An fMRI task battery for assessing hemispheric language dominance in children

The long-term negative impact of childhood stroke on language

Objectives

This study aims to investigate the long-term language outcome in children with unilateral childhood stroke in comparison to those with perinatal strokes and typically developing individuals and to explore the impact of lesion-specific modifiers.

Methods

We examined nine patients with childhood stroke, acquired between 0;2 and 16;1 years (CHILD; 3 female, median = 13.5 years, 6 left-sided), 23 patients with perinatal strokes (PERI; 11 female, median = 12.5 years, 16 left-sided), and 33 age-matched typically developing individuals (CONTROL; 15 female, median = 12.33 years). The language outcome was assessed using age-appropriate tasks of the Potsdam Illinois Test of Psycholinguistic Abilities (P-ITPA) or the Peabody Picture Vocabulary Test (PPVT). For group comparisons, study-specific language z-scores were calculated. Non-verbal intelligence was assessed using the Test of Non-verbal Intelligence (TONI-4), language lateralization with functional MRI, and lesion size with MRI-based volumetry.

Results

All four patients with childhood stroke who initially presented with aphasic symptoms recovered from aphasia. Patients with childhood stroke showed significantly lower language scores than those in the control group, but their scores were similar to those of the patients with perinatal stroke, after adjusting for general intelligence (ANCOVA, language z-score CHILD = -0.30, PERI = -0.38, CONTROL = 0.42). Among the patients with childhood stroke, none of the possible modifying factors, including lesion side, correlated significantly with the language outcome.

Conclusion

Childhood stroke, regardless of the affected hemisphere, can lead to chronic language deficits, even though affected children show a "full recovery." The rehabilitation of children and adolescents with childhood stroke should address language abilities, even after the usually quick resolution of clear aphasic symptoms.

Atypical language organization following perinatal infarctions of the left hemisphere is associated with structural changes in right-hemispheric grey matter

AIM

To assess how atypical language organization after early left-hemispheric brain lesions affects grey matter in the contralesional hemisphere.

METHOD

This was a cross-sectional study with between-group comparisons of 14 patients (six female, 8-26 years) with perinatal left-hemispheric brain lesions (two arterial ischemic strokes, 11 periventricular haemorrhagic infarctions, one without classification) and 14 typically developing age-matched controls (TDC) with functional magnetic resonance imaging (fMRI) documented left-hemispheric language organization (six female, 8-28 years). MRI data were analysed with SPM12, CAT12, and custom scripts. Language lateralization indices were determined by fMRI within a prefrontal mask and right-hemispheric grey matter group differences by voxel-based morphometry (VBM).

RESULTS

FMRI revealed left-dominance in seven patients with typical language organization (TYP) and right-dominance in seven patients with atypical language organization (ATYP) of 14 patients. VBM analysis of all patients versus controls showed grey matter reductions in the middle temporal gyrus of patients. A comparison between the two patient subgroups revealed an increase of grey matter in the middle frontal gyrus in the ATYP group. Voxel-based regression analysis confirmed that grey matter increases in the middle frontal gyrus were correlated with atypical language organization.

INTERPRETATION

Compatible with a non-specific lesion effect, we found areas of grey matter reduction in patients as compared to TDC. The grey matter increase in the middle frontal gyrus seems to reflect a specific compensatory effect in patients with atypical language organization.

WHAT THIS PAPER ADDS

Perinatal stroke leads to decreased grey matter in the contralesional hemisphere. Atypical language organization is associated with grey matter increases in contralesional language areas.

Associations between afternoon napping, left amygdala volume and cognitive performance in elderly with normal cognitive function

BACKGROUND

The relationship between afternoon napping and cognitive function in the elderly is very complex and the mechanism is unknown.

METHODS

In the current study, 194 community elders with normal cognitive functions were included. All subjects completed baseline clinical assessment, baseline neuropsychological test as well as baseline structural MRI. Based on their napping status, these 194 participants were divided into the napping group (n = 88) and the non-napping group (n = 106). We then compared the differences in cognitive performance and structural magnetic resonance between the two groups.

RESULTS

In the intergroup analysis, we found that the nappers showed poorer cognitive performance on both overall cognitive function and domain specific cognitive function; while on the whole sample, we found a significant negative association (F = 20.27, p<0.001) between afternoon napping and left amygdala volume. However, we did not find any effect of night sleep length or napping frequency on cognitive performance or left amygdala volume.

CONCLUSIONS

In community elders with normal cognitive functions, afternoon napping is associated with cognitive performance, and left amygdala may play an important role in this process.

Language lateralization and outcome in perinatal stroke patients with different vascular types

Perinatal stroke affects child's language development and can change language lateralization. Language generation and comprehension tasks in functional magnetic resonance imaging were used to determine language lateralization in term born children with perinatal left-side arterial ischemic stroke (AIS) (n = 9, mean age (SD) 13.4 (3.1) y.) and periventricular venous infarction (PVI) (n = 12, 11.8 (2.8) y.), and in healthy right-handed controls (n = 30, 11.6 (2.6) y.). Lateralization index was calculated for the Broca and Wernicke areas and correlated with language and cognitive outcomes measured by the Kaufman Assessment Battery for Children II ed. Language outcome in children with perinatal stroke is poorer compared to healthy controls. Children with small AIS lesions and most children with PVI showed left-side language activation. Most children with large AIS lesions and one child with large PVI had language activation reorganized to the right hemisphere. Language reorganization to the unlesioned right hemisphere did not ensure normal language outcome.

Cognitive development after perinatal unilateral infarctions: No evidence for preferential sparing of verbal functions

BACKGROUND

Even children with extensive perinatal left-sided lesions have been reported to show normal language functions based on right-hemispheric language reorganization. This reorganization can lead to deficits in originary right hemispheric functions ("crowding hypothesis"). In a previous study, however, we identified epilepsy (even when well-controlled), and not language reorganization, as the major risk factor for impaired nonverbal functions. Here, we asked whether verbal and nonverbal functions develop differently, and whether they share the same risk factors.

METHODS

We investigated 23 patients (11f, Md = 12.56 years) with perinatal strokes (16 left-sided, 8 with epilepsy), and 23 healthy age-matched controls (8 f, Md = 12.42years). Language functions were assessed using the Potsdam Illinois Test of Psycholinguistic Abilities, nonverbal intelligence with the Test of Nonverbal Intelligence, language lateralization with functional MRI, and lesion size with MRI-based volumetry.

RESULTS

We found no systematic difference between verbal and nonverbal skills in our patients or controls [median difference Z(PITPA)-Z(TONI): patients = -0.03, controls = -0.06]. Accordingly, verbal and nonverbal functions were strongly correlated in patients (r = 0.80) and in controls (r = 0.74). Language ability correlated significantly with epilepsy. Furthermore, in patients with epilepsies, verbal skills were significantly lower than in controls.

CONCLUSION

In our cohort, we found no evidence for a differential effect of perinatal strokes on the development of verbal versus nonverbal functions, and, specifically, no evidence for a preferential sparing of verbal functions. Epilepsy, even when well-controlled, was confirmed as a single key risk factor for verbal functions.

