Left Insular Region Research Articles

Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke

BackgroundPrevious studies on left hemisphere (LH) stroke patients reported effector-specific (hand, fingers, bucco-facial) differences in imitation performance. Furthermore, imitation performance differed between meaningless (ML) and meaningful (MF) gestures. Recent work suggests that a gesture’s meaning impacts the body-part specificity of gesture imitation. MethodsWe tested the hypothesis that the gesture’s meaning (ML vs MF) affects the lesion correlates of effector-specific imitation deficits (here: bucco-facial vs arm/hand gestures) using behavioural data and support vector regression-based lesion-symptom mapping (SVR-LSM) in a large sample of 194 sub-acute LH stroke patients. ResultsBehavioural data revealed a significant interaction between the effector used for imitation and the meaning of the imitated gesture. SVR-LSM analyses revealed shared lesion correlates for impaired imitation independent of effector or gesture meaning in the left supramarginal (SMG) and superior temporal gyri (STG). Besides, within the territory of the left middle cerebral artery, impaired imitation of bucco-facial gestures was associated with more anterior lesions, while arm/hand imitation deficits were associated with more posterior lesions. MF gestures were specifically associated with lesions in the left inferior frontal gyrus and the left insular region. Notably, an interaction of effector-specificity and gesture meaning was also present at the lesion level: A more pronounced difference in imitation performance between the effectors for ML (versus MF) gestures was associated with left-hemispheric lesions in the STG, SMG, putamen, precentral gyrus and white matter tracts. ConclusionThe current behavioural data show that ML gestures are particularly sensitive in assessing effector-specific imitation deficits in LH stroke patients. Moreover, a gesture’s meaning modulated the effector-specific lesion correlates of bucco-facial and arm/hand gesture imitation. Hence, it is crucial to consider gesture meaning in apraxia assessments.

TH65. POLYGENIC RISK SCORES FOR ADHD AND TREATMENT RESPONSE TO METHYLPHENIDATE

Gliomas are rare, slow-growing brain tumors. The insula is related to self-knowledge, theory of the mind, interpersonal relationships, distortion of reality and the appearance of positive symptoms. There is little current literature on these type of tumors in the insula and psychosis.A 32-year-old male patient, diagnosed with Paranoid Schizophrenia with significant auditory hallucinations, and a low-grade glioma in the left insular region on routine brain MRI examination. We discuss the possible relationship between the persistence and refractoriness of psychotic symptoms with this finding.The insula may be the main affected brain region in schizophrenia. In psychotic patients, deficits in the insular structure are associated with the presence and severity of positive and negative symptoms. They had reduced volumes of bilateral gray matter from the insula, especially on the right side.

Meynert nucleus-related cortical thinning in Parkinson's disease with mild cognitive impairment.

Cognitive impairment in Parkinson's disease (PD) involves the cholinergic system and cholinergic neurons, especially the nucleus basalis of Meynert (NBM/Ch4) located in the basal forebrain (BF). We analyzed associations between NBM/Ch4 volume and cortical thickness to determine whether the NBM/Ch4-innervated neocortex shows parallel atrophy with the NBM/Ch4 as disease progresses in PD patients with cognitive impairment (PD-MCI). We enrolled 35 PD-MCI patients, 48 PD patients with normal cognition (PD-NC), and 33 age- and education-matched healthy controls (HCs), with all participants undergoing neuropsychological assessment and structural magnetic resonance imaging (MRI). Correlation analyses between NBM/Ch4 volume and cortical thickness and correlation coefficient comparisons were conducted within and across groups. In the PD-MCI group, NBM/Ch4 volume was positively correlated with cortical thickness in the bilateral posterior cingulate, parietal, and frontal and left insular regions. Based on correlation coefficient comparisons, the atrophy of NBM/Ch4 was more correlated with the cortical thickness of right posterior cingulate and precuneus, anterior cingulate and medial orbitofrontal lobe in PD-MCI versus HC, and the right medial orbitofrontal lobe and anterior cingulate in PD-NC versus HC. Further partial correlations between cortical thickness and NBM/Ch4 volume were significant in the right medial orbitofrontal (PD-NC: r=0.3, P=0.045; PD-MCI: r=0.51, P=0.003) and anterior cingulate (PD-NC: r=0.41, P=0.006; PD-MCI: r=0.43, P=0.013) in the PD groups and in the right precuneus (r=0.37, P=0.04) and posterior cingulate (r=0.46, P=0.008) in the PD-MCI group. The stronger correlation between NBM/Ch4 and cortical thinning in PD-MCI patients suggests that NBM/Ch4 volume loss may play an important role in PD cognitive impairment.

Cerebral lesion correlates of sympathetic cardiovascular activation in multiple sclerosis.

