Significant Increase In Fractional Anisotropy Research Articles

Features of changes in fractional anisotropy of different brain parts during the progression of Parkinson's disease

BACKGROUND: Parkinson's disease is a neurodegenerative disease, in second place in terms of incidence in the world after Alzheimer's disease. It is currently believed that the presymptomatic stages of Parkinson's disease are mainly associated with degeneration of the subcortical and vegetetive nervous systems, and lesions of the cerebral cortex appear on later stages of the disease, however, it is of interest to study in more detail the involvement of the pathways of the brain in the pathological process in depending the disease progression.
 OBJECTIVE: to study features of damage to the brain pathways during the progression of Parkinson's disease by magnetic resonance tractography.
 MATERIAL AND METHODS: 88 patients with Parkinson's disease were examined (stage II disease — 42 people, stage III — 46 people according to the Hoehn and Yahr scale). The control group consisted of 35 people who did not differ in gender. All patients included in the study underwent a neurological examination, as well as magnetic resonance imaging of the brain with diffusion tensor imaging.
 RESULTS: We found that with increasing stage of Parkinson's disease, there was a significant increase in fractional anisotropy in the hippocampus, insular cortex, and inferior and superior temporal sulcus cortex in patients with Parkinson's disease; we also noted a significant decrease in putamen fractional anisotropy.
 CONCLUSION: the tractography study of the brain pathways during disease progression is a promising method that allows us to clarify in the pathogenesis of Parkinson's disease, including the role of extra-nigral pathology in the development of some non-motor disorders.

Hippocampal cingulum white matter increases over time in young people at high genetic risk for bipolar disorder

BackgroundBipolar disorder (BD) is a strongly familial psychiatric disorder associated with white matter (WM) brain abnormalities. It is unclear whether such abnormalities are present in relatives without BD, and little is known about WM trajectories in those at increased genetic risk. MethodsDiffusion magnetic resonance imaging (dMRI) data were acquired at baseline and after two years in 91 unaffected individuals with a first-degree relative with bipolar disorder (HR), and 85 individuals with no family history of mental illness (CON). All participants were aged between 12 and 30 years at baseline. We examined longitudinal change in Fractional Anisotropy (FA) using tract-based spatial statistics (TBSS). ResultsCompared to the CON group, HR participants showed a significant increase in FA in the right cingulum (hippocampus) (CGH) over a two-year period (p < .05, FDR corrected). This effect was more pronounced in HR individuals without a lifetime diagnosis of a mood disorder than those with a mood disorder. LimitationsWhile our study is well powered to achieve the primary objectives, our sub-group analyses were under powered. ConclusionsIn one of the very few longitudinal neuroimaging studies of young people at high risk for BD, this study reports novel evidence of atypical white matter development in HR individuals in a key cortico-limbic tract involved in emotion regulation. Our findings also suggest that this different white matter developmental trajectory may be stronger in HR individuals without affective psychopathology. As such, increases in FA in the right CGH of HR participants may be a biomarker of resilience to mood disorders.

CNS imaging characteristics in fibromyalgia patients with and without peripheral nerve involvement

We tested the hypothesis that reduced skin innervation in fibromyalgia syndrome is associated with specific CNS changes. This prospective case–control study included 43 women diagnosed with fibromyalgia syndrome and 40 healthy controls. We further compared the fibromyalgia subgroups with reduced (n = 21) and normal (n = 22) skin innervation. Brains were analysed for cortical volume, for white matter integrity, and for functional connectivity. Compared to controls, cortical thickness was decreased in regions of the frontal, temporal and parietal cortex in the fibromyalgia group as a whole, and decreased in the bilateral pericalcarine cortices in the fibromyalgia subgroup with reduced skin innervation. Diffusion tensor imaging revealed a significant increase in fractional anisotropy in the corona radiata, the corpus callosum, cingulum and fornix in patients with fibromyalgia compared to healthy controls and decreased FA in parts of the internal capsule and thalamic radiation in the subgroup with reduced skin innervation. Using resting-state fMRI, the fibromyalgia group as a whole showed functional hypoconnectivity between the right midfrontal gyrus and the posterior cerebellum and the right crus cerebellum, respectively. The subgroup with reduced skin innervation showed hyperconnectivity between the inferior frontal gyrus, the angular gyrus and the posterior parietal gyrus. Our results suggest that the subgroup of fibromyalgia patients with pronounced pathology in the peripheral nervous system shows alterations in morphology, structural and functional connectivity also at the level of the encephalon. We propose considering these subgroups when conducting clinical trials.

