Medial Temporal Lobe Atrophy in Older Adults With Subjective Cognitive Impairments Affects Gait Parameters in the Spatial Navigation Task.

Both navigation abilities and gait can be affected by the atrophy in the medial temporal cortex. This study aimed to determine whether navigation abilities could differentiate seniors with and without medial temporal lobe atrophy who complained about their cognitive status. The participants, classified to either the medial temporal atrophy group (n = 23) or the control group (n = 22) underwent neuropsychological assessment and performed a spatial navigation task while their gait parameters were recorded. The study showed no significant differences between the two groups in memory, fluency, and semantic knowledge or typical measures of navigating abilities. However, gait parameters, particularly the propulsion index during certain phases of the navigation task, distinguished between seniors with and without medial temporal lobe lesions. These findings suggest that the gait parameters in the navigation task may be a valuable tool for identifying seniors with cognitive complaints and subtle medial temporal atrophy.

Multivariate multiscale entropy (mMSE) as a tool for understanding the resting-state EEG signal dynamics: the spatial distribution and sex/gender-related differences.

BACKGROUND: The study aimed to determine how the resting-state EEG (rsEEG) complexity changes both over time and space (channels). The complexity of rsEEG and its sex/gender differences were examined using the multivariate Multiscale Entropy (mMSE) in 95 healthy adults. Following the probability maps (Giacometti et al. in J Neurosci Methods 229:84-96, 2014), channel sets have been identified that correspond to the functional networks. For each channel set the area under curve (AUC), which represents the total complexity, MaxSlope-the maximum complexity change of the EEG signal at thefine scales (1:4 timescales), and AvgEnt-to the average entropy level at coarse-grained scales (9:12 timescales), respectively, were extracted. To check dynamic changes between the entropy level at the fine and coarse-grained scales, the difference in mMSE between the #9 and #4 timescale (DiffEnt) was also calculated. RESULTS: We found the highest AUC for the channel sets corresponding to the somatomotor (SMN), dorsolateral network (DAN) and default mode (DMN) whereas the visual network (VN), limbic (LN), and frontoparietal (FPN) network showed the lowest AUC. The largest MaxSlope were in the SMN, DMN, ventral attention network (VAN), LN and FPN, and the smallest in the VN. The SMN and DAN were characterized by the highest and the LN, FPN, and VN by the lowest AvgEnt. The most stable entropy were for the DAN and VN while the LN showed the greatest drop of entropy at the coarse scales. Women, compared to men, showed higher MaxSlope and DiffEnt but lower AvgEnt in all channel sets. CONCLUSIONS: Novel results of the present study are: (1) an identification of the mMSE features that capture entropy at the fine and coarse timescales in the channel sets corresponding to the main resting-state networks; (2) the sex/gender differences in these features.

An MR spectroscopy study of temporal areas excluding primary auditory cortex and frontal regions in subjective bilateral and unilateral tinnitus.

Previous studies indicate changes in neurotransmission along the auditory pathway in subjective tinnitus. Most authors, however, investigated brain regions including the primary auditory cortex, whose physiology can be affected by concurrent hearing deficits. In the present MR spectroscopy study we assumed increased levels of glutamate and glutamine (Glx), and other Central Nervous System metabolites in the temporal lobe outside the primary auditory cortex, in a region involved in conscious auditory perception and memory. We studied 52 participants with unilateral (n = 24) and bilateral (n = 28) tinnitus, and a control group without tinnitus (n = 25), all with no severe hearing losses and a similar hearing profile. None of the metabolite levels in the temporal regions of interest were found related to tinnitus status or laterality. Unexpectedly, we found a tendency of increased concentration of Glx in the control left medial frontal region in bilateral vs unilateral tinnitus. Slightly elevated depressive and anxiety symptoms were also shown in participants with tinnitus, as compared to healthy individuals, with the bilateral tinnitus group marginally more affected. We discuss no apparent effect in the temporal lobes, as well as the role of frontal brain areas, with respect to hearing loss, attention and psychological well-being in chronic tinnitus. We furthermore elaborate on the design-related and technical obstacles of MR spectroscopy.

