White matter microstructure alterations of the posterior limb of internal capsule in first-episode drug naive schizophrenia patients.

OBJECTIVES: Previous studies have shown that microstructural alterations in white matter (WM) could contribute to the symptom manifestation and support the dysconnectivity hypothesis in schizophrenia patients. These alterations were pervasive, non-specific, and reported inconsistently across the literature. This study aimed to specifically investigate the microstructure alterations of the posterior limb of the internal capsule (PLIC) in first-episode, drug-naive schizophrenia patients. Utilizing a multicompartmental biophysical model, we further explored the correlation between these alterations and syndrome scale scores. METHODS: Thirty-two individuals with first-episode, drug-naive schizophrenia (FES) and thirty demographically matched healthy controls were enrolled. High-resolution multi-shell diffusion MRI data were collected, followed by the application of a three-compartment Neurite Orientation Dispersion and Density Imaging (NODDI) model to scrutinize the alterations in white matter microstructure. Changes in sensory and motor fibers within the PLIC were specifically focused on. Additionally, the correlation between these pathological changes and scores on the Positive and Negative Syndrome Scale (PANSS) was investigated. RESULTS: The Neurite density index (NDI) in the left PLIC was significantly lower in FES patients compared to healthy individuals, and positively correlated with PANSS positive syndrome scores (r = 0.0379, p = 0.046). In the sensory component (left superior thalamic radiation within PLIC, STR_P), the NDI was significantly elevated (p < 0.0001). Conversely, the NDI in the motor component (left corticospinal tract within PLIC, CST_P) was reduced (p = 0.007) in FES patients compared to healthy individuals, and strongly correlated with PANSS positive syndrome scores (p < 0.020) and PANSS total scores (p < 0.045). Moreover, the NDI deviation of STR from total PLIC (fSTR_P) and NDI deviation in STR_P and CST_P compared to PLIC region (fPLIC) were significantly higher in FES patients than in healthy controls (p < 0.00001), with an area under the curve (AUC) of fPLIC reaching 0.872. CONCLUSION: The study's findings provided new insights into the discrepancy of white matter microstructure changes associated with the sensory and motor fibers in the PLIC region in FES patients. These results contribute to the growing body of evidence suggesting that WM microstructural alterations play a critical role in schizophrenia pathophysiology.

Ventral targeted anterior capsulotomy for treatment-resistant depression and obsessive-compulsive disorder: A treatment method with cases.

BACKGROUND: Ablative surgery using bilateral anterior capsulotomy (BAC) is an option for treatment resistant depression (TRD) and obsessive-compulsive disorder (TROCD). The location and extent of the lesion within anterior limb of the internal capsule (ALIC) remains uncertain. Accumulating evidence has suggested that the lesion should be located ventrally while limiting the dorsal extent. Our center is now targeting specific fiber tracts within the lower half of the ALIC. METHOD: Presurgical diffusion tensor Magnetic Resonance Imaging (MRI) was used to identify individual fibre tracts within the ventral aspect of the ALIC in the last two patients who underwent BAC at our center. One patient had TRD and the other had both TROCD and TRD. Radiofrequency-induced thermal lesions were created in the identified targets with lesion volumes between 20 and 229 mm3 (average 95 mm3). FINDINGS: Both patients were responders with neither experiencing significant side effects including compromised executive functions. LIMITATIONS: The generalizability of our findings is limited because the outcome is based on two subjects. CONCLUSION: This work suggests that BAC can be individually tailored and more limited to the ventral aspect of the ALIC and is effective and safe for TRD and TROCD. Accumulating data also suggests that to be clinically effective the length of the capsulotomy should be about 10mm. BAC's use may increase with the growing utilization and mastery of magnetic resonance guided focused ultrasound.

Spatial patterns of intrinsic brain activity in rats with capsular stroke.

