BackgroundAlcohol related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD), but individuals do not demonstrate the facial characteristics associated with fetal alcohol syndrome (FAS), making diagnosis difficult. While attentional problems in ARND are similar to those found in attention-deficit/hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different.MethodsFunctional magnetic resonance imaging (fMRI) of a working memory (1-back) task of 63 children, 10 to 14 years old, diagnosed with ARND and ADHD, as well as typically developing (TD) controls, was conducted at 3 T. Diffusion tensor imaging (DTI) data were also acquired.ResultsActivations were observed in posterior parietal and occipital regions in the TD group and in dorsolateral prefrontal and posterior parietal regions in the ARND group, whereas the ADHD group activated only dorsolateral prefrontal regions, during the working memory component of the task (1-back minus 0-back contrast). The increases in frontal and parietal activity were significantly greater in the ARND group compared to the other groups. This increased activity was associated with reduced accuracy and increased response time variability, suggesting that ARND subjects exert greater effort to manage short-term memory load. Significantly greater intra-subject variability, demonstrated by fMRI region-of-interest analysis, in the ADHD and ARND groups compared to the TD group suggests that moment-to-moment lapses in attention contributed to their poorer task performance. Differences in functional activity in ARND subjects with and without a diagnosis of ADHD resulted primarily from reduced activation by the ARND/ADHD + group during the 0-back task. In contrast, children with ADHD alone clearly showed reduced activations during the 1-back task. DTI analysis revealed that the TD group had significantly higher total tract volume and number of fibers than the ARND group. These measures were negatively correlated with errors on the 1-back task, suggesting a link between white matter integrity and task performance.ConclusionsfMRI activations suggest that the similar behavior of children with ARND and ADHD on a spatial working memory task is the result of different cognitive events. The nature of ADHD in children with ARND appears to differ from that of children with ADHD alone.

BackgroundAlcohol-related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD). Diagnosis of ARND is difficult because individuals do not demonstrate the characteristic facial features associated with fetal alcohol syndrome (FAS). While attentional problems in ARND are similar to those found in attention-deficit/hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different.MethodsFunctional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) was conducted at 3 T. Sixty-three children aged 10 to 14 years diagnosed with ARND, ADHD, and typically developing (TD) controls performed a single-feature and a feature-conjunction visual search task.ResultsDorsal and ventral attention pathways were activated during both attention tasks in all groups. Significantly greater activation was observed in ARND subjects during a single-feature search as compared to TD and ADHD groups, suggesting ARND subjects require greater neural recruitment to perform this simple task. ARND subjects appear unable to effectively use the very efficient automatic perceptual ‘pop-out’ mechanism employed by TD and ADHD groups during presentation of the disjunction array. By comparison, activation was lower in ARND compared to TD and ADHD subjects during the more difficult conjunction search task as compared to the single-feature search. Analysis of DTI data using tract-based spatial statistics (TBSS) showed areas of significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) in the right inferior longitudinal fasciculus (ILF) in ARND compared to TD subjects. Damage to the white matter of the ILF may compromise the ventral attention pathway and may require subjects to use the dorsal attention pathway, which is associated with effortful top-down processing, for tasks that should be automatic. Decreased functional activity in the right temporoparietal junction (TPJ) of ARND subjects may be due to a reduction in the white matter tract’s ability to efficiently convey information critical to performance of the attention tasks.ConclusionsLimited activation patterns in ARND suggest problems in information processing along the ventral frontoparietal attention pathway. Poor integrity of the ILF, which connects the functional components of the ventral attention network, in ARND subjects may contribute to the attention deficits characteristic of the disorder.

Purpose: To use spinal cord diffusion tensor imaging (DTI) for investigating human cervical funiculi, acquire axial diffusion magnetic resonance imaging (MRI) data with an in-plane resolution sufficient to delineate subquadrants within the spinal cord, obtain corresponding DTI metrics, and assess potential regional differences. Materials and Methods:Healthy volunteers were studied with a 3 T Siemens Trio MRI scanner. DTI data were acquired using a single-shot spin echo EPI sequence. The spatial resolution allowed for the delineation of regions of interest (ROIs) in the ventral, dorsal, and lateral spinal cord funiculi. ROI-based and tractography-based analyses were performed.Results: Significant fractional anisotropy (FA) differences were found between ROIs in the dorsal and ventral funiculi (P ¼ 0.0001), dorsal and lateral funiculi (P ¼ 0.015), and lateral and ventral funiculi (P ¼ 0.0002). Transverse diffusivity was significantly different between ROIs in the ventral and dorsal funiculi (P ¼ 0.003) and the ventral and lateral funiculi (P ¼ 0.004). Tractography-based quantifications revealed DTI parameter regional differences that were generally consistent with the ROI-based analysis. IN THE LAST TWO DECADES basic research on spinal cord injury and pathology has made exciting progress in identifying factors that beneficially influence spinal cord repair and regeneration. In the human, the evaluation of treatment efficacy and spinal cord fiber tract integrity in vivo is limited to behavioral sensorimotor assessments (1-4). Notwithstanding the importance of these assessments there is a growing interest to noninvasively assess human spinal cord white matter micro-architecture in vivo (5-9).Diffusion tensor imaging (DTI) is a noninvasive magnetic resonance technique that is sensitive to the diffusion of water molecules within and across extracellular spaces of tissues. Anisotropic diffusion in the central nervous system (CNS) is caused by barriers to diffusion, such as cell membranes and myelin found in CNS white matter (WM). Higher anisotropy in WM compared to gray matter (GM) has been demonstrated in vivo in both animals and humans and it is generally understood that the primary reason for this higher anisotropy in WM is due to packed axon bundles in various WM regions (10,11). Although WM delineation with DTI is well established in brain, the application of DTI in the spinal cord is more difficult because of its small cross-sectional size, susceptibility artifacts, and motion artifacts from cerebrospinal fluid (CSF) pulsation and respiration.The diameter of the human cervical spinal cord enlargement is %13 mm. In cross-section the spinal cord is typically characterized by the butterfly-shaped GM surrounded by WM. The WM on each side of the spinal cord can be grossly divided into dorsal, lateral, and ventral funiculi. The dorsal funiculus is the spinal cord WM on either side between the dorsal median sulcus and the dorsal root. Similarly, the ventral funiculus is the WM lying on either side between the ventral me...

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