Does abnormal interhemispheric inhibition play a role in mirror dystonia?

The presence of mirror dystonia (dystonic movement induced by a specific task performed by the unaffected hand) in the dominant hand of writer's cramp patients when the nondominant hand is moved suggests an abnormal interaction between the 2 hemispheres. In this study we compare the level of interhemispheric inhibition (IHI) in 2 groups of patients with writer's cramp, one with the presence of a mirror dystonia and the other without as well as a control group. The level of bidirectional IHI was measured in wrist muscles with dual‐site transcranial magnetic stimulation with a 10‐millisecond (short IHI) and a 40‐millisecond (long IHI) interstimulus interval during rest and while holding a pen in 9 patients with mirror dystonia 7 without mirror dystonia, and 13 controls. The group of patients without mirror dystonia did not differ from the controls in their IHI level. In contrast, IHI was significantly decreased in the group of patients with mirror dystonia in comparison with the group without mirror dystonia and the controls in both wrist muscles of both the dystonic and unaffected hand whatever the resting or active condition (P = 0.001). The decrease of IHI level in the group of patients with mirror dystonia was negatively correlated with the severity and the duration of the disease: the weaker the level of IHI, the more severe was the disease and the longer its duration. Interhemispheric inhibition disturbances are most likely involved in the occurrence of mirror dystonia. This bilateral deficient inhibition further suggests the involvement of the unaffected hemisphere in the pathophysiology of unilateral dystonia. © 2013 International Parkinson and Movement Disorder Society     

Pharmacotherapeutic targeting of cation‐chloride cotransporters in neonatal seizures

Seizures are a common manifestation of acute neurologic insults in neonates and are often resistant to the standard antiepileptic drugs that are efficacious in children and adults. The paucity of evidence‐based treatment guidelines, coupled with a rudimentary understanding of disease pathogenesis, has made the current treatment of neonatal seizures empiric and often ineffective, highlighting the need for novel therapies. Key developmental differences in γ‐aminobutyric acid (GABA)ergic neurotransmission between the immature and mature brain, and trauma‐induced alterations in the function of the cation‐chloride cotransporters (CCCs) NKCC1 and KCC2, probably contribute to the poor efficacy of standard antiepileptic drugs used in the treatment of neonatal seizures. Although CCCs are attractive drug targets, bumetanide and other existing CCC inhibitors are suboptimal because of pharmacokinetic constraints and lack of target specificity. Newer approaches including isoform‐specific NKCC1 inhibitors with increased central nervous system penetration, and direct and indirect strategies to enhance KCC2‐mediated neuronal chloride extrusion, might allow therapeutic modulation of the GABAergic system for neonatal seizure treatment. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here .     

Conceptualising Loneliness in Adolescents: Development and Validation of a Self-report Instrument

This paper reports the development and psychometric evaluations of a multidimensional model of loneliness in Australian adolescents. In the first study a new instrument was designed and administered to 1,074 adolescents (ages 10–18 years, M = 13.01). An exploratory factor analysis from data supplied by 694 of these participants yielded a 4-factor structure (friendship, isolation, negative attitude to solitude, and positive attitude to solitude). Competing measurement models were then evaluated using confirmatory factor analysis with data from the remaining 380 participants; strong support was demonstrated for the conceptual model. Significant main effects were evident for geographical location (rural remote/urban), age and sex. In a second study, involving 235 Australian adolescents (ages 10.0–16 years, M = 13.8) the superiority of the first-order model represented by four correlated factors was confirmed. The findings have clinical and practical implications for professional groups represented by child and adolescent psychiatry, pediatric and clinical psychology services, researchers, and educators. Specifically, the new self-report instrument identifies adolescents who are at risk of loneliness and its associated adverse outcomes and in doing has the potential to offer new insights into prevention and intervention.     

