MRI morphometry of the anterior and posterior cerebellar vermis and its relationship to sensorimotor and cognitive functions in children.

INTRODUCTION: The human cerebellum emerges as a posterior brain structure integrating neural networks for sensorimotor, cognitive, and emotional processing across the lifespan. Developmental studies of the cerebellar anatomy and function are scant. We examine age-dependent MRI morphometry of the anterior cerebellar vermis, lobules I-V and posterior neocortical lobules VI-VII and their relationship to sensorimotor and cognitive functions. METHODS: Typically developing children (TDC; n=38; age 9-15) and healthy adults (HAC; n=31; 18-40) participated in high-resolution MRI. Rigorous anatomically informed morphometry of the vermis lobules I-V and VI-VII and total brain volume (TBV) employed manual segmentation computer-assisted FreeSurfer Image Analysis Program [http://surfer.nmr.mgh.harvard.edu]. The neuropsychological scores (WASI-II) were normalized and related to volumes of anterior, posterior vermis, and TBV. RESULTS: TBVs were age independent. Volumes of I-V and VI-VII were significantly reduced in TDC. The ratio of VI-VII to I-V (∼60%) was stable across age-groups; I-V correlated with visual-spatial-motor skills; VI-VII with verbal, visual-abstract and FSIQ. CONCLUSIONS: In TDC neither anterior I-V nor posterior VI-VII vermis attained adult volumes. The "inverted U" developmental trajectory of gray matter peaking in adolescence does not explain this finding. The hypothesis of protracted development of oligodendrocyte/myelination is suggested as a contributor to TDC's lower cerebellar vermis volumes.

Early Behavioral Markers of Anxiety and Reduced Frontal Brain Alpha May Predict High Risk for Bullying Victimization.

Bullying victimization has a profound negative impact on a child's emotional, social, and cognitive development. Childhood bullying victimization is reported across various social settings, suggesting common characteristics that increase a child's vulnerability to victimization. It is critical to identify early markers of such vulnerability to design preventative tools. Comprehensive semi-structured clinical interviews from mothers of child-victims and non-engaged control children included assessment of early developmental rituals and behavioral inhibition to social novelty, as potential behavioral correlates of anxiety. Neuropsychological and clinical assessment tools were used, and resting state spectral resting state EEG (rsEEG) was recorded. Increased frequency/severity of early developmental rituals and behaviorally inhibited responses to social novelty were apparent in all child-victims, alongside significantly reduced power of ventral prefrontal brain rsEEG alpha oscillations (8-13 Hz). This triad of findings, in line with prior studies, suggested an elevated early childhood anxiety, which, as current findings indicate, may be a cross-diagnostic marker of increased risk for life-long bullying victimization. Gaining insight into early childhood markers of anxiety may meaningfully complement neuropsychiatric prognosis and preventative efforts.

Posterior brain sensorimotor recruitment for inhibition of delayed responses in children.

Inhibitory control, the ability to suppress irrelevant thoughts or actions, is central to cognitive and social development. Protracted maturation of frontal brain networks has been reported as a major restraint for this ability, yet, young children, when motivated, successfully inhibit delayed responses. A better understanding of the age-dependent neural inhibitory mechanism operating during the awaiting-to-respond window in children may elucidate this conundrum. We recorded ERPs from children and parental adults to a visual-spatial working memory task with delayed responses. Cortical activation elicited during the first 1000 ms of the awaiting-to-respond window showed, as predicted by prior studies, early inhibitory effects in prefrontal ERPs (P200, 160-260 ms) associated with top-down attentional-biasing, and later effects in parietal/occipital ERPs (P300, 270-650 ms) associated with selective inhibition of task-irrelevant stimuli/responses and recurrent memory retrieval. Children successfully inhibited delayed responses and performed with a high level of accuracy (often over 90%), although, the prefrontal P200 displayed reduced amplitude and uniformly delayed peak latency, suggesting low efficacy of top-down attentional-biasing. P300, however, with no significant age-contrasts in latency was markedly elevated in children over the occipital/inferior parietal regions, with effects stronger in younger children. These results provide developmental evidence supporting the sensorimotor recruitment model of visual-spatial working memory relying on the occipital/parietal regions of the early maturing dorsal-visual network. The evidence is in line with the concept of age-dependent variability in the recruitment of cognitive inhibitory networks, complementing the former predominant focus on frontal lobes.

Maturational Changes in Human Dorsal and Ventral Visual Networks.

Developmental neuroimaging studies report the emergence of increasingly diverse cognitive functions as closely entangled with a rise-fall modulation of cortical thickness (CTh), structural cortical and white-matter connectivity, and a time-course for the experience-dependent selective elimination of the overproduced synapses. We examine which of two visual processing networks, the dorsal (DVN; prefrontal, parietal nodes) or ventral (VVN; frontal-temporal, fusiform nodes) matures first, thus leading the neuro-cognitive developmental trajectory. Three age-dependent measures are reported: (i) the CTh at network nodes; (ii) the matrix of intra-network structural connectivity (edges); and (iii) the proficiency in network-related neuropsychological tests. Typically developing children (age ~6 years), adolescents (~11 years), and adults (~21 years) were tested using multiple-acquisition structural T1-weighted magnetic resonance imaging (MRI) and neuropsychology. MRI images reconstructed into a gray/white/pial matter boundary model were used for CTh evaluation. No significant group differences in CTh and in the matrix of edges were found for DVN (except for the left prefrontal), but a significantly thicker cortex in children for VVN with reduced prefrontal ventral-fusiform connectivity and with an abundance of connections in adolescents. The higher performance in children on tests related to DVN corroborates the age-dependent MRI structural connectivity findings. The current findings are consistent with an earlier maturational course of DVN.