fMRI Examination Research Articles

Functional connectivity pattern during motor imagery and execution of paretic hand movements of stroke patients

Motor imagery (MI) has emerged as a promising technique for promoting neuroplasticity and recovery of motor function after a stroke. It is used as an alternative to movement execution (ME). The brain structures involved in MI are largely documented but the existent functional connectivity (FC) during MI and the differences with ME in stroke patients remain underinvestigated. Functional magnetic resonance imaging (fMRI) techniques have the potential to reveal these changes. We aimed to investigate the FC during MI and ME and correlate FC measures between sensorimotor (SMN) regions with motor function of stroke patients. Twenty-four stroke patients with hemiparesis (time post-stroke = 10 ± 21 months; Upper-limb Fugl-Meyer Score (FMS) = 27.2 ± 13.5/66) were included. The patients underwent fMRI examination while they either imagined or executed wrist extension with their affected hand (AH). We studied FC using seed-to-voxels analysis. We compared the FC of SMN regions between MI and ME of AH movement. Additionally, correlations among brain FC measures and behavioral scores of motor function (FMS) were computed. During MI of the AH in comparison with ME, FC of the ipsilesional SMN (BA 40) was decreased with the ipsilesional somatosensory cortex (BA 2, 40, 5) and the cerebellum. In parallel, it was increased with the bilateral frontal cortex (BA 8, 10) ( Fig. 1 ). Besides this, correlation analyses with the FMS revealed that during MI, more impaired patients relied more on functional connections between contralasional BA4 and cerebellum (crus 1 and 2) than less impaired patients did. The connectivity changes observed may reveal compensatory networks for MI implicating more the frontal lobe and the contralesional hemisphere in most impaired patients. These results characterized the connectivity patterns of ME and MI and may provide new insights into the neural mechanism underlying them.

Review on biomarkers in the resting-state networks of chronic pain patients

Biomarkers indicating characteristic alterations in the brains of pain patients would in comparison to behavioral examinations allow for earlier diagnoses of pain disease development, a more immediate monitoring of pain disease progression, and for the development of interventions to reverse or compensate for the alterations. To reveal causal relations between an observed alteration and the pain disease longitudinal examinations are essential. Resting-state fMRI examinations can readily be included in large longitudinal cohorts allowing to achieve sufficiently large patient samples even for rare diseases.Our literature review on longitudinal resting-state fMRI examinations of pain patients indicates that pain chronicity is predicted by alterations to the brain's reward system and default mode network. A brain wide reorganization of the resting-state networks is associated with the emergence of the chronic pain state. The functional connectivity of the left frontoparietal network predicts the evolution of pain intensity in the chronic state. Further investigations are necessary concerning the generalization of the biomarkers across the phases in pain development especially for the healthy state, across different pain etiologies, and their specificity to chronic pain. The currently acquired representative longitudinal cohorts will allow for clarification of those issues within the next decades.

Specific Changes in Brain Activity during Urgency in Women with Overactive Bladder after Successful Sacral Neuromodulation: A Functional Magnetic Resonance Imaging Study

The mechanism of sacral neuromodulation is poorly understood. We compared brain activity during urgency before and after sacral neuromodulation in women with overactive bladder and according to the response to treatment. Women with refractory overactive bladder who elected sacral neuromodulation were invited to undergo functional magnetic resonance imaging before and after treatment. During imaging the bladder was filled until urgency was experienced. Regions of interest were identified a priori and brain activity in these regions of interest was compared before and after treatment as well as according to the treatment response. Whole brain exploratory analysis with an uncorrected voxel level threshold of p <0.001 was also performed to identify additional brain regions which changed after sacral neuromodulation. Of the 12 women who underwent a pretreatment functional magnetic resonance imaging examination 7 were successfully treated with sacral neuromodulation and underwent a posttreatment examination. After sacral neuromodulation brain activity decreased in the left anterior cingulate cortex, the bilateral insula, the left dorsolateral prefrontal cortex and the bilateral orbitofrontal cortex (each p <0.05). No new brain regions showed increased activity after sacral neuromodulation. Pretreatment brain activity levels in the bilateral anterior cingulate cortex, the right insula, the bilateral dorsolateral prefrontal cortex, the right orbitofrontal cortex, the right supplementary motor area and the right sensorimotor cortex were higher in women who underwent successful treatment (each p <0.05). Brain activity during urgency changes after successful sacral neuromodulation. Sacral neuromodulation may be more effective in women with higher levels of pretreatment brain activity during urgency.