Role of NODDI in the MRI Characterization of Hippocampal Abnormalities in Temporal Lobe Epilepsy: Clinico-histopathologic Correlations.

The identification of possible hippocampal alterations is a crucial point for the diagnosis and therapy of patients with unilateral temporal lobe epilepsy (TLE). This study aims to investigate the role of neurite orientation dispersion and density imaging (NODDI) compared to diffusion tensor imaging (DTI) in the comprehension of hippocampal microstructure in TLE. DTI and NODDI metrics were calculated in the hippocampi of adult patients with TLE, with and without histology-confirmed hippocampal sclerosis (HS), and in age/sex-matched healthy controls (HC). Diffusion metrics and hippocampal volumes of the pathologic side were compared within participants and between participants among the HS, non-HS, and HC groups. Diffusion metrics were also correlated with hippocampal volume and patients' clinical features. After surgery, hippocampal specimens were processed for neuropathology examinations. Fifteen patients with TLE (9 with and 6 without HS) and 11 HC were included. Hippocampal analyses resulted in a significant increase in fractional anisotropy (FA) and mean diffusivity (MD; mm2/s × 10-3) and decrease in orientation dispersion index (ODI) comparing the pathologic side of patients with HS and their relative nonpathologic side (0.203 vs 0.183, 0.825 vs 0.724, 0.366 vs 0.443, respectively), the pathologic side of patients without HS (0.203 vs 0.169, 0.825 vs 0.745, 0.366 vs 0.453, respectively), and HC (0.203 vs 0.172, 0.825 vs 0.729, 0.366 vs 0.447, respectively). Moreover, neurite density (ND) was significantly decreased comparing both hippocampi of patients with HS (0.416 vs 0.460). A significant increase in free-water isotropic volume fraction (fiso) was found in the comparison of pathologic hippocampi of patients with HS and nonpathologic hippocampi of patients with HS (0.323 vs 0.258) and HC (0.323 vs 0.226). Hippocampal volume of all patients with TLE negatively correlated with MD (r = -0.746, p = 0.0145) and positively correlated with ODI (r = 0.719, p = 0.0145). Fiso and ND of sclerotic hippocampi positively correlated with disease duration (r = 0.684, p = 0.0424 and r = 0.670, p = 0.0486, respectively). Immunohistochemistry in sclerotic hippocampal specimens revealed neuronal loss in the pyramidal layer and fiber reorganization at the level of stratum lacunosum-moleculare, confirming ODI and ND metrics. This study shows the capability of diffusion MRI metrics to detect hippocampal microstructural alterations. Among them, ODI seems to better highlight the fiber reorganization observed by neuropathology in sclerotic hippocampi.

Hyperbaric oxygen therapy improves symptoms, brain's microstructure and functionality in veterans with treatment resistant post-traumatic stress disorder: A prospective, randomized, controlled trial.

Post-traumatic stress disorder (PTSD) is characterized by changes in both brain activity and microstructural integrity. Cumulative evidence demonstrates that hyperbaric oxygen therapy (HBOT) induces neuroplasticity and case-series studies indicate its potentially positive effects on PTSD. The aim of the study was to evaluate HBOT's effect in veterans with treatment resistant PTSD. Veterans with treatment resistant PTSD were 1:1 randomized to HBOT or control groups. All other brain pathologies served as exclusion criteria. Outcome measures included clinician-administered PTSD scale-V (CAPS-V) questionnaires, brief symptom inventory (BSI), BECK depression inventory (BDI), brain microstructural integrity evaluated by MRI diffuse tensor imaging sequence (DTI), and brain function was evaluated by an n-back task using functional MRI (fMRI). The treatment group underwent sixty daily hyperbaric sessions. No interventions were performed in the control group. Thirty-five veterans were randomized to HBOT (N = 18) or control (n = 17) and 29 completed the protocol. Following HBOT, there was a significant improvement in CAPS-V scores and no change in the control (F = 30.57, P<0.0001, Net effect size = 1.64). Significant improvements were also demonstrated in BSI and BDI scores (F = 5.72, P = 0.024 Net effect size = 0.89, and F = 7.65, P = 0.01, Net effect size = 1.03). Improved brain activity was seen in fMRI in the left dorsolateral prefrontal, middle temporal gyri, both thalami, left hippocampus and left insula. The DTI showed significant increases in fractional anisotropy in the fronto-limbic white-matter, genu of the corpus callosum and fornix. HBOT improved symptoms, brain microstructure and functionality in veterans with treatment resistant PTSD.