[Hemispherotomy in pediatric epilepsy surgery-Surgical, epileptological and functional aspects]

Hemispherotomies represent a major part of surgical interventions for epilepsy in childhood (16-21%). The anatomical resection has been replaced by minimally invasive disconnection techniques with lower perioperative mortality and fewer postoperative complications. Today the procedure is not only carried out from the lateral aspect via the Sylvian fissure/insula but also via a vertical parasagittal approach. Depending on the publication, hemispherotomy leads to freedom from postoperative seizures in 60-90% of patients. Despite changes in the surgical technique, disturbances of the cerebrospinal fluid circulation continue to be the main complication in 5-15% of cases. Hemispheric epileptogenic lesions usually lead to early onset and difficult to treat epilepsy in childhood. These epilepsies are characterized by a high frequency of seizures and propagation of epileptic discharges to the healthy hemisphere. The aim of a hemispherotomy is, in addition to postoperative freedom from seizures, the complete disconnection of the affected hemisphere. When deciding on a hemispherotomy, the expected functional consequences play a major role in addition to epileptological aspects. In the case of deficits already present preoperatively (hemianopia, hemiparesis) or reorganization of functions in the contralesional hemisphere (language), no new deficits are to be expected from the operation. In terms of cognition, a hemispherotomy can improve function by releasing the neuroplastic potential of the healthy hemisphere. In order to keep the negative and often irreversible effects of epilepsy as low as possible and to be able to use as much potential for neuroplasticity of the healthy hemisphere as possible, surgery should be considered as early as possible.

Clinical Speech fMRI in Children and Adolescents : Development of an Optimal Protocol and Analysis Algorithm

Purpose

In patients with drug-resistant focal epilepsy, surgical resection is often the only treatment option to achieve long-term seizure control. Prior to brain surgery involving potential language areas, identification of hemispheric language dominance is crucial. Our group developed and validated a functional magnetic resonance imaging (fMRI) battery of four pediatric language tasks. The present study aimed at optimizing fMRI data acquisition and analysis using these tasks.

Methods

We retrospectively analyzed speech fMRI examinations of 114 neuropediatric patients (age range 5.8–17.8 years) who were examined prior to possible epilepsy surgery. In order to evaluate hemispheric language dominance, 1–4 language tasks (vowel identification task VIT, word-chain task WCT, beep-story task BST, synonym task SYT) were measured.

Results

Language dominance was classified using fMRI activation in the 13 validly lateralizing ROIs (VLR) in frontal, temporal and parietal lobes and cerebellum of the recent validation study from our group: 47/114 patients were classified as left-dominant, 34/114 as bilateral and 6/114 as right-dominant. In an attempt to enlarge the set of VLR, we then compared for each task agreement of these ROI activations with the classified language dominance. We found four additional task-specific ROIs showing concordant activation and activation in ≥ 10 sessions, which we termed validly lateralizing (VLR_new). The new VLRs were: for VIT the temporal language area and for SYT the middle frontal gyrus, the intraparietal sulcus and cerebellum. Finally, in order to find the optimal sequence of measuring the different tasks, we analyzed the success rates of single tasks and all possible task combinations. The sequence 1) VIT 2) WCT 3) BST 4) SYT was identified as the optimal sequence, yielding the highest chance to obtain reliable results even when the fMRI examination has to be stopped, e.g., due to lack of cooperation.

Conclusion

Our suggested task order together with the enlarged set of VLR_new may contribute to optimize pediatric speech fMRI in a clinical setting.

Supplementary Information

The online version of this article (10.1007/s00062-021-01097-z) contains supplementary material, which is available to authorized users.

The role of the left and right inferior frontal gyrus in processing metaphoric and unrelated co-speech gestures

Gestures are an integral part of in-person conversations and complement the meaning of the speech they accompany. The neural processing of co-speech gestures is supported by a mostly left-lateralized network of fronto-temporal regions. However, in contrast to iconic gestures, metaphoric as well as unrelated gestures have been found to more strongly engage the left and right inferior frontal gyrus (IFG), respectively. With this study, we conducted the first systematic comparison of all three types of gestures and resulting potential laterality effects. During collection of functional imaging data, 74 subjects were presented with 5 s videos of abstract speech with related metaphoric gestures, concrete speech with related iconic gestures and concrete speech with unrelated gestures. They were asked to judge whether the content of the speech and gesture matched or not. Differential contrasts revealed that both abstract related and concrete unrelated compared to concrete related stimuli elicited stronger activation of the bilateral IFG. Analyses of lateralization indices for IFG activation further showed a left hemispheric dominance for metaphoric gestures and a right hemispheric dominance for unrelated gestures. Our results give support to the hypothesis that the bilateral IFG is activated specifically when processing load for speech-gesture combinations is high. In addition, laterality effects indicate a stronger involvement of the right IFG in mismatch detection and conflict processing, whereas the left IFG performs the actual integration of information from speech and gesture.

Non-verbal Intelligence in Unilateral Perinatal Stroke Patients With and Without Epilepsies

Background: The risk factors for impaired cognitive development after unilateral perinatal stroke are poorly understood. Non-verbal intelligence seems to be at particular risk, since language can shift to the right hemisphere and may thereby reduce the capacity of the right hemisphere for its originary functions. Pharmaco-refractory epilepsies, a frequent complication of perinatal strokes, often lead to impaired intelligence. Yet, the role of well-controlled epilepsies is less well-understood. Here, we investigated whether well-controlled epilepsies, motor impairment, lesion size, lesion side, and lateralization of language functions influence non-verbal functions. Methods: We recruited 8 patients with well-controlled epilepsies (9-26 years), 15 patients without epilepsies (8-23 years), and 23 healthy controls (8-27 years). All underwent the Test of Non-verbal Intelligence, a motor-independent test, which excludes biased results due to motor impairment. Language lateralization was determined with functional MRI, lesion size with MRI-based volumetry, and hand motor impairment with the Jebson-Taylor Hand Function-Test. Results: Patients with epilepsies showed significantly impaired non-verbal intelligence [Md = 89.5, interquartile range (IQR) = 13.5] compared with controls (Md = 103, IQR = 17). In contrast, patients without epilepsies (Md = 97, IQR = 15.0) performed within the range of typically developing children. A multiple regression analysis revealed only epilepsy as a significant risk factor for impaired non-verbal functions. Conclusion: In patients with unilateral perinatal strokes without epilepsies, the neuroplastic potential of one healthy hemisphere is able to support the development of normal non-verbal cognitive abilities, regardless of lesion size, lesion side, or language lateralization. In contrast, epilepsy substantially reduces this neuroplastic potential; even seizure-free patients exhibit below-average non-verbal cognitive functions.

Functional organisation for verb generation in children with developmental language disorder

Developmental language disorder (DLD) is characterised by difficulties in learning one's native language for no apparent reason. These language difficulties occur in 7% of children and are known to limit future academic and social achievement. Our understanding of the brain abnormalities associated with DLD is limited. Here, we used a simple four-minute verb generation task (children saw a picture of an object and were instructed to say an action that goes with that object) to test children between the ages of 10-15 years (DLD N = 50, typically developing N = 67). We also tested 26 children with poor language ability who did not meet our criteria for DLD. Contrary to our registered predictions, we found that children with DLD did not have (i) reduced activity in language relevant regions such as the left inferior frontal cortex; (ii) dysfunctional striatal activity during overt production; or (iii) a reduction in left-lateralised activity in frontal cortex. Indeed, performance of this simple language task evoked activity in children with DLD in the same regions and to a similar level as in typically developing children. Consistent with previous reports, we found sub-threshold group differences in the left inferior frontal gyrus and caudate nuclei, but only when analysis was limited to a subsample of the DLD group (N = 14) who had the poorest performance on the task. Additionally, we used a two-factor model to capture variation in all children studied (N = 143) on a range of neuropsychological tests and found that these language and verbal memory factors correlated with activity in different brain regions. Our findings indicate a lack of support for some neurological models of atypical language learning, such as the procedural deficit hypothesis or the atypical lateralization hypothesis, at least when using simple language tasks that children can perform. These results also emphasise the importance of controlling for and monitoring task performance.