Longitudinal brain activation changes related to electrophysiological findings in patients with cervical spondylotic myelopathy before and after spinal cord decompression: an fMRI study.

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction, potentially leading to severe disability. Abnormal cervical spine magnetic resonance imaging (MRI) and motor evoked potentials (MEPs) are independent predictors of disease progression. Abnormal MRI is accompanied by various activation changes in functional brain MRI (fMRI), whereas preoperative and postoperative fMRI adaptations associated with abnormal preoperative MEP remain unknown. Twenty patients (9 males, average age 56.6) with evidence of spinal cord compression on MRI and clinical signs of mild CSM were included. Participants were classified according to their preoperative MEP and underwent three brain fMRI examinations: before surgery, 6, and 12months after surgery while performing repeated extension-flexion of each wrist. Functional MRI activation was compared between two subsets of patients, with normal and clearly abnormal MEP (right wrist: 8 vs. 8; left wrist: 7 vs. 9). At baseline, abnormal MEPs were associated with hyperactivation in the cerebellum. At the first follow-up, further hyperactivations emerged in the contralateral sensorimotor cortices and persisted for 1year. In normal baseline MEP, activation mostly decreased in the ipsilateral sensorimotor cortex postoperatively. The ipsilateral sensorimotor activation after 1-year follow-up correlated with baseline MEP. Abnormal corticospinal MEP findings in cervical spondylotic myelopathy were associated with differences in brain activation, which further increased after spinal cord decompression and did not resolve within 12-month follow-up. In summary, surgery may come too late for those patients with abnormal MEP to recover completely despite their mild clinical signs and symptoms.

Improvement of Speech Function in Patients with Aphasia: The Right Hemisphere, an Enemy or a Friend?

The purpose of our research is to investigate interhemispheric language functional reorganization in patients with gliomas of the left hemisphere using functional magnetic resonance tomography (fMRI) in comparison with the dynamics of speech disorders. A total of 20 patients with a glioma in the left hemisphere underwent fMRI examination and Luria’s neuropsychological testing. The age of patients varied from 26 to 67 years; the mean age was 40 years (median, interquartile range; 13 women and 7 men). The glioma was located in the frontal lobe (12 patients) 34.50–49.75 years; or in the temporal lobe (8 patients). All patients underwent both fMRI scanning and neuropsychological testing on the same day before the surgery and then 3–10 days and 3, 5–7, 12 months after tumor surgery. The handedness was determined by using self-assessment and the Annett Hand Preference Questionnaire. Almost all the subjects were right-handed, and one was ambidexter. On the basis of the analysis of fMRI data in dynamics, all subjects were divided into two groups: (1) patients with no signs of activation of the right hemisphere homologues of Broca’s and Wernicke’s areas (even in 4 patients with severe aphasia) during the follow-up period (at least one year), and (2) patients with signs of activation in the right-sided Broca’s and Wernicke’s areas, which were found in at least several tests (16 patients; 3 of them had normal speech function during the whole follow-up period). We conclude that the lack of consistency between the presence/absence of aphasia and the activation of homologous speech areas in the right hemisphere in fMRI results from individual differences in the involvement of the right hemisphere in speech processes. Thus, we should be very cautious about the hypothesis of reciprocal relationships of the hemispheres in speech function and the use of this hypothesis in speech rehabilitation.

A behavioral and fMRI examination of the effect of rhythm on reading noun-verb homographs aloud

ABSTRACTThese experiments explored the connection between rhythm and reading by examining whether reading is affected by a rhythmic prime that was either congruent or incongruent with the syllabic stress of the target letterstring. Previous research has shown congruency effects but only in a between-item design, which leaves open the possibility of extraneous variables contributing to the effects. The present design used noun-verb homographs (conflict vs. conflict), and their corresponding pseudohomophones (konflikt vs. konflikt). The results demonstrated significant congruency effects, whereby RTs were faster when the prime was congruent with the syllabic stress. The fMRI experiment identified several brain regions that underlie the rhythm-priming effect, and particularly the putamen’s involvement given recent research suggesting its role in phonetic decoding. These experiments provide the strongest within-item/within-participant evidence to date that a rhythm prime has an effect on lexical and sublexical reading, and inform our understanding of how rhythm and reading interact.