White Matter Microstructure Alterations Associated With Paroxetine Treatment Response in Major Depression.

More than one-third of depressive patients do not achieve remission after the first antidepressant treatment. The “watch and wait” approach used to find the most effective antidepressant leads to an increased personal, social, and economic burden in society. In order to overcome this challenge, there has been a focus on studying neural biomarkers associated with antidepressant response. Diffusion tensor imaging measures have shown a promising role as predictors of antidepressant response by pointing to pretreatment differences in the white matter microstructural integrity between future responders and non-responders to different pharmacotherapies. Therefore, the aim of the present study was to explore whether response to paroxetine treatment was associated with differences in the white matter microstructure at baseline. Twenty drug-naive patients diagnosed with major depressive disorder followed a 6- to 12-week treatment with paroxetine. All patients completed magnetic resonance brain imaging and a clinical assessment at baseline and 6–12 weeks after treatment. Whole-brain tract-based spatial statistics was used to explore differences in white matter microstructural properties estimated from diffusion magnetic resonance imaging. Voxel-wise statistical analysis revealed a significant increase in fractional anisotropy and a decrease in radial diffusivity in forceps minor and superior longitudinal fasciculus in responders compared to non-responders. Thus, alterations in white matter integrity, specifically in forceps minor and the superior longitudinal fasciculus, are associated with paroxetine treatment response. These findings pave the way for personalized treatment strategies in major depression.

DTI parameters in neonates with hypoxic-ischemic encephalopathy after total body hypothermia

Background and purpose MR imaging provides means for discriminating different patterns of Hypoxic-ischemic encephalopathy (HIE) and may distinguish most severe cases from less severe but is unable to predict long-term outcome. Diffusion tensor imaging (DTI) offers information for a more complete characterization of HIE. The purpose of this study is to compare the modifications of DTI parameters in newborns one week and six months following total-body cooling to healthy controls. Methods Forty-seven cooled newborns were studied with MRI, 20 underwent follow-up at 6 months. 12 healthy newborns and nine children at 6 months were enrolled as control groups (HC). Inferior Longitudinal Fasciculus (ILF), Corpus Callosum Fasciculus (CCF), Corticospinal Tract (CST), Optical Tract (OT), Optic Radiation (OR) were generated in all subjects. DTI parameters were evaluated in basal ganglia (BG), thalamus (TH) and tracks. Statistical analysis was performed with MANOVA. Results In newborns HIE versus HC, there were significantly lower fractional anisotropy (FA) on OR and CST and higher axial diffusivity (AD), apparent diffusion coefficient (ADC) and radial diffusivity (RD) values on CST, BG and TH in HIE-N. At 6 months there were no significant grouping effects. The analysis showed a significant increase of FA, decrease of ADC, AD, RD after 6 months for HIE and HC. Conclusions We observed modifications of parameter values in HIE newborns vs HC; however normalization of values at 6 months suggests that changes of parameters cannot be considered early biomarkers for evaluation of therapeutic hypothermia in newborns with moderate HIE and normal conventional MRI.

Breast cancer survivors living with chronic neuropathic pain show improved brain health following mindfulness-based stress reduction: a preliminary diffusion tensor imaging study.