BACKGROUND: To explore the neural changes of brain activity in rats with circumscribed capsular infarcts to find a new therapeutic target for promoting the functional recovery. METHODS: A total of 18 capsular infarct rats and 18 normal rats were conducted in this study. All animal use procedures were strictly in accordance with the guide for the care and use of laboratory animals. After establishing the photothrombotic capsular infarct model, the functional magnetic resonance imaging (fMRI) data were collected and analyzed. RESULTS: The fMRI results indicated that the passive movement would induce strong activation in caudate, putamen, frontal association somatosensory cortex, thalamus dorsolateral, and thalamus midline dorsal in control group, and the passive movement would only induce limited activation mostly in somatosensory cortex, thalamus dorsolateral, and thalamus midline dorsal in capsular infarct models. Capsular infarct makes the cortical activity weaken in sensory-related cortex and subcortical nuclei, including capsular area and thalamus. CONCLUSIONS: Such findings imply that the posterior limb of internal capsule (PLIC) is connected to these structures in function, interacts together with them, and, accordingly, the lesion of PLIC manifests the related symptoms.

Dural Arteriovenous Fistulas Presenting as Symmetric Lesions in the Internal Capsule on Imaging Studies: A Case Report and Literature Review.

BACKGROUND: Dural arteriovenous fistulas (DAVFs) leading to oedema, primarily in the internal capsule, are extremely rare and, to our knowledge, have never been reported. We reported a case of DAVFs with oedema in bilateral internal capsule oedema and reviewed the literature. METHODS: The report describes a unique imaging presentation of cases of DAVFs as symmetric lesions, mainly in the bilateral internal capsule. It also reviews the literature for symmetric lesions in the internal capsule and central grey matter caused by DAVFs to further characterize this rare entity and differential diagnosis through imaging features. RESULTS: In cases of symmetric oedema caused by DAVFs, the most common artery involved in arterial supply was the middle meningeal artery (13/24; 54%). The main vein involved in the drainage was the Galen vein (18/29; 62%). Most cases were treated with transarterial embolization (23/29; 79%), and the probability of effective treatment or complete cure is 100%. On imaging, the vasogenic oedema signal caused by DAVFs is a symmetrical lesion of the bilateral internal capsule, that is, DWI MRI shows a high signal in the unrestricted diffusion area on the apparent diffusion coefficient map. CONCLUSIONS: MR has good diagnostic value in abnormal basal ganglia symmetric signals caused by DAVFs, and can quickly identify DAVFs early.

Pharmacological treatment promoting remyelination enhances motor function after internal capsule demyelination in mice.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system characterized by remyelination failure, axonal degeneration, and progressive worsening of motor functions. Animal models of demyelination are frequently used to develop and evaluate therapies for MS. We recently reported that focal internal capsule (IC) demyelination in mice with lysophosphatidylcholine injection induced acute motor deficits followed by recovery through remyelination. However, it remains unknown whether the IC demyelination mouse model can be used to evaluate changes in motor functions caused by pharmacological treatments that promote remyelination using behavioral testing and histological analysis. In this study, we examined the effect of clemastine, an anti-muscarinic drug that promotes remyelination, in the mouse IC demyelination model. Clemastine administration improved motor function and changed forepaw preference in the IC demyelinated mice. Moreover, clemastine-treated mice showed increased mature oligodendrocyte density, reduced axonal injury, an increased number of myelinated axons and thicker myelin in the IC lesions compared with control (PBS-treated) mice. These results suggest that the lysophosphatidylcholine-induced IC demyelination model is useful for evaluating changes in motor functions following pharmacological treatments that promote remyelination.

Astrocytosis, Inflammation, Axonal Damage and Myelin Impairment in the Internal Capsule following Striatal Ischemic Injury.