Comparative study of interhemispheric functional connectivity in left eye monocular blindness versus right eye monocular blindness: a resting-state functional MRI study.

ObjectiveIn the present study, we investigated the brain interhemispheric functional connectivity changes in left eye MB versus right eye MB patients by voxel-mirrored homotopic connectivity (VMHC) methods.MethodsA total of 31 patients with MB (15 with left eye MB and 16 with right eye MB), and 31 healthy controls (HCs) closely matched for age were recruited. All subjects underwent functional magnetic resonance imaging (fMRI) examinations. The VMHC method was used to evaluate directly functional interactions between the hemispheres. A one-way ANOVA was performed to determine the regions in which the VMHC differs between the three groups. Patients with MB were distinguished from HCs by a receiver operating characteristic (ROC) curve. The relationships between the mean VMHC signal values in many brain regions and clinical features in MB patients were calculated by pearson correlation analysis.ResultsCompared with HCs, MB patients had significantly decreased VMHC values in the cuneus/calcarine/lingual gyrus. Furthermore, left eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus and showed increased VMHC values in the insula and middle frontal gyrus compared with HC. In addition, right eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus, primary motor cortex (M1)/primary somatosensory cortex (S1) and superior parietal lobule.ConclusionMB subjects showed abnormal brain interhemispheric functional connectivity in visual pathways. Furthermore, different patterns of brain interhemispheric functional connectivity occurred in the left eye and right eye MB. These VMHC values provide much useful information to explain the neural mechanism changes in MB.

Reducing task-based fMRI scanning time using simultaneous multislice echo planar imaging.

To maintain alertness and to remain motionless during scanning represent a substantial challenge for patients/subjects involved in both clinical and research functional magnetic resonance imaging (fMRI) examinations. Therefore, availability and application of new data acquisition protocols allowing the shortening of scan time without compromising the data quality and statistical power are of major importance. Higher order category-selective visual cortical areas were identified individually, and rapid event-related fMRI design was used to compare three different sampling rates (TR = 2000, 1000, and 410ms, using state-of-the-art simultaneous multislice imaging) and four different scanning lengths to match the statistical power of the traditional scanning methods to high sampling-rate design. The results revealed that ~ 4min of the scan time with 1Hz (TR = 1000ms) sampling rate and ~ 2min scanning at ~ 2.5Hz (TR = 410ms) sampling rate provide similar localization sensitivity and selectivity to that obtained with 11-min session at conventional, 0.5Hz (TR = 2000ms) sampling rate. Our findings suggest that task-based fMRI examination of clinical population prone to distress such as presurgical mapping experiments might substantially benefit from the reduced (20-40%) scanning time that can be achieved by the application of simultaneous multislice sequences.

Pharmaco-fMRI in Patients With Traumatic Brain Injury: A Randomized Controlled Trial With the Monoaminergic Stabilizer (–)-OSU6162

To examine the effects of monoaminergic stabilizer (-)-OSU6162 on brain activity, as measured by blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI), in patients in the chronic phase of traumatic brain injury suffering from fatigue. Neurorehabilitation clinic. Patients with traumatic brain injury received either placebo (n = 24) or active treatment (n = 28). Healthy controls (n = 27) went through fMRI examination at one point and were used in sensitivity analysis on normalization of BOLD response. Randomized, double-blinded, placebo-controlled design. Effects on BOLD signal changes from before to after treatment during performance of a fatiguing attention task. The fMRI results revealed treatment effects within the right occipitotemporal cortex and the right orbitofrontal cortex. In these regions, the BOLD response was normalized relative to healthy controls at the postintervention fMRI session. No effects were seen in regions in which we previously observed activity differences between patients and healthy controls while performing this fMRI task, such as the striatum. (-)-OSU6162 treatment had influences on functional brain activity, although the normalized regional BOLD response was observed in regions that were not a priori hypothesized to be sensitive to this particular treatment, and was not accompanied by any effects on in-scanner test performance or on fatigue.

