Idiom comprehension deficits in relation to corpus callosum agenesis and hypoplasia in children with spina bifida meningomyelocele

Proverb comprehension in schizophrenia: A comprehensive review and meta-analysis.2

BACKGROUND

Examination of proverb comprehension has a long tradition in clinical diagnostics of individuals with schizophrenia (iSCZ). Deficits in the comprehension are considered common. Interpretations of proverbs are traditionally measured by their degree of abstraction and concreteness ('literalness'), but iSCZ's responses may also be illogical or 'bizarre'. Experimental research on proverb comprehension starts in the 1940s. Since then, the specificity of proverb tests has often been questioned, but has never been the subject of a meta-analysis. The aim of this meta-analysis is to include all experimental research, including historical studies, that meets quality criteria and compares the responses to proverbs in iSCZ with those in healthy controls (HC) or clinical controls (CC).

METHODS

PubMed, Web of Science, and PsycInfo databases were searched. After coding 121 articles, 27 (median publication year 1982) were included and multi-level meta-analyses performed. Moderator analyses were performed on response format (multiple-choice vs. verbal responses), proverb test, scoring method, language, acute vs. chronic stage of iSCZ, time of publication, clinical vs. healthy control group, age, IQ/education, and gender. Publication bias was assessed using funnel plots, trim and fill method and Egger's test.

RESULTS

The search identified 27 eligible studies for inclusion. Studies were published between 1956 and 2020 and predominantly older than 30 years (median: 1982). The Gorham Proverbs Test was the most established test and predominantly conducted in English. CC mostly consisted of depressive disorders. Pooled estimates yielded statistically significant less abstract (g = -1.00; 95%CI, -1.34 to -1.67), more concrete (g = 0.69; 95%CI, 0.35-1.03), and more bizarre (g = 1.08; 95%CI, 0.74-1.41) responses in iSCZ compared to controls. The type of control group moderated all three effects, with greater differences of iSCZ compared to HC than to CC in abstraction and bizarreness, and no significant group difference between iSCZ and CC in concreteness. Meta-regressions indicated IQ/education and age as possible sources of variability in abstraction and bizarreness.

CONCLUSIONS

While lower abstraction and higher bizarreness seems a characteristic of iSCZ, the diagnostic specificity of a concrete response was astonishingly low. The lack of a unified definition for concretism and limited consideration of cultural diversity contributed to these complex findings. Future research should focus on exploring the qualitative aspects of proverb comprehension and the association between symptomatology types and misinterpretations to improve diagnostic accuracy.

Hydrocephalus: A neuropsychological and theoretical primer

Hydrocephalus is a common neurological condition, the hallmark feature of which is an excess in production, or accumulation, of cerebrospinal fluid in the ventricles. Although it is associated with diffuse damage to paraventricular brain areas, patients are broadly typified by a particular pattern of cognitive impairments that include deficits in working memory, attention, and spatial abilities. There have, however, been relatively few neuropsychological accounts of the condition. Moreover, theories of the relationship between aetiology and impairment appear to have emerged in isolation of each other, and proffer fundamentally different accounts. In this primer, we aim to provide a comprehensive and contemporary overview of hydrocephalus for the neuropsychologist, covering cognitive sequelae and theoretical interpretations of their origins. We review clinical and neuropsychological assays of cognitive profiles, along with the few studies that have addressed more integrative behaviours. In particular, we explore the distinction between congenital or early-onset hydrocephalus with a normal-pressure variant that can be acquired later in life. The relationship between these two populations is a singularly interesting one in neuropsychology since it can allow for the examination of typical and atypical developmental trajectories, and their interaction with chronic and acute impairment, within the same broad neurological condition. We reflect on the ramifications of this for our subject and suggest avenues for future research.

Neuropsychological functions in a pediatric case of partial agenesis of the corpus callosum: Clinical implications

The corpus callosum (CC) is involved in several cognitive processes and the interhemispheric transfer of information. The current case study investigated neurocognitive and emotional processes in a 7-year-old female with partial agenesis of the corpus callosum, with an absent splenium and posterior body, with comorbid autism and ADHD. We measured cognitive functions, such as response inhibition, error monitoring, attentional disengagement, and attention capture by irrelevant emotional stimuli. We found that response inhibition was intact in the case. When happy faces were used as stop-signals, it interfered with response inhibition compared to angry-face-stop-signals. Similarly, happy faces (relative to angry faces) interfered with error monitoring; irrelevant angry faces captured attention more than happy faces. Attentional disengagement functions were impaired in the case compared to healthy controls. The findings give an insight into the interaction between cognition and emotion in pediatric partial agenesis of the CC, and have important clinical and theoretical implications.

Incidence and patterns of abnormal corpus callosum in fetuses with isolated spina bifida aperta

OBJECTIVE

To determine the incidence and characterise corpus callosum (CC) abnormalities in fetuses with spina bifida aperta (SBA) between 18 and 26 weeks of gestation.

METHODS

This was a retrospective study on fetuses with isolated SBA and who were assessed for fetal surgery. Digitally stored ultrasound images of the brain were reviewed for the presence/absence of the CC, and the length and diameter of its constituent parts (rostrum, genu, body and splenium). We used regression analysis to determine the relationship between CC abnormalities and gestational age, head circumference, ventricle size, lesion level and lesion type.

RESULTS

Nearly three-quarters of fetuses with isolated SBA had an abnormal CC (71.7%, 76/106). Partial agenesis was most common in the splenium (18.9%, 20/106) and the rostrum (13.2%, 14/106). The most common abnormal pattern was of a short CC with normal diameter throughout. Of note, 20.8% (22/106) had a hypoplastic genu and 28.3% (30/106) had a thick body part. Larger lateral ventricle size was associated with partial agenesis of the CC (odds ratio [OR]: 0.14, p < 0.001) and inversely associated with a shorter CC (OR: 2.60, p < 0.01).