The Clinical Utility of Transcranial Magnetic Stimulation in Determining Hemispheric Dominance for Language: A Magnetoencephalography Comparison Study

PURPOSE

Transcranial magnetic stimulation (TMS) has recently emerged as a noninvasive alternative to the intracarotid sodium amytal (Wada) procedure for establishing hemispheric dominance (HD) for language. The accuracy of HD determined by TMS was examined by comparing against the HD derived by magnetoencephalography (MEG), a prominent clinical technique with excellent concordance with the Wada procedure.

METHODS

Sixty-seven patients (54 patients ≤18 years) underwent language mapping with TMS and MEG as part of clinical epilepsy and tumor presurgical assessment. Language was mapped in MEG during an auditory word recognition paradigm, and a laterality index was calculated using the number of dipoles and their spatial extent in the two hemispheres. Transcranial magnetic stimulation language mapping was performed as patients performed a naming task, and TMS-induced speech disruptions were recorded during 5-Hz TMS applied to anterior and posterior language cortices. Transcranial magnetic stimulation laterality index was estimated using the number and type of speech disruption in the language regions of each hemisphere.

RESULTS

Transcranial magnetic stimulation and MEG estimates of HD were concordant in 42 (63%) patients, resulting in a sensitivity of 74% and a specificity of 72%. The overall accuracy of TMS was 73%, equivalent to an odds ratio of 7.35.

CONCLUSIONS

In this first large-scale comparative study in a clinical population, we demonstrate that TMS is a safe and reliable noninvasive tool in determining HD for language. Improving the accuracy of TMS by optimizing TMS parameters and improving task choice will further facilitate the use of TMS to characterize language function, especially in pediatrics.

Concordance Between Transcranial Magnetic Stimulation and Functional Magnetic Resonance Imaging (MRI) Derived Localization of Language in a Clinical Cohort

Transcranial magnetic stimulation (TMS) is a newer noninvasive language mapping tool that is safe and well-tolerated by children. We examined the accuracy of TMS-derived language maps in a clinical cohort by comparing it against functional magnetic resonance imaging (MRI)-derived language map. The number of TMS-induced speech disruptions and the volume of activation during functional MRI tasks were localized to Brodmann areas for each modality in 40 patients with epilepsy or brain tumor. We examined the concordance between TMS- and functional MRI-derived language maps by deriving statistical performance metrics for TMS including sensitivity, specificity, accuracy, and diagnostic odds ratio. Brodmann areas 6, 44, and 9 in the frontal lobe and 22 and 40 in the temporal lobe were the most commonly identified language areas by both modalities. Overall accuracy of TMS compared to functional MRI in localizing language cortex was 71%, with a diagnostic odds ratio of 1.27 and higher sensitivity when identifying left hemisphere regions. TMS was more accurate in determining the dominant hemisphere for language with a diagnostic odds ratio of 6. This study is the first to examine the accuracy of the whole brain language map derived by TMS in the largest cohort examined to date. While this comparison against functional MRI confirmed that TMS reliably localizes cortical areas that are not essential for speech function, it demonstrated only slight concordance between TMS- and functional MRI-derived language areas. That the localization of specific language cortices by TMS demonstrated low accuracy reveals a potential need to use concordant tasks between the modalities and other avenues for further optimization of TMS parameters.

Presurgical Language fMRI in Children, Adolescents and Young Adults : A Validation Study

PURPOSE

To validate four established, child-friendly functional magnetic resonance imaging (fMRI) language tasks (word chain task [WCT], vowel identification task [VIT], synonym task [SYT] and beep story task [BST]) in a predominantly pediatric cohort.

METHODS

Intracarotid amobarbital procedures (IAP) (n = 17) and unchanged language after hemispherotomy (n = 6) were used as gold standards. The fMRI activations of nine regions of interest (ROI) in the frontal, temporal and parietal lobes as well as in the cerebellum were visually assessed in 23 fMRI examinations (in total 117 fMRI task sessions) of 23 patients (age range 10.0-23.0 years) with drug-refractory epilepsies.

RESULTS

The ROIs were considered valid when they showed activation in more than 25% of all sessions for the respective task and never showed false lateralization (in comparison to gold standards). Thus, 13 valid, task-specific ROIs were identified: 5 ROIs for the WCT (frontal operculum, inferior frontal gyrus, middle frontal gyrus, intraparietal sulcus, cerebellum), 3 ROIs for the VIT (frontal operculum, inferior frontal gyrus, middle frontal gyrus), 3 ROIs for the SYT (frontal operculum, inferior frontal gyrus, temporal language area) and 2 ROIs for the BST (inferior frontal gyrus, middle frontal gyrus).

CONCLUSION

Clinical fMRI using the battery of four tasks is a valid tool for lateralizing language in children, adolescents and young adults. Each task proved to be specifically useful, which confirms that applying different tasks increases the probability of diagnosing language dominance in presurgical candidates.

A Functional Magnetic Resonance Imaging Approach for Language Laterality Assessment in Young Children

Functional magnetic resonance imaging (fMRI) is a usable technique to determine hemispheric dominance of language function, but high-quality fMRI images are difficult to acquire in young children. Here we aimed to develop and validate an fMRI approach to reliably determine hemispheric language dominance in young children. We designed two new tasks (story, SR; Letter picture matching, LPM) that aimed to match the interests and the levels of cognitive development of young children. We studied 32 healthy children (6-10 years old, median age 8.7 years) and seven children with epilepsy (7-11 years old, median age 8.6 years) and compared the lateralization index of the new tasks with those of a well-validated task (verb generation, VG) and with clinical measures of hemispheric language dominance. A conclusive assessment of hemispheric dominance (lateralization index ≤-0.2 or ≥0.2) was obtained for 94% of the healthy participants who performed both new tasks. At least one new task provided conclusive language laterality assessment in six out of seven participants with epilepsy. The new tasks may contribute to assessing language laterality in young and preliterate children and may benefit children who are scheduled for surgical treatment of disorders such as epilepsy.

An fMRI-study on single-sided deafness: Spectral-temporal properties and side of stimulation modulates hemispheric dominance

Objective

Our main aim was to investigate the blood oxygenation level dependent (BOLD) response to monaural and binaural speech- and non-speech stimuli as measured with fMRI in subjects with single-sided deafness and in normal hearing controls. We hypothesised that the response to monaural stimulation in both normal hearing subjects and persons with single-sided deafness would vary with the complexity and nature of the stimuli and the side of stimulation.

Design

Patients with left- and right single-sided deafness and controls with normal hearing receiving either binaural or monaural stimuli were tested using speech and non-speech auditory stimuli in an event-related fMRI experiment.

Study sample

Twenty-two patients with single-sided deafness after treatment for vestibular schwannoma and 50 normal hearing controls.

Results

Normal hearing persons receiving right side monaural stimuli activate bilateral temporal regions. Activation following left side monaural stimulation is more right lateralized. Persons with single-sided deafness respond similarly to controls to monaural stimulation. Persons with right side single-sided deafness show activation of frontal cortical regions not seen in persons with left side single-sided deafness following speech stimuli. This is possibly related to increased effort and more frequently reported problems with communication. Right side single-sided deafness is related to increased activation of areas usually related to processing of degraded input, including the thalamus.