Cardiovascular autonomic dysfunction is common in multiple sclerosis (MS) and contributes significantly to disability. We hypothesized that cerebral MS‐lesions in specific areas of the central autonomic network might account for imbalance of the sympathetic and parasympathetic cardiovascular modulation. Therefore, we used voxel‐based lesion symptom mapping (VLSM) to determine associations between cardiovascular autonomic dysfunction and cerebral MS‐related lesion sites. In 74 MS‐patients (mean age 37.0 ± 10.5 years), we recorded electrocardiographic RR‐intervals and systolic and diastolic blood pressure. Using trigonometric regressive spectral analysis, we assessed low (0.04–0.15 Hz) and high (0.15–0.5 Hz) frequency RR‐interval‐and blood pressure‐oscillations and determined parasympathetically mediated RR‐interval–high‐frequency modulation, mainly sympathetically mediated RR‐interval–low‐frequency modulation, sympathetically mediated blood pressure‐low‐frequency modulation, and the ratios of sympathetic and parasympathetic RR‐interval‐modulation as an index of sympathetic‐parasympathetic balance. Cerebral MS‐lesions were analyzed on imaging scans. We performed a VLSM‐analysis correlating parameters of autonomic dysfunction with cerebral MS‐lesion sites. The VLSM‐analysis showed associations between increased RR‐interval low‐frequency/high‐frequency ratios and lesions most prominently in the left insular, hippocampal, and right frontal inferior opercular region, and a smaller lesion cluster in the right middle cerebellar peduncle. Increased blood pressure‐low‐frequency powers were associated with lesions primarily in the right posterior parietal white matter and again left insular region. Our data indicate associations between a shift of cardiovascular sympathetic‐parasympathetic balance toward increased sympathetic modulation and left insular and hippocampal lesions, areas of the central autonomic network. The VLSM‐analysis further distinguished between right inferior fronto‐opercular lesions disinhibiting cardiac sympathetic activation and right posterior parietal lesions increasing sympathetic blood pressure modulation.

Estimation of the Composition of the Resting State fMRI Networks in Subjects with Mild Depression and Healthy Volunteers.

Depressive disorders can be associated with changes in not only interaction between neural networks, but also in their composition. Resting state fMRI scanning was performed for 4 min twice for each subject and the results of patients with mild depression (N=15) and healthy subjects (N=19) were analyzed. The fMRI signal was reduced into the independent components and the contrasts between the groups and between the first and second records were constructed for each component. During the first scanning, the auditory network of individuals with depression involved greater volume in the left insular region and lower volume in the right hemisphere. In record 2, depression patients were characterized by expansion of the executive network in the left hemisphere in the region of the middle and inferior frontal cortex. In healthy people, from record 1 to record 2, representation of the dorsal default mode network (DMN) increased in the left medial prefrontal area, the precuneus network expanded in the left hemisphere, and presentation of the ventral DMN in the right precuneus decreased. In the depression group, the auditory network lost some part of the left temporo-insular cortex; the sensorimotor network expanded in the left hemisphere to the cerebellum or to the central parietal region depending on the evaluation method, and the visuospatial network included or excluded a cluster in the left parietal lobe (in different points). Our findings indicate that connection of the auditory network with the left insular cortex could be a possible depression marker and also demonstrate a possibility of evaluating the composition of cerebral networks in intergroup comparisons and in dynamics without interventions.

Stroke Patterns and Implications for Ventricular Functional Remodeling in Left Ventricular Assist Systems

Ischemic stroke-related complications (particularly in the right hemisphere) are frequently encountered with Left Ventricular Assist Systems (LVAS). The neuro-cardiac axis may influence ventricular remodeling. However it remains unknown if stroke patterns are related to ventricular remodeling after facilitated hemodynamic support with LVAS. We hypothesized that strokes occurring in the right hemisphere, within the insula region, may enhance left ventricular remodeling through unopposed activation of the left insular region.

Insular multiple sclerosis lesions are associated with erectile dysfunction

Erectile function (EF) is frequently compromised in men with multiple sclerosis (MS). Functional neuroimaging in healthy men identified a network of brain areas, such as the insula, visual and somatosensory association areas, cingulate gyrus, prefrontal cortex, as well as subcortical regions, contributing to EF. This study intended to determine associations between EF deterioration during MS and cerebral MS-associated lesion sites. In 31 men with MS (mean age 38.2±11.2years), we evaluated MS-related EF deterioration by comparing scores of the 5-item International Index of Erectile Function-5 questionnaire (IIEF5) at the time of study and retrospectively, 3months prior to MS diagnosis, by calculating score differences as DeltaIIEF5 (DeltaIIEF5 score<0 indicated EF deterioration). To assess the impact of confounding factors of EF, patient age, disease duration, disease severity, depressiveness, bladder and bowel symptoms, and total cerebral MS lesion volume were correlated with DeltaIIEF5 scores (Spearman rank correlation) and compared between patients with and without EF deterioration(t tests or Mann-Whitney U test). MS lesions were assessed on T2-weighted magnetic resonance imaging (MRI; 1.5 or 3T). We determined the lesion overlap (prevalence of identical lesion sites among patients), subtracted lesion overlaps in patients without EF deterioration from overlaps in patients with EF deterioration, and compared DeltaIIEF5 scores voxel-wise between patients with and without lesions in a given voxel (t test; significance: p<0.05). In 14 patients (45.2%), DeltaIIEF5 scores indicated EF deterioration. DeltaIIEF5 scores were not associated with age (ρ=0.06; p=0.74), disease duration (ρ=0.26; p=0.15), disease severity (ρ=-0.19; p=0.31), depressiveness (ρ=0.07; p=0.72), bladder symptoms (ρ=-0.11; p=0.57), bowel symptoms (ρ=0.17; p=0.37), and total lesion volume (ρ=-0.13; p=0.47). The voxel-wise analysis showed associations between EF deterioration and MS lesions primarily in the bilateral, and predominantly left juxtacortical insular region. In conclusion, MS lesions particularly in the left insular region, which is activated with sexual arousal, contribute to erectile dysfunction.