CONCLUSION

An abnormal CC is common in fetuses with isolated SBA who are referred for fetal surgery.

Functional anatomy of idiomatic expressions

Idiomatic expressions (IE) are groups of words whose meaning is different from the sum of its components. Neural mechanisms underlying their processing are still debated, especially regarding lateralization, main structures involved, and whether this neural network is independent from the spoken language. To investigate the neural correlates of IE processing in healthy Spanish speakers.Twenty one native speakers of Spanish were asked to select one of 4 possible meanings for IE or literal sentences. fMRI scans were performed in a 3.0T scanner and processed by SPM 12 comparing IE vs. literal sentences. Laterality indices were calculated at the group level. IE activated a bilateral, slightly right-sided network comprising the pars triangularis and areas 9 and 10. In the left hemisphere (LH): the pars orbitalis, superior frontal, angular and fusiform gyrus. In the right hemisphere (RH): anterior insula, middle frontal, and superior temporal gyrus. This network reveals the importance of the RH, besides traditional LH areas, to comprehend IE. This agrees with the semantic coding model: the LH activates narrow semantic fields choosing one single meaning and ignoring others, and the RH detects distant semantic relationships, activating diffuse semantic fields. It is also in line with the configuration hypothesis: both meanings, literal and figurative, are executed simultaneously, until the literal meaning is definitively rejected and the figurative one is accepted. Processing IE requires the activation of fronto-temporal networks in both hemispheres. The results concur with previous studies in other languages, so these networks are independent from the spoken language. Understanding these mechanisms sheds light on IE processing difficulties in different clinical populations and must be considered when planning resective surgery.

The correlation between white matter integrity and pragmatic language processing in first episode schizophrenia

Objective: Higher-order language disturbances could be the result of white matter tract abnormalities. The study explores the relationship between white matter and pragmatic skills in first-episode schizophrenia. Methods: Thirty-four first-episode patients with schizophrenia and 32 healthy subjects participated in a pragmatic language and Diffusion Tensor Imaging study, where fractional anisotropy of the arcuate fasciculus, corpus callosum and cingulum was correlated with the Polish version of the Right Hemisphere Language Battery. Results: The patients showed reduced fractional anisotropy in the right arcuate fasciculus, left anterior cingulum bundle and left forceps minor. Among the first episode patients, reduced understanding of written metaphors correlated with reduced fractional anisotropy of left forceps minor, and greater explanation of written and picture metaphors correlated with reduced fractional anisotropy of the left anterior cingulum. Conclusions: The white matter dysfunctions may underlie the pragmatic language impairment in schizophrenia. Our results shed further light on the functional neuroanatomical basis of pragmatic language use by patients with schizophrenia.

Cognitive and motor function in adults with spina bifida myelomeningocele: a pilot study

PURPOSE

Determine the feasibility and utility of using a battery of tests utilized, so far, to assess neurological-cognitive functions in the typical adult population and identify the spectrum of these functions in adult SBM patients.

METHODS

Prospective study in which 15 participants (mean age = 28.7 ± 8.7 years, range = 19-45 years) completed the targeted battery of tests (n = 5-15/test) previously standardized to the general population. Results were compared with normative data.

RESULTS

Statistically significant differences with normative means were noted in the following tests: Montreal Cognitive Assessment (MoCA), Functional Activities Questionnaire (FAQ), and NIH Toolbox Fine Motor (Dexterity and Grip Strength) tests. Cohort means for NIH Toolbox Fluid, Crystallized, and Cognitive Composite Scores and Timed Up and GO (TUG) were not different from normative means.

CONCLUSION

All tests were successfully completed by cohort. Whereas many aspects of cognition were normal, tests assessing visual-constructural, calculation, motor, and fluency functions did show differences from population means. Numerous tests assessing multiple domains are needed and can be used in future aging studies to appreciate the spectrum of cognitive and motor abilities in adults with SBM.

Cranial findings detected by second-trimester ultrasound in fetuses with myelomeningocele: a systematic review

Background

Abnormal intracranial findings are often detected at mid‐trimester ultrasound (US) in fetuses with myelomeningocele (MMC). It is unclear whether these findings constitute a spectrum of the disease or are an independent finding, which should contraindicate fetal surgery.

Objective

To ascertain the spectrum and frequency of US‐detected cranial findings in fetuses with MMC.

Search strategy

MEDLINE, Embase, Web of Science and CENTRAL were searched from January 2000 to June 2020.

Selection criteria

Study reporting incidence of cranial US findings in consecutive cases of second‐trimester fetuses with MMC.

Data collection and analysis

Publication quality was assessed by Newcastle–Ottawa Scale (NOS) and modified NOS. Meta‐analysis could not be performed as a result of high clinical diversity and study heterogeneity.

Main results

Fourteen cranial US findings were reported in 15 studies. Findings in classic Chiari II malformation (CIIM) spectrum included posterior fossa funnelling (96%), small transcerebellar diameter (82–96%), ‘banana’ sign (50–100%), beaked tectum (65%) and ‘lemon’ sign (53–100%). Additional cranial findings were small biparietal diameter (BPD) and head circumference (HC) (<5th centile; 53 and 71%, respectively), ventriculomegaly (45–89%), abnormal pointed shape of the occipital horn (77–78%), thinning of the posterior cerebrum, perinodular heterotopia (11%), abnormal gyration (3%), corpus callosum disorders (60%) and midline interhemispheric cyst (42%).