Conclusion

Hemispheric dominance following monaural auditory stimulation is modulated by the spectral-temporal properties of the stimuli and by which ear is stimulated. Differences between patients with right- and left side deafness suggests that right side deafness is related to increased activation of areas involved in processing of degraded input.

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Hemispheric dominance following monaural stimulation is modulated by stimuli properties and by which ear is stimulated

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Results suggests that right side deafness is related to increased activation of eares involved in processing degraded input

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Self-assessed communication ability and the BOLD-response to phonetic stimuli correlate in several brain regions.

Assessing motor, visual and language function using a single 5-minute fMRI paradigm: three birds with one stone

Clinical functional Magnetic Resonance Imaging (fMRI) requires inferences on localization of major brain functions at the individual subject level. We hypothesized that a single "triple use" task would satisfy sensitivity and reliability requirements for successfully assessing the motor, visual and language domain in this context. This was tested here by the application in a group of healthy adults, assessing sensitivity and reliability at the individual subject level, separately for each domain.Our "triple use" task consisted of 2 conditions (condition 1, assessing motor and visual domain, and condition 2, assessing the language domain), serving mutually as active/control. We included 20 healthy adult subjects. Random effect analyses showed activation in primary motor, visual and language regions, as expected. Less expected regions were activated both for the motor and visual domains. Further, reliability of primary activation patterns was very high across individual subjects, with activation seen in 70-100% of subjects in primary motor, visual, and left-lateralized language regions.These findings suggest the "triple use" task to be reliable at the individual subject's level to assess motor, visual and language domains in the clinical fMRI context. Benefits of such an approach include shortening of acquisition time, simplicity of the task for each domain, and using a visual stimulus. Following establishment of reliability in adults, the task may also be a valuable addition in the pediatric clinical fMRI context, where each of these factors is of high relevance.

Role of presurgical functional MRI and diffusion MR tractography in pediatric low-grade brain tumor surgery: a single-center study

PURPOSE

Presurgical functional MRI (fMRI) and diffusion MRI tractography (dMRI tractography) are widely employed to delineate eloquent brain regions and their connections prior to brain tumor resection in adults. However, such studies are harder to perform in children, resulting in suboptimal neurosurgical care in pediatric brain tumor surgery as compared to adults. Thus, our objective was to assess the feasibility and the influence of presurgical advanced MR imaging on neurosurgical care in pediatric brain tumor surgery.

METHODS

Retrospective analyses of 31 presurgical fMRI/dMRI tractography studies were performed in children with low-grade tumors near eloquent brain regions at our site between 2005 and 2017.

RESULTS

In only 3/31 cases, imaging results were not interpretable (10%). All 28 successful imaging sessions were used for neurosurgical risk assessment. Based on this, surgery was canceled in 2/28 patients, and intention to treat was changed in 5/28 patients. In 4/28 cases, the surgical approach was changed and in 10/28, electrode placement for intraoperative neurophysiological monitoring was guided by imaging results. Gross total resection (GTR) was planned in 21/28 cases and could be achieved in 15/21 (71%). Despite highly eloquent tumor location, only four children suffered from a mild permanent neurological deficit after the operation.

CONCLUSIONS

We demonstrate that presurgical fMRI/dMRI tractography can have a profound impact on pediatric brain tumor management, optimizing preoperative risk-assessment and pre- as well as intraoperative decision-making. We believe that these tools should be offered to children suffering from eloquent brain tumors as part of a comprehensive operative work-up.

Clinical application of advanced MR methods in children: points to consider

The application of both functional MRI and diffusion MR tractography prior to a neurosurgical operation is well established in adults, but less so in children, for several reasons. For this review, we have identified several aspects (task design, subject preparation, actual scanning session, data processing, interpretation of results, and decision-making) where pediatric peculiarities should be taken into account. Further, we not only systematically identify common issues, but also provide solutions, based on our experience as well as a review of the pertinent literature. The aim is to provide the clinician as well as the imaging scientist with information that helps to plan, conduct, and interpret such a clinically-indicated exam in a way that maximizes benefit for, and minimizes the burden on the individual child.

Lesion characteristics driving right-hemispheric language reorganization in congenital left-hemispheric brain damage

Pre- or perinatally acquired ("congenital") left-hemispheric brain lesions can be compensated for by reorganizing language into homotopic brain regions in the right hemisphere. Language comprehension may be hemispherically dissociated from language production. We investigated the lesion characteristics driving inter-hemispheric reorganization of language comprehension and language production in 19 patients (7-32years; eight females) with congenital left-hemispheric brain lesions (periventricular lesions [n=11] and middle cerebral artery infarctions [n=8]) by fMRI. 16/17 patients demonstrated reorganized language production, while 7/19 patients had reorganized language comprehension. Lesions to the insular cortex and the temporo-parietal junction (predominantly supramarginal gyrus) were significantly more common in patients in whom both, language production and comprehension were reorganized. These areas belong to the dorsal stream of the language network, participating in the auditory-motor integration of language. Our data suggest that the integrity of this stream might be crucial for a normal left-lateralized language development.

The time window for successful right-hemispheric language reorganization in children

AIM

To identify, in a retrospective, observational study, the time window during which successful right-hemispheric language reorganization is possible after left-hemispheric brain damage.

METHOD

25 patients (10 females; age 6-41 years; ≥12 months after insult; age at insult 0;3-15;11 years) with acute, language-relevant left-hemispheric insults acquired during childhood and adolescence completed questionnaires for self-assessment of language problems. 12 patients of those reporting no (n = 8) or only moderate (n = 4) language problems participated in language fMRI.

RESULTS

Language outcome of lesions occurring before 5 years of age (n = 7) was always favorable, and language was right-lateralized (2 patients: age at lesion < 2 years) or bilateral (3 patients: age at lesion 2-5 years). Following lesions occurring after 5 years of age, language outcome was often unfavorable (11/18 patients: moderate or severe problems), and of the 7 patients without problems, none showed right-hemispheric reorganization (fMRI available in 4).

INTERPRETATION

The combination of normal language outcome and right-hemispheric language reorganization after a left-hemispheric lesion sustained after the neonatal period is extremely rare. Functionally sufficient right-hemispheric language was documented in only two patients with lesions acquired before two years of age.

How Auditory Experience Differentially Influences the Function of Left and Right Superior Temporal Cortices

To investigate how hearing status, sign language experience, and task demands influence functional responses in the human superior temporal cortices (STC) we collected fMRI data from deaf and hearing participants (male and female), who either acquired sign language early or late in life. Our stimuli in all tasks were pictures of objects. We varied the linguistic and visuospatial processing demands in three different tasks that involved decisions about (1) the sublexical (phonological) structure of the British Sign Language (BSL) signs for the objects, (2) the semantic category of the objects, and (3) the physical features of the objects.

Neuroimaging data revealed that in participants who were deaf from birth, STC showed increased activation during visual processing tasks. Importantly, this differed across hemispheres. Right STC was consistently activated regardless of the task whereas left STC was sensitive to task demands. Significant activation was detected in the left STC only for the BSL phonological task. This task, we argue, placed greater demands on visuospatial processing than the other two tasks. In hearing signers, enhanced activation was absent in both left and right STC during all three tasks. Lateralization analyses demonstrated that the effect of deafness was more task-dependent in the left than the right STC whereas it was more task-independent in the right than the left STC. These findings indicate how the absence of auditory input from birth leads to dissociable and altered functions of left and right STC in deaf participants.

