestimations of the 1-second interval, and they showed poor motor output as reflected by increased timing variability. Reward and response cost improved motor output (timing variability), with similar effects for both groups. Methylphenidate increased performance (timing variability) compared with placebo, with a higher dose showing greater effects. Effect sizes of reinforcement and medication were medium to large. Contrary to expectations, MPH did not add to the reinforcement effect. The results of this study confirm the value of reward and response cost being similar to that of MPH to optimize (timing) performance of children with ADHD.

Reduced Efficiency and Capacity of Cognitive Control in Autism Spectrum Disorder.

Cognitive control constrains mental operations to prioritize information that reaches conscious awareness and is essential to flexible, adaptive behavior under conditions of uncertainty. Cognitive control can be compromised by neurodevelopmental disorders such as autism spectrum disorder (ASD), which is characterized by the presence of social and communicative deficits, and restricted interests/repetitive behaviors. Although prior investigations have attempted to elucidate the nature of cognitive control in ASD, whether there is an underlying information processing deficit associated with cognitive control remains unclear. This study challenged cognitive control in 15 high-functioning adults with ASD and 15 typically developing (TD) controls using three novel tasks designed to systematically manipulate uncertainty. We aimed to investigate the efficiency of cognitive control in sequential information processing, cognitive control of nonsequential information processing across a range of cognitive loads and cognitive control capacity under time constraint. Results demonstrated that the ASD group performed less efficiently on sequential and nonsequential information processing, and had reduced cognitive control capacity under time constraint relative to the TD group. These findings suggest that inefficient cognitive control of information processing may be a fundamental deficit in ASD.

P129. Deficits of early information processing in patients with alcohol dependence: On the way to optimized mismatch-negativity

Introduction The mismatch negativity (MMN) represents one of the major paradigms in cognitive neurophysiology. The attenuation of this subtraction wave of auditory event-related potentials (being a marker of discrimination of rare deviant stimuli among a series of standard stimuli) is well established in schizophrenia research. Moreover, first MMN results in patients with alcohol dependence mostly indicated an enhanced MMN though heterogeneously. In contrast to this “traditional” oddball MMN an optimized MMN including a higher number of deviants but within the same time interval was deficient in schizophrenia patients as shown by our group. Interestingly, the two clinical entities (schizophrenia, alcohol dependence) are in a close connection to glutamate neurotransmitter system underlying the generation of MMN. Methods 25 inpatients with alcohol dependence received a multichannel EEG with auditory MMN in i) oddball (20% deviants) as well as optimized MMN (50% standards, five deviants with 10% each). 25 healthy subjects without harmful use of alcohol served as controls. Results Following alcohol withdrawal patients showed decreased MMN amplitudes in the fronto-central region and increased latencies as compared to controls. Especially when taking the optimized MMN, the amplitudes of the cortico-central region significantly correlated positively (deviants: duration, intensity, localization: 0.001 > p’s) with length of time of alcohol abstinence. Conclusion Attenuation of optimized MMN might indicate down-regulation of glutamatergic systems after withdrawal. Further, this study confirms the alteration of latencies representing delay of early auditory information processing in alcohol patients. Efficient neurospychobiological monitoring could improve diagnostic evaluation and potentially prediction of effects of psychotropic agents in patients with substance dependence.

Influence of the affective valence of visual materials in recognition among healthy individuals and patients with Alzheimer's disease dementia

Patients with Alzheimer's disease (AD) present with impairments both at the structures associated with emotions, and in episodic memory. The involvement of the amygdala in patients with AD might imply emotional deficit in information processing. It has been reported that the impairment of patients with AD to perceive emotions might be lower than their deficit at the level of other cognitive functions, with a higher recalling of materials when the materials have emotional content. To research into the influence of the affective valence of picture in visual recognition tests among healthy individuals and patients with mild Alzheimer's Disease Dementia (ADD). Fifteen healthy individuals (age (mean±Standard Deviation) 73±8.48 years, education 13.2±3.9 years, Mini Mental State Examination (MMSE) 29.4±1.55), and 15 patients with ADD (age 75.47±7.61 years, education 10.8±4 years, MMSE 24.6±2.85), paired by age and education were included. Ten pictures with neutral valence and 10 pictures with negative valence were selected from the International Affective Picture System, paired by arousal level. Successful recognition of pictures and reaction time by picture valence were assessed by ANOVA test. A better performance was recorded both in terms of the number of successful recognition instances (F=1570;p=0.01) and of reaction time (F=285.40;p=0.01) in the control group compared to patients with ADD. Both groups evidenced a better recognition accuracy with negative-valence pictures than with neutral-valence pictures (F=4.66;p=0.04). A better performance of the control group was noted both in terms of processing rate and of recognition accuracy. In both groups, the recognition accuracy was higher with negative-valence prompts. These findings suggest that the emotional content of the information facilitates recognition.