The segregated connectome of late-life depression: a combined cortical thickness and structural covariance analysis

Late-life depression (LLD) has been associated with both generalized and focal neuroanatomical changes including gray matter atrophy and white matter abnormalities. However, previous literature has not been consistent and, in particular, its impact on the topology organization of brain networks remains to be established. In this multimodal study, we first examined cortical thickness, and applied graph theory to investigate structural covariance networks in LLD. Thirty-three subjects with LLD and 25 controls underwent T1-weighted, fluid-attenuated inversion recovery and clinical assessments. Freesurfer was used to perform vertex-wise comparisons of cortical thickness, whereas the Graph Analysis Toolbox (GAT) was implemented to construct and analyze the structural covariance networks. LLD showed a trend of lower thickness in the left insular region (p < 0.001 uncorrected). In addition, the structural network of LLD was characterized by greater segregation, particularly showing higher transitivity (i.e., measure of clustering) and modularity (i.e., tendency for a network to be organized into subnetworks). It was also less robust against random failure and targeted attacks. Despite relative cortical preservation, the topology of the LLD network showed significant changes particularly in segregation. These findings demonstrate the potential for graph theoretical approaches to complement conventional structural imaging analyses and provide novel insights into the heterogeneous etiology and pathogenesis of LLD.

Neuroanatomic Correlates of Female Sexual Dysfunction in Multiple Sclerosis.

This study intended to determine associations between alterations of female sexual arousal as well as vaginal lubrication and the site of cerebral multiple sclerosis (MS) lesions. In 44 women with MS (mean age: 36.5 ± 9.9 years), we assessed their medical history and evaluated sexual function using the Female Sexual Function Index scores for arousal and vaginal lubrication. We determined potential confounding factors of sexual dysfunction: age; disease duration; physical disability; depression; bladder or urinary dysfunction; and total volume of cerebral lesions. Arousal and lubrication scores were correlated with one another and with potential confounding factors. Cerebral MS lesions were recorded on imaging scans. A voxel-based lesion symptom mapping (VLSM) analysis adjusted for confounding variables was performed correlating cerebral sites of MS lesions with arousal and lubrication scores. Decreased arousal scores correlated with decreased lubrication scores; decreased lubrication scores were associated with bladder or urinary symptoms. Arousal and lubrication scores were not associated with any other variables. Multivariate VLSM analysis, including arousal and lubrication scores as covariables of interest, showed right occipital lesions associated with impaired arousal and left insular lesions associated with decreased lubrication. Impaired lubrication remained associated with left insular lesions after adjustment for bladder or urinary dysfunction. Our data indicate that impaired female sexual arousal is associated with MS lesions in the occipital region, integrating visual information and modulating attention toward visual input. Impaired lubrication correlated with lesions in the left insular region, contributing to mapping and generating visceral arousal states. Ann Neurol 2016;80:490-498.

Structural brain differences in alcohol dependent subjects with and without comorbid affective pathology - a cMRI study

There is a paucity of reports on structural brain differences comparing alcohol dependent subjects with and without comorbid affective pathology. 3-T MRI (Siemens MAGNETOM Trio) scans of 115 alcohol dependent subjects with or without affective comorbid diagnoses that underwent qualified detoxification inpatient treatment were evaluated using a T1-weighted, 3D-MPRAGE sequence. Variables for severity of dependence were analysed. Alcohol dependent subjects compared to alcohol dependent subjects with comorbid affective pathology showed a higher level of cerebral atrophy in the entire brain. Distinct areas in the frontal, parietal, cerebellar, rigth temporal, and left insular region showed specific atrophy patterns. Patients without affective comorbidity had significantly higher Gamma-GT levels and higher MCH, however, no differences in alcohol intake, duration of addiction and CDT. Alcohol addicted subjects without comorbid affective disorder display a significantly greater cerebral atrophy compared to comorbid patients. The results suggest that affective comorbidity may have a protective role for cerebral atrophy in patients with alcohol dependence. Higher atrophy and GGT values combined with comparable alcohol intake and duration of addiction may