The present study explores the benefits of an 8-week mindfulness-based stress reduction (MBSR) program to white matter integrity among breast cancer survivors experiencing chronic neuropathic pain (CNP). Twenty-three women were randomly assigned to either a MBSR treatment group (n = 13) or a waitlist control group (n = 10). Participants were imaged with MRI prior to and post-MBSR training using diffusion tensor imaging. Compared with controls, the MBSR group showed a significant increase in fractional anisotropy (FA), particularly in the left subcortical regions including the uncinate fasciculus, amygdala, and hippocampus, as well as in the external capsule and in the left sagittal stratum. No decreases to FA were found in any brain regions following MBSR training. The FA values also negatively correlated with the pain severity and pain interference scores from the BRIEF pain questionnaire. The present findings demonstrate that MBSR training may enhance the integrity of cerebral white matter that coincides with a reduction in pain perception. Further research with a larger sample size is required. This study highlights the potential for MBSR, as a non-pharmacological intervention, to provide both brain health improvement and pain perception relief for female breast cancer survivors experiencing CNP.

T18. EFFECTS OF COGNITIVE REMEDIATION ON WHITE MATTER IN INDIVIDUALS AT ULTRA-HIGH RISK FOR PSYCHOSIS – A RANDOMIZED, CONTROLLED CLINICAL TRIAL

BackgroundIndividuals at ultra-high risk for psychosis (UHR) present with subtle white matter alterations, which have been associated with clinical and functional outcome. The effect of cognitive remediation on white matter (WM) in UHR-individuals has not been investigated.MethodsIn a randomized, clinical intervention-trial (FOCUS), UHR-individuals aged 18–40 years were assigned to treatment as usual (TAU) or TAU plus cognitive remediation (CR) for 20 weeks. CR comprised 20 x 2-hour sessions of neurocognitive and social-cognitive training (SCIT). Primary outcome was whole brain fractional anisotropy (FA) derived from diffusion weighted imaging. Secondary outcomes pertained to regions of interest analyses. Planned post-hoc analyses explored dose-response effects of CR on WM. Main analyses of treatment effect of CR on primary and secondary outcomes were conducted using linear mixed models, assessing the interaction of timepoint by group (CR and TAU). Analyses were conducted according to the intention-to-treat principle.Results111 UHR-individuals and 59 healthy controls were included. Attrition-rate was 30% at 6 months post-treatment follow-up. The CR group completed a mean of 12 hours of neurocognitive training.We found no effect of CR on whole-brain or regional FA. Planned post-hoc analyses revealed significant time*group (high- and low-attendance to CR) interactions in left superior corona radiata (p<0.01), left cingulum cingulate gyrus (P=0.03), and right superior longitudinal fasciculus (P<0,01), corrected. Specifically, when compared to UHR-individuals with high attendance (UHR-high >12 hours), those with low attendance (UHR-low <12 hours) had more co-morbid diagnoses, larger recreational smoking (nicotine and cannabis), more depressive and negative symptoms, and had significantly lower global FA at baseline, and showed a significant increase in FA after treatment. Furthermore, UHR-low displayed large effect-size (ES) improvements on depressive and negative symptoms, and moderate to large ES improvements in several cognitive functions (verbal fluency, verbal working memory, and processing speed). In contrast, UHR-high displayed large ES improvements in UHR-symptoms, and moderate ES improvement on social and occupational functioning.DiscussionContradicting our main hypothesis, we found no effect of CR on whole-brain or regional FA after six months. This may be explained by both the low number of neurocognitive training sessions and the attrition rate. The average of 12 hours of neurocognitive training is considerably lower than the recommended dosage of 25–30 hours necessary for cognitive improvements. The continuous need to develop feasible interventions and enhance adherence is stressed.Nevertheless, non-specific treatment may improve WM-integrity in UHR-individuals with lower global baseline FA in those with more severe psychopathology. The UHR-low subgroup exhibited improvements with large ES in levels of depressive and negative symptoms, as well as cognitive functions. We speculate, whether our results reflect that UHR-individuals with higher baseline FA (approaching the healthy controls), present with a preserved structural capacity for increased demands and new learning, while UHR-individuals characterized by lower FA at baseline may be more amendable to neuroplastic treatment-effects. The results support the value of subgrouping in a clinically heterogenous UHR-population, which also applies to examining WM integrity.

The diffusion-tensor imaging reveals alterations in water diffusion parameters in acute pediatric concussion.

