Left Anterior Cingulum Research Articles

Atypical age-dependency of executive function and white matter microstructure in children and adolescents with autism spectrum disorders.

Executive function (EF) performance is associated with measurements of white matter microstructure (WMS) in typical individuals. Impaired EF is a hallmark symptom of autism spectrum disorders (ASD) but it is unclear how impaired EF relates to variability in WMS. Twenty-one male youth (8-18years) with ASD and without intellectual disability and twenty-one typical male participants (TP) matched for age, intelligence quotient, handedness, race and parental socioeconomic status were recruited. Five EF domains were assessed and several DTI-based measurements of WMS [fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD)] were estimated for eighteen white matter tracts. The ASD group had lower scores for attention (F=8.37, p=0.006) and response inhibition (F=13.09, p=0.001). Age-dependent changes of EF performance and WMS measurements were present in TP but attenuated in the ASD group. The strongest diagnosis-by-age effect was found for forceps minor, left anterior thalamic radiation and left cingulum angular bundle (all p's≤0.002). In these tracts subjects with ASD tended to have equal or increased FA and/or reduced MD and/or RD at younger ages while controls had increased FA and/or reduced MD and/or RD thereafter. Only for TP individuals, increased FA in the left anterior thalamic radiation was associated with better response inhibition, while reduced RD in forceps minor and left cingulum angular bundle was related to better problem solving and working memory performance respectively. These findings provide novel insight into the age-dependency of EF performance and WMS in ASD, which can be instructive to cognitive training programs.

Habitual sleep durations and subjective sleep quality predict white matter differences in the human brain

Self-imposed short sleep durations are increasingly commonplace in society, and have considerable health and performance implications for individuals. Reduced sleep duration over multiple nights has similar behavioural effects to those observed following acute total sleep deprivation, suggesting that lack of sleep affects brain function cumulatively. A link between habitual sleep patterns and functional connectivity has previously been observed, and the effect of sleep duration on the brain's intrinsic functional architecture may provide a link between sleep status and cognition. However, it is currently not known whether differences in habitual sleep patterns across individuals are related to changes in the brain's white matter, which underlies structural connectivity. In the present study we use diffusion–weighted imaging and a group comparison application of tract based spatial statistics (TBSS) to investigate changes to fractional anisotropy (FA) and mean diffusivity (MD) in relation to sleep duration and quality, hypothesising that white matter metrics would be positively associated with sleep duration and quality. Diffusion weighted imaging data was acquired from a final cohort of 33 (23–29 years, 10 female, mean 25.4 years) participants. Sleep patterns were assessed for a 14day period using wrist actigraphs and sleep diaries, and subjective sleep quality with the Pittsburgh Sleep Quality Index (PSQI). Median splits based on total sleep time and PSQI were used to create groups of shorter/longer and poorer/better sleepers, whose imaging data was compared using TBSS followed by post-hoc correlation analysis in regions identified as significantly different between the groups. There were significant positive correlations between sleep duration and FA in the left orbito-frontal region and the right superior corona radiata, and significant negative correlations between sleep duration and MD in right orbito-frontal white matter and the right inferior longitudinal fasciculus. Improved sleep quality was positively correlated with FA in left caudate nucleus, white matter tracts to the left orbito-frontal region, the left anterior cingulum bundle and the white matter tracts associated with the right operculum and insula, and negatively correlated with MD in left orbito-frontal white matter and the left anterior cingulum bundle. Our findings suggest that reduced cumulative total sleep time (cTST) and poorer subjective sleep quality are associated with subtle white matter micro-architectural changes. The regions we identified as being related to habitual sleep patterns were restricted to the frontal and temporal lobes, and the functions they support are consistent with those which have previously been demonstrated as being affected by short sleep durations (e.g., attention, cognitive control, memory). Examining how inter-individual differences in brain structure are related to habitual sleep patterns could help to shed light on the mechanisms by which sleep habits are associated with brain function, behaviour and cognition, as well as potentially the networks and systems responsible for variations in sleep patterns themselves.

MRI Study for the Features of Brain Conduction Pathways in Patients with an Ultra-High Risk of Endogenous Psychoses.