Neural oscillatory deficits in schizophrenia predict behavioral and neurocognitive impairments.

Paying attention to visual stimuli is typically accompanied by event-related desynchronizations (ERD) of ongoing alpha (7–14 Hz) activity in visual cortex. The present study used time-frequency based analyses to investigate the role of impaired alpha ERD in visual processing deficits in schizophrenia (Sz). Subjects viewed sinusoidal gratings of high (HSF) and low (LSF) spatial frequency (SF) designed to test functioning of the parvo- vs. magnocellular pathways, respectively. Patients with Sz and healthy controls paid attention selectively to either the LSF or HSF gratings which were presented in random order. Event-related brain potentials (ERPs) were recorded to all stimuli. As in our previous study, it was found that Sz patients were selectively impaired at detecting LSF target stimuli and that ERP amplitudes to LSF stimuli were diminished, both for the early sensory-evoked components and for the attend minus unattend difference component (the Selection Negativity), which is generally regarded as a specific index of feature-selective attention. In the time-frequency domain, the differential ERP deficits to LSF stimuli were echoed in a virtually absent theta-band phase locked response to both unattended and attended LSF stimuli (along with relatively intact theta-band activity for HSF stimuli). In contrast to the theta-band evoked responses which were tightly stimulus locked, stimulus-induced desynchronizations of ongoing alpha activity were not tightly stimulus locked and were apparent only in induced power analyses. Sz patients were significantly impaired in the attention-related modulation of ongoing alpha activity for both HSF and LSF stimuli. These deficits correlated with patients’ behavioral deficits in visual information processing as well as with visually based neurocognitive deficits. These findings suggest an additional, pathway-independent, mechanism by which deficits in early visual processing contribute to overall cognitive impairment in Sz.

Some social abilities cross ASD and ADHD, but not OCD, researchers find

Repetitive behavior, inattention, social deficits, and hyperactivity — these traits are often identified, at varying levels, in autism spectrum disorder (ASD), attention‐deficit hyperactivity disorder (ADHD), and obsessive‐compulsive disorder (OCD). While deficits in social information processing are known to be a core symptom of ASD, social deficits are also being found in other conditions, including ADHD and OCD. Researchers wanted to find out the extent to which deficits are specific for ASD. Children with ADHD have greater difficulty recognizing fear, sadness, and anger than typical children, researchers have found. Individuals with ASD have impairments in recognizing anger, fear, and surprise, and individuals with OCD have difficulty recognizing disgust and anger.

Hoarding as a Disorder of the Obsessive-Compulsive Spectrum

Hoarding often occurs without obsessive-compulsive disorder (OCD), it shows distinguishable neuropsychological and neurobiological correlates and a distinct comorbidity spectrum. Further, it occurs secondarily to other psychiatric and neurobiological disorders. Therefore hoarding disorder has been included as a distinct diagnosis in DSM-5.Neuroimaging studies point to functional and structural abnormalities of networks subserving decision making, attention, action planning and emotional regulation.The cognitive-behavioral model outlines the most important characteristics of pathological hoarding, comprising deficits of information processing, maladaptive beliefs about information processing deficits, maladaptive beliefs about posessions as well as emotional attachment to them accompanied with emotional distress and avoidance.Because of a low willingness for therapy plus a high rate of discontinuation of therapy, a manualized cognitive-behavioral therapy approach for pathological hoarding has been established. It builds on observational learning, cognitive strategies, graduated exposure, response prevention, training/coaching to sort out, and relapse prevention are key components of the treatment. Particularily in case of lacking motivation for any kind of behavioral therapy or other psychological treatments, a pharmacotherapy with SSRIs is recommended.

Adaptation to Laterally Displacing Prisms in Anisometropic Amblyopia.