The less complex temporal patterns of resting­state EEG activity, the lower the visual temporal order threshold.

Speech understanding, watching a movie, listening to music etc., requires perception of the temporal order of at least two incoming events. A history of performing these tasks may be reflected in spontaneous brain activity. Here, we examined the relationship between the complexity (temporal dynamics) of resting­state EEG (rsEEG) signal, assessed using the multivariate MultiScale Entropy (mMSE) algorithm, and the perception of event ordering, indexed by a visual temporal order threshold (TOT), i.e., the minimum duration necessary to correctly identify the before­after relation between two stimuli. Healthy adolescents and young adults performed a psychophysical task measuring the TOT and underwent an eyes­closed rsEEG study. The features of mMSE vectors, namely the area under curve (AUC) that represents total signal complexity, as well as the MaxSlope and the AvgEnt, corresponding to the entropy at fine­ and coarse­grained timescales, respectively, were obtained for the central (midline), anterior, middle and posterior channel sets. The greater the AUC and AvgEnt values in the central, left and right posterior areas, and the higher AUC in the right middle region, the higher the TOT. The most significant relationships were found for the midline electrodes (Fz, Cz, Pz, Oz). There were no significant correlations between the MaxSlope values and the TOT. To the best of our knowledge, this is the first study demonstrating that spontaneous EEG signal complexity is associated with the temporal order perception of two stimuli presented in rapid succession. Our findings may indicate that low total and coarse entropy levels of rsEEG signal are beneficial for visual temporal order judgments.

Resting-state fMRI functional connectivity of the left temporal parietal junction is associated with visual temporal order threshold.

The study aimed to determine the relationship between the millisecond timing, measured by visual temporal order threshold (TOT), i.e. a minimum gap between two successive stimuli necessary to judge a before-after relation, and resting-state fMRI functional connectivity (rsFC). We assume that the TOT reflects a relatively stable feature of local internal state networks and is associated with rsFC of the temporal parietal junction (TPJ). Sixty five healthy young adults underwent the visual TOT, fluid intelligence (Gf) and an eyes-open resting-state fMRI examination. After controlling for the influence of gender, the higher the TOT, the stronger was the left TPJ's rsFC with the left postcentral and the right precentral gyri, bilateral putamen and the right supplementary motor area. When the effects of Gf and TOT × Gf interaction were additionally controlled, the TOT-left TPJ's rsFC relationship survived for almost all above regions with the exception of the left and right putamen. This is the first study demonstrating that visual TOT is associated with rsFC between the areas involved both in sub-second timing and motor control. Current outcomes indicate that the local neural networks are prepared to process brief, rapidly presented, consecutive events, even in the absence of such stimulation.

Gait Analysis under Spatial Navigation Task in Elderly People-A Pilot Study.

A decline in the Spatial Navigation (SN) abilities has been observed in the course of healthy aging. Walking is an inseparable part of the navigation process; however, research tasks overlook this aspect in studies involving seniors. The present study was designed to overcome this limitation by recording gait parameters during natural environment navigation and to determine gait indicators that most accurately assign the participants to the proper age category. Thirteen elderly (mean age = 69.1 ± 5.4 year) and sixteen young women (mean age = 21.5 ± 2.2 year) equipped with gait sensors were asked to learn a path while walking in a real building (Learning Phase), reproduce the path (Memory Phase) and reach targets after a 30 min delay (Delayed Phase). The Receiver Operating Characteristics (ROC) analysis showed that our self-developed Gait Style Change indicator, that is, the difference in the probability of feet landing between particular SN task phases, classified the participants into either the elderly or the young group with the highest accuracy (0.91). The second most important indicator, the Task-Related (step counts in each SN task phase), achieved the accuracy discrimination of 0.83. The gait indicators, comprising single gait parameters measured while navigating, might be considered as accurately differentiating older from younger people.

Spatiotemporal complexity patterns of resting-state bioelectrical activity explain fluid intelligence: Sex matters.