Diffusion parameters of brain tracts (n=18) were studied in 27 men with ultra-high risk of endogenous attack-like psychoses and 27 mentally healthy men of the same age group (fractional anisotropy; and average, radial, and axial diffusion). Correlation analysis was performed between these parameters and severity of mental disorders (SOPS scale). The indexes of radial diffusion and axial diffusion were shown to change in the left anterior thalamic radiation and right posterior cingulum bundle, respectively. Our results are consistent with published data that disturbances in the frontal and temporal lobes play an important role in the pathogenesis of schizophrenia. The degree of mental disorders correlated with diffusion parameters in the left and right anterior cingulum bundle.

An fMRI study of executive control during translation and oral reading in Cantonese-English bilingual speakers

An fMRI study of executive control during translation and oral reading in Cantonese-English bilingual speakers

Disrupted functional connectivity related to differential degeneration of the cingulum bundle in mild cognitive impairment patients.

Previous studies have demonstrated that Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) exhibited anatomical and functional abnormalities in the anterior cingulate cortex (ACC) and accumulating evidence supported the hypothesis that changes in the ACC predict the progression from aMCI to AD. In this study, we aimed to explore how the two functional and structural heterogeneous sub-regions of ACC, namely the dorsal ACC (dACC) and the ventral ACC (vACC), changed in aMCI and whether the structural connectivity affects the functional connectivity between the two ACC subregions. To investigate this hypothesis, we studied resting-state fMRI and DTI images in a group of 24 aMCIs and 29 healthy controls. The dACC exhibited a significantly increased functional connectivity in the Salience Network (SN) and a decreased functional connectivity with the vACC in aMCI. The DTI results showed that the bilateral cingulum fibers were the most damaged tracts in aMCI and that the fractional anisotrophy of the left anterior cingulum was significantly correlated with the functional connectivity between the two ACC sub-regions. In conclusion, this study revealed the pathological changes in the intrinsic functional connectivity of the ACC within SN, as well as the connectivity between the dACC and vACC in aMCI. Our study also revealed that disrupted white matter integrity of the anterior regions of the cingulum was associated with the alterations in subregional connectivity in the ACC.

MRS differentiates people with MCI who progress to dementia with Lewy bodies from people who progress to Alzheimer's disease

patients with and without apathy throughmeasurement of fractional anisotropy (FA) using by tract-based spatial statistics (TBSS). In addition, we explored the correlation pattern between FAvalues and the severity of apathy in AD patients with apathy.Results: The apathy group had significantly reduced FAvalues (p corrected<0.05) in the genu of the corpus callosum, compared to the nonapathy group. The severity of apathy was negatively correlated with FA values of the left anterior and posterior cingulum, right superior longitudinal fasciculus, splenium, body and genu of the corpus callosum and bilateral uncinate fasciculusin the apathy group (p corrected<0.05). Conclusions: This study was the first to explore FAvalues in whole brainWM inAD patients with apathy. The findings of thesemicrostructural alterations ofWMmay be the key to the understanding of underlying neurobiological mechanism and clinical significances of apathy in AD.

Diffusion tensor imaging (DTI) in the detection of white matter lesions in patients with mild cognitive impairment (MCI)

Mild cognitive impairment (MCI) is recognized as a precursor to dementia. The amnestic MCI progresses usually to Alzheimer disease. Amnestic MCI multiple domain (md-MCI) seems to progress more rapidly than amnestic MCI single domain (a-MCI). In an attempt to identify patients at risk, we examined white matter changes in MCI subtypes using diffusion tensor imaging (DTI). We also tried to correlate DTI findings to neuropsychological tests. Forty-four amnestic single domain (a-MCI) patients, 19 amnestic multi domain (md-MCI), and 25 cognitively normal (NC) controls were included in the present study. All participants were assessed clinically using a battery of cognitive tests. DTI was performed to measure fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Areas studied were corpus callosum, posterior cingulum (PC), anterior cingulum (AC), and superior longitudinal fasciculus (SLF). ADC and FA of the above areas were related to the scores of certain neuropsychological tests that evaluate visual and verbal memory. No difference in DTI measurements was found between the two MCI subtypes. ADC in MCI cases was increased in comparison with NC in the genu, PC, right SLF, and left AC. FA was spared. Verbal memory was related to ADC of the genu, PC, right AC and right SLF, and to FA of the left SLF. Visual memory was related to ADC of the genu, PC, right AC, and SLF. The strongest correlation found was between the visual memory and the ADC of the right PC (Spearman ρ = 0.45, p < 0.001). DTI revealed that ADC was increased in certain brain areas in MCI patients. No difference in DTI measurements was found between the two MCI subtypes. DTI indices correlate with cognitive performance.

