We present a technique for automatically assigning a neuroanatomical label to each location on a cortical surface model based on probabilistic information estimated from a manually labeled training set. This procedure incorporates both geometric information derived from the cortical model, and neuroanatomical convention, as found in the training set. The result is a complete labeling of cortical sulci and gyri. Examples are given from two different training sets generated using different neuroanatomical conventions, illustrating the flexibility of the algorithm. The technique is shown to be comparable in accuracy to manual labeling.

/pdf/automatically-parcellating-the-human-cerebral-cortex-16g7uhc9ep.pdf

Automatically Parcellating the Human Cerebral Cortex

on to develop full blown Parkinson's disease with rigidity and bradykinesia in the next few years. For those interested in the mechanisms of tremor, there are the customary authoritative reviews by Llinas, De Long, Lamarre, Rothwell and Deuschl, but uncertainty remains with respect to the relative importance of central autonomous generators and instability of peripheral reflex loops. Well written chapters are also included on primary orthostatic tremor and its relationship to essential tremor, writing tremor, neuropathic tremor, midbrain tremor and the increasingly acknowledged psychogenic tremors. Complex interrelationship between dystonia and postural tremor is also covered in depth. This cornucopia will be coveted and dipped into by those neurologists with a special interest in abnormal movement disorders, but who would not consider themselves to have a research interest in tremor. However, for the majority of clinicians involved in the hurly burly of clinical practice, I suspect that regrettably time and cost factors will conspire together to keep this excellent book out of reach. ANDREW LEES

https://jnnp.bmj.com/content/jnnp/59/3/346.1.full.pdf

Contributions to Neuropsychological Assessment

Brain development and ADHD

Most studies of attention-deficit/hyperactivity disorder (ADHD) have focused on the combined type and emphasized a core problem in response inhibition. It is proposed here that the core problem in the truly inattentive type of ADHD (not simply the subthreshold combined type) is in working memory. It is further proposed that laboratory measures, such as complex-span and dual-task dichotic listening tasks, can detect this. Children with the truly inattentive type of ADHD, rather than being distractible, may instead be easily bored, their problem being more in motivation (underarousal) than in inhibitory control. Much converging evidence points to a primary disturbance in the striatum (a frontal-striatal loop) in the combined type of ADHD. It is proposed here that the primary disturbance in truly inattentive-type ADHD (ADD) is in the cortex (a frontal-parietal loop). Finally, it is posited that these are not two different types of ADHD, but two different disorders with different cognitive and behavioral profiles, different patterns of comorbidities, different responses to medication, and different underlying neurobiologies.

Attention-deficit disorder (attention-deficit/ hyperactivity disorder without hyperactivity): a neurobiologically and behaviorally distinct disorder from attention-deficit/hyperactivity disorder (with hyperactivity).

Hand preference for writing and associations with selected demographic and behavioral variables in 255,100 subjects: the BBC internet study.

Clinical diagnosis of attention-deficit hyperactivity disorder (ADHD) is based on evaluation of behavioral functioning in three domains: inattentiveness, hyperactivity, and impulsivity. Caudate and frontal lobe function figures prominently in several neuroanatomic models of attentional functioning. Studies comparing children with and without ADHD have found differences in the size and symmetry of the caudate nuclei. Using multiple regression, we tested the hypothesis that caudate volume symmetry (log left minus log right caudate volume) measured from serial sagittal magnetic resonance images in a sample of nonreferred children (12 girls/15 boys, 7.0 to 16.6 years, 81 to 129 IQ) would predict the cumulative severity of parent-reported ADHD diagnostic behaviors beyond variance predicted by age, sex, and level of internalizing problems as measured by the Child Behavior Checklist. No child had been previously diagnosed with ADHD, although one child was found to meet diagnostic criteria based on the rating scale used for the study. The degree of caudate asymmetry significantly predicted cumulative severity ratings of inattentive behaviors (P = .015), uniquely accounting for 17.1% of the variance in inattention symptomatology over demographic variables and internalizing problems, which collectively predicted 28.9% of the variance. Caudate asymmetry uniquely accounted for only 4.3% of the variance in cumulative severity ratings of hyperactive/impulsive symptomatology over demographic variables and internalizing problems that collectively predicted 21.2% of the variance. A greater degree of right to left caudate volume asymmetry predicted subclinical inattentive behaviors in a sample of nonreferred children. This finding is congruent with neuroanatomic models of attention emphasizing lateralized alteration in prefrontal/striatal systems. The results support the view that clinical ADHD is the extreme of a behavioral continuum that extends into the normal population.

Caudate nucleus volume asymmetry predicts attention-deficit hyperactivity disorder (ADHD) symptomatology in children.

Background Neurofibromatosis type 1 (NF-1) is associated with learning disabilities and cognitive impairment in childhood and adolescence. Individuals with NF-1 have a propensity for brain hyperintensities on T2-weighted magnetic resonance images, macrocephaly, and optic gliomas. Few clear relationships between these central nervous system abnormalities and cognitive function, however, have been found in this population. Objectives To determine whether planum temporale (PT) and planum parietale (PP) morphologic features are associated with learning disabilities in NF-1. Patients and Methods We measured and compared the surface area, gray matter volume, and asymmetry of the PT and PP on T1-weighted MRIs from 24 children and adolescents with NF-1 and an equal number of controls. Relationships between these measurements and cognitive and academic achievement scores were examined. Results The left PT in boys with NF-1 was significantly smaller in both surface area and gray matter volume compared with girls with NF-1 and controls. Boys with NF-1 also showed greater symmetry between the left and right hemispheres in this region compared with girls with NF-1 and controls, who showed a pattern of left greater than right asymmetry of the PT. Intelligence-based discrepancy scores of reading and math achievement, which are commonly used to define learning disabilities, were significantly related to PT asymmetry in the NF-1 group as a whole. Less leftward asymmetry of the PT was associated with poorer reading and math achievement in relation to intellectual test scores. Conclusions The high susceptibility of individuals with NF-1 to develop reading and other learning disabilities seems to be related to the development of the sylvian fissure. These results provide further support for the hypothesized association between sylvian fissure morphologic features and learning disabilities.

https://jamanetwork.com/journals/jamaneurology/articlepdf/781764/noc10233.pdf

Significance of Planum Temporale and Planum Parietale Morphologic Features in Neurofibromatosis Type 1

Although clinical syndromes of visual-spatial neglect have been well described in adults, clinical features of neglect associated with subcortical dysfunction are infrequently reported in children and have not been described in detail. Unilateral visual-spatial neglect in a 7-year-old male following removal of a right subcortical juvenile pilocytic astrocytoma is reported. Preoperative baseline neurocognitive assessment of the patient established intact attentional and intellectual functioning. Postoperatively visual-spatial neglect was observed that was not accounted for by the patient's visual field deficit. Consistent with classic features of attentional neglect, increases in attentional demands led to greater errors in performance. The risk of unilateral neglect following resection of subcortical tumors that abut the thalamus or disrupt thalamo-cortical projections was confirmed in a retrospective analysis of patients referred for neurocognitive testing at our site. It was concluded that the ventral thalamus may play a role in visual-spatial attention early in development.

Gregory W. Schrimsher

Papers

Caudate nucleus volume asymmetry predicts attention-deficit hyperactivity disorder (ADHD) symptomatology in children.

Significance of Planum Temporale and Planum Parietale Morphologic Features in Neurofibromatosis Type 1

Visual-spatial neglect in a child following sub-cortical tumor resection.