Using visual feedback to modify sensorimotor output in response to changes in the external environment is essential for daily function. Prism adaptation is a well-established experimental paradigm to quantify sensorimotor adaptation; that is, how the sensorimotor system adapts to an optically-altered visuospatial environment. Amblyopia is a neurodevelopmental disorder characterized by spatiotemporal deficits in vision that impacts manual and oculomotor function. This study explored the effects of anisometropic amblyopia on prism adaptation. Eight participants with anisometropic amblyopia and 11 visually-normal adults, all right-handed, were tested. Participants pointed to visual targets and were presented with feedback of hand position near the terminus of limb movement in three blocks: baseline, adaptation, and deadaptation. Adaptation was induced by viewing with binocular 11.4° (20 prism diopter [PD]) left-shifting prisms. All tasks were performed during binocular viewing. Participants with anisometropic amblyopia required significantly more trials (i.e., increased time constant) to adapt to prismatic optical displacement than visually-normal controls. During the rapid error correction phase of adaptation, people with anisometropic amblyopia also exhibited greater variance in motor output than visually-normal controls. Amblyopia impacts on the ability to adapt the sensorimotor system to an optically-displaced visual environment. The increased time constant and greater variance in motor output during the rapid error correction phase of adaptation may indicate deficits in processing of visual information as a result of degraded spatiotemporal vision in amblyopia.

Auditory event-related potentials in methadone substituted opiate users

The effects of methadone maintenance treatment (MMT) on neurophysiological function are unclear. Using an auditory oddball paradigm, event-related potential (ERP) amplitudes and latencies were measured in 32 patients undertaking MMT, 17 opiate users who were addicted but not receiving substitution treatment and 25 healthy control subjects. Compared with healthy control subjects, the MMT and opiate user groups showed an increased P200 amplitude in response to target stimuli. The opiate user group also exhibited a decreased amplitude and an increased latency of N200, and a greater number of task-related errors than either healthy control subjects or patients undertaking MMT. There were no significant group differences in the P300 amplitude. However, it is noteworthy that the frontal P300 amplitude of the MMT group was greater than that of opiate users or healthy controls. Our findings suggest that altered sensory information processing associated with a history of opiate use remains in patients undertaking MMT. However, there are less marked ERP abnormalities in those receiving MMT than in active opiate users. The deficits in information processing associated with illicit opiate use are likely to be reduced during MMT.

Neural correlates of out-group bias predict social impairment in patients with schizophrenia

BackgroundSocial impairments are a hallmark feature of schizophrenia and are a key predictor of functional disability. Deficits in social information processing likely underlie social impairment; however, this relationship is understudied. We previously demonstrated that patients with schizophrenia fail to habituate to neutral faces, providing evidence for an alteration in basic social information processing. It remains unknown whether patients with schizophrenia also show deficits in processing of more complex social information. Out-group bias provides an excellent opportunity to test complex social information processing because the bias requires basic face processing skills, the ability to discriminate between groups, as well as the ability to categorize oneself into a salient social group. MethodsStudy participants were 23 patients with schizophrenia and 21 controls. Using functional magnetic resonance imaging, habituation of response to 120s of repeated presentations of faces was assessed in participants who viewed either same-gender faces or opposite-gender faces. The interaction between face gender (same/opposite) and group was examined in three key regions: amygdala, hippocampus, and visual cortex. Social impairment was measured using the PANSS and correlations between social impairment and out-group effect (main effect of face type) were performed in patients. ResultsPatients with schizophrenia had aberrant neural responses to opposite-gender faces (interaction, p<.05 corrected). Healthy controls showed an immediate heightened response to opposite-gender faces relative to same-gender faces; but in patients this effect was substantially delayed (~70s). In patients with schizophrenia, the out-group bias was significantly correlated with social impairment. Patients with no social impairment showed a heightened neural response to opposite-gender faces after 30s, whereas patients with mild–moderate social impairment failed to ever show a heightened response. ConclusionAlterations in neural responses during out-group processing predicted degree of social impairment in patients with schizophrenia; thus, neural responses to opposite-gender faces may provide a novel measure for studies of treatment response and disease outcome.

No deficit in neurocortical information processing in patients with cleft lip and palate.