Conclusions

We identified 14 cranial findings by second‐trimester US in fetuses with MMC. The relatively high incidence of these findings and their unclear prognostic significance might not contraindicate fetal surgery in the case of normal fetal genetic testing. Some cranial findings may independently affect postnatal outcome, however. Long‐term detailed follow‐up is required to investigate this.

Tweetable abstract

A high rate of cranial abnormalities found on second‐trimester ultrasound in fetuses with myelomeningocele.

A high rate of cranial abnormalities found on second‐trimester ultrasound in fetuses with myelomeningocele.

Neurobehavioral outcomes in patients with myelomeningocele

This paper describes some of the more common patterns in neurobehavioral deficits and their underlying neuroanatomical basis in myelomeningocele (MMC). Patients with MMC can face a lifetime of specific organ system dysfunction, chief among them spinal cord malformations, orthopedic issues, hydrocephalus, and urological disabilities. In addition, patients can experience specific patterns of neurobehavioral difficulties due to the changes in neuroanatomy associated with the open spinal defect. Although there is variability in these patterns, some trends have been described among MMC patients. It is thought that early recognition of these potential neurobehavioral deficits by treating neurosurgeons and other members of the treatment team could lead to earlier intervention and positively impact the overall outcome for patients. Neurodevelopmental and neurobehavioral follow-up assessments are recommended to help guide planning for relevant treatments or accommodations.

Integration Between Cerebral Hemispheres Contributes to Defense Mechanisms

Defense mechanisms are mental functions which facilitate coping when real or imagined events challenge personal wishes, needs, and feelings. Whether defense mechanisms have a specific neural basis is unknown. The present research tested the hypothesis that interhemispheric integration plays a critical role in defense mechanism development, by studying a unique sample of patients born without the corpus callosum (agenesis of the corpus callosum; AgCC). Adults with AgCC (N = 27) and matched healthy volunteers (N = 30) were compared on defense mechanism use across increasing levels of developmental maturity (denial, least; projection, intermediate; identification, most). Narratives generated in response to Thematic Apperception Test images were scored according to the Defense Mechanism Manual. Greater use of denial and less identification was found in persons with AgCC, compared to healthy comparisons. This difference emerged after age 18 when full maturation of defenses among healthy individuals was expected. The findings provide clinically important characterization of social and emotional processing in persons with AgCC. More broadly, the results support the hypothesis that functional integration across the hemispheres is important for the development of defense mechanisms.

Neuropsychological care guidelines for people with spina bifida

While the neuropsychological profile for individuals with Spina Bifida (SB) can vary, often certain patterns of strengths and weaknesses are evident across the lifespan. Understanding variability related to neural structure, genetics, ethnicity, and the environment is key to understanding individual differences in outcomes and can be vital in planning interventions and tracking progress. This article outlines the SB Guideline for the Neuropsychological Care of People with Spina Bifida from the 2018 Spina Bifida Association's Fourth Edition of the Guidelines for the Care of People with Spina Bifida and acknowledges that further research in SB neurocognitive profiles is warranted.

A Neuropsychological Profile for Agenesis of the Corpus Callosum? Cognitive, Academic, Executive, Social, and Behavioral Functioning in School-Age Children

OBJECTIVES

Agenesis of the corpus callosum (AgCC), characterized by developmental absence of the corpus callosum, is one of the most common congenital brain malformations. To date, there are limited data on the neuropsychological consequences of AgCC and factors that modulate different outcomes, especially in children. This study aimed to describe general intellectual, academic, executive, social and behavioral functioning in a cohort of school-aged children presenting for clinical services to a hospital and diagnosed with AgCC. The influences of age, social risk and neurological factors were examined.

METHODS

Twenty-eight school-aged children (8 to 17 years) diagnosed with AgCC completed tests of general intelligence (IQ) and academic functioning. Executive, social and behavioral functioning in daily life, and social risk, were estimated from parent and teacher rated questionnaires. MRI findings reviewed by a pediatric neurologist confirmed diagnosis and identified brain characteristics. Clinical details including the presence of epilepsy and diagnosed genetic condition were obtained from medical records.

RESULTS

In our cohort, ~50% of children experienced general intellectual, academic, executive, social and/or behavioral difficulties and ~20% were functioning at a level comparable to typically developing children. Social risk was important for understanding variability in neuropsychological outcomes. Brain anomalies and complete AgCC were associated with lower mathematics performance and poorer executive functioning.

CONCLUSIONS

This is the first comprehensive report of general intellectual, academic, executive social and behavioral consequences of AgCC in school-aged children. The findings have important clinical implications, suggesting that support to families and targeted intervention could promote positive neuropsychological functioning in children with AgCC who come to clinical attention. (JINS, 2018, 24, 445-455).

Individuals with agenesis of the corpus callosum show sensory processing differences as measured by the sensory profile

OBJECTIVE

Given reports of high pain thresholds and reduced auditory response in individuals with agenesis of the corpus callosum (AgCC), this study investigated whether affected participants report atypical experiences and behaviors on a well-established sensory processing measure.

METHODS

Fourteen participants with AgCC (ages 11-59) completed the Adolescent/Adult Sensory Profile (Brown & Dunn, 2001). Sensory profile scales were classified as "Atypical" if they were more than 1 standard deviation from the mean.

RESULTS

Fifty-seven percent of participants with AgCC reported reduced sensory registration as compared to an expected 16% of the normative sample. Similarly, 50% of the AgCC participants reported atypically increased auditory processing difficulties.