Secondary degeneration is defined as a set of destructive events that damage cells and structures that were initially spared or only peripherally affected by the primary insult, constituting a key factor for functional impairment after traumatic brain injury or stroke. In the present study, we evaluated the patterns of astrocytosis, inflammatory response, axonal damage and oligodendrocytes/myelin impairment in the internal capsule following a focal injection of endothelin-1 (ET-1) into the dorsal striatum. Animals were perfused at 1, 3 and 7 post-lesion days (PLD), and tissue was processed to immunohistochemistry for neutrophils (MBS1), macrophages/microglia (ED1), astrocytes (GFAP), axonal lesion (ßAPP), oligodendrocytes (Tau) and myelin (MBP). A significant number of neutrophils was observed at 1PLD, followed by intense recruitment/activation of macrophages/microglia at 3PLD and astrocytic reaction with a peak at 7PLD. Oligodendrocyte damage was pronounced at 3PLD, remaining at 7PLD. Progressive myelin impairment was observed, with reduction of immunoreactivity at 7PLD. Axonal lesion was also identified, mainly at 7PLD. Our results indicate that acute inflammatory response elicited by the ischemic insult in the striatum can be associated with the axonal impairment and damage of both oligodendrocytes and myelin sheath identified in the internal capsule, which may be related to loss of tissue functionality observed in secondary degeneration.

Neurological Soft Signs Are Associated With Altered White Matter in Patients With Schizophrenia.

Neurological soft signs (NSS) are related to grey matter and functional brain abnormalities in schizophrenia. Studies in healthy subjects suggest, that NSS are also linked to white matter. However, the association between NSS and white matter abnormalities in schizophrenia remains to be elucidated. The present study investigated, if NSS are related to white matter alterations in patients with schizophrenia. The total sample included 42 healthy controls and 41 patients with schizophrenia. We used the Neurological Evaluation Scale (NES), and we acquired diffusion weighted magnetic resonance imaging to assess white matter on a voxel-wise between subject statistic. In patients with schizophrenia, linear associations between NES with fractional anisotropy (FA), radial, axial, and mean diffusivity were analyzed with tract-based spatial statistics while controlling for age, medication dose, the severity of the disease, and motion. The main pattern of results in patients showed a positive association of NES with all diffusion measures except FA in important motor pathways: the corticospinal tract, internal capsule, superior longitudinal fascicle, thalamocortical radiations and corpus callosum. In addition, exploratory tractography analysis revealed an association of the right aslant with NES in patients. These results suggest that specific white matter alterations, that is, increased diffusivity might contribute to NSS in patients with schizophrenia.

Protocatechudehyde improves mitochondrial energy metabolism through the HIF1α/PDK1 signaling pathway to mitigate ischemic stroke-elicited internal capsule injury.

ETHNOPHARMACOLOGICAL RELEVANCE: The internal capsule is vulnerable to ischemia, and mild ischemic stroke often results in lesion of the internal capsule, manifested as contralateral hemiplegia. Protocatechudehyde (PCA), a potential neuroprotective agent, has shown therapeutic effects in the study of a variety of nervous system diseases, including ischemic stroke. AIM OF THE STUDY: The aim of this study was to evaluate the effects of PCA on cerebral ischemia reperfusion (CI/R)-elicited internal capsule injury and to elucidate the role of mitochondrial energy metabolism in the underlying mechanism of neuroprotective effects on ischemic stroke. MATERIALS AND METHODS: A rat tMCAO model was established to investigate the therapeutic effects of intravenous PCA (20, 40, and 80 mg/kg, once per day, continued for 7 days) on CI/R-induced internal capsule injury and the regulation of PCA on molecules related to mitochondrial energy metabolism. In vitro, an OGD/R model of PC12 cells was established to further verify the therapeutic mechanism of PCA. RESULTS: Results showed that PCA dose-dependently attenuated neurological deficit, reduced cerebral infarction, alleviated histopathological damage, and improved mitochondrial ultrastructure of the internal capsule after CI/R. Moreover, PCA reversed the upregulation of HIF1α, PDK1 and pPDHA1 expression induced by CI/R and significantly increased the content of acetyl-CoA, ATP, and the activity of ATP synthase. In vitro, PCA treatment promoted cell survival, inhibited apoptosis, attenuated the dissipation of mitochondrial membrane potential in OGD/R-treated PC12 cells, and these therapeutic effects were reversed by the combination of cobalt chloride (CoCl2), a specific pharmacological inducer of HIF1a expression. CONCLUSIONS: These results indicate that PCA exerts a protective effect against CI/R-induced internal capsule injury and improves mitochondrial energy metabolism in the internal capsule, and the mechanism is associated with the inhibition of HIF1α/PDK1 signaling pathway.