SIGNIFICANCE STATEMENT Those born deaf can offer unique insights into neuroplasticity, in particular in regions of superior temporal cortex (STC) that primarily respond to auditory input in hearing people. Here we demonstrate that in those deaf from birth the left and the right STC have altered and dissociable functions. The right STC was activated regardless of demands on visual processing. In contrast, the left STC was sensitive to the demands of visuospatial processing. Furthermore, hearing signers, with the same sign language experience as the deaf participants, did not activate the STCs. Our data advance current understanding of neural plasticity by determining the differential effects that hearing status and task demands can have on left and right STC function.

Potential role of a cognitive rehabilitation program following left temporal lobe epilepsy surgery

ABSTRACT Research into memory and epilepsy has focused on measuring problems and exploring causes with limited attention directed at the role of neuropsychological rehabilitation in alleviating post-operative memory difficulties. Objectives To assess the effects of a memory rehabilitation program in patients with left temporal lobe epilepsy following surgery. Methods Twenty-four patients agreed to participate and 18 completed the study; nine received memory rehabilitation while nine had no input and were designated as controls. Verbal learning efficiency, naming abilities, memory subjective ratings, ecological activity measures and a language fMRI paradigm were used as outcome measures. Results Improved verbal learning and naming test performance, increase in memory strategy use and improved self-perception were observed following the rehabilitation. Changes in fMRI activation patterns were seen in the rehabilitation group over the long term. Conclusion The findings support the potential role of a cognitive rehabilitation program following left temporal lobe surgery.

The diminishing dominance of the dominant hemisphere: Language fMRI in focal epilepsy

“Which is the dominant hemisphere?” is a question that arises frequently in patients considered for neurosurgery. The concept of the dominant hemisphere implies uniformity of language lateralisation throughout the brain. It is increasingly recognised that this is not the case in the healthy control brain, and it is especially not so in neurological diseases such as epilepsy.

In the present work we adapt our published objective lateralisation method (based on the construction of laterality curves) for use with sub-lobar cortical, subcortical and cerebellar regions of interest (ROIs). We apply this method to investigate regional lateralisation of language activation in 12 healthy controls and 18 focal epilepsy patients, using three different block design language fMRI paradigms, each tapping different aspects of language processing. We compared lateralisation within each ROI across tasks, and investigated how the quantity of data collected affected the ability to robustly estimate laterality across ROIs.

In controls, lateralisation was stronger, and the variance across individuals smaller, in cortical ROIs, particularly in the Inferior Frontal (Broca) region. Lateralisation within temporal ROIs was dependent on the nature of the language task employed. One of the healthy controls was left lateralised anteriorly and right lateralised posteriorly. Consistent with previous work, departures from normality occurred in ~ 15–50% of focal epilepsy patients across the different ROIs, with atypicality most common in the Lateral Temporal (Wernicke) region. Across tasks and ROIs the absolute magnitude of the laterality estimate increased and its across participant variance decreased as more cycles of task and rest were included, stabilising at ~ 4 cycles (~ 4 min of data collection).

Our data highlight the importance of considering language as a complex task where lateralisation varies at the subhemispheric scale. This is especially important for presurgical planning for focal resections where the concept of ‘hemispheric dominance’ may be misleading. This is a precision medicine approach that enables objective evaluation of language dominance within specific brain regions and can reveal surprising and unexpected anomalies that may be clinically important for individual cases.

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Different brain regions support different aspects of language function.

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The degree of language lateralisation varies in different brain regions.

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Atypical lateralisation is common in focal epilepsy patients, particularly in the temporal lobe.

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Even in normal controls, frontal and temporal language systems can be in opposite hemispheres.

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Language dominance is more complex than often thought.

Neural change following different memory training approaches in very preterm born children - A pilot study

OBJECTIVE

There is mixed evidence regarding neural change following cognitive training. Brain activation increase, decrease, or a combination of both may occur. We investigated training-induced neural change using two different memory training approaches.

METHODS

Very preterm born children (aged 7-12 years) were randomly allocated to a memory strategy training, an intensive working memory practice or a waiting control group. Before and immediately after the trainings and the waiting period, brain activation during a visual working memory task was measured using fMRI and cognitive performance was assessed.

RESULTS

Following both memory trainings, there was a significant decrease of fronto-parietal brain activation and a significant increase of memory performance. In the control group, no neural or performance change occurred after the waiting period.

CONCLUSION

These pilot data point towards a training-related decrease of brain activation, independent of the training approach. Our data highlight the high training-induced plasticity of the child's brain during development.

Processing verbal morphology in patients with congenital left-hemispheric brain lesions

The goal of this study was to test whether children, teenagers and adults with congenital left-hemispheric brain lesions master the regularities of German verbal inflectional morphology. Thirteen patients and 35 controls without brain damage participated in three experiments. A grammaticality judgment task, a participle inflection task and a nonce-verb inflection task revealed significant differences between patients and controls. In addition, a main effect of verb type could be observed as patients and controls made more mistakes with irregular than with regular verbs. The findings indicate that the congenitally damaged brain not only has difficulties with complex syntactic structures during language development, as reported by earlier studies, but also has persistent deficits on the morphological level. These observations suggest that the plasticity of the developing brain cannot fully compensate for congenital brain damage which affects regions associated with language functions.

Getting the Cocktail Party Started: Masking Effects in Speech Perception

Spoken conversations typically take place in noisy environments, and different kinds of masking sounds place differing demands on cognitive resources. Previous studies, examining the modulation of neural activity associated with the properties of competing sounds, have shown that additional speech streams engage the superior temporal gyrus. However, the absence of a condition in which target speech was heard without additional masking made it difficult to identify brain networks specific to masking and to ascertain the extent to which competing speech was processed equivalently to target speech. In this study, we scanned young healthy adults with continuous fMRI, while they listened to stories masked by sounds that differed in their similarity to speech. We show that auditory attention and control networks are activated during attentive listening to masked speech in the absence of an overt behavioral task. We demonstrate that competing speech is processed predominantly in the left hemisphere within the same pathway as target speech but is not treated equivalently within that stream and that individuals who perform better in speech in noise tasks activate the left mid-posterior superior temporal gyrus more. Finally, we identify neural responses associated with the onset of sounds in the auditory environment; activity was found within right lateralized frontal regions consistent with a phasic alerting response. Taken together, these results provide a comprehensive account of the neural processes involved in listening in noise.

A "one size fits all" approach to language fMRI: increasing specificity and applicability by adding a self-paced component

We have previously established an fMRI task battery suitable for mapping the language processing network in children. Among the tasks used, the synonyms and the vowel identification task induced robust task-related activations in children with average language abilities; however, the fixed presentation time seems to be a drawback in participants with above- or below-average language abilities. This feasibility study in healthy adults (n = 20) was aimed at adapting these tasks to the individual level of each patient by implementing a self-paced stimulus presentation. The impact of using a block- versus an event-related statistical approach was also evaluated. The self-paced modification allowed our participants with above-average language abilities to process stimuli much faster than originally implemented, likely increasing task adherence. A higher specificity of the event-related analysis was confirmed by stronger left inferior frontal and crossed cerebellar activations. We suggest that self-paced paradigms and event-related analyses may both increase specificity and applicability.

Fusing DTI and fMRI data: a survey of methods and applications

The relationship between brain structure and function has been one of the centers of research in neuroimaging for decades. In recent years, diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) techniques have been widely available and popular in cognitive and clinical neurosciences for examining the brain's white matter (WM) micro-structures and gray matter (GM) functions, respectively. Given the intrinsic integration of WM/GM and the complementary information embedded in DTI/fMRI data, it is natural and well-justified to combine these two neuroimaging modalities together to investigate brain structure and function and their relationships simultaneously. In the past decade, there have been remarkable achievements of DTI/fMRI fusion methods and applications in neuroimaging and human brain mapping community. This survey paper aims to review recent advancements on methodologies and applications in incorporating multimodal DTI and fMRI data, and offer our perspectives on future research directions. We envision that effective fusion of DTI/fMRI techniques will play increasingly important roles in neuroimaging and brain sciences in the years to come.