Cleft lip and palate (CLP) represents the most common malformation of the midfacial region worldwide. It can be suggested that the facial stigmatization, the speech impediment, and the long-standing pressure of treatment cause a range of life stressors. Neurocortical information is influenced by physiological and psychological factors and varies significantly in patients suffering from chronic stress, anxiety, depression, or other psychopathological conditions following maladaptation. The aims of the present study were to investigate the neurocortical information processing of patients with CLP using the contingent negative variation (CNV) paradigm and to evaluate secondary psychopathology, anxiety, and depression. Twenty-five adults with CLP and 25 healthy volunteers, matched in age and gender, were investigated using recordings of the CNV. Initial CNV (iCNV), late CNV (lCNV), and total CNV (tCNV) as well as habituation slope of the iCNV were determined in each subject. Additionally, each participant had to complete the hospital anxiety and depression questionnaire (HADS) and the Symptom Checklist-90-R (SCL-90-R). Individuals with CLP did not differ significantly from healthy subjects according to any of the CNV parameters investigated. No correlations could be revealed between the measured items and the confounding factors age and gender. Additionally, there were no differences between the groups regarding depression and SCL-90-R; however, anxiety showed significant group differences on a subclinical level. These data suggest that subjects with CLP show normal neurocortical information processing. It seems likely that CLP and its treatment have no impact on psychosocial functioning and neurophysiological mechanisms of attention. The specific living conditions of patients with CLP do not result in disease-specific neurophysiological changes.

Neuropsychological and neurophysiological insights into hoarding disorder.

Hoarding disorder (HD) is associated with significant personal impairment in function and constitutes a severe public health burden. Individuals who hoard experience intense distress in discarding a large number of objects, which results in extreme clutter. Research and theory suggest that hoarding may be associated with specific deficits in information processing, particularly in the areas of attention, memory, and executive functioning. There is also growing interest in the neural underpinnings of hoarding behavior. Thus, the primary aim of this review is to summarize the current state of evidence regarding neuropsychological deficits associated with hoarding and review research on its neurophysiological underpinnings. We also outline the prominent theoretical model of hoarding and provide an up-to-date description of empirically based psychological and medical treatment approaches for HD. Finally, we discuss important future avenues for elaborating our model of HD and improving treatment access and outcomes for this disabling disorder.

A Brief Overview of Amblyaudia

Amblyaudia, a recent subcategory of auditory processing disorder, is characterized by asymmetrical auditory processing of an individual’s ears. Amblyaudia can result in speech comprehension difficulties, reading difficulties, information processing deficits, and inattention. These difficulties can be mistakenly attributed to Attention Deficit Hyperactivity Disorder (ADHD), Specific Learning Disorders (SLD), depression, anxiety disorders, and communication disorders. Unfortunately, traditional hearing tests do not place the two ears in competition and cannot detect asymmetry. Therefore, students who exhibit these difficulties and have normal performance on traditional hearing tests should be also evaluated for amblyaudia with dichotic listening tests. Amblyaudia can be addressed through dichotic listening tasks that strengthen the non-dominant ear, as well as minor adjustments to the classroom environment. This paper will examine the current literature on amblyaudia and provide a brief overview of the causes, diagnosis, treatments, and prognosis.

Disorders of Accommodative Convergation and Accommodation (AC/A) Relations at Traumatic Brain Injury.

Dear Editor, We read with interest the article by Serdarevic (1) regarding the disorders of accommodative-convergence/accommodation (AC/A) relation in patients with traumatic brain injury (TBI). Similar to the results of previous studies, the author found that the individuals with TBI may have various degrees of convergence insufficiency (CI) (2, 3). Traumatic brain injury (TBI) is defined as an alteration in brain function, or other evidence of brain pathology, caused by an external force. It can affect multiple aspects of vision, where mild TBI frequently leads to different disruptions in visual functioning, while moderate or severe TBI often cause structural lesions (4). There are two basic mechanisms of TBI: blast-related (BR TBI) which is caused by the blast wave itself or by direct head trauma caused by events surrounding the blast and non-blast-related (NBR TBI) which are caused by direct head trauma (5). The recent reports show that majority of patients with mild TBI can have different visual abnormalities, including oculomotor dysfunction (up to 90%) (2, 3), binocular vision (up to 29%) (2, 3) and visual field deficits (up to 39%) (2). Convergence insufficiency is an eye coordination and alignment problem that can be observed in 43 to 46% patients with mild TBI (2, 3). Moderate and severe TBI might additionally lead to ocular motor palsies, optic neuropathies, and orbital pathologies (4) However, CI without simultaneous visual or vestibular dysfunctions can be observed in only 9% of the visually symptomatic TBI patients (3). The mechanism of TBI injury can also be a prognostic factor, where light sensitivity is reported more often in BR TBI patients (67%) than in NBR TBI patients (33%). However, saccadic dysfunction is measured more often in NBR TBI patients (85%) than in BR TBI patients (58%) (5). Patients with TBI can suffer from various physical and mental disorders, therefore the treatment of patients with TBI with presenting signs of vision impairment can be extremely complicated. The new concept for treatment of these patients focuses on 4 main problems that need to be addressed: 1. Basic optometric vision examination (includes: assessment of refractive status, binocular status and ocular health status); 2. Oculomotor-based vision problems (refers to more comprehensive investigation and testing related to the specific oculomotor-based vision problems–accommodative vergence and the AC/A ratio, fusional vergence ranges at distance and near, phorias at distance and near, vergence flexibility at near, and the near point of convergence); 3. non-oculomotor-based vision problems (photo sensitivity, motion sensitivity, vestibular problems, visual field defects and various a range of deficits in visual information processing and perception) and 4. non-vision-based problems (refers to depression, fatigue, cognitive impairment, behavioral problems, postural problems, attentional problems and neurological problems). These problems tend to confound and complicate the vision examination procedures and can lead to inadequate treatment and result interpretation (6). For these reasons, we would kindly ask the authors to perform the correlations for Glasgow Coma Scale (GCS) scores, severity and mechanism of TBI, time between the injury and symptoms onset, refractive status and visual acuity, type of visual field deficits, presence of reading disorders, light sensitivity, presence of non-oculomotor-based vision problems and non-vision-based problems, type and length of visual rehabilitation with AC/C ratio. Without these information’s it would be difficult to hypothesize AC/C ratio changes as isolated consequence of CI as a result of TBI. These findings will significantly contribute to the papers scientific value and contribution. Overall we agree with Serdarevic that CI presents important visual deficit in patients with TBI. Other systemic and ophthalmic factors such as severity of brain injury, visual acuity and visual field deficits, together with presence of non-oculomotor-based vision problems and non-vision-based problems should be carefully monitored too.