Early Thrombectomy Protects the Internal Capsule in Patients With Proximal Middle Cerebral Artery Occlusion.

BACKGROUND AND PURPOSE: Proximal middle cerebral artery (MCA) occlusions impede blood flow to the noncollateralized lenticulostriate artery territory. Previous work has shown that this almost inevitably leads to infarction of the dependent gray matter territories in the striate even if perfusion is restored by mechanical thrombectomy. Purpose of this analysis was to evaluate potential sparing of neighboring fiber tracts, ie, the internal capsule. METHODS: An observational single-center study of patients with proximal MCA occlusions treated with mechanical thrombectomy and receiving postinterventional high-resolution diffusion-weighted imaging was conducted. Patients were classified according to internal capsule ischemia (IC+ versus IC-) at the postero-superior level of the MCA lenticulostriate artery territory (corticospinal tract correlate). Associations of IC+ versus IC- with baseline variables as well as its clinical impact were evaluated using multivariable logistic or linear regression analyses adjusting for potential confounders. RESULTS: Of 92 included patients with proximal MCA territory infarctions, 45 (48.9%) had an IC+ pattern. Longer time from symptom-onset to groin-puncture (adjusted odds ratio, 2.12 [95% CI, 1.19-3.76] per hour), female sex and more severe strokes were associated with IC+. Patients with IC+ had lower rates of substantial neurological improvement and functional independence (adjusted odds ratio, 0.26 [95% CI, 0.09-0.81] and adjusted odds ratio, 0.25 [95% CI, 0.07-0.86]) after adjustment for confounders. These associations remained unchanged when confining analyses to patients without ischemia in the corona radiata or the motor cortex and here, IC+ was associated with higher National Institutes of Health Stroke Scale motor item scores (ß, +2.8 [95% CI, 1.5 to 4.1]) without a significant increase in nonmotor items (ß, +0.8 [95% CI, -0.2 to 1.9). CONCLUSIONS: Rapid mechanical thrombectomy with successful reperfusion of the lenticulostriate arteries often protects the internal capsule from subsequent ischemia despite early basal ganglia damage. Salvage of this eloquent white matter tract within the MCA lenticulostriate artery territory seems strongly time-dependent, which has clinical and pathophysiological implications.

Acute motor deficit and subsequent remyelination-associated recovery following internal capsule demyelination in mice.

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system (CNS), characterized by accumulated motor disability. However, whether remyelination promotes motor recovery following demyelinating injury remains unclear. Damage to the internal capsule (IC) is known to result in motor impairment in multiple sclerosis and stroke. Here, we induced focal IC demyelination in mice by lysophosphatidylcholine (LPC) injection, and examined its effect on motor behavior. We also compared the effect of LPC-induced IC damage to that produced by endothelin-1 (ET1), a potent vasoconstrictor used in experimental stroke lesions. We found that LPC or ET1 injections induced asymmetric motor deficit at 7 days post-lesion (dpl), and that both lesion types displayed increased microglia/macrophage density, myelin loss, and axonal dystrophy. The motor deficit and lesion pathology remained in ET1-injected mice at 28 dpl. In contrast, LPC-injected mice regained motor function by 28 dpl, with corresponding reduction in activated microglia/macrophage density, and recovery of myelin staining and axonal integrity in lesions. These results suggest that LPC-induced IC demyelination results in acute motor deficit and subsequent recovery through remyelination, and may be used to complement future drug screens to identify drugs for promoting remyelination.

The prognosis of brain magnetic resonance imaging injury pattern for outcomes of hypothermia-treated infants.