Neural complexity is thought to be associated with efficient information processing but the exact nature of this relation remains unclear. Here, the relationship of fluid intelligence (gf) with the resting-state EEG (rsEEG) complexity over different timescales and different electrodes was investigated. A 6-min rsEEG blocks of eyes open were analyzed. The results of 119 subjects (57 men, mean age = 22.85 ± 2.84 years) were examined using multivariate multiscale sample entropy (mMSE) that quantifies changes in information richness of rsEEG in multiple data channels at fine and coarse timescales. gf factor was extracted from six intelligence tests. Partial least square regression analysis revealed that mainly predictors of the rsEEG complexity at coarse timescales in the frontoparietal network (FPN) and the temporo-parietal complexities at fine timescales were relevant to higher gf. Sex differently affected the relationship between fluid intelligence and EEG complexity at rest. In men, gf was mainly positively related to the complexity at coarse timescales in the FPN. Furthermore, at fine and coarse timescales positive relations in the parietal region were revealed. In women, positive relations with gf were mostly observed for the overall and the coarse complexity in the FPN, whereas negative associations with gf were found for the complexity at fine timescales in the parietal and centro-temporal region. These outcomes indicate that two separate time pathways (corresponding to fine and coarse timescales) used to characterize rsEEG complexity (expressed by mMSE features) are beneficial for effective information processing.

Electrophysiological correlates of focused attention on low- and high-distressed tinnitus.

OBJECTIVES: The study aimed at determining the EEG correlates of concentration on either low or high-distressed tinnitus. METHODS: Sixty-seven patients (36 women, mean age = 50.34 ± 12.94 years) with chronic tinnitus were assigned to either a high (HD) or low (LD) tinnitus-related distress group based on THI results. All participants took part in the EEG study comprising two 3-4 min blocks of focusing on either tinnitus (Tinnitus Focus Condition, TFC) or the sensations from one's own body (Body Focus Condition, BFC). The absolute power and current density of 8 frequency bands in 7 clusters were compared between conditions and groups. RESULTS: The most pronounced differences were found in the HD patients in the TFC, relative to the BFC, i.e. reduced power of frontally distributed low alpha (8-10 Hz) and posterior high alpha (10-12 Hz) as well as lower current density of 8-10 Hz rhythm over the right frontal/anterior cingulate cortex and higher middle beta (15-18 Hz) density in the precuneus. The HD, relative to LD patients, in both conditions, exhibited increased low beta (12-15 Hz) power over the left middle area and greater higher beta (15-25 Hz) power in the left posterior region. CONCLUSIONS: The present study contrasted bioelectrical activity, acquired when concentrating on tinnitus with EEG data collected whilst patients focused on their body. Decreased alpha power and current density in the frontal/cingulate cortex when listening to bothersome tinnitus might reflect greater cortical arousal whereas increased beta power and density in the precuneus/posterior cingulate activity in this condition could be indicative for elevated tension or augmented cognitive/emotional processing of tinnitus sound. Enhanced beta rhythm in patients with high versus low tinnitus distress, observed independently of the study condition, may be due to greater self-focused attention or more active processing of sensations derived from the own body.

Altered functional brain imaging in migraine patients: BOLD preliminary study in migraine with and without aura.

DESIGN: Migraine is regarded as a complex brain dysfunction of sensory and modulatory networks with the secondary sensitisation of the trigeminal system as well as the affected brain area's activities. The particular role of the hippocampus and the brainstem in the first phase of the attack, the disrupted cognitive network, and the activation of the limbic and visual systems, are the main discoveries in the field of migraine imaging that have been achieved using functional techniques. Thus advanced neuroimaging has been widely employed to study the pathogenesis of migraine. OBJECTIVE: The evaluation of fMRI BOLD images of migraine patients with or without aura, with particular attention to the interictal phase. SUBJECTS AND METHODS: The aim of this study was to compare brain activity during visual stimuli by fMRI BOLD in the interictal phase (black and white checkerboard tests, static or flickering) of 16 migraine patients, eight with aura and eight without. RESULTS: We demonstrated differences in the right part of the brainstem, the left part of the cerebellum, and in the right middle temporal gyrus. However, the bilateral brain activation in the occipital and frontal lobe remained similar. CONCLUSIONS: Results of our preliminary study suggest that migraine with aura and migraine without aura might be separate disorders, and this requires further investigation.