Radiological and clinical findings following distraction osteogenesis of the lower limb in children with or without botox injection: A preliminary report

Context: Limb lengthening correction according to Ilizarov distraction osteogenesis (DO) usually yields excellent results. While pediatric orthopedic surgeons anecdotally report that botulinum toxin A (Botox) alleviates spasm and pain during DO, no study has examined the effects of this surgery and Botox injection on muscle morphology in children. Aims: (1) To evaluate the clinical and radiological effects of lower limb lengthening in children and (2) the effects of adjunctive Botox muscle injection. Setting and Design: This was a center and randomized control trial. Methods: Seven children underwent tibial (n = 3) or femoral lengthening (n = 4) and were randomized to receive either a Botox or sterile saline solution. Quality of life and functional mobility outcomes, muscle testing, and magnetic resonance imaging examination were obtained at baseline, 12-, and 24-month postoperative. Muscle measurements were acquired on axial T1-weighted images and included: (1) total cross-sectional area (TCSA), (2) functional cross-sectional area (FCSA, fat-free area), (3) ratio of FCSA to TCSA, and (4) asymmetry between sides. Results: Physical performance improved at 12- and 24-month postoperative. Muscle strength remained functional across the three time points. A decrease in TCSA and FCSA was observed at 12-month follow-up in the operated thigh of patients undergoing femur lengthening, but muscle mass was regained at 24 months. However, TCSA and FCSA remained lower in the operated femur at 24 months. Similar findings were also observed in patients who underwent tibial lengthening. Patients in the Botox group appeared to have a slightly greater decrease in muscle mass and increase in fatty infiltration in the operated leg. Conclusions: Children undergoing DO preserved their muscle strength and improved physical performance 2-year postoperative. Our results suggest that muscle size and muscle mass remained lower in the operated leg; a finding that was slightly more prominent in children who received a Botox injection.

Imaging of Convergence Insufficiency Treatment Effects (ICITE) Pilot Study: Design and Methods

Background: The blood-oxygen-level-dependent (BOLD) signal from functional magnetic resonance imaging (fMRI) identifies brain activation during specific tasks.1,2 This paper describes the design and methodology of the Imaging of Convergence Insufficiency Treatment Effects (ICITE) Study, a two-phase study comparing BOLD activations during vergence eye movements in symptomatic convergence insufficiency (CI) subjects (1) to those with normal binocular vision (NBV) and (2) after office-based vergence/accommodative therapy (OBVAT) versus office-based placebo therapy (OBPT). Methods: Young adults, 18 to 30 years, with NBV or symptomatic CI (near exophoria at least 4Δ [prism diopters] greater than at distance, receded near point of convergence [NPC], and insufficient positive fusional vergence [PFV]) were enrolled. During fMRI scanning, subjects were instructed to fuse a random-dot stereogram stimulus with vergence demands ranging from -3Δ to +25Δ. CI subjects were then randomized to 12 weeks of OBVAT or OBPT. Vision and fMRI examination at outcome were performed by a masked examiner. BOLD signal at baseline was compared between NBV and CI patients. Later, the BOLD response at baseline was compared to that following vision therapy for those with CI. Conclusion: The imaging results are expected to advance understanding of neurological mechanisms of CI and the effects of therapy on the vergence system, which in turn may guide development of future research that could lead to new treatment strategies.

Brain activity in the right-frontal pole and lateral occipital cortex predicts successful postoperatory outcome after surgery for anterior glenoumeral instability

Shoulder apprehension is more complex than a pure mechanical problem of the shoulder, creating a scar at the brain level that prevents the performance of specific movements. Surgery corrects for shoulder instability at the physical level, but a re-dislocation within the first year is rather common. Predicting which patient will be likely to have re-dislocation is therefore crucial. We hypothesized that the assessment of neural activity at baseline and follow-up is the key factor to predict the postoperatory outcome. Thirteen patients with shoulder apprehension (30.03 ± 7.64 years) underwent clinical and fMRI examination before and one year after surgery for shoulder dislocation contrasting apprehension cue videos and control videos. Data analyses included task-related general linear model (GLM) and correlations imaging results with clinical scores. Clinical examination showed decreased pain and increased shoulder functions for postoperative vs. preoperative. Coherently, GLM results show decreased activation of the left pre-motor cortex for post-surgery vs. pre-surgery. Right-frontal pole and right-occipital cortex activity predicts good recovery of shoulder function measured by STT. Our findings demonstrate that beside physical changes, changes at the brain level also occur one year after surgery. In particular, decreased activity in pre-motor and orbito-frontal cortex is key factor for a successful postoperatory outcome.