Magnetic resonance imaging (MRI) can be a tool that allows the observation of structural injury patterns after cooling. The aim of this study was to determine the early pattern of brain injury in the MRIs of infants with hypoxic ischemic encephalopathy (HIE) after cooling and to search for any clinical factors related to abnormal MRI findings.The study retrospectively recruited 118 infants who were treated with therapeutic hypothermia (TH) between 2013 and 2016.Forty-three patients had normal brain MRI, and 75 had abnormal brain MRI findings. The TH-treated infants with abnormal brain MRI readings showed significantly more clinical seizures and the use of additional antiepileptic drugs (AEDs) than the normal MRI group. As a long-term outcome, more lesions in the basal ganglia and thalamus, posterior limb of internal capsule, or severe white matter lesions were associated with abnormal neurodevelopmental outcomes at 18 to 24 months of age.A higher frequency of clinical seizures and AED use were related to abnormal brain injury on MRI. A significant risk for poor long-term outcomes was found in the abnormal brain MRI group.

The role of infarct location in patients with DWI-ASPECTS 0-5 acute stroke treated with thrombectomy.

OBJECTIVE: To determine whether hemisphere involvement and infarct location on the Alberta Stroke Program CT Score (ASPECTS) template should serve as predictors of 90-day clinical outcome in patients with acute ischemic stroke with pretreatment diffusion-weighted imaging (DWI)-ASPECTS 0-5 treated with mechanical thrombectomy (MT). METHODS: We analyzed data of all consecutive patients included in the Endovascular Treatment in Ischemic Stroke registry between January 1, 2012, and August 31, 2018, who presented with a pretreatment DWI-ASPECTS 0-5 and underwent MT. Multivariable analyses were performed in order to identify the role of infarct location and hemisphere involvement on good outcome defined by a modified Rankin Scale (mRS) score 0-2 at 90 days and on the whole distribution of mRS (shift analysis). RESULTS: A total of 344 patients with a DWI-ASPECTS 0-5 (median 4, IQR 3-5) were included. Neither infarct location nor hemisphere involvement was found to be an independent predictor of good outcome. Involvement of the M6 region in right-sided strokes (adjusted odds ratio [aOR] 2.6, 99% confidence interval [CI] 1.14-5.8; p = 0.003) and the internal capsule in left-sided strokes (aOR 2.6, 99% CI 0.8-7.9; p < 0.020) independently predicted increased disability on the mRS distribution in the affected subpopulations. CONCLUSION: Our study suggests that neither hemisphere nor infarct location should be considered as an exclusion criterion for MT in patients with stroke with pretreatment DWI-ASPECTS 0-5. The involvement of specific regions of interest was associated with increased disability. These may provide valuable information regarding stroke management options and neurologic recovery for use of caregivers in the postacute phase.

Ethnicity-Dependent Effects of Schizophrenia Risk Variants of the OLIG2 Gene on OLIG2 Transcription and White Matter Integrity.

Previous studies have indicated associations between several OLIG2 gene single-nucleotide polymorphisms (SNPs) and susceptibility to schizophrenia among Caucasians. Consistent with these findings, postmortem brain and diffusion tensor imaging studies have indicated that the schizophrenia-risk-associated allele (A) in the OLIG2 SNP rs1059004 predicts lower OLIG2 gene expression in the dorsolateral prefrontal cortex (DLPFC) of schizophrenia patients and reduced white matter (WM) integrity of the corona radiata in normal brains among Caucasians. In an effort to replicate the association between this variant and WM integrity among healthy Japanese, we found that the number of A alleles was positively correlated with WM integrity in some fiber tracts, including the right posterior limb of the internal capsule, and with mean blood flow in a widespread area, including the inferior frontal operculum, orbital area, and triangular gyrus. Because the A allele affected WM integrity in opposite directions in Japanese and Caucasians, we investigated a possible association between the OLIG2 gene SNPs and the expression level of OLIG2 transcripts in postmortem DLPFCs. We evaluated rs1059004 and additional SNPs in the 5' upstream and 3' downstream regions of rs1059004 to cover the broader region of the OLIG2 gene. The 2 SNPs (rs1059004 and rs9653711) had opposite effects on OLIG2 gene expression in the DLPFC in Japanese and Caucasians. These findings suggest ethnicity-dependent opposite effects of OLIG2 gene SNPs on WM integrity and OLIG2 gene expression in the brain, which may partially explain the failures in replicating associations between genetic variants and psychiatric phenotypes among ethnicities.