Early general development and central auditory system maturation in children with cochlear implants - A case series.

OBJECTIVES: A cochlear implant (CI) has the potential to improve the functioning of a deaf child in many aspects. Nevertheless, the dynamics of the general development, beyond the typically measured language abilities, directly after CI, is still unknown, especially if a child is implanted early. In this study we present a methodological framework for assessment of different domains of development, as well as the central auditory nervous system (CANS) maturation in infants and toddlers with a CI. METHODS: Three children with bilateral congenital hearing loss and a unilateral CI, aged below 2.5 years, participated in a longitudinal study. Children were tested at three time points after cochlear implantation using the Polish Children Development Scale (CDS) consisting of a comprehensive battery of tests, as well as recordings of Cortical Auditory Evoked Potentials (CAEP). RESULTS: All three children revealed gradual improvement in the overall CDS result as well as most of the CDS subscales. After 9 months of CI experience two younger children showed age-appropriate performance. In CAEP measurements a decrease of latency of the P1 component (an established biomarker of cortical auditory maturation) was observed in the same two children, with one achieving normal ranges of P1 latency after 9 months of CI use. CONCLUSIONS: Our novel methodological framework can be successfully applied in small children with cochlear implants. It contributes to better understanding of the general development in early implanted children. The preliminary results indicate variability in children's performance in various developmental domains and thus the need to monitor the development of each child individually and holistically.

The relationship between alpha burst activity and the default mode network.

Alpha rhythm, described by Hans Berger, is mainly recorded from the occipital cortex (OCC) of relaxed subjects with their eyes closed.Early studies indicated the thalamo­cortical circuit as the origin of alpha rhythm. Recent works suggest an additional relationship between alpha rhythm and the Default Mode Network (DMN). We simultaneously recorded electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) signals in 36 young males asked to alternately close and open their eyes in 30­s blocks. Using an EEG source channel montage (the recorded signal was interpolated to designated source positions corresponding to certain brain regions) we found an alpha rhythm sub­activity composed of its intrinsic events, called alpha bursting segments (ABS). More ABS were observed on source channels related to the DMN than those located over the OCC. Similarly, both the beamformer source analysis and fMRI indicated that the specific ABS activity detected on the posterior cingulate cortex/precuneus (PCC) source channel was less related to the OCC than to the DMN source channels. The fMRI analysis performed using the PCC­ABS as a general linear model regressor indicated an increased blood oxygenation level­dependent signal change in DMN nodes - precuneus and prefrontal cortex. These results confirm the OCC source of alpha activity a nd additional specific sources of ABS in the DMN.

Abnormal Resting-State Quantitative Electroencephalogram in Children With Central Auditory Processing Disorder: A Pilot Study.

In this study, we showed an abnormal resting-state quantitative electroencephalogram (QEEG) pattern in children with central auditory processing disorder (CAPD). Twenty-seven children (16 male, 11 female; mean age = 10.7 years) with CAPD and no symptoms of other developmental disorders, as well as 23 age- and sex-matched, typically developing children (TDC, 11 male, 13 female; mean age = 11.8 years) underwent examination of central auditory processes (CAPs) and QEEG evaluation consisting of two randomly presented blocks of "Eyes Open" (EO) or "Eyes Closed" (EC) recordings. Significant correlations between individual frequency band powers and CAP tests performance were found. The QEEG studies revealed that in CAPD relative to TDC there was no effect of decreased delta absolute power (1.5-4 Hz) in EO compared to the EC condition. Furthermore, children with CAPD showed increased theta power (4-8 Hz) in the frontal area, a tendency toward elevated theta power in EO block, and reduced low-frequency beta power (12-15 Hz) in the bilateral occipital and the left temporo-occipital regions for both EO and EC conditions. Decreased middle-frequency beta power (15-18 Hz) in children with CAPD was observed only in the EC block. The findings of the present study suggest that QEEG could be an adequate tool to discriminate children with CAPD from normally developing children. Correlation analysis shows relationship between the individual EEG resting frequency bands and the CAPs. Increased power of slow waves and decreased power of fast rhythms could indicate abnormal functioning (hypoarousal of the cortex and/or an immaturity) of brain areas not specialized in auditory information processing.