CONCLUSIONS

Using a well-established sensory processing questionnaire, participants with AgCC reported measurable differences in multiple aspects of sensory processing. The most notable difference was in the quadrant of low sensory registration, suggesting that individuals with AgCC may require sensory information to be presented more slowly or at a higher intensity for adequate processing. The sensory modality that was most affected was the auditory system, which is consistent with increased rates of language disorders and autism spectrum disorders in this population. Understanding sensory processing in individuals with AgCC can both elucidate the role of interhemispheric transfer in the development of intact sensory processing as well as contribute to our knowledge of the role of the corpus callosum in a range of disorders in which sensory processes are impacted. (PsycINFO Database Record

Structure, integrity, and function of the hypoplastic corpus callosum in spina bifida myelomeningocele

Although there are many studies of people with complete or partial hypogenesis of the corpus callosum (CC), little is understood about the hypoplastic CC in which all structures are present but thinned. Spina bifida myelomeningocele (SBM) is a model organism for such studies because many have either a hypogenetic or hypoplastic CC. We used diffusion tensor tractography (DTT) to evaluate the hypoplastic CC in SBM and its relation to interhemispheric functions and intelligence quotient (IQ). Participants were individuals with SBM and an intact or hypoplastic CC (n=28), who were compared to a typically developing comparison group (n=32). Total and regional DTT volume and integrity measures (fractional anisotropy, axial diffusivity, and radial diffusivity) of the CC were related to measures of intelligence (IQ), bimanual motor functioning, and dichotic auditory performance. As predicted, DTT showed variations in volume and integrity that were maximized in the entire CC and the posterior CC. IQ correlated with entire CC volume, anterior and posterior regional CC volumes, and also with measures of integrity. Bimanual motor functioning correlated with the anterior and posterior volumes of the CC but not with any integrity measures. Axial diffusivity in the posterior CC was negatively correlated with right ear dichotic listening performance. The hypoplastic CC is not macrostructurally or microstructurally intact in SBM, even when it appears radiologically intact. Both volume and integrity of the posterior regions were related to reductions in IQ and to interhemispheric processing. These findings may transfer to other disorders characterized by a hypoplastic CC.

Facial emotion recognition in agenesis of the corpus callosum

BACKGROUND

Impaired social functioning is a common symptom of individuals with developmental disruptions in callosal connectivity. Among these developmental conditions, agenesis of the corpus callosum provides the most extreme and clearly identifiable example of callosal disconnection. To date, deficits in nonliteral language comprehension, humor, theory of mind, and social reasoning have been documented in agenesis of the corpus callosum. Here, we examined a basic social ability as yet not investigated in this population: recognition of facial emotion and its association with social gaze.

METHODS

Nine individuals with callosal agenesis and nine matched controls completed four tasks involving emotional faces: emotion recognition from upright and inverted faces, gender recognition, and passive viewing. Eye-tracking data were collected concurrently on all four tasks and analyzed according to designated facial regions of interest.

RESULTS

Individuals with callosal agenesis exhibited impairments in recognizing emotions from upright faces, in particular lower accuracy for fear and anger, and these impairments were directly associated with diminished attention to the eye region. The callosal agenesis group exhibited greater consistency in emotion recognition across conditions (upright vs. inverted), with poorest performance for fear identification in both conditions. The callosal agenesis group also had atypical facial scanning (lower fractional dwell time in the eye region) during gender naming and passive viewing of faces, but they did not differ from controls on gender naming performance. The pattern of results did not differ when taking into account full-scale intelligence quotient or presence of autism spectrum symptoms.

CONCLUSIONS

Agenesis of the corpus callosum results in a pattern of atypical facial scanning characterized by diminished attention to the eyes. This pattern suggests that reduced callosal connectivity may contribute to the development and maintenance of emotion processing deficits involving reduced attention to others' eyes.

Agenesis of the corpus callosum and autism: a comprehensive comparison

The corpus callosum, with its ∼200 million axons, remains enigmatic in its contribution to cognition and behaviour. Agenesis of the corpus callosum is a congenital condition in which the corpus callosum fails to develop; such individuals exhibit localized deficits in non-literal language comprehension, humour, theory of mind and social reasoning. These findings together with parent reports suggest that behavioural and cognitive impairments in subjects with callosal agenesis may overlap with the profile of autism spectrum disorders, particularly with respect to impairments in social interaction and communication. To provide a comprehensive test of this hypothesis, we directly compared a group of 26 adults with callosal agenesis to a group of 28 adults with a diagnosis of autism spectrum disorder but no neurological abnormality. All participants had full-scale intelligence quotient scores >78 and groups were matched on age, handedness, and gender ratio. Using the Autism Diagnostic Observation Schedule together with current clinical presentation to assess autistic symptomatology, we found that 8/26 (about a third) of agenesis subjects presented with autism. However, more formal diagnosis additionally involving recollective parent-report measures regarding childhood behaviour showed that only 3/22 met complete formal criteria for an autism spectrum disorder (parent reports were unavailable for four subjects). We found no relationship between intelligence quotient and autism symptomatology in callosal agenesis, nor evidence that the presence of any residual corpus callosum differentiated those who exhibited current autism spectrum symptoms from those who did not. Relative to the autism spectrum comparison group, parent ratings of childhood behaviour indicated children with agenesis were less likely to meet diagnostic criteria for autism, even for those who met autism spectrum criteria as adults, and even though there was no group difference in parent report of current behaviours. The findings suggest two broad conclusions. First, they support the hypothesis that congenital disruption of the corpus callosum constitutes a major risk factor for developing autism. Second, they quantify specific features that distinguish autistic behaviour associated with callosal agenesis from autism more generally. Taken together, these two findings also leverage specific questions for future investigation: what are the distal causes (genetic and environmental) determining both callosal agenesis and its autistic features, and what are the proximal mechanisms by which absence of the callosum might generate autistic symptomatology?