Applications of blood-oxygen-level-dependent functional magnetic resonance imaging and diffusion tensor imaging in epilepsy

The lifetime prevalence of epilepsy ranges from 2.7 to 12.4 per 1000 in Western countries. Around 30% of patients with epilepsy remain refractory to antiepileptic drugs and continue to have seizures. Noninvasive imaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) have helped to better understand mechanisms of seizure generation and propagation, and to localize epileptic, eloquent, and cognitive networks. In this review, the clinical applications of fMRI and DTI are discussed, for mapping cognitive and epileptic networks and organization of white matter tracts in individuals with epilepsy.

Cerebellar language mapping and cerebral language dominance in pediatric epilepsy surgery patients

Objective

Children with epilepsy often have reorganization of language networks and abnormal brain anatomy, making determination of language lateralization difficult. We characterized the proportion and distribution of language task activation in the cerebellum to determine the relationship to cerebral language lateralization.

Methods

Forty-six pediatric epilepsy surgery candidates (aged 7–19 years) completed an fMRI auditory semantic decision language task. Distribution of activated voxels and language laterality indices were computed using: (a) Broca's and Wernicke's areas and their right cerebral homologues; and (b) left and right cerebellar hemispheres. Language task activation was anatomically localized in the cerebellum.

Results

Lateralized language task activation in either cerebral hemisphere was highly correlated with lateralized language task activation in the contralateral cerebellar hemisphere (Broca vs. cerebellar: ρ = −0.54, p < 0.01). Cerebellar language activation was located within Crus I/II, areas previously implicated in non-motor functional networks.

Conclusions

Cerebellar language activation occurs in homologous regions of Crus I/II contralateral to cerebral language activation in patients with both right and left cerebral language dominance. Cerebellar language laterality could contribute to comprehensive pre-operative evaluation of language lateralization in pediatric epilepsy surgery patients. Our data suggest that patients with atypical cerebellar language activation are at risk for having atypical cerebral language organization.

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We examine fMRI cerebellar language activation in pediatric epilepsy surgery patients.

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A semantic decision task is employed to lateralize cerebral and cerebellar language.

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Cerebral and contralateral cerebellar language activations are highly correlated.

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Cerebellar language activation is located in right or left Crus I/II.

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Cerebellar language laterality may aid pre-operative cerebral language localization.

Different plasticity patterns of language function in children with perinatal and childhood stroke

Plasticity of language function after brain damage can depend on maturation of the brain. Children with left-hemisphere perinatal (n = 7) or childhood stroke (n = 5) and 12 controls were investigated using functional magnetic resonance imaging. The verb generation and the sentence comprehension tasks were employed to activate the expressive and receptive language areas, respectively. Weighted laterality indices were calculated and correlated with results assessed by neuropsychological test battery. Compared to controls, children with childhood stroke showed significantly lower mean scores for the expressive (P < .05) and receptive (P = .05) language tests. On functional magnetic resonance imaging they showed left-side cortical activation, as did controls. Perinatal stroke patients showed atypical right-side or bilateral language lateralization during both tasks. Negative correlation for stroke patients was found between scores for expressive language tests and laterality index during the verb generation task. (Re)organization of language function differs in children with perinatal and childhood stroke and correlates with neurocognitive performance.

Processing of non-canonical word-order: a case-series on lesion-induced reorganized language and age-effects in typical development

Complex grammatical structures are mastered late in language acquisition. We studied age-effects on performance in object topicalization in 48 typically developing German-speaking participants (aged 8-30years) and in five patients (children and adolescents) with lesion-induced atypical language representation. Production was tested by a sentence repetition task, comprehension by an acting out task. Three topicalized conditions with differing disambiguation (agreement, case, and case plus agreement) were contrasted with canonical control sentences. Children's (aged 8-13years) performance was significantly below that of adolescents and adults in all topicalized conditions. All participants made most mistakes in the agreement condition. Patients showed remarkable difficulties as compared with age-appropriate control groups in all topicalization conditions and across age-groups. Despite the small sample size, the consistency of these difficulties might hint to the importance of an intact typical neural language substrate for processing complex grammatical structures even in very early brain lesions.

Children with specific language impairment are not impaired in the acquisition and retention of Pavlovian delay and trace conditioning of the eyeblink response

Three converging lines of evidence have suggested that cerebellar abnormality is implicated in developmental language and literacy problems. First, some brain imaging studies have linked abnormalities in cerebellar grey matter to dyslexia and specific language impairment (SLI). Second, theoretical accounts of both dyslexia and SLI have postulated impairments of procedural learning and automatisation of skills, functions that are known to be mediated by the cerebellum. Third, motor learning has been shown to be abnormal in some studies of both disorders. We assessed the integrity of face related regions of the cerebellum using Pavlovian eyeblink conditioning in 7-11year-old children with SLI. We found no relationship between oral language skills or literacy skills with either delay or trace conditioning in the children. We conclude that this elementary form of associative learning is intact in children with impaired language or literacy development.

Specific impairment of functional connectivity between language regions in former early preterms

Very preterm (PT) birth (≤32 weeks of gestation) carries a high risk for an adverse neurodevelopmental outcome. In recent years, the importance of neurocognitive deficits in the language domain has been increasingly recognized, which can be well-characterized using neuropsychological testing and noninvasive imaging approaches. We compared former early PT born children and adolescents (PT, n = 29, 20M) and typically developing children (TD, n = 19, 7M), using conventional fMRI group analyses as well as functional connectivity analyses. We found only small regions with significantly different group activation (PT > TD) but significantly stronger connectivity between superior temporal lobe (STL) language regions in TD participants. There were also significant differences in local and global network efficiency (TD > PT). Surprisingly, there was a stronger connectivity of STL regions with non-STL regions both intrahemispherically and interhemispherically in PT participants, suggesting the coexistence of reduced and increased connectivity in the language network of former PTs. Very similar results were obtained when using task-based versus resting state functional connectivity approaches. Finally, lateralization of functional connectivity correlated with verbal comprehension abilities, suggesting that a more bilateral language comprehension representation is associated with better performance. Our results underline the importance of interhemispheric crosstalk for language comprehension.

Long-term neurobiological consequences of early postnatal hCMV-infection in former preterms: a functional MRI study

Early postnatal infection with human cytomegalovirus (hCMV) may contribute to an adverse cognitive outcome in early preterm-born children (PT). We here set out to explore whether long-term neurobiological consequences of such an infection are detectable using fMRI in children and adolescents who were born very preterm and who either did (PThCMV+ ) or did not (PT(hCMV-)) suffer from an early postnatal hCMV-infection, when compared with typically developing healthy control (HC) subjects. Overall, data from 71 children and adolescents could be included, 34 PT (of which 15 were PT(hCMV+) and 19 were PT(hCMV-)) and 37 HC. Using a recently established "dual use" fMRI task, we investigated language and visuospatial functions. There were significant activation differences in the left hippocampus (PT > HC and PT(hCMV+) > HC), and in the right anterior cingulate cortex (PT(hCMV-) > PT(hCMV+)) when performing the language task. Surprisingly, only a small region in the occipital cortex showed a significant activation difference (HC > PT(HCMV-)) when performing the visuospatial task. Targeted analyses revealed differences in gray matter volume, but not density, in several brain regions. Our results suggest that long-term neurobiological consequences of an early postnatal hCMV infection are detectable even in older children and adolescents formerly born very preterm, compatible with a higher effort when performing a cognitive task. This suggests that measures to prevent such an infection are warranted. Furthermore, an interrelation of brain structure and function was detected that may constitute a severe confound when using fMRI to compare structurally differing groups.