The positive effects of Xueshuan Xinmai tablets on brain functional connectivity in acute ischemic stroke: a placebo controlled randomized trial

Through a placebo controlled randomized study, the purpose of this report was to investigate the effects of Xueshuan Xinmai tablets (XXMT) on neurologic deficits, quality of life and brain functional connectivity in acute ischemic stroke patients and to explore the mechanism of action of XXMT. In total, 44 acute ischemic stroke patients were randomly divided to the XXMT treatment group (n = 22) or the placebo group (n = 22) in a 2-week trial. Before and after the treatment, the neurological assessment and functional magnetic resonance imaging examinations were carried out. Compared to the placebo group, the scores of the National Institutes of Health Stroke Scale (NIHSS) and Stroke-Specific Quality of Life Scale (SSQOL) significantly improved in the treatment group. In addition, XXMT-treated patients demonstrated significantly enhanced functional connectivity within the default mode, frontal-parietal, and motor control networks. Furthermore, the changed connectivity in the left precuneus was positively correlated to the improvement of NIHSS and SSQOL scores. The present study indicated that XXMT treatment significantly improved the neurologic deficit and quality of life of acute ischemic stroke patients and that the therapeutic effect may be based on the modulation of XXMT on the functional connectivity of brain networks.

Alterations in resting-state functional connectivity of the default mode network in amnestic mild cognitive impairment: an fMRI study

BackgroundAmnestic mild cognitive impairment (aMCI) is characterized by cognitive functional decline, especially in memory. Resting-state functional magnetic resonance imaging (fMRI) has been widely used in neuroimaging studies that explore alterations between patients and normal individuals to elucidate the pathological mechanisms of different diseases. The current study was performed to investigate alterations in the functional connectivity of the default mode network (DMN) in aMCI patients compared to healthy elderly controls, as well as further define the association between neurological alterations and memory function.MethodsTwenty-five aMCI patients and 25 healthy individuals were recruited and underwent both fMRI and neuropsychological examinations. fMRI data was analyzed by independent component analysis.ResultsCompared to healthy individuals, aMCI patients exhibited a significant increase in functional connectivity between the DMN and right-middle and right-superior frontal gyri, left-middle occipital gyrus, and left-middle temporal gyrus, but reduced functional connectivity between the DMN and left-middle and left-inferior frontal gyri and left insula. These alterations were found to be associated with reduced memory function.ConclusionsaMCI patients exhibited abnormal functional connectivity between the DMN and certain brain regions which is associated with changes in memory function associated with aMCI.

Value of Frequency Domain Resting-State Functional Magnetic Resonance Imaging Metrics Amplitude of Low-Frequency Fluctuation and Fractional Amplitude of Low-Frequency Fluctuation in the Assessment of Brain Tumor-Induced Neurovascular Uncoupling.

The aim of this study was to explore whether the phenomenon of brain tumor-related neurovascular uncoupling (NVU) in resting-state blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) (rsfMRI) may also affect the resting-state fMRI (rsfMRI) frequency domain metrics the amplitude of low-frequency fluctuation (ALFF) and fractional ALFF (fALFF). Twelve de novo brain tumor patients, who underwent clinical fMRI examinations, including task-based fMRI (tbfMRI) and rsfMRI, were included in this Institutional Review Board-approved study. Each patient displayed decreased/absent tbfMRI activation in the primary ipsilesional (IL) sensorimotor cortex in the absence of a corresponding motor deficit or suboptimal task performance, consistent with NVU. Z-score maps for the motor tasks were obtained from general linear model analysis (reflecting motor activation vs. rest). Seed-based correlation analysis (SCA) maps of sensorimotor network, ALFF, and fALFF were calculated from rsfMRI data. Precentral and postcentral gyri in contralesional (CL) and IL hemispheres were parcellated using an automated anatomical labeling template for each patient. Region of interest (ROI) analysis was performed on four maps: tbfMRI, SCA, ALFF, and fALFF. Voxel values in the CL and IL ROIs of each map were divided by the corresponding global mean of ALFF and fALFF in the cortical brain tissue. Group analysis revealed significantly decreased IL ALFF (p = 0.02) and fALFF (p = 0.03) metrics compared with CL ROIs, consistent with similar findings of significantly decreased IL BOLD signal for tbfMRI (p = 0.0005) and SCA maps (p = 0.0004). The frequency domain metrics ALFF and fALFF may be markers of lesion-induced NVU in rsfMRI similar to previously reported alterations in tbfMRI activation and SCA-derived resting-state functional connectivity maps.