Mild Traumatic Brain Injury: Longitudinal Regional Brain Volume Changes

To investigate longitudinal changes in global and regional brain volume in patients 1 year after mild traumatic brain injury (MTBI) and to correlate such changes with clinical and neurocognitive metrics. This institutional review board-approved study was HIPAA compliant. Twenty-eight patients with MTBI (with 19 followed up at 1 year) with posttraumatic symptoms after injury and 22 matched control subjects (with 12 followed up at 1 year) were enrolled. Automated segmentation of brain regions to compute regional gray matter (GM) and white matter (WM) volumes was performed by using three-dimensional T1-weighted 3.0-T magnetic resonance imaging, and results were correlated with clinical metrics. Pearson and Spearman rank correlation coefficients were computed between longitudinal brain volume and neurocognitive scores, as well as clinical metrics, over the course of the follow-up period. One year after MTBI, there was measurable global brain atrophy, larger than that in control subjects. The anterior cingulate WM bilaterally and the left cingulate gyrus isthmus WM, as well as the right precuneal GM, showed significant decreases in regional volume in patients with MTBI over the 1st year after injury (corrected P < .05); this was confirmed by means of cross-sectional comparison with data in control subjects (corrected P < .05). Left and right rostral anterior cingulum WM volume loss correlated with changes in neurocognitive measures of memory (r = 0.65, P = .005) and attention (r = 0.60, P = .01). At 1-year follow-up, WM volume in the left cingulate gyrus isthmus correlated with clinical scores of anxiety (Spearman rank correlation r = -0.68, P = .007) and postconcussive symptoms (Spearman rank correlation r = -0.65, P = .01). These observations demonstrate structural changes to the brain 1 year after injury after a single concussive episode. Regional brain atrophy is not exclusive to moderate and severe traumatic brain injury but may be seen after mild injury. In particular, the anterior part of the cingulum and the cingulate gyrus isthmus, as well as the precuneal GM, may be distinctively vulnerable 1 year after MTBI.

Apathy and White Matter Integrity in Alzheimer’s Disease: A Whole Brain Analysis with Tract-Based Spatial Statistics

The aim of this study was to investigate the microstructural alterations of white matter (WM) in Alzheimer’s disease (AD) patients with apathy and to observe the relationships with the severity of apathy. Sixty drug-naïve subjects took part in this study (30 apathetic and 30 nonapathetic subjects with AD). The loss of integrity in WM was compared in AD patients with and without apathy through measurement of fractional anisotropy (FA) using by tract-based spatial statistics (TBSS). In addition, we explored the correlation pattern between FA values and the severity of apathy in AD patients with apathy. The apathy group had significantly reduced FA values (pcorrected<0.05) in the genu of the corpus callosum compared to the nonapathy group. The severity of apathy was negatively correlated with FA values of the left anterior and posterior cingulum, right superior longitudinal fasciculus, splenium, body and genu of the corpus callosum and bilateral uncinate fasciculusin the apathy group (pcorrected<0.05). This study was the first to explore FA values in whole brain WM in AD patients with apathy. The findings of these microstructural alterations of WM may be the key to the understanding of underlying neurobiological mechanism and clinical significances of apathy in AD.