Self-referential and social cognition in a case of autism and agenesis of the corpus callosum

BACKGROUND

While models of autism spectrum conditions (ASC) are emerging at the genetic level of analysis, clear models at higher levels of analysis, such as neuroanatomy, are lacking. Here we examine agenesis of the corpus callosum (AgCC) as a model at the level of neuroanatomy that may be relevant for understanding self-referential and social-cognitive difficulties in ASC.

METHODS

We examined performance on a wide array of tests in self-referential and social-cognitive domains in a patient with both AgCC and a diagnosis of ASC. Tests included a depth-of-processing memory paradigm with self-referential and social-cognitive manipulations, self-report measures of self-consciousness, alexithymia, and empathy, as well as performance measures of first-person pronoun usage and mentalizing ability. The performance of the AgCC patient was compared to a group of individuals with ASC but without AgCC and with neurotypical controls. These comparison groups come from a prior study where group differences were apparent across many measures. We used bootstrapping to assess whether the AgCC patient exhibited scores that were within or outside the 95% bias-corrected and accelerated bootstrap confidence intervals observed in both comparison groups.

RESULTS

Within the depth-of-processing memory paradigm, the AgCC patient showed decreased memory sensitivity that was more extreme than both comparison groups across all conditions. The patient's most pronounced difficulty on this task emerged in the social-cognitive domain related to information-processing about other people. The patient was similar to the ASC group in benefiting less from self-referential processing compared to the control group. Across a variety of other self-referential (i.e. alexithymia, private self-consciousness) and social-cognitive measures (i.e. self-reported imaginative and perspective-taking subscales of empathy, mentalizing), the AgCC patient also showed more extreme scores than those observed for both of the comparison groups. However, the AgCC patient scored within the range observed in the comparison groups on measures of first-person pronoun usage and self-reported affective empathy subscales.

CONCLUSIONS

We conclude that AgCC co-occurring with a diagnosis of ASC may be a relevant model at the level of neuroanatomy for understanding mechanisms involved in self-referential and high-level social-cognitive difficulties in ASC.

Callosal dysgenesis in fetuses with ventriculomegaly: levels of agreement between imaging modalities and postnatal outcome

OBJECTIVE

To assess neurodevelopmental outcome of fetuses diagnosed with callosal abnormalities after referral for ventriculomegaly.

METHODS

This sub-analysis of a prospective study of 430 fetuses, which were referred for ventriculomegaly and underwent sonography and magnetic resonance imaging (MRI), included those fetuses with a diagnosis of corpus callosal abnormalities after recruitment into the main study. Between three and six radiologists independently reviewed ultrasound and MR images and recorded central nervous system (CNS) abnormalities, with final diagnoses being decided by consensus. Postnatal outcomes of fetuses with callosal abnormalities were compared between those with and those without other abnormalities.

RESULTS

Callosal abnormalities were detected in 13% (58/430) of the fetuses referred with ventriculomegaly. Callosal dysgenesis was isolated in 24% (14/58) of these cases, with the remainder complicated by CNS, karyotypic or other major abnormalities. Five fetuses diagnosed prenatally as having isolated callosal abnormalities had additional CNS findings on postnatal assessment. Preconference kappa for callosal abnormalities was 0.76 for ultrasound and 0.78 for MRI, indicating that these investigations had a similar level of operator dependence. Neurodevelopmental outcome was normal or showed only mild delay that resolved in 67% (8/12) children with isolated callosal abnormalities compared to 7% (2/27) in those with non-isolated callosal abnormalities (P = 0.003).

CONCLUSION

Callosal abnormalities are present in a significant proportion of fetuses with a diagnosis of ventriculomegaly. Isolated callosal abnormalities are associated with normal neurodevelopmental outcome in approximately two-thirds of fetuses.

Cerebellar motor function in spina bifida meningomyelocele

Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children and adults with SBM have widespread motor deficits in trunk, upper limbs, eyes, and speech articulators that are broadly congruent with those observed in adults with cerebellar lesions. The structure and function of the cerebellum are correlated with a range of motor functions. While motor learning is generally preserved in SBM, those motor functions requiring predictive signals and precise calibration of the temporal features of movement are impaired, resulting in deficits in smooth movement coordination as well as in the classical cerebellar triad of dysmetria, ataxia, and dysarthria. That motor function in individuals with SBM is disordered in a manner phenotypically similar to that in adult cerebellar lesions, and appears to involve similar deficits in predictive cerebellar motor control, suggests that age-based cerebellar motor plasticity is limited in individuals with this neurodevelopmental disorder.

Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

The cognitive phenotype of spina bifida meningomyelocele

A cognitive phenotype is a product of both assets and deficits that specifies what individuals with spina bifida meningomyelocele (SBM) can and cannot do and why they can or cannot do it. In this article, we review the cognitive phenotype of SBM and describe the processing assets and deficits that cut within and across content domains, sensory modality, and material, including studies from our laboratory and other investigations. We discuss some implications of the SBM cognitive phenotype for assessment, rehabilitation, and research.

Language disorders in children with central nervous system injury

Children with injury to the central nervous system (CNS) exhibit a variety of language disorders that have been described by members of different disciplines, in different journals, using different descriptors and taxonomies. This paper is an overview of language deficits in children with CNS injury, whether congenital or acquired after a period of normal development. It first reviews the principal CNS conditions associated with language disorders in childhood. It then describes a functional taxonomy of language, with examples of the phenomenology and neurobiology of clinical deficits in children with CNS insults. Finally, it attempts to situate language in the broader realm of cognition and in current theoretical accounts of embodied cognition.