“Not Just Right Experiences” in Adolescents: Phenomenology and Associated Characteristics

Efforts to understand the nature of “Not Just Right Experiences” (NJREs) have expanded the scientific understanding of obsessive–compulsive (OC) behavior. Approximately 80 % of unselected adults report experiencing NJREs and these experiences have been found to highly correlate with OC behavior. The purpose of this study was to assess NJREs in an unselected sample of adolescents (ages 14–17; N = 152), to compare their experience with adults (N = 237), and to assess the relation between NJREs and OC symptoms. Findings from questionnaires completed on the Internet were consistent with previous findings in adults, 81 % of adolescents endorsed recently having an NJRE. Some reactions differed according to age: adults reported NJREs as more frequent and adolescents endorsed feeling more compelled to respond. Surprisingly, OC symptoms were not significantly related to NJREs in the adolescents. Implications, limitations, and future directions for the study of NJREs in youth are discussed.     

Efferent and afferent connections of the olfactory bulb and prepiriform cortex in the pigeon (Columba livia)

Although olfaction in birds is known to be involved in a variety of behaviors, there is comparatively little detailed information on the olfactory brain. In the pigeon brain, the olfactory bulb (OB) is known to project to the prepiriform cortex (CPP), piriform cortex (CPi), and dorsolateral corticoid area (CDL), which together are called the olfactory pallium, but centrifugal pathways to the OB have not been fully explored. Fiber connections of CPi and CDL have been reported, but those of other olfactory pallial nuclei remain unknown. The present study examines the fiber connections of OB and CPP in pigeons to provide a more detailed picture of their connections using tract‐tracing methods. When anterograde and retrograde tracers were injected in OB, projections to a more extensive olfactory pallium were revealed, including the anterior olfactory nucleus, CPP, densocellular part of the hyperpallium, tenia tecta, hippocampal continuation, CPi, and CDL. OB projected commissural fibers to the contralateral OB but did not receive afferents from the contralateral olfactory pallium. When tracers were injected in CPP, reciprocal ipsilateral connections with OB and nuclei of the olfactory pallium were observed, and CPP projected to the caudolateral nidopallium and the limbic system, including the hippocampal formation, septum, lateral hypothalamic nucleus, and lateral mammillary nucleus. These results show that the connections of OB have a wider distribution throughout the olfactory pallium than previously thought and that CPP provides a centrifugal projection to the OB and acts as a relay station to the limbic system. J. Comp. Neurol. 522:1728–1752, 2014. © 2013 Wiley Periodicals, Inc.     

Factor Structure of Autistic Traits in Children with ADHD

Attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) often co-occur. Factor analyses of ASD traits in children with and without ASD indicate the presence of social and restrictive–repetitive behaviour (RRB) factors. This study used exploratory factor analyses to determine the structure of ASD traits (assessed using the Social Communication Questionnaire) in children with ADHD. Distinct factors were observed for ‘social’ and ‘rigidity’ traits, corresponding to previous factor analyses in clinical ASD and population samples. This indicates that the split between social-communicative and RRB dimensions is unaffected by ADHD in children. Moreover, the study also finds that there is some overlap across hyperactive-impulsive symptoms and RRB traits in children with ADHD, which merits further investigation.     

Prevalence of cortical superficial siderosis in patients with cognitive impairment

Cortical superficial siderosis (cSS) is a magnetic resonance imaging marker of cerebral amyloid angiopathy (CAA) and can be its sole imaging sign. cSS has further been identified as a risk marker for future intracranial hemorrhage. Although uncommon in the general population, cSS may be much more prevalent in high risk populations for amyloid pathology. We aimed to determine the frequency of cSS in patients with cognitive impairment presenting to a memory clinic. We prospectively evaluated consecutive patients presenting to our memory clinic between April 2011 and April 2013. Subjects received neuropsychological testing using the Consortium to Establish a Registry for Alzheimer’s Disease battery (CERAD-NP). Two hundred and twelve patients with documented cognitive impairment further underwent a standardized 3T-MR-imaging protocol with T2*-weighted gradient-echo sequences for detection of cSS. Thirteen of 212 patients (6.1 %) displayed cSS. In seven of them (54 %) cSS was the only imaging sign of CAA. Patients with cSS did not differ from patients without cSS with regard to medical history, age or cardiovascular risk profile. Subjects with cSS performed worse in the mini-mental state examination (p = 0.001), showed more white matter hyperintensities (p = 0.005) and more often had microbleeds (p = 0.001) compared to those without cSS. cSS is common in patients with cognitive impairment. It is associated with lower cognitive scores, white matter hyperintensities and microbleeds and can be the only imaging sign for CAA in this patient group.