Wide-spread visualization methods which are computed tomography (CT) and magnetic resonance imaging (MRI) are not sensitive to mild traumatic brain injury (mTBI). However, mTBI may cause changes of cerebral microstructure that could be found using diffusion-tensor imaging. The aim of this study is to reveal the impact of acute mTBI (no more than 3days after trauma) on diffusion parameters in corpus callosum, corticospinal tract, and thalamus in children (aged 14-18). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were analyzed. Significant increase in FA and decrease in ADC were observed in thalamus. The trend to an increase in FA is observed in corpus callosum.

THE EFFECTS OF INTERNAL JUGULAR VEIN COMPRESSION FOR PRESERVING WHITE MATTER INTEGRITY IN HIGH SCHOOL FOOTBALL PLAYERS COMPARISON OF HIGH VS LOW

Background:Repetitive head impacts experienced during competitive sports contribute to neurologic changes over the course of a season. Internal jugular vein compression, by means of an externally worn neck collar device has shown efficacy in mitigating white matter (WM) alterations following repeated head impact exposure. However, its relative effectiveness in high versus low head impact exposures is unknown.Hypothesis/Purpose:The purpose of this study was to investigate the effectiveness of an externally worn neck collar device in limiting WM alterations over a season of high school football in players who receive high and low cumulative head impact exposures over 90 g.Methods:213 male high-school football athletes were prospectively assigned to two study groups: a control group (non-collar; n=106) and an experimental group who wore the jugular vein compression collar during all practices and games (collar; n=107). MRI data was collected from all participants pre- and post-season. Fractional anisotropy (FA), and mean, axial and radial diffusivity (MD/AD/RD) were calculated to assess WM integrity at both time points. Cumulative head impact exposure was monitored by accelerometers attached to each athlete’s left mastoid process during every exposure. Participants were dichotomized into subgroups based on accumulated exposures to hits over 90 g, which divided the entire cohort into four subgroups, using a cut-off of 40 hits : (1) non-collar group (≥40 hits, n=57); (2) collar group (≥40 hits, n=51); (3) non-collar group (<40 hits, n=49); (4) collar group (<40 hits, n=56).Results:As seen in Table 1, in athletes with ≥40 hits, both the non-collar and collar group showed significant pre- to post- season reductions in MD, AD, and/or RD. The non-collar group with ≥40 hits also showed a significant increase in FA, MD, and AD. RD, FA, and MD changes were greater in the non-collar group compared to the control group with ≥40 hits, while AD changes were greater in the collar group compared to the non-collar group with ≥ 40 hits. The non-collar group with <40 hits presented significant pre- to post-season reductions in MD, AD, and RD that were greater than the collar group with < 40 hits (whom did not show pre-to post-season changes).Discussion & Conclusion:The present results provide support for internal jugular vein compression to protect the brain from both low- and high-level repeated head impact exposure. However, less consistent changes were observed for athletes exposed to repeated, high-level head impacts, warranting further investigation.Table 1.Number of WM voxels (1x1x1mm) with significant (p < .05 after correcting for multiple comparisons) pre- to post-season DTI changes and/or significant group difference (red indicates group difference for non-collar group; blue indicates group difference for collar group) for high and low head impact exposure FA ↓ MD↓ AD↓ RD↓ FA↑ MD↑ AD↑ RD↑ #hits ≥ 40 Noncollar,n= 5701390381 702965186110Collar, n=51013313350 0000Grp_diff-011511 24660-#hits <40 Noncollar,n= 4905925956340 0000Collar, n=560000 0000Grp_diff-308627611 ----

Characterization of age-related microstructural changes in locus coeruleus and substantia nigra pars compacta

Locus coeruleus (LC) and substantia nigra pars compacta (SNpc) degrade with normal aging, but not much is known regarding how these changes manifest in MRI images, or whether these markers predict aspects of cognition. Here, we use high-resolution diffusion-weighted MRI to investigate microstructural and compositional changes in LC and SNpc in young and older adult cohorts, as well as their relationship with cognition. In LC, the older cohort exhibited a significant reduction in mean and radial diffusivity, but a significant increase in fractional anisotropy compared with the young cohort. We observed a significant correlation between the decrease in LC mean, axial, and radial diffusivities and measures examining cognition (Rey Auditory Verbal Learning Test delayed recall) in the older adult cohort. This observation suggests that LC is involved in retaining cognitive abilities. In addition, we observed that iron deposition in SNpc occurs early in life and continues during normal aging.