Anomalous development of brain structure and function in spina bifida myelomeningocele

Spina bifida myelomeningocele (SBM) is a specific type of neural tube defect whereby the open neural tube at the level of the spinal cord alters brain development during early stages of gestation. Some structural anomalies are virtually unique to individuals with SBM, including a complex pattern of cerebellar dysplasia known as the Chiari II malformation. Other structural anomalies are not necessarily unique to SBM, including altered development of the corpus callosum and posterior fossa. Within SBM, tremendous heterogeneity is reflected in the degree to which brain structures are atypical in qualitative appearance and quantitative measures of morphometry. Hallmark structural features of SBM include overall reductions in posterior fossa and cerebellum size and volume. Studies of the corpus callosum have shown complex patterns of agenesis or hypoplasia along its rostral-caudal axis, with rostrum and splenium regions particularly susceptible to agenesis. Studies of cortical regions have demonstrated complex patterns of thickening, thinning, and gyrification. Diffusion tensor imaging studies have reported compromised integrity of some specific white matter pathways. Given equally complex ocular motor, motor, and cognitive phenotypes consisting of relative strengths and weaknesses that seem to align with altered structural development, studies of SBM provide new insights to our current understanding of brain structure-function associations.

The comprehension of idiomatic expressions in schizophrenic patients

Recent fMRI and TMS studies on idiom comprehension have shown that the prefrontal cortex is involved in idiom processing. Since schizophrenic patients exhibit prefrontal structural changes and dysexecutive behavioural deficits, we hypothesised an impairment in idiom comprehension, correlating with performance on executive tasks. In this study, idiom comprehension was evaluated by means of a sentence-to-picture-matching task in 45 schizophrenic patients and 45 control subjects, matched for age and educational level. The task included 62 idiomatic and 62 literal sentences. Participants were presented with a written sentence, either literal or idiomatic, followed by a picture, which appeared below the sentence. They were instructed to judge whether the picture represented the meaning of the sentence or not, and responded by pressing one of two response keys. Half of the items correctly represented the meaning, half did not. Reaction times and accuracy were measured. Schizophrenics were impaired in both types of idiomatic sentence. However, their performance was particularly poor in the case of ambiguous idioms. Wisconsin Card Sorting Test and Digit Sequencing were the unique predictors of performance for idiom comprehension in general, while thought disorganization was not. Cognitive decline either did not appear to predict performance.

Transcallosal connectivity and cortical rhythms: findings in children with spina bifida

We studied the relation between cortical oscillatory rhythms and the structural integrity of the corpus callosum in 21 children with spina bifida and hydrocephalus. Participants underwent resting state neuromagnetic recordings and diffusion tensor imaging. Areas of three segments of the corpus callosum (genu, body, splenium) were derived through diffusion tensor imaging-based morphometrics. Children with spina bifida showed reduced values of spectral power in the theta, alpha and beta bands when compared with age-matched controls, but only in the posterior and temporal regions. Reduced spectral power in posterior regions correlated with decreased area of the posterior segments of the corpus callosum. Atypical cortical oscillatory activity is associated with reduced transcallosal connectivity in children with spina bifida.

Neuropsychological assessment of attention in children with spina bifida

BACKGROUND

Children with the severe form of spina bifida (SBM: spina bifida with myelomeningocele with accompanying hydrocephalus) may manifest attention deficits, and have a similar psychological profile to children with hydrocephalus due to other etiologies. It is unclear to what extent tests to assess attention in SBM are confounded by the accompanying cognitive or visual-motor impairments. The aim of this study was to analyse attention functions by administering two different types of attention tests, one with high and the other with low cognitive and motor requirements. This enabled the possible interaction between attention and cognitive and motor impairment to be assessed.

METHODS

The study group comprised 31 children with SBM with shunted hydrocephalus. Twenty children with SB-only formed a closely matched comparison group. Of these, 19 children with SBM and 18 with SB had a full-scale IQ (FSIQ) higher than 70. All had undergone spinal surgery and all children with SBM had been shunted within the first months of life. Between 6 and 15 years of age, the children were assessed on focused and sustained attention, encoding, and distractibility/impulsivity, using both traditional tests and computerized attention tests.

RESULTS

Compared to the SB group, attention scores of children with SBM were lower on the traditional tests, but when interfering cognitive and visual-motor requirements were eliminated using the computerised tasks, most differences disappeared. Furthermore, in contrast to traditional attention tasks, computerized tests showed no significant correlations with IQ-scores and visual-motor skills.

CONCLUSION

Assessment of attention functions in children with SBM by traditional tests may be misleading, because this paediatric population with complex cerebral malformations has difficulty with the cognitive and visual-motor requirements. To control for these interactions, the use of both traditional and computerized attention tests is recommended.

Agenesis of the corpus callosum in California 1983-2003: a population-based study

The objective of this study was to characterize the prevalence, demographic risk factors, and malformations associated with agenesis and hypoplasia of the corpus callosum diagnosed in infancy. Using a large population-based registry of birth defects, we ascertained 630 cases of agenesis (ACC) and hypoplasia (HCC) of the corpus callosum diagnosed in the first year of life among 3.4 million live births from 1983 to 2003. Infants with destructive lesions or specific complex central nervous system (CNS) malformations (neural tube defects, lissencephaly, and holoprosencephaly) were excluded. Multivariable Poisson regression analysis was used to examine demographic risk factors. The combined prevalence of ACC and HCC was 1.8 per 10,000 live births. Fifty-two percent of cases were male. Infants with ACC had an almost fourfold higher prevalence among infants born prematurely when compared with children born > or =37 weeks gestation (RR 3.7, 95% CI 2.5-5.3). After adjusting for paternal age, advanced maternal age >/=40 years was associated with ACC in infants with a chromosomal disorder (ACC RR 5.9; 95% CI 1.8-19.3, HCC RR 3.5; 95% CI 0.9-14.1). Paternal age was not significantly associated with ACC after adjusting for maternal age. Callosal anomalies were often seen in the context of a chromosomal abnormality (17.3%) and with accompanying somatic (musculoskeletal 33.5% and cardiac 27.6%) and CNS malformations (49.5%). Callosal anomalies form a clinically significant and relatively frequent group of malformations of the CNS that are associated with increased risk of premature birth, are more common with advanced maternal age and are frequently part of a complex, multisystem disorder.