Functional near-infrared-spectroscopy-based measurement of changes in cortical activity in macaques during post-infarct recovery of manual dexterity.

Because compensatory changes in brain activity underlie functional recovery after brain damage, monitoring of these changes will help to improve rehabilitation effectiveness. Functional near-infrared spectroscopy (fNIRS) has the potential to measure brain activity in freely moving subjects. We recently established a macaque model of internal capsule infarcts and an fNIRS system for use in the monkey brain. Here, we used these systems to study motor recovery in two macaques, for which focal infarcts of different sizes were induced in the posterior limb of the internal capsule. Immediately after the injection, flaccid paralysis was observed in the hand contralateral to the injected hemisphere. Thereafter, dexterous hand movements gradually recovered over months. After movement recovery, task-evoked hemodynamic responses increased in the ventral premotor cortex (PMv). The response in the PMv of the infarcted (i.e., ipsilesional) hemisphere increased in the monkey that had received less damage. In contrast, the PMv of the non-infarcted (contralesional) hemisphere was recruited in the monkey with more damage. A pharmacological inactivation experiment with muscimol suggested the involvement of these areas in dexterous hand movements during recovery. These results indicate that fNIRS can be used to evaluate brain activity changes crucial for functional recovery after brain damage.

Tractographic description of major subcortical projection pathways passing the anterior limb of the internal capsule. Corticopetal organization of networks relevant for psychiatric disorders.

BACKGROUND: Major depression (MD) and obsessive-compulsive disorder (OCD) are psychiatric diseases with a huge impact on individual well-being. Despite optimal treatment regiments a subgroup of patients remains treatment resistant and stereotactic surgery (stereotactic lesion surgery, SLS or Deep Brain Stimulation, DBS) might be an option. Recent research has described four networks related to MD and OCD (affect, reward, cognitive control, default network) but only on a cortical and the adjacent sub-cortical level. Despite the enormous impact of comparative neuroanatomy, animal science and stereotactic approaches a holistic theory of subcortical and cortical network interactions is elusive. Because of the dominant hierarchical rank of the neocortex, corticofugal approaches have been used to identify connections in subcortical anatomy without anatomical priors and in part confusing results. We here propose a different corticopetal approach by identifying subcortical networks and search for neocortical convergences thereby following the principle of phylogenetic and ontogenetic network development. MATERIAL AND METHODS: This work used a diffusion tensor imaging data from a normative cohort (Human Connectome Project, HCP; n = 200) to describe eight subcortical fiber projection pathways (PPs) from subthalamic nucleus (STN), substantia nigra (SNR), red nucleus (RN), ventral tegmental area (VTA), ventrolateral thalamus (VLT) and mediodorsal thalamus (MDT) in a normative space (MNI). Subcortical and cortical convergences were described including an assignment of the specific pathways to MD/OCD-related networks. Volumes of activated tissue for different stereotactic stimulation sites and procedures were simulated to understand the role of the distinct networks, with respect to symptoms and treatment of OCD and MD. RESULTS: The detailed course of eight subcortical PPs (stnPP, snrPP, rnPP, vlATR, vlATRc, mdATR, mdATRc, vtaPP/slMFB) were described together with their subcortical and cortical convergences. The anterior limb of the internal capsule can be subdivided with respect to network occurrences in ventral-dorsal and medio-lateral gradients. Simulation of stereotactic procedures for OCD and MD showed dominant involvement of mdATR/mdATRc (affect network) and vtaPP/slMFB (reward network). DISCUSSION: Corticofugal search strategies for the evaluation of stereotactic approaches without anatomical priors often lead to confusing results which do not allow for a clear assignment of a procedure to an involved network. According to our simulation of stereotactic procedures in the treatment of OCD and MD, most of the target regions directly involve the reward (and affect) networks, while side-effects can in part be explained with a co-modulation of the control network. CONCLUSION: The here proposed corticopetal approach of a hierarchical description of 8 subcortical PPs with subcortical and cortical convergences represents a new systematics of networks found in all different evolutionary and distinct parts of the human brain.