Zonally Magnified Oblique Multislice and Non-Zonally Magnified Oblique Multislice DWI of the Cervical Spinal Cord

The zonally magnified oblique multislice EPI (ZOOM-EPI) diffusion-weighted sequence has been visually shown to provide superior MR diffusion image quality compared with the full-FOV single-shot EPI sequence (non-ZOOM-EPI) in the adult cervical spinal cord. The purpose of this study was to examine the diffusion tensor imaging indices in the normal human cervical spinal cord between ZOOMED and non-ZOOMED DTI acquisitions and determine whether DTI values are comparable between direct and indirect age-matched groups. Fifty-four subjects 23-58 years of age (9 direct age-matched and 45 indirect age-matched) were scanned using a 1.5T scanner. Diffusion tensor indices including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were generated from the DTI dataset. These DTI values were calculated for both ZOOM and non-ZOOM acquisitions and compared at each intervertebral disc level. The variability of the DTI values for ZOOM and non-ZOOM sequences was measured using a coefficient of variation within direct and indirect age-matched controls. The mean diffusivity, axial diffusivity, and radial diffusivity values obtained along the cervical spinal cord in the age-matched controls showed a significant decrease using the ZOOM sequence (P = .05, P = .002, and P < .001). Mean fractional anisotropy showed a significant increase (P = .04) using the ZOOM sequence. The indirect age-matched controls showed a statistically significant increase in fractional anisotropy (P = .03) and a decrease in mean diffusivity (P = .002), axial diffusivity (P < .001), and radial diffusivity (P = .002) using the ZOOM sequence. Less variability has been shown in DTI using the ZOOM sequence compared with the non-ZOOM sequence in both direct and indirect age groups. The ZOOM sequence exhibited higher SNR (SNRZOOM = 22.84 ± 7.59) compared with the non-ZOOM sequence (SNRnon-ZOOM = 19.7 ± 7.05). However, when we used a 2-tailed t test assuming unequal variances, the ZOOM sequence did not demonstrate a statistically significant increase. ZOOM DTI acquisition methods provide superior image quality and precision over non-ZOOM techniques and are recommended over conventional full-FOV single-shot EPI DTI for clinical applications in cervical spinal cord imaging.

Fingolimod-improved axonal and myelin integrity of white matter tracts associated with multiple sclerosis-related functional impairments.

Fingolimod hydrochloride is an effective immunomodulatory drug in improving relapsing-remitting multiple sclerosis (RRMS). However, data on the neuroradiologic effects on white matter (WM) have not been demonstrated. In this study, we aimed elucidating the impact of 1-year fingolimod treatment on WM integrity in patients with RRMS. Diffusion tensor imaging (DTI) was applied to assess axonal and myelin integrity in specific WM tracts of patients with RRMS prior to and 1year postfingolimod treatment (n=30). The fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity, and mean diffusivity were analyzed using tract-based spatial statistics on specific regions of interest associated with impaired Expanded Disability Status Scale functional scores before treatment. In patients with impaired pyramidal function at baseline (average score 2.3±0.2, n=25), fingolimod induced a significant increase in FA (P=0.002) and decrease in RD (P=0.03) in the corticospinal tract. In patients with impaired cerebellar function at baseline (average score 2.0±0.1, n=19), significant increases in FA and decreases in RD were observed in the superior (P=0.02, P=0.01, respectively) and inferior (P=0.03, P=0.05, respectively) cerebellar peduncles. The observed results suggest increased microstructural integrity and decreased demyelination of damaged WM tracts and support the possible direct mechanism of fingolimod action.

Diffusion tensor imaging reveals morphological alterations of the lateral pterygoid muscle in patients with mandibular asymmetry.