Cingulum Microstructure Predicts Cognitive Control in Older Age and Mild Cognitive Impairment

Cognitive control, an important facet of human cognition, provides flexibility in response to varying behavioral demands. Previous work has focused on the role of prefrontal cortex, notably the anterior cingulate cortex. However, it is now clear that this is one node of a distributed cognitive network. In this emerging network view, structural connections are inherent elements, but their role has not been emphasized. Furthermore, lesion and functional imaging studies have contributed little knowledge about anatomical segregation, functional specialization, and behavioral importance of white matter connections. The relationship between cognitive control and microstructure of connections within the cingulum, a major white matter tract and conduit of projections to prefrontal sites, was probed in vivo in humans with diffusion MRI. Twenty healthy controls and 25 individuals with amnestic mild cognitive impairment (MCI), an early stage of age-associated cognitive deterioration, underwent cognitive testing, including several measures of cognitive control. For each individual, the anterior, middle, posterior, and parahippocampal portions of the cingulum bundle were reconstructed separately using deterministic tractography and anatomical landmarks. Microstructural variation in the left anterior cingulum was closely related to interindividual control based on verbal or symbolic rules. Errors in a task that involved maintenance of spatial rules were largely restricted to patients with MCI and were related, additionally, to right anterior cingulum microstructure. Cognitive control in MCI was also independently related to posterior parahippocampal connections. These results show how specific subpopulations of connections are critical in cognitive control and illustrate fine-grained anatomical specializations in the white matter infrastructure of this network.

Abnormal white matter on diffusion tensor imaging in children with new-onset seizures

The aim of this study was to use whole brain quantitative analysis to identify impaired white matter (WM) integrity using diffusion tensor imaging (DTI) in children with new-onset seizures. Thirty-five children with new-onset seizures and normal MRI were recruited. Twelve patients had generalized seizures, and 23 had partial seizures. Thirty-one healthy controls were also recruited. Whole brain fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity (RD) and axial diffusivity (AD) maps of patients were compared to controls, corrected for multiple comparisons. There was significantly reduced FA in left postcentral, elevated RD in left posterior cingulum and right external capsule, elevated AD in left middle temporal WM and left thalamus, and reduced AD in left anterior cingulum, left temporal, and right supramarginal WM in patients relative to controls. Patients with partial epilepsy showed elevated RD in bilateral posterior cingulum, increased AD in left middle frontal, reduced AD in left temporal, right parietal and right supramarginal WM. Patients with generalized epilepsy showed increased AD in right cerebellum, and reduced AD in left anterior cingulum and left middle temporal WM. The findings indicate that impaired WM integrity with abnormal myelin and axons is present in children with new-onset seizures.

Asymmetry of the Dorsal Anterior Cingulate Cortex: Evidences from Multiple Modalities of MRI

The dorsal anterior cingulate cortex (dACC) has been consistently implicated in cognitive control processes. Many studies have found higher fractional anisotropy (FA) in the left anterior cingulum bundle (aCB) than in the right. However, the asymmetry of gray matter density (GMD) is not clear. Using multiple modalities of MRI, we investigated both FA and GMD in the dACC in two independent groups of healthy participants (50 per group, 18-24years old, half males and half females). Consistent with previous findings, the mean FA of the left aCB was significantly higher than that of the right. Males showed higher FA in the bilateral aCB than females. Voxel-based analysis of GMD in the dACC presented a region-specific significant asymmetry: right > left in the lower part (around callosal sulcus) but left > right in the upper part (around cingulate sulcus). No significant sex effect was found for GMD in the dACC. All these results were almost the same across the two independent groups. The complex pattern of asymmetry in GMD may imply highly differentiated functions of the dACC. Future fine-scale structural and diffusion MRI studies and a battery of cognitive behavioral measurements are needed to fully elucidate the asymmetry of the dACC.

Evidence for fractional anisotropy and mean diffusivity white matter abnormalities in the internal capsule and cingulum in patients with obsessive–compulsive disorder