Do not throw out the baby with the bath water: choosing an effective baseline for a functional localizer of speech processing

Speech processing engages multiple cortical regions in the temporal, parietal, and frontal lobes. Isolating speech-sensitive cortex in individual participants is of major clinical and scientific importance. This task is complicated by the fact that responses to sensory and linguistic aspects of speech are tightly packed within the posterior superior temporal cortex. In functional magnetic resonance imaging (fMRI), various baseline conditions are typically used in order to isolate speech-specific from basic auditory responses. Using a short, continuous sampling paradigm, we show that reversed ("backward") speech, a commonly used auditory baseline for speech processing, removes much of the speech responses in frontal and temporal language regions of adult individuals. On the other hand, signal correlated noise (SCN) serves as an effective baseline for removing primary auditory responses while maintaining strong signals in the same language regions. We show that the response to reversed speech in left inferior frontal gyrus decays significantly faster than the response to speech, thus suggesting that this response reflects bottom-up activation of speech analysis followed up by top-down attenuation once the signal is classified as nonspeech. The results overall favor SCN as an auditory baseline for speech processing.

Functional MRI-guided probabilistic tractography of cortico-cortical and cortico-subcortical language networks in children

In this study, we analyzed the structural connectivity of cortico-cortical and cortico-subcortical language networks in healthy children, using probabilistic tractography based on high angular resolution diffusion imaging. In addition to anatomically defining seed and target regions for tractography, we used fMRI to target inferior frontal and superior temporal cortical language areas on an individual basis. Further, connectivity between these cortical and subcortical (thalamus, caudate nucleus) language regions was assessed. Overall, data from 15 children (8f) aged 8-17 years (mean age 12.1 ±3 years) could be included. A slight but non-significant trend towards leftward lateralization was found in the arcuate fasciculus/superior longitudinal fasciculus (AF/SLF) using anatomically defined masks (p>.05, Wilcoxon rank test), while the functionally-guided tractography showed a significant lateralization to the left (p<.01). Connectivity of the thalamus with language regions was strong but not lateralized. Connectivity of the caudate nucleus with inferior-frontal language regions was also symmetrical, while connectivity with superior-temporal language regions was strongly lateralized to the left (p<.01). To conclude, we could show that tracking the arcuate fasciculus/superior longitudinal fasciculus is possible using both anatomically and functionally-defined seed and target regions. With the latter approach, we could confirm the presence of structurally-lateralized cortico-cortical language networks already in children, and finally, we could demonstrate a strongly asymmetrical connectivity of the caudate nucleus with superior temporal language regions. Further research is necessary in order to assess the usability of such an approach to assess language dominance in children unable to participate in an active fMRI study.

Co-localisation of abnormal brain structure and function in specific language impairment

We assessed the relationship between brain structure and function in 10 individuals with specific language impairment (SLI), compared to six unaffected siblings, and 16 unrelated control participants with typical language. Voxel-based morphometry indicated that grey matter in the SLI group, relative to controls, was increased in the left inferior frontal cortex and decreased in the right caudate nucleus and superior temporal cortex bilaterally. The unaffected siblings also showed reduced grey matter in the caudate nucleus relative to controls. In an auditory covert naming task, the SLI group showed reduced activation in the left inferior frontal cortex, right putamen, and in the superior temporal cortex bilaterally. Despite spatially coincident structural and functional abnormalities in frontal and temporal areas, the relationships between structure and function in these regions were different. These findings suggest multiple structural and functional abnormalities in SLI that are differently associated with receptive and expressive language processing.

Testing the language of German cerebral palsy patients with right hemispheric language organization after early left hemispheric damage

Language functions are generally represented in the left cerebral hemisphere. After early (prenatally acquired or perinatally acquired) left hemispheric brain damage language functions may be salvaged by reorganization into the right hemisphere. This is different from brain lesions acquired in adulthood which normally lead to aphasia. Right hemispheric reorganized language (RL) is not associated with obvious language deficits. In this pilot study we compared a group of German-speaking patients with left hemispheric brain damage and RL with a group of matched healthy controls. The novel combination of reliable language lateralization as assessed by neuroimaging (functional magnetic resonance imaging) and specific linguistic tasks revealed significant differences between patients with RL and healthy controls in both language comprehension and production. Our results provide evidence for the hypothesis that RL is significantly different from normal left hemispheric language. This knowledge can be used to improve counselling of parents and to develop specific therapeutic approaches.

Functional brain activation differences in stuttering identified with a rapid fMRI sequence

The purpose of this study was to investigate whether brain activity related to the presence of stuttering can be identified with rapid functional MRI (fMRI) sequences that involved overt and covert speech processing tasks. The long-term goal is to develop sensitive fMRI approaches with developmentally appropriate tasks to identify deviant speech motor and auditory brain activity in children who stutter closer to the age at which recovery from stuttering is documented. Rapid sequences may be preferred for individuals or populations who do not tolerate long scanning sessions. In this report, we document the application of a picture naming and phoneme monitoring task in 3 min fMRI sequences with adults who stutter (AWS). If relevant brain differences are found in AWS with these approaches that conform to previous reports, then these approaches can be extended to younger populations. Pairwise contrasts of brain BOLD activity between AWS and normally fluent adults indicated the AWS showed higher BOLD activity in the right inferior frontal gyrus (IFG), right temporal lobe and sensorimotor cortices during picture naming and higher activity in the right IFG during phoneme monitoring. The right lateralized pattern of BOLD activity together with higher activity in sensorimotor cortices is consistent with previous reports, which indicates rapid fMRI sequences can be considered for investigating stuttering in younger participants.

EDUCATIONAL OBJECTIVES

The reader will learn about and be able to describe the: (1) use of functional MRI to study persistent developmental stuttering; (2) differences in brain activation between persons who stutter and normally fluent speakers; and (3) potential benefit of time efficient fMRI sequences combined with a range of speech processing tasks for investigating stuttering in younger populations.

Presurgical language mapping in children with epilepsy: clinical usefulness of functional magnetic resonance imaging for the planning of cortical stimulation

PURPOSE

Presurgical language mapping in dominant hemisphere epilepsy to evaluate the risk of postoperative deficit is particularly difficult in children. Extraoperative invasive cortical stimulation can show some areas critical to language, but not all of them, due to scarce sampling, poor cooperation, cortical immaturity, or network reorganization, whereas functional magnetic resonance imaging (fMRI) displays entire networks involved in, but not necessarily critical to, language. In a homogeneous series of children with epilepsy, we compared the contributions of language fMRI and depth electrode stimulations to optimize language mapping.

METHODS

Eight children (7.5-15.5 years) with left frontal or temporal epilepsy underwent language fMRI and language stimulation with depth electrodes as part of their comprehensive presurgical workup. fMRI data collected during sentence generation were analyzed using statistical parametric mapping (SPM2) (false discovery rate [FDR] p < 0.05). Bipolar stimulations were performed during language production tasks. By coregistering fMRI and postimplantation computed tomography (CT) images, we were able to directly compare the cortical areas identified by both investigations.

