Objective. We investigated the changes of the vestibulospinal tract (VST) and parietoinsular vestibular cortex (PIVC) using diffusion tensor imaging (DTI) and relation to balance between old and young healthy adults. Methods. This study recruited eleven old adults (6 males, 5 females; mean age 63.36±4.25 years) and 12 young adults (7 males, 5 females; mean age 28.42±4.40 years). The lateral and medial VST and PIVC were reconstructed using DTI. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. The six-minute walk test (6-MWT), the timed up and go test (TUG), and the Berg balance scale (BBS) were conducted. Spatiotemporal parameters during tandem gait and values of sway during one-leg standing using the wearable sensors were measured. All parameters between two groups were analyzed by the Mann-Whitney U test and independent t-test. Results. Statistically significant decrease in old adults was detected in the tract volume of lateral (p=0.005) and medial VST (p≤0.001) and PIVC (p=0.020). A significant decrease in FA of lateral VST (p=0.044) and MD of medial VST (p=0.001) was seen in old adults. Stride length (p=0.003) and velocity (p=0.001) during tandem gait in old adults were significantly decreased. 6MWT (p≤0.001) showed significant decrease, while TUG (p≤0.001) showed significant increase in old adults. However, mean BSS (p=0.296) was nonsignificantly different. In eyes-open condition during one-leg standing, all parameters except for reciprocal compensatory index (RCI) values were significantly decreased in old adults. The RCI in the anteroposterior (AP) direction (p≤0.001) was increased in old adults; however, the mediolateral direction (p=0.301) was nonsignificantly different between the two groups. In eye-closed condition, the changes of ankle (p=0.031) and hip (p=0.004) sway and the center of mass in the AP direction (p=0.014) showed to be significantly higher in old adults than in young adults. Conclusion. The results suggested that there was a relationship between DTI parameters in the vestibular neural pathway and balance according to aging.

Sunwoo YK, et al. Psychiatry Investig. 2009 Sep;6(3):226-229. http://dx.doi.org/10.4306/pi.2009.6.3.226

Cerebellar injury can not only cause gait and postural instability, nystagmus, and vertigo but also affect the vestibular system. However, changes in connectivity regarding the vestibular projection pathway after cerebellar injury have not yet been reported. Therefore, in the current study, we investigated differences in the connectivity of the vestibular projection pathway after cerebellar injury using diffusion tensor imaging (DTI) tractography. We recruited four stroke patients with cerebellar injury. Neural connectivity in the vestibular nucleus (VN) of the pons and medulla oblongata in patients with cerebellar injury was measured using DTI. Connectivity was defined as the incidence of connection between the VN on the pons and medulla oblongata and target brain regions such as the cerebellum, thalamus, parieto-insular vestibular cortex (PIVC), and parietal lobe. At thresholds of 10 and 30, there was lower connectivity in the ipsilateral hemisphere between the VN at the medullar level and thalamus in the patients than in healthy adults. At a threshold of 1 and 10, the patient group showed lower VN connectivity with the PIVC than healthy adults. At a threshold of 1, VN connectivity with the parietal lobe in the contralateral hemisphere was lower in the patients than in healthy adults. Additionally, at a threshold of 30, VN connectivity at the pons level with the cerebellum was lower in healthy adults than in the patients. Cerebellar injury seems to be associated with decreased vestibular projection pathway connectivity, especially in the ipsilateral thalamus, PIVC, and contralateral parietal lobe.

BACKGROUND: Walking in daily life is often accompanied by an attention-demanding task, which requires a different attentional load and external environments. Therefore, various gaits require complex and systematic interactions between several nervous

Background: The medial longitudinal fasciculus (MLF) interacts with eye movement control circuits involved in the adjustment of horizontal, vertical, and torsional eye movements. In this study, we attempted to identify and investigate the anatomical characteristics of the MLF in human brain, using probabilistic diffusion tensor imaging (DTI) tractography. Methods: We recruited 31 normal healthy adults and used a 1.5-T scanner for DTI. To reconstruct MLFs, a seed region of interest (ROI) was placed on the interstitial nucleus of Cajal at the midbrain level. A target ROI was located on the MLF of the medulla in the reticular formation of the medulla. Mean values of fractional anisotropy, mean diffusivity, and tract volumes of MLFs were measured. Results: The component of the MLF originated from the midbrain MLF, descended through the posterior side of the medial lemniscus (ML) and terminated on the MLF of medulla on the posterior side of the ML in the medulla midline. DTI parameters of right and left MLFs were not significantly different. Conclusion: The tract of the MLF in healthy brain was identified by probabilistic DTI tractography. We believe this study will provide basic data and aid future comparative research on lesion or age-induced MLF changes.