Tonotopic organisation of the auditory cortex in sloping sensorineural hearing loss.

Although the tonotopic organisation of the human primary auditory cortex (PAC) has already been studied, the question how its responses are affected in sensorineural hearing loss remains open. Twenty six patients (aged 38.1 ± 9.1 years; 12 men) with symmetrical sloping sensorineural hearing loss (SNHL) and 32 age- and gender-matched controls (NH) participated in an fMRI study using a sparse protocol. The stimuli were binaural 8s complex tones with central frequencies of 400 HzCF, 800 HzCF, 1600 HzCF, 3200 HzCF, or 6400 HzCF, presented at 80 dB(C). In NH responses to all frequency ranges were found in bilateral auditory cortices. The outcomes of a winnermap approach, showing a relative arrangement of active frequency-specific areas, was in line with the existing literature and revealed a V-shape high-frequency gradient surrounding areas that responded to low frequencies in the auditory cortex. In SNHL frequency-specific auditory cortex responses were observed only for sounds from 400 HzCF to 1600 HzCF, due to the severe or profound hearing loss in higher frequency ranges. Using a stringent statistical threshold (p < 0.05; FWE) significant differences between NH and SNHL were only revealed for mid and high-frequency sounds. At a more lenient statistical threshold (p < 0.001, FDRc), however, the size of activation induced by 400 HzCF in PAC was found statistically larger in patients with a prelingual, as compared to a postlingual onset of hearing loss. In addition, this low-frequency range was more extensively represented in the auditory cortex when outcomes obtained in all patients were contrasted with those revealed in normal hearing individuals (although statistically significant only for the secondary auditory cortex). The outcomes of the study suggest preserved patterns of large-scale tonotopic organisation in SNHL which can be further refined following auditory experience, especially when the hearing loss occurs prelingually. SNHL can induce both enlargement and reduction of the extent of responses in the topically organized auditory cortex.

Transition of the functional brain network related to increasing cognitive demands.

Network neuroscience provides tools that can easily be used to verify main assumptions of the global workspace theory (GWT), such as the existence of highly segregated information processing during effortless tasks performance, engagement of multiple distributed networks during effortful tasks and the critical role of long-range connections in workspace formation. A number of studies support the assumptions of GWT by showing the reorganization of the whole-brain functional network during cognitive task performance; however, the involvement of specific large scale networks in the formation of workspace is still not well-understood. The aims of our study were: (1) to examine changes in the whole-brain functional network under increased cognitive demands of working memory during an n-back task, and their relationship with behavioral outcomes; and (2) to provide a comprehensive description of local changes that may be involved in the formation of the global workspace, using hub detection and network-based statistic. Our results show that network modularity decreased with increasing cognitive demands, and this change allowed us to predict behavioral performance. The number of connector hubs increased, whereas the number of provincial hubs decreased when the task became more demanding. We also found that the default mode network (DMN) increased its connectivity to other networks while decreasing connectivity between its own regions. These results, apart from replicating previous findings, provide a valuable insight into the mechanisms of the formation of the global workspace, highlighting the role of the DMN in the processes of network integration. Hum Brain Mapp 38:3659-3674, 2017. © 2017 Wiley Periodicals, Inc.

Influence of Acoustic Overstimulation on the Central Auditory System: An Functional Magnetic Resonance Imaging (fMRI) Study.