KEY FINDINGS

fMRI during sentence generation robustly showed activation in the whole perisylvian regions with little reorganization (left hemisphere dominant in 7). Of the 184 electrode contacts tested for language, only 8 were positive (language disruption) in three of the seven patients with periictal language impairment and left language dominance. All of the positive contacts colocalized with an fMRI activated cluster, that is, fMRI did not miss any region critical to language (sensitivity = 100%). However, 54 of the 176 negative contacts were within activated clusters (low specificity).

SIGNIFICANCE

In children with epilepsy, the sensitivity of fMRI during sentence generation allows for the detection of all critical regions displayed by cortical stimulation within the large perisylvian language network, but with a low specificity. It is, therefore, useful to optimize the placement of intracranial electrodes when language mapping is necessary. Systematic planning of the electrode placement according to language fMRI maps should increase the yield of extraoperative cortical stimulation, which appears rather low in children when compared to adults.

Language comprehension vs. language production: age effects on fMRI activation

Normal language acquisition is a process that unfolds with amazing speed primarily in the first years of life. However, the refinement of linguistic proficiency is an ongoing process, extending well into childhood and adolescence. An increase in lateralization and a more focussed productive language network have been suggested to be the neural correlates of this process. However, the processes underlying the refinement of language comprehension are less clear. Using a language comprehension (Beep Stories) and a language production (Vowel Identification) task in fMRI, we studied language representation and lateralization in 36 children, adolescents, and young adults (age 6-24 years). For the language comprehension network, we found a more focal activation with age in the bilateral superior temporal gyri. No significant increase of lateralization with age could be observed, so the neural basis of language comprehension as assessed with the Beep Stories task seems to be established in a bilateral network by late childhood. For the productive network, however, we could confirm an increase with age both in focus and lateralization. Only in the language comprehension task did verbal IQ correlate with lateralization, with higher verbal IQ being associated with more right-hemispheric involvement. In some subjects (24%), language comprehension and language production were lateralized to opposite hemispheres.

The effect of fMRI task combinations on determining the hemispheric dominance of language functions

Introduction

The purpose of this study is to establish the most suitable combination of functional magnetic resonance imaging (fMRI) language tasks for clinical use in determining language dominance and to define the variability in laterality index (LI) and activation power between different combinations of language tasks.

Methods

Activation patterns of different fMRI analyses of five language tasks (word generation, responsive naming, letter task, sentence comprehension, and word pair) were defined for 20 healthy volunteers (16 right-handed). LIs and sums of T values were calculated for each task separately and for four combinations of tasks in predefined regions of interest. Variability in terms of activation power and lateralization was defined in each analysis. In addition, the visual assessment of lateralization of language functions based on the individual fMRI activation maps was conducted by an experienced neuroradiologist.

Results

A combination analysis of word generation, responsive naming, and sentence comprehension was the most suitable in terms of activation power, robustness to detect essential language areas, and scanning time. In general, combination analyses of the tasks provided higher overall activation levels than single tasks and reduced the number of outlier voxels disturbing the calculation of LI.

Conclusions

A combination of auditory and visually presented tasks that activate different aspects of language functions with sufficient activation power may be a useful task battery for determining language dominance in patients.

Abnormal functional lateralization and activity of language brain areas in typical specific language impairment (developmental dysphasia)

Atypical functional lateralization and specialization for language have been proposed to account for developmental language disorders, yet results from functional neuroimaging studies are sparse and inconsistent. This functional magnetic resonance imaging study compared children with a specific subtype of specific language impairment affecting structural language (n = 21), to a matched group of typically developing children using a panel of four language tasks neither requiring reading nor metalinguistic skills, including two auditory lexico-semantic tasks (category fluency and responsive naming) and two visual phonological tasks based on picture naming. Data processing involved normalizing the data with respect to a matched pairs paediatric template, groups and between-groups analysis, and laterality indices assessment within regions of interest using single and combined task analysis. Children with specific language impairment exhibited a significant lack of left lateralization in all core language regions (inferior frontal gyrus-opercularis, inferior frontal gyrus-triangularis, supramarginal gyrus and superior temporal gyrus), across single or combined task analysis, but no difference of lateralization for the rest of the brain. Between-group comparisons revealed a left hypoactivation of Wernicke's area at the posterior superior temporal/supramarginal junction during the responsive naming task, and a right hyperactivation encompassing the anterior insula with adjacent inferior frontal gyrus and the head of the caudate nucleus during the first phonological task. This study thus provides evidence that this subtype of specific language impairment is associated with atypical lateralization and functioning of core language areas.

Assessing language and visuospatial functions with one task: a "dual use" approach to performing fMRI in children

In order to increase the rate of successful functional MR studies in children it is helpful to shorten the time spent in the scanner. To this effect, assessing two cognitive functions with one task seems to be a promising approach. The hypothesis of this study was that the control condition of an established language task (vowel identification task, VIT) requires visuospatial processing and that the control condition (VIT(CC)) therefore may also be applicable to localize visuospatial functions. As a reference task, a visual search task (VST, previously established for use in children) was employed. To test this hypothesis, 43 children (19 f, 24 m; 12.0±2.6, range 7.9 to 17.8 years) were recruited and scanned using both tasks. Second-level random effects group analyses showed activation of left inferior-frontal cortex in the active condition of the VIT, as in previous studies. Additionally, analysis of the VIT(CC) demonstrated activation in right-dominant superior parietal and high-frontal brain regions, classically associated with visuospatial functions; activation seen in the VST was similar with a substantial overlap. However, lateralization in the parietal lobe was significantly more bilateral in the VST than in the VIT(CC). This suggests that the VIT can not only be applied to assess language functions (using the active>control contrast), but also that the control>active condition is useful for assessing visuospatial functions. Future task design may benefit from such a "dual use" approach to performing fMRI not only, but also particularly in children.

Clinical functional MRI of the language domain in children with epilepsy

Functional MRI (fMRI) for the assessment of language functions is increasingly used in the diagnostic workup of patients with epilepsy. Termed "clinical fMRI," such an approach is also feasible in children who may display specific patterns of language reorganization. This study was aimed at assessing language reorganization in pediatric epilepsy patients, using fMRI. We studied 26 pediatric epilepsy patients (median age, 13.05 years; range, 5.6-18.7 years) and 23 healthy control children (median age, 9.37 years; range, 6.2-15.4 years), using two child-friendly fMRI tasks and adapted data-processing streams. Overall, 81 functional series could be analyzed. Reorganization seemed to occur primarily in homotopic regions in the contralateral hemisphere, but lateralization in the frontal as well as in the temporal lobes was significantly different between patients and controls. The likelihood to find atypical language organization was significantly higher in patients. Additionally, we found significantly stronger activation in the healthy controls in a primarily passive task, suggesting a systematic confounding influence of antiepileptic medication. The presence of a focal cortical dysplasia was significantly associated with atypical language lateralization. We conclude that important confounds need to be considered and that the pattern of language reorganization may be distinct from the patterns seen in later-onset epilepsy.

Why one task is not enough: functional MRI for atypical language organization in two children

Functional MRI is increasingly used to determine the hemispheric dominance for language. This is especially relevant in children who may not be able to comply with the high demands of a Wada test. We here report on two children in which the full extent of language reorganization was only determined when two fMRI tasks were analyzed; in the first case, the results from the second task corroborated the shifted hemispheric dominance seen in the first task. In the second case, the second task showed an opposite hemispheric dominance, suggesting a hemispheric dissociation of language functions. These cases underline the necessity to use more than one fMRI task for the determination of hemispheric dominance, whenever possible. This is particularly relevant in children as unusual patterns of reorganization may be more likely.