To evaluate non-invasively the morphological features of both lateral pterygoid muscle (LPM) and masseter muscle by using diffusion tensor Imaging on two patients affected by mandibular asymmetry. Two female patients with mandibular excess and asymmetry who underwent Le Fort I osteotomy and bilateral sagittal split osteotomy were recruited for this study. Morphological (T1 weighted) and diffusion weighted images were acquired with a 3T scanner 1 week before (T0) and 1 month after the surgery (T1). Probabilistic tensor-based tractography reconstruction of bilateral masseters and LPMs was performed and mean fractional anisotropy (FA) values for both muscles were extracted. Diffusion tensor imaging was able to identify the muscle geometrical morphology and diffusion microstructural changes. Both at T0 and T1, mean FA values had no significant differences between the right and left side of masseter (at T0: p = 0.91; at T1: p = 0.54) and LPM (at T0: p = 0.92; at T1: p = 0.43), respectively. Both patients reported a significant improvement in FA mean values of the left LPM (p = 0.03) between T0 and T1, whereas no diffusion parameters' changes were observed for the bilateral masseter muscles and right LPM. We found that after the surgery the LPM ipsilateral to the deviation side showed a significant increase of FA compared to the baseline. Although preliminary, our findings suggest that diffusion tensor imaging may represent a promising tool to investigate non-invasively the masticatory muscles in temporomandibular joint disorders.

Neuroanatomical variations as a function of experience in a complex daily task: A VBM and DTI study on driving experience

Complex tasks require the learning and integration of multiple cognitive, sensory, and psychomotor skills for correct execution. Driving-related skills are developed step by step through the increase of mileage driven and the accumulation of practice in different traffic situations. The acquisition of these skills should be reflected in the brain structure. However, no previous studies have explored brain structural variations associated with driving experience. The aim of the present study was to investigate whether driving frequency, defined as average annual driving mileage, is related to neuroanatomical variations in gray matter (GM) volume and white matter (WM) integrity using voxel-based morphometry (VBM) and DTI-based fractional anisotropy (FA), respectively. We recruited 83 drivers with variable range of annual driving mileage and controlled for age, sex, handedness, IQ, time since the acquisition of driving license, use of motorcycles/mopeds and bicycles, perceived driving skills, and subjective probability of having an accident. Our results showed variations in white matter FA as a function of mileage driven. Driving experience was related to a significant increase of FA in parts of the right hemisphere superior and inferior longitudinal fasciculus, anterior thalamic radiation, forceps majors, inferior fronto-occipital fasciculus, and corticospinal tract. No significant differences were observed in gray matter volumes. FA variations were found in brain regions that have been associated with cognitive, visual, and motor processes necessary for skilled performance in driving. These results suggest that variations in white matter diffusivity can underlie the development of driving skills and safer driving.

White matter alterations in college football players: a longitudinal diffusion tensor imaging study.

The aim of this study was to evaluate longitudinal changes in the diffusion characteristics of brain white matter (WM) in collegiate athletes at three time points: prior to the start of the football season (T1), after one season of football (T2), followed by six months of no-contact rest (T3). Fifteen male collegiate football players and 5 male non-athlete student controls underwent diffusion MR imaging and computerized cognitive testing at all three timepoints. Whole-brain tract-based spatial statistics (TBSS) were used to compare fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD), and trace between all timepoints. Average diffusion values were obtained from statistically significant clusters for each individual. No athlete suffered a concussion during the study period. After one season of play (T1 to T2), we observed a significant increase in trace in a cluster located in the brainstem and left temporal lobe, and a significant increase in FA in the left parietal lobe. After six months of no-contact rest (T2 to T3), there was a significant decrease in trace and FA in clusters that were partially overlapping or in close proximity with the initial clusters (T1 to T2), with no significant changes from T1 to T3. Repetitive head impacts (RHI) sustained during a single football season may result in alterations of the brain's WM in collegiate football players. These changes appear to return to baseline after 6months of no-contact rest, suggesting remission of WM alterations. Our preliminary results suggest that collegiate football players might benefit from periods without exposure to RHI.

Pattern of structural brain changes in social anxiety disorder after cognitive behavioral group therapy: a longitudinal multimodal MRI study.