Characteristics of a spina bifida population including North American Caucasian and Hispanic individuals

BACKGROUND

Meningomyelocele (MM) is a common human birth defect. MM is a disorder of neural development caused by contributions from genes and environmental factors that result in the NTD and lead to a spectrum of physical and neurocognitive phenotypes.

METHODS

A multidisciplinary approach has been taken to develop a comprehensive understanding of MM through collaborative efforts from investigators specializing in genetics, development, brain imaging, and neurocognitive outcome. Patients have been recruited from five different sites: Houston and the Texas-Mexico border area; Toronto, Canada; Los Angeles, California; and Lexington, Kentucky. Genetic risk factors for MM have been assessed by genotyping and association testing using the transmission disequilibrium test.

RESULTS

A total of 509 affected child/parent trios and 309 affected child/parent duos have been enrolled to date for genetic association studies. Subsets of the patients have also been enrolled for studies assessing development, brain imaging, and neurocognitive outcomes. The study recruited two major ethnic groups, with 45.9% Hispanics of Mexican descent and 36.2% North American Caucasians of European descent. The remaining patients are African-American, South and Central American, Native American, and Asian. Studies of this group of patients have already discovered distinct corpus callosum morphology and neurocognitive deficits that associate with MM. We have identified maternal MTHFR 667T allele as a risk factor for MM. In addition, we also found that several genes for glucose transport and metabolism are potential risk factors for MM.

CONCLUSIONS

The enrolled patient population provides a valuable resource for elucidating the disease characteristics and mechanisms for MM development.

Auditory interhemispheric transfer in relation to patterns of partial agenesis and hypoplasia of the corpus callosum in spina bifida meningomyelocele

Spina bifida meningomyelocele with hydrocephalus (SBM) is commonly associated with anomalies of the corpus callosum (CC). We describe MRI patterns of regional CC agenesis and relate CC anomalies to functional laterality based on a dichotic listening test in 90 children with SBM and 27 typically developing controls. Many children with SBM (n = 40) showed regional CC anomalies in the form of agenesis of the rostrum and/or splenium, and a smaller number (n = 20) showed hypoplasia (thinning) of all CC regions (rostrum, genu, body, and splenium). The expected right ear advantage (REA) was exhibited by normal controls and children with SBM having a normal or hypoplastic splenium. It was not shown by children with SBM who were left handed, missing a splenium, or had a higher level spinal cord lesion. Perhaps the right hemisphere of these children is more involved in processing some aspects of linguistic stimuli.

Learning, memory and executive functions in children with hydrocephalus

AIMS

To explore learning, memory and executive abilities in children with hydrocephalus without learning disabilities, and to find out whether children with an isolated hydrocephalus differed from those with hydrocephalus in combination with myelomeningocele (MMC).

METHODS

Thirty-six children with an intelligence quotient (IQ) of >or=70 from a population of all the 107 children with hydrocephalus born in western Sweden in 1989-1993 were examined and compared with age- and gender-matched controls. The neuropsychological assessment of the school-aged child (NIMES) test battery was used.

RESULTS

The children with hydrocephalus differed significantly from controls in all functions apart from registration skills and recognition. Learning, memory and executive functions were all impaired. Twenty children with infantile hydrocephalus did not differ from those with hydrocephalus associated with MMC. Also, children with an IQ of >84 performed significantly worse than controls.

CONCLUSIONS

Despite an IQ of >or=70, children with hydrocephalus had significantly impaired learning, memory and executive functions. When major brain lesions resulting in learning disability had been excluded, the hydrocephalus, rather than the underlying aetiology, was most important for the development of cognitive functions.

The old and the new: supratentorial MR findings in Chiari II malformation

OBJECTIVE

The objective of this study was to use magnetic resonance imaging to develop an improved morphological understanding of the abnormalities of the forebrain in Chiari II malformation.

MATERIALS AND METHODS

Seventy-four patients with Chiari II malformations investigated between 1999 and 2007 were enrolled. Imaging was retrospectively reviewed by two pediatric neuroradiologists, with special attention given to diencephalon, midline commissures, hemispheric white matter, and cortex.

RESULTS

An abnormal gray matter structure that we called hypothalamic adhesion across the anterior-inferior portion of the third ventricle was noted in 48.6%. The anterior commissure was in a low position in the lamina terminalis in 38%. Gross abnormalities of the corpus callosum/hippocampal commissure were found in 57%; they were, however, different from the abnormalities seen in classical commissural agenesis. An abnormal bundle of white matter forming a callosal ridge was noted on the dorsal callosal surface in 60%; it is believed to represent the aberrant cingular bundle recently identified using diffusion tensor imaging. Hemispheric white matter could be considered as normal in 48%, deficient posteriorly in 55%, and globally in 10%. Cortical posterior medial stenogyria was observed in 72%. Gray matter heterotopias were found in 19%. The posterior limbic cortex was thin and dysplastic in 46%. Hippocampi were commonly abnormal (85%), with atypical sulcation of the adjacent temporo-mesial cortex (93%).