BACKGROUND The goal of the fMRI experiment was to explore the involvement of central auditory structures in pathomechanisms of a behaviorally manifested auditory temporary threshold shift in humans. MATERIAL AND METHODS The material included 18 healthy volunteers with normal hearing. Subjects in the exposure group were presented with 15 min of binaural acoustic overstimulation of narrowband noise (3 kHz central frequency) at 95 dB(A). The control group was not exposed to noise but instead relaxed in silence. Auditory fMRI was performed in 1 session before and 3 sessions after acoustic overstimulation and involved 3.5-4.5 kHz sweeps. RESULTS The outcomes of the study indicate a possible effect of acoustic overstimulation on central processing, with decreased brain responses to auditory stimulation up to 20 min after exposure to noise. The effect can be seen already in the primary auditory cortex. Decreased BOLD signal change can be due to increased excitation thresholds and/or increased spontaneous activity of auditory neurons throughout the auditory system. CONCLUSIONS The trial shows that fMRI can be a valuable tool in acoustic overstimulation studies but has to be used with caution and considered complimentary to audiological measures. Further methodological improvements are needed to distinguish the effects of TTS and neuronal habituation to repetitive stimulation.

Slow Cortical Potential Neurofeedback in Chronic Tinnitus Therapy: A Case Report.

This study is the first to demonstrate outcomes of slow cortical potential (SCP) Neurofeedback training in chronic tinnitus. A 50-year old male patient with tinnitus participated in three SCP training blocks, separated with 1-month breaks. After the training the patient reported decreased tinnitus loudness and pitch, as well as improved quality of daily life. A quantitative electroencephalography analysis revealed close to normal changes of resting state bioelectrical activity in cortical areas considered to be involved in tinnitus generation. The present case study indicates that SCP Neurofeedback training can be considered a promising method for tinnitus treatment.

Health-related quality of life and mental distress in patients with partial deafness: preliminary findings.

The aim of the study was to evaluate mental distress and health-related quality of life in patients with bilateral partial deafness (high-frequency sensorineural hearing loss) before cochlear implantation, with respect to their audiological performance and time of onset of the hearing impairment. Thirty-one patients and 31 normal-hearing individuals were administered the Beck Depression Inventory (BDI), the State-Trait-Anxiety-Inventory (STAI) and the World Health Organization Quality of Life-BREF questionnaire (WHOQOL-BREF). Patients also completed the Nijmegen-Cochlear-Implant-Questionnaire (NCIQ), a tool for evaluation of quality of life related to hearing loss. Patients revealed increased depressive and anxiety symptoms, as well as decreased health-related quality of life (psychological health, physical health), in comparison with their healthy counterparts (t tests, p < 0.05). Furthermore, a General Linear Model demonstrated in patients with a prelingual onset of hearing loss enhanced self-evaluated social interactions and activity (NCIQ), when their outcomes were contrasted with those obtained in individuals with postlingual partial deafness (p < 0.05). The study failed to show any effect of collateral tinnitus. Patients not using hearing aids had better audiological performance and, therefore, better sound perception and speech production, as measured with NCIQ. There was no effect of hearing aid use with respect to mental distress. Additional statistically significant correlations seen in patients included those between a steeper slope hearing loss configuration (averaged pure-tone thresholds at 1 and 2 kHz with subtracted threshold at 0.5 kHz) and better audiometric speech detection, between audiometric thresholds and the subjectively rated sound perception (NCIQ), as well as left-ear audiometric word recognition scores and the subjectively perceived ability to recognize advanced sounds (NCIQ). In addition, a longer duration of postlingual deafness, as well as a younger age at the onset were both related to worse speech detection thresholds. The results of the study provide evidence that successful rehabilitation in patients with partial deafness might have to go beyond the standard speech therapy. Enhancement of the regular diagnostic assessment with additional psychological tools is highly recommended. Further investigation is required as to the role of functional residual hearing, hearing aid use and tinnitus, in relation to future outcomes of cochlear implantation.

[The possibilities and limitations of simultaneous EEG-fMRI registration--the alpha rhythm study]. / Mozliwosci i problemy jednoczesnych rejestracji EEG-fMRI--badanie rytmu alfa.