Social anxiety disorder (SAD) is characterized by fears of social and performance situations. Cognitive behavioral group therapy (CBGT) has in general positive effects on symptoms, distress and avoidance in SAD. Prior studies found increased cortical volumes and decreased fractional anisotropy (FA) in SAD compared with healthy controls (HCs). Thirty-three participants diagnosed with SAD attended in a 10-week CBGT and were scanned before and after therapy. We applied three neuroimaging methods-surface-based morphometry, diffusion tensor imaging and network-based statistics-each with specific longitudinal processing protocols, to investigate CBGT-induced structural brain alterations of the gray and white matter (WM). Surface-based morphometry revealed a significant cortical volume reduction (pre- to post-treatment) in the left inferior parietal cortex, as well as a positive partial correlation between treatment success (indexed by reductions in Liebowitz Social Anxiety Scale) and reductions in cortical volume in bilateral dorsomedial prefrontal cortex. Diffusion tensor imaging analysis revealed a significant increase in FA in bilateral uncinate fasciculus and right inferior longitudinal fasciculus. Network-based statistics revealed a significant increase of structural connectivity in a frontolimbic network. No partial correlations with treatment success have been found in WM analyses. For, we believe, the first time, we present a distinctive pattern of longitudinal structural brain changes after CBGT measured with three established magnetic resonance imaging analyzing techniques. Our findings are in line with previous cross-sectional, unimodal SAD studies and extent them by highlighting anatomical brain alterations that point toward the level of HCs in parallel with a reduction in SAD symptomatology.

Changes of White Matter Diffusion Anisotropy in Response to a 6-Week iPad Application-Based Occupational Therapy Intervention in Children with Surgically Treated Hydrocephalus: A Pilot Study.

Objective Our aims were (1) to test whether diffusion tensor imaging (DTI) could detect underlying white matter (WM) changes after a 6-week iPad application-based occupational therapy (OT) intervention in children with surgically treated hydrocephalus (HCP); and (2) to explore the association between WM changes and performance outcomes. Methods Five children (age range: 6.05-9.10 years) with surgically treated HCP completed an intensive iPad-based OT intervention targeting common domains of long-term deficits in children with HCP. The intervention included 6 weekly sessions in an OT clinic supplementing home-based program (1 hour/day, 4 days/week). DTI and neuropsychological assessments were performed before and after the intervention. Observation After the therapy, significant increases in fractional anisotropy (FA) and/or decreases in radial diffusivity were found in extensive WM areas. All participants demonstrated an increased perceptual reasoning index (PRI, Wechsler Abbreviated Scale of Intelligence: 2nd edition, PRI gains = 14.20 ± 7.56, p = 0.014). A significant positive correlation was found between PRI increase and the increase of FA in the right posterior limb of the internal capsule and the right external capsule (both p < 0.05). Conclusion This study provides initial evidence of DTI's sensitivity to detect subtle WM changes associated with performance improvements in response to a 6-week OT intervention in children with HCP.

Mindfulness-Based Stress Reduction, Fear Conditioning, and The Uncinate Fasciculus: A Pilot Study.

Mindfulness has been suggested to impact emotional learning, but research on these processes is scarce. The classical fear conditioning/extinction/extinction retention paradigm is a well-known method for assessing emotional learning. The present study tested the impact of mindfulness training on fear conditioning and extinction memory and further investigated whether changes in white matter fiber tracts might support such changes. The uncinate fasciculus (UNC) was of particular interest in the context of emotional learning. In this pilot study, 46 healthy participants were quasi-randomized to a Mindfulness-Based Stress Reduction (MBSR, N = 23) or waitlist control (N = 23) group and underwent a two-day fear conditioning, extinction learning, and extinction memory protocol before and after the course or control period. Skin conductance response (SCR) data served to measure the physiological response during conditioning and extinction memory phases. Diffusion tensor imaging (DTI) data were analyzed with probabilistic tractography and analyzed for changes of fractional anisotropy in the UNC. During conditioning, participants were able to maintain a differential response to conditioned vs. not conditioned stimuli following the MBSR course (i.e., higher sensitivity to the conditioned stimuli), while controls dropped the response. Extinction memory results were not interpretable due to baseline differences. MBSR participants showed a significant increase in fractional anisotropy in the UNC, while controls did not (group by time interaction missed significance). Pre-post changes in UNC were correlated with changes in the response to the conditioned stimuli. The findings suggest effects of mindfulness practice on the maintenance of sensitivity of emotional responses and suggest underlying neural plasticity. (ClinicalTrials.gov, Identifier NCT01320969, https://clinicaltrials.gov/ct2/show/NCT01320969).