Reorganization of language centers in patients with brain tumors located in eloquent speech areas – A pre- and postoperative preliminary fMRI study

IntroductionThe aim of this study was to determine in pre- and postsurgical fMRI studies the rearrangement of the Broca's and Wernicke's areas and the lateralization index for these areas in patients with brain tumors located near speech centers. Impact of the surgical treatment on the brain plasticity was evaluated. Materials and methodsPre- and postoperative fMRI examinations were performed in 10 patients with low grade glial, left-sided brain tumors located close to the Broca's (5 patients) or Wernicke's area (5 patients). BOLD signal was recorded in regions of interest: Broca's and Wernicke's areas, and their anatomic right-sided homologues. ResultsIn the preoperative fMRI study the left Broca's area was activated in all cases. The right Broca's area was activated in all the patients with no speech disorders. In the postoperative fMRI the activation of both Broca's areas increased in two cases. In other two cases activation of one of the Broca's area increased along with the decrease in the contralateral hemisphere.In all patients with temporal lobe tumors, the right Wernicke's area was activated in the pre- and postsurgical fMRI. After the operation, in two patients with speech disorder, the activation of both Broca's areas decreased and the activation of one of the Wernicke's areas increased. ConclusionsIn the cases of tumors localized near the left Broca's area, a transfer of the function to the healthy hemisphere seems to take place. Resection of tumors located near Broca's or Wernicke's areas may lead to relocation of the brain language centers.

ALTERED CEREBELLUM-LIMBIC NETWORK CONNECTIVITY IN MCI AND AD

To evaluate the pattern of cerebral limbic network of the AD spectrum through mapping the coupled cerebrocerebellar network. Eighteen MCI patients, sixteen AD patients, and twenty normal controls (NCs) participated in the study. Resting-state fMRI examination was performed with a 3T Siemens Trio system and preprocessed with the Connectome Computation System (https://github.com/zuoxinian/CCS). We employed the seed-based method to construct a cerebellar-cerebral limbic network by using a predefined seed cerebellar region of interests. Two-sample t-tests were performed to detect significant changes of the cerebellar limbic network connectivity between each pair of the three groups. Correlational analyses were conducted between the MMSE score and the mean limbic network connectivity across all vertices within each cluster exhibiting significant differences in functional connectivity with the cerebellar limbic network across the three groups. Comparison among the three groups showed that:1).increased functional connectivity in right mid-cingulate cortex(MCC), right lingual gyrus and decreased functional connectivity in left temporal pole to cerebellar limbic network were observed in NC compared to AD,2).increased functional connectivity in left paracentral lobule, right paracentral lobule extending to right MCC and decreased functional connectivity in left posterior part of orbital-fronto cortex(POFC) extending to anterior insular cortex(AIC), left inferior parietal lobule(IPL), right POFC-AIC, right fusiform gyrus to cerebellar limbic network were observed in NC compared to MCI,3).increased functional connectivity in left POFC-AIC, left IPL, right POFC-AIC to the cerebellar limbic network was observed in MCI compared to AD. Among these clusters, right MCC (NC vs. AD), right lingual gyrus(NC vs. AD), bilateral POFC-AIC (MCI vs. AD), left IPL(MCI vs. AD) showed a positive correlation with MMSE score in the level of p<0.05, and a negative correlation was observed between left temporal pole(NC vs. AD) and MMSE score in the level of P<0.01. AD patients showed more compromised functional connectivity to cerebellar limbic network than that in MCI patients. Different pattern of bilateral POFC-AIC and left IPL activity (increased in MCI vs. NC and decreased in MCI vs. AD) may be a key role in the modulation of limbic network in AD spectrum.

Disrupted small-world brain functional network topology in male patients with severe obstructive sleep apnea revealed by resting-state fMRI.

PurposeObstructive sleep apnea (OSA) is a common sleep-related breathing disorder that can damage cognitive function. However, the functional network organization remains poorly understood. The aim of this study was to investigate the topological properties of OSA patients using a graph theoretical analysis.Patients and methodsA total of 30 male patients with untreated severe OSA and 25 male education- and age-matched good sleepers (GSs) underwent functional magnetic resonance imaging (MRI) examinations. Clinical and cognitive evaluations were conducted by an experienced psychologist. GRETNA (a toolbox for topological analysis of imaging connectomics) was used to construct the brain functional network and calculate the small-world properties (γ, λ, σ, Eglob, and Eloc). Relationships between these small-world properties and clinical and neuropsychological assessments were investigated in OSA patients.ResultsThe networks of both OSA patients and GSs exhibited efficient small-world topology over the sparsity range of 0.05–0.40. Compared with GSs, the OSA group had significantly decreased γ, but significantly increased λ and σ. The OSA group’s brain network showed significantly decreased Eglob (P<0.05) over the sparsity range of 0.09–0.15, but significantly increased Eloc over the sparsity range of 0.23–0.40. In OSA patients, γ was significantly negatively correlated with apnea–hypopnea index (AHI; r=−0.326, P=0.015) and Epworth Sleepiness Scale (ESS; r=−0.274, P=0.043), λ was significantly positively correlated with AHI (r=0.373, P=0.005) and ESS (r=0.269, P=0.047), and σ was significantly negatively correlated with AHI (r=−0.363, P=0.007) and ESS (r=−0.295, P=0.029).ConclusionOur results suggest that the high degree of local integration and integrity of the brain connections in OSA patients may be disrupted. The topological alterations of small-world properties may be the mechanism of cognitive impairment in OSA patients. In addition, σ, γ, and λ could be used as a quantitative physiological index for auxiliary clinical diagnoses.

Functional Evaluation of Awareness in Vegetative and Minimally Conscious State

Objective:The aim of this study was to assess differences in brain activation in a large sample of Vegetative State (VS) and Minimally Conscious State (MCS) patients, using functional magnetic resonance imaging (fMRI).Methods:We studied 50 patients four to seven months after brain injury. By using international clinical criteria and validated behavioural scales such as the Glasgow Coma Scale and the Clinical Unawareness Assessment Scale, the patients were grouped into VS (n=23) and MCS (n=27). All patients underwent to fMRI examination. After 6 months, the patients were reassessed using Glasgow Outcome Scale and Revised Coma Recovery Scale.Results:fMRI showed significant (p<0.01, cluster-corrected) brain activation in the primary auditory cortex bilaterally during the acoustic stimuli in patients with both VS and MCS. However, ten patients clinically classified as VS, showed a pattern of brain activation very similar to that of MCS patients. Six months later, these ten VS patients had significant clinical improvement, evolving into MCS, whereas the other VS patients and patients with MCS remained clinically stable.Conclusion:Brain activity could help in discerning whether the status of wakefulness in VS is also accompanied by partial awareness, as occurs in MCS. This may have very important prognostic implications.

Morphological Detection and Functional Assessment of Regenerated Nerve after Neural Prosthesis with a PGLA Nerve Conduit

This study aimed to observe the morphological characteristics of a PGLA [poly(glycolide-co-L-lactide)] nerve conduit and regenerated nerve bundle in the human body using high-frequency ultrasound and examine functional recovery of the regenerated nerve using functional magnetic resonance imaging (fMRI) after neural prosthesis with a PGLA nerve conduit. Thirty-nine patients underwent high-frequency ultrasound, and one patient with superficial radial nerve injury (27-mm defect) underwent fMRI at one, three, and six postoperative months. The fMRI examination results were compared with sensory detection and high-frequency ultrasound results during the same follow-up window period. The normal and regenerated nerve bundles had similar ultrasonic imaging features. At one postoperative month, fMRI displayed activeness of the normal cortex in the brain region corresponding to the contralateral superficial radial nerve, while no activeness was observed on the ipsilateral side. From three to six postoperative months, fMRI revealed gradually increasing activeness in the brain region corresponding to the ipsilateral superficial radial nerve, but the activation area on the ipsilateral side was smaller than that on the contralateral side. Combining morphological detection of the regenerated nerve using high-frequency ultrasound and functional detection of the regenerated nerve using fMRI may be a valuable method for evaluating repair of peripheral nerve injury.