Congenital amusia: A cognitive disorder limited to resolved harmonics and with no peripheral basis

Pitch plays a fundamental role in audition, from speech and music perception to auditory scene analysis. Congenital amusia is a neurogenetic disorder that appears to affect primarily pitch and melody perception. Pitch is normally conveyed by the spectro-temporal fine structure of low harmonics, but some pitch information is available in the temporal envelope produced by the interactions of higher harmonics. Using 10 amusic subjects and 10 matched controls, we tested the hypothesis that amusics suffer exclusively from impaired processing of spectro-temporal fine structure. We also tested whether the inability of amusics to process acoustic temporal fine structure extends beyond pitch by measuring sensitivity to interaural time differences, which also rely on temporal fine structure. Further tests were carried out on basic intensity and spectral resolution. As expected, pitch perception based on spectro-temporal fine structure was impaired in amusics; however, no significant deficits were observed in amusics' ability to perceive the pitch conveyed via temporal-envelope cues. Sensitivity to interaural time differences was also not significantly different between the amusic and control groups, ruling out deficits in the peripheral coding of temporal fine structure. Finally, no significant differences in intensity or spectral resolution were found between the amusic and control groups. The results demonstrate a pitch-specific deficit in fine spectro-temporal information processing in amusia that seems unrelated to temporal or spectral coding in the auditory periphery. These results are consistent with the view that there are distinct mechanisms dedicated to processing resolved and unresolved harmonics in the general population, the former being altered in congenital amusia while the latter is spared.

Overlapping auditory M100 and M200 abnormalities in schizophrenia and bipolar disorder: A MEG study

ObjectivesSchizophrenia and bipolar disorder share common etiological factors and pathophysiological pathways and have overlapping clinical features. Only few studies have directly compared early auditory information processing in the two disorders. The objective of this study was to investigate the M100 and M200 auditory responses in patients with schizophrenia and bipolar disorder and compare them with healthy controls using magnetoencephalography (MEG). MethodsWhole-head MEG data were acquired during an auditory oddball paradigm in 24 schizophrenia patients, 26 bipolar I disorder patients, and 31 healthy controls. The strengths and latencies of M100 and M200 in both hemispheres and the dipole source localizations were investigated from the standard stimuli. ResultsThe M100 and M200 dipolar sources were localized to the left and right posterior portion of the superior temporal gyrus (STG) in all the subjects. An asymmetric pattern of M100 and M200 auditory response with more anterior sources in the right STG was observed in the healthy controls. However, both the schizophrenia and bipolar disorder patients showed a symmetric M100 and M200 source pattern. When compared with the healthy control group, both patient groups showed significantly reduced M100 and M200 source strength in both hemispheres. ConclusionsOur study suggests that early auditory information processing deficits may be similar in schizophrenia and bipolar disorder and may be related to abnormalities of the STG.