A fixel-based analysis of micro- and macro-structural changes to white matter following adult traumatic brain injury.

Diffusion tensor imaging is often used to assess white matter (WM) changes following traumatic brain injury (TBI), but is limited in voxels that contain multiple fibre tracts. Fixel-based analysis (FBA) addresses this limitation by using a novel method of analysing high angular resolution diffusion-weighted imaging (HARDI) data. FBA examines three aspects of each fibre tract within a voxel: tissue micro-structure (fibre density [FD]), tissue macro-structure (fibre-bundle cross section [FC]) and a combined measure of both (FD and fibre-bundle cross section [FDC]). This study used FBA to identify the location and extent of micro- and macro-structural changes in WM following TBI. A large TBI sample (Nmild = 133, Nmoderate-severe = 29) and control group (healthy and orthopaedic; N = 107) underwent magnetic resonance imaging with HARDI and completed reaction time tasks approximately 7 months after their injury (range: 98-338 days). The TBI group showed micro-structural differences (lower FD) in the corpus callosum and forceps minor, compared to controls. Subgroup analyses revealed that the mild TBI group did not differ from controls on any fixel metric, but the moderate to severe TBI group had significantly lower FD, FC and FDC in multiple WM tracts, including the corpus callosum, cerebral peduncle, internal and external capsule. The moderate to severe TBI group also had significantly slower reaction times than controls, but the mild TBI group did not. Reaction time was not related to fixel findings. Thus, the WM damage caused by moderate to severe TBI manifested as fewer axons and a reduction in the cross-sectional area of key WM tracts.

Disownership of body parts as revealed by a visual scale evaluation. An observational study.

The disownership of body parts, that most frequently occurs on the left side of the body, contralateral to right-hemispheric lesions, is an infrequent disorder, as usually assessed by interviews asking for dichotomic "yes/no" responses. This observational study in right-brain-damaged stroke patients investigated the efficacy of a continuous Visual Analog Scale (VAS) to detect body disownership after right brain damage, compared to dichotomic questions. Thirty-two right-handed right-brain-damaged stroke patients were given a Standardized Interview (SI), asking "Whose hand/arm/leg is this?", followed by a VAS (asking patients to mark on a vertical line their agreement with the statement that a body part belonged to them). The neural correlates of this disorder and measures of extra-personal and personal spatial neglect were also assessed. Control data were recorded from 18 neurologically unimpaired right-handed participants. During the interview, no patient showed disownership of body parts. Conversely, on the VAS eight out of 32 (25%) patients' scores, but none of the controls' scores, indicated a judgement of disownership for left body parts, with a left-right difference larger than that of control participants. VAS-detected disownership was not systematically associated with extra-personal and personal unilateral spatial neglect. Lesion sites associated with disownership of left body parts included the caudate nucleus and the anterior part of the internal capsule. To conclude, the VAS task, compared to the interview, is a novel tool to detect disownership of left body parts in right brain-damaged patients. A revised classification of body-ownership disorders is proposed. The present variant, assessed and detected by the VAS task, is termed Covert disownership and distinguished from the Overt disownership assessed by a SI.

Deficits of white matter axial diffusivity in bipolar disorder relative to major depressive disorder: No relationship to cerebral perfusion or body mass index.