INTRODUCTION: Simultaneous EEG-fMRI registration is rapidly evolving and has received substantial attention. This technique provides precise information in both spatial and temporal domain. The biological basis of the EEG and fMRI signal is different which, on the one hand makes results interpretation more difficult but, on the other hand, gives more convincing arguments on the neural correlates of sensory and cognitive processes. In this paper we present an example of implementation of simultaneous EEG-fMRI registration for alpha rhythm source mapping. MATERIAL AND METHODS: 60 young males took part in this study. For the group analysis we selected 33 individuals to obtain homogenous group. Siemens Magnetom Trio 3T and 64-electrode SynAmp2 Neuroscan EEG system was applied. Participants took part in fMRI imaging which adapted arrest reaction study. RESULTS: Averaged spectra amplitude distribution of alpha rhythm (8-13Hz) showed high activation in the occipito-parietal region and smaller but noticeable activity in the frontal area. FMRI results revealed activity in bilateral occipital lobe. Additional regions included the posterior cingulate gyrus, middle and superior frontal gyrus. Statistically significant areas with BOLD signal decrease were located in the temporal lobe and anterior cingulate gyrus. CONCLUSION: The obtained results indicate overlapping regions of the presented EEG outcomes and fMRI maps for alpha rhythm study. Simultaneous EEG-fMRI technique allows for registration of spontaneous EEG activity with both high temporal and spatial resolution. The alpha rhythm might reflect the extensive brain process involving the thalamo-occipito-frontal connections.

Attention dysfunction subtypes of developmental dyslexia.

BACKGROUND: Previous studies indicate that many different aspects of attention are impaired in children diagnosed with developmental dyslexia (DD). The objective of the present study was to identify cognitive profiles of DD on the basis of attentional test performance. MATERIAL/METHODS: 78 children with DD (30 girls, 48 boys, mean age of 12 years ±8 months) and 32 age- and sex-matched non-dyslexic children (14 girls, 18 boys) were examined using a battery of standardized tests of reading, phonological and attentional processes (alertness, covert shift of attention, divided attention, inhibition, flexibility, vigilance, and visual search). Cluster analysis was used to identify subtypes of DD. RESULTS: Dyslexic children showed deficits in alertness, covert shift of attention, divided attention, flexibility, and visual search. Three different subtypes of DD were identified, each characterized by poorer performance on the reading, phonological awareness, and visual search tasks. Additionally, children in cluster no. 1 displayed deficits in flexibility and divided attention. In contrast to non-dyslexic children, cluster no. 2 performed poorer in tasks involving alertness, covert shift of attention, divided attention, and vigilance. Cluster no. 3 showed impaired covert shift of attention. CONCLUSIONS: These results indicate different patterns of attentional impairments in dyslexic children. Remediation programs should address the individual child's deficit profile.

Reduced resting-state brain activity in the default mode network in children with (central) auditory processing disorders.

BACKGROUND: In recent years, there has been a growing interest in Central Auditory Processing Disorder (C)APD. However, the neural correlates of (C)APD are poorly understood. Previous neuroimaging experiments have shown changes in the intrinsic activity of the brain in various cognitive deficits and brain disorders. The present study investigated the spontaneous brain activity in (C)APD subjects with resting-state fMRI (rs-fMRI). METHODS: Thirteen children diagnosed with (C)APD and fifteen age and gender-matched controls participated in a rs-fMRI study during which they were asked to relax keeping their eyes open. Two different techniques of the rs-fMRI data analysis were used: Regional Homogeneity (ReHo) and Independent Component Analysis (ICA), which approach is rare. RESULTS: Both methods of data analysis showed comparable results in the pattern of DMN activity within groups. Additionally, ReHo analysis revealed increased co-activation of the superior frontal gyrus, the posterior cingulate cortex/the precuneus in controls, compared to the (C)APD group. ICA yielded inconsistent results across groups. CONCLUSIONS: Our ReHo results suggest that (C)APD children seem to present reduced regional homogeneity in brain regions considered a part of the default mode network (DMN). These findings might contribute to a better understanding of neural mechanisms of (C)APD.