CONCLUSION

Major structural abnormalities were common in Chiari II malformation and were probably not related to hydrocephalus. Important anatomical structures involved in neurocognitive function should be considered as factors in the prognostic assessment of Chiari II patients.

A model of comprehension in spina bifida meningomyelocele: meaning activation, integration, and revision

Spina bifida meningomyelocele (SBM) is a neurodevelopmental disorder associated with adequate development of word reading and single word comprehension, but deficient text and discourse comprehension. Studies of comprehension in children with SBM are reviewed in relation to a comprehension model in which meanings are either activated from the surface code or constructed through resource-intensive integration and revision processes to form representations of the text base and models of the situation described by the text. Two new studies probed the construction of situation models in SBM. Experiment 1 tested the ability to build spatial and affective situation models from single sentences in 86 children with SBM (8 to 18 years of age) and 37 control children (8 to 16 years of age). Experiment 2 tested the ability to integrate across sentences to build spatial situation models in 15 children with SBM and 15 age-matched controls. Compared to age peers, children with SBM did not construct situation models that required integration of information across sentences, even though they could construct such models from single sentences. The data bear on the distinctive SBM neurocognitive profile, and more generally, on the significance of integration processes for the constructive aspects of language comprehension.

Idiom Comprehension: A Prefrontal Task?

We investigated the neural correlates of idiomatic sentence processing using event-related functional magnetic resonance imaging. Twenty-two healthy subjects were presented with 62 literal sentences and 62 idiomatic sentences, each followed by a picture and were required to judge whether the sentence matched the picture or not. A common network of cortical activity was engaged by both conditions, with the nonliteral task eliciting overall greater activation, both in terms of magnitude and spatial extent. The network that was specifically activated by the nonliteral condition involved the left temporal cortex, the left superior medial frontal gyrus (Brodmann area 9), and the left inferior frontal gyrus (IFG). Activations were also present in the right superior and middle temporal gyri and temporal pole and in the right IFG. In contrast, literal sentences selectively activated the left inferior parietal lobule and the right supramarginal gyrus. An analysis of effective connectivity indicated that the medial prefrontal area significantly increased the connection between frontotemporal areas bilaterally during idiomatic processing. Overall, the present findings indicate a crucial role of the prefrontal cortex in idiom comprehension, which could reflect the selection between alternative sentence meanings.

Agenesis of the corpus callosum: genetic, developmental and functional aspects of connectivity

Agenesis of the corpus callosum (AgCC), a failure to develop the large bundle of fibres that connect the cerebral hemispheres, occurs in 1:4000 individuals. Genetics, animal models and detailed structural neuroimaging are now providing insights into the developmental and molecular bases of AgCC. Studies using neuropsychological, electroencephalogram and functional MRI approaches are examining the resulting impairments in emotional and social functioning, and have begun to explore the functional neuroanatomy underlying impaired higher-order cognition. The study of AgCC could provide insight into the integrated cerebral functioning of healthy brains, and may offer a model for understanding certain psychiatric illnesses, such as schizophrenia and autism.

Evidence for bilateral involvement in idiom comprehension: An fMRI study

The goal of the current study was to identify the neural substrate of idiom comprehension using fMRI. Idioms are familiar, fixed expressions whose meaning is not dependent on the literal interpretation of the component words. We presented literally plausible idioms in a sentence forcing a figurative or a literal interpretation and contrasted them with sentences containing idioms for which no literal interpretation was available and with unambiguously literal sentences. The major finding of the current study is that figurative comprehension in the case of both ambiguous and unambiguous idioms is supported by bilateral inferior frontal gyri and left middle temporal gyrus. The right middle temporal gyrus is also involved, but seems to exclusively process the ambiguous idioms. Therefore, our data suggest a bilateral neural network underlying figurative comprehension, as opposed to the exclusive participation of the right hemisphere. The data also provide evidence against proposed models of idiom comprehension in which literal processing is by-passed, since figurative processing demanded more resources than literal processing in the language network.

Is the right hemisphere involved in idiom comprehension? A neuropsychological study

Nonambiguous idiom comprehension was assessed in 15 right brain-damaged (RBD) and 12 left brain-damaged (LBD) aphasic patients by means of a string-to-picture matching task. Idiom comprehension was found to be severely impaired with a bias toward literal interpretation. The RBD patients, though impaired, performed significantly better than LBD patients; their performance was correlated with visuospatial abilities and was significantly affected by lesion site. The results of this study suggest that the performance of RBD patients in the comprehension of idiomatic sentences may be affected by (a) an involvement of the frontal lobe and/or (b) visuospatial deficits that may impair their performance on the picture-matching task.

A model of neurocognitive function in spina bifida over the life span

Spina bifida myelomeningocele (SBM), a neural tube defect that is the product of a complex pattern of gene-environment interactions, is associated with naturally occurring, systematic variability in the neural phenotype and in environmental factors that lead to systematic variability in the cognitive phenotype. We characterize the basis for variability in the cognitive phenotype of children with SBM with reference to a model of key biological, cognitive, and environmental events unfolding over the course of development from infancy to middle age. The cognitive phenotype is not domain-specific, but represents manifestations of unobservable constructs involving associative and assembled processing, the latter directly reflecting the impact of the neural phenotype on core deficits involving movement, timing, and attention orienting. The expression of the cognitive phenotype is variable, being moderated by features of the neural phenotype involving secondary CNS insults (such as hydrocephalus) that impair assembled processing, as well as by environmental factors (such as poverty, parenting, and education) that impair associative processing. The preservation of strengths in associative processing depends in part on the severity of the CNS deficits in SBM and the impact of the environment.