OBJECTIVE: To compare white matter integrity (WMI) in bipolar disorder (BD) relative to healthy volunteers (HVs) and major depressive disorder (MDD). To determine the relationship of bipolar-specific differences in WMI to cerebral perfusion, body mass index (BMI), and blood pressure as indices of cardiovascular function. METHODS: Thirty-two participants with BD, 44 with MDD, and 41 HV were recruited. All BD and MDD participants were in a major depressive episode, and all but 12 BD participants were medication-free. 64-direction diffusion tensor imaging (DTI) and arterial spin labeling (ASL) sequences were obtained. Tract-based spatial statistics (TBSS) on four DTI indices were employed to distinguish patterns of DTI in BD relative to HV and MDD groups. BMI, blood pressure, and medical histories were also obtained for the BD participants. RESULTS: A cluster of lower axial diffusivity (AD) was found in BD participants in comparison to the HVs in the left posterior thalamic radiation, superior longitudinal fasciculus, inferior longitudinal fasciculus, fronto-occipital fasciculus, and internal capsule. Mean AD in the significant cluster was not associated with cerebral blood flow (CBF) in the region as measured by ASL, and was not associated with BMI or blood pressure. A cluster of lower AD was also found in the BD group when compared to MDD that had spatial overlap with the HV comparison. CONCLUSIONS: The results indicate a deficit of AD in BD when compared to MDD and HV groups. No association between AD values and either cerebral perfusion, BMI, or blood pressure was found in BD.

Neuroimaging auditory verbal hallucinations in schizophrenia patient and healthy populations.

BACKGROUND: Auditory verbal hallucinations (AVH) are a cardinal feature of schizophrenia, but they can also appear in otherwise healthy individuals. Imaging studies implicate language networks in the generation of AVH; however, it remains unclear if alterations reflect biologic substrates of AVH, irrespective of diagnostic status, age, or illness-related factors. We applied multimodal imaging to identify AVH-specific pathology, evidenced by overlapping gray or white matter deficits between schizophrenia patients and healthy voice-hearers. METHODS: Diffusion-weighted and T1-weighted magnetic resonance images were acquired in 35 schizophrenia patients with AVH (SCZ-AVH), 32 healthy voice-hearers (H-AVH), and 40 age- and sex-matched controls without AVH. White matter fractional anisotropy (FA) and gray matter thickness (GMT) were computed for each region comprising ICBM-DTI and Desikan-Killiany atlases, respectively. Regions were tested for significant alterations affecting both SCZ-AVH and H-AVH groups, relative to controls. RESULTS: Compared with controls, the SCZ-AVH showed widespread FA and GMT reductions; but no significant differences emerged between H-AVH and control groups. While no overlapping pathology appeared in the overall study groups, younger (<40 years) H-AVH and SCZ-AVH subjects displayed overlapping FA deficits across four regions (p < 0.05): the genu and splenium of the corpus callosum, as well as the anterior limbs of the internal capsule. Analyzing these regions with free-water imaging ascribed overlapping FA abnormalities to tissue-specific anisotropy changes. CONCLUSIONS: We identified white matter pathology associated with the presence of AVH, independent of diagnostic status. However, commonalities were constrained to younger and more homogenous groups, after reducing pathologic variance associated with advancing age and chronicity effects.

Differential loss of position sense and kinesthesia in sub-acute stroke.

Position sense and kinesthesia are thought to be independent sub-modalities of proprioception, based on neuromuscular recordings in the periphery. However, little evidence has demonstrated separation in the central nervous system (CNS). Stroke provides an interesting model to examine this dissociation in the CNS due to the heterogeneity of lesion locations and high incidence of proprioceptive impairment. Here, we aimed to determine if position sense and kinesthesia are behaviorally dissociable in a stroke patient model, and if behavioral dissociations in proprioception corresponded to different stroke lesion damage. Position sense and kinesthesia were assessed in subjects with unilateral stroke (N = 285) using two robotic tasks: Position Matching (PM) and Kinesthetic Matching (KIN). Without vision, the robot moved the subjects' stroke-affected arm and they mirror-matched perceived location (PM) or movement (KIN) with their opposite arm. Fifty-two percent of subjects had deficits in both PM and KIN, 22% had impairments in only one sub-modality (7% PM only, 15% KIN only). These subjects tended to have smaller lesions (internal capsule, basal ganglia, insula) compared to those with larger lesions affecting both sub-modalities. Overall, we observed separation of proprioceptive sub-modalities in a large number of stroke subjects, and that lesion load impacted the pattern of proprioceptive impairment.