There is evidence to suggest that obsessive-compulsive disorder (OCD) is associated with structural abnormalities in cortico-striato-thalamic circuits, yet the extent of white matter abnormalities is not well established. In this study, we used diffusion tensor imaging (DTI) to examine white matter integrity in specific regions of interest (ROIs) in patients with OCD. Patients with OCD and sex-, age- and IQ-matched healthy controls underwent DTI. The primary objective was to explore whether patients with OCD had white matter abnormalities in the anterior limb of the internal capsule (ALIC), the uncinate fasciculus, the genu of the corpus callosum and the cingulum. The secondary objective was to evaluate the relation between fractional anisotropy and mean diffusivity in these ROIs and other clinical variables (including age at onset of OCD, OCD severity and levels of depressive and anxiety symptomatology) in patients with OCD. There were 15 patients and 17 controls enrolled in our study. Compared with healthy controls, patients with OCD showed increased fractional anisotropy in bilateral regions of the ALIC adjacent to the body of the caudate, as well as decreased fractional anisotropy in the right anterior limb near the head of the caudate. Patients also had decreased mean diffusivity in the body of the right cingulum and the left anterior cingulum compared with controls. Correlational analyses revealed significant associations of fractional anisotropy and mean diffusivity in select circuits with OCD, depression and anxiety severity scores. Inclusion of patients with OCD receiving pharmacotherapy may have been a limitation. In addition, the patients were heterogeneous in terms of their obsessive-compulsive symptom profiles; we did not distinguish between different obsessive-compulsive symptom dimensions. The study results provide further evidence for OCD-related white matter abnormalities in the ALIC and cingulum, consistent with a cortico striatal model of OCD.

Tract-specific analysis of white matter integrity disruption in schizophrenia

Several studies have suggested that white matter integrity is disrupted in some brain regions in patients with schizophrenia. The purpose of this study was to assess the white matter integrity of the cingulum, uncinate fasciculus, fornix, and corpus callosum using diffusion tensor imaging (DTI). Participants comprised 39 patients with schizophrenia (19 males and 20 females) and 40 age-matched normal controls (20 males and 20 females). We quantitatively assessed the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the anterior cingulum, body of the cingulum, uncinate fasciculus, fornix, and corpus callosum on a tract-specific basis using diffusion tensor tractography (DTT). Group differences in FA and ADC between the patients and normal controls were sought. Additional exploratory analyses of the relationship between the FA or ADC and four clinical parameters (i.e., illness duration, positive symptom scores, negative symptom scores, and medication dosage) were performed. Results were analyzed in gender-combined and gender-separated group comparisons. FA was significantly lower on both sides of the anterior cingulum, uncinate fasciculus, and fornix in the schizophrenia patients irrespective of gender group separation. In the gender-combined analyses, significantly higher ADC values were demonstrated in the schizophrenia patients in both sides of the anterior cingulum, body of the cingulum and uncinate fasciculus, the left fornix, and the corpus callosum, compared with those of the normal controls. In the gender-separated analyses, the male patients showed higher ADC in the left anterior cingulum, the bilateral cingulum bodies, and the bilateral uncinate fasciculi. The female patients showed higher ADC in the right anterior cingulum, the left fornix, and the bilateral uncinate fasciculus. In correlation analyses, a significant negative correlation was found between illness duration and ADC in the right anterior cingulum in the gender-combined analyses. The gender-separated analyses found that the male patients had a significant negative correlation between negative symptom scores and FA in the right fornix, a positive correlation between illness duration and FA in the right anterior cingulum, and a negative correlation between illness duration and FA in the left uncinate fasciculus. Our DTI study showed that the integrity of white matter is disrupted in patients with schizophrenia. The results of our sub-analyses suggest that changes in FA and ADC may be related to negative symptom scores or illness duration.

Microstructural Alteration of the Anterior Cingulum is Associated With Apathy in Alzheimer Disease

To identify regional alterations of white matter integrity associated with apathy in Alzheimer disease (AD). Cross-sectional study. University Dementia Clinic. Fifty-one very mild or mild probable AD subjects. Volumetric magnetic resonance imaging with diffusion tensor imaging. Volume of interest analyses were performed to compare regional fractional anisotropy (FA) between apathy and apathy-free group, and to test linear relationship between regional FA and apathy severity. Apathy was assessed by the Neuropsychiatric Inventory. Apathy group showed significantly lower FA values than apathy-free group in the left anterior cingulum (A-C), regardless of concomitant depression and psychotropic medications. Left A-C FA values also had significant linear relationship with apathy-composite scores as a measure of apathy severity, even after controlling gray matter density of the ipsilateral anterior cingulate cortex. Our findings support that communication failure between the anterior cingulate cortex and other brain structures via the A-C contributes to the development and aggravation of apathy in AD, additionally supporting the general notion of disconnection syndrome for clinical manifestation of AD.

Regionally Specific White Matter Disruptions of Fornix and Cingulum in Schizophrenia

Limbic circuitry disruptions have been implicated in the psychopathology and cognitive deficits of schizophrenia, which may involve white matter disruptions of the major tracts of the limbic system, including the fornix and the cingulum. Our study aimed to investigate regionally specific abnormalities of the fornix and cingulum in schizophrenia using diffusion tensor imaging (DTI). We determined the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) profiles along the fornix and cingulum tracts using a fibertracking technique and a brain mapping algorithm, the large deformation diffeomorphic metric mapping (LDDMM), in the DTI scans of 33 patients with schizophrenia and 31 age-, gender-, and handedness-matched healthy controls. We found that patients with schizophrenia showed reduction in FA and increase in RD in bilateral fornix, and increase in RD in left anterior cingulum when compared to healthy controls. In addition, tract-based analysis revealed specific loci of these white matter differences in schizophrenia, that is, FA reductions and AD and RD increases occur in the region of the left fornix further from the hippocampus, FA reductions and RD increases occur in the rostral portion of the left anterior cingulum, and RD and AD increases occur in the anterior segment of the left middle cingulum. In patients with schizophrenia, decreased FA in the specific loci of the left fornix and increased AD in the right cingulum adjoining the hippocampus correlated with greater severity of psychotic symptoms. These findings support precise disruptions of limbic-cortical integrity in schizophrenia and disruption of these structural networks may contribute towards the neural basis underlying the syndrome of schizophrenia and clinical symptomatology.

P02-363 - Exploration of irony comprehension in schizophrenia with fMRI

IntroductionIrony is a form of speech used to convey feelings in an indirect way. Schizophrenic patients usually demonstrate impaired irony processing, associated with poor theory of mind.AimsWe used fMRI to examine neural circuitry underlying deficits in understanding irony in schizophrenia.Methods21 schizophrenic patients and 24 healthy subjects were studied. Short scenarios and three conditions were used: irony condition (IC), irony with linguistic help condition (IHC), and control condition (CC). We used event-related design. Scenarios started with a contextual part, followed by a 2–4s ISI. The ironic sentence appeared next, and a question followed. Between trials an ITI of 5–7s were used.ResultsPatients performed significantly worse in the conditions (IC:p = 0.0003;IHC:p = 0.0034;CC:p = 0.0036). In the IC: patients activated the left insula, left anterior cingulum, right and left superior frontal gyrus (SFG), right middle frontal gyrus (MFG) during the contextual part, and activated the left inferior frontal gyrus (IFG), left middle temporal gyrus (MTG) and right superior temporal gyrus during the statement. In the IHC: patients activated the left precuneus, left IFG, left SFG, left and right MFG, right cuneus and left MTG during the context, and activated right SFG and left posterior cingulum during the statement.ConclusionsPatients probably have an abnormal contextual processing and a missing activation of the theory of mind network during the interpretation of ironic statements. The given linguistic help proved to be efficient help for many patients in processing the context correctly, and in understanding ironic situations more successfully.

Abnormal Cingulate and Prefrontal Cortical Neurochemistry in Major Depression After Electroconvulsive Therapy

Metabolic changes after electroconvulsive therapy (ECT) have been described in depressed patients, but results are heterogeneous. To determine the concentrations of N-acetyl-aspartate (NAA), choline-containing compounds, creatine + phosphocreatine (tCr), and glutamate in the left dorsolateral prefrontal cortex (DLPFC) and left anterior cingulum of depressed patients before and after ECT, we used proton magnetic resonance spectroscopy. Metabolite concentrations in the DLPFC and anterior cingulum were determined in 25 patients with major depressive disorder (MDD) and 27 healthy control subjects using the point resolved spectroscopy sequence. Neuropsychological and clinical parameters were determined before and after nine sessions of right unilateral ultrabrief pulse ECT. In the cingulum, baseline glutamate and NAA levels were decreased in depressed patients. High glutamate at baseline predicted a greater treatment response. After ECT, increased NAA levels were observed in responders to treatment and tCr levels were significantly decreased across all depressive patients. In the left DLPFC, NAA levels were significantly decreased in responders to ECT compared with nonresponders. Autobiographic memory was deteriorated in all patients after ECT. Low glutamatergic state in depressive patients emphasizes the role of dysfunctional glutamatergic neurotransmission in the pathophysiology of MDD. The low NAA level at baseline in the patients supports neurodegenerative changes in MDD. N-acetyl-aspartate levels might serve as early surrogate marker for dynamic metabolic changes due to ECT, reflecting both neuroprotection and lowered neuronal viability. The tCr decrease in the cingulum suggests altered mitochondrial energy metabolism.

Structural neuroplasticity in the sensorimotor network of professional female ballet dancers.

Evidence suggests that motor, sensory, and cognitive training modulates brain structures involved in a specific practice. Functional neuroimaging revealed key brain structures involved in dancing such as the putamen and the premotor cortex. Intensive ballet dance training was expected to modulate the structures of the sensorimotor network, for example, the putamen, premotor cortex, supplementary motor area (SMA), and the corticospinal tracts. We investigated gray (GM) and white matter (WM) volumes, fractional anisotropy (FA), and mean diffusivity (MD) using magnetic resonance-based morphometry and diffusion tensor imaging in 10 professional female ballet dancers compared with 10 nondancers. In dancers compared with nondancers, decreased GM volumes were observed in the left premotor cortex, SMA, putamen, and superior frontal gyrus, and decreased WM volumes in both corticospinal tracts, both internal capsules, corpus callosum, and left anterior cingulum. FA was lower in the WM underlying the dancers' left and right premotor cortex. There were no significant differences in MD between the groups. Age of dance commencement was negatively correlated with GM and WM volume in the right premotor cortex and internal capsule, respectively, and positively correlated with WM volume in the left precentral gyrus and corpus callosum. Results were not influenced by the significantly lower body mass index of the dancers. The present findings complement the results of functional imaging studies in experts that revealed reduced neural activity in skilled compared with nonskilled subjects. Reductions in brain activity are accompanied by local decreases in GM and WM volumes and decreased FA.

White matter damage in frontotemporal dementia and Alzheimer's disease measured by diffusion MRI

Frontotemporal dementia (FTD) and Alzheimer's disease are sometimes difficult to differentiate clinically because of overlapping symptoms. Using diffusion tensor imaging (DTI) measurements of fractional anisotropy (FA) can be useful in distinguishing the different patterns of white matter degradation between the two dementias. In this study, we performed MRI scans in a 4 Tesla MRI machine including T1-weighted structural images and diffusion tensor images in 18 patients with FTD, 18 patients with Alzheimer's disease and 19 cognitively normal (CN) controls. FA was measured selectively in specific fibre tracts (including corpus callosum, cingulum, uncinate and corticospinal tracts) as well as globally in a voxel-by-voxel analysis. Patients with FTD were associated with reductions of FA in frontal and temporal regions including the anterior corpus callosum (P < 0.001), bilateral anterior (left P < 0.001; right P = 0.005), descending (left P < 0.001; right P = 0.003) cingulum tracts, and uncinate tracts (left P < 0.001; right P = 0.005), compared to controls. Patients with Alzheimer's disease were associated with reductions of FA in parietal, temporal and frontal regions including the left anterior (P = 0.003) and posterior (P = 0.002) cingulum tracts, bilateral descending cingulum tracts (P < 0.001) and left uncinate tracts (P < 0.001) compared to controls. When compared with Alzheimer's disease, FTD was associated with greater reductions of FA in frontal brain regions, whereas no region in Alzheimer's disease showed greater reductions of FA when compared to FTD. In conclusion, the regional patterns of anisotropy reduction in FTD and Alzheimer's disease compared to controls suggest a characteristic distribution of white matter degradation in each disease. Moreover, the white matter degradation seems to be more prominent in FTD than in Alzheimer's disease. Taken together, the results suggest that white matter degradation measured with DTI may improve the diagnostic differentiation between FTD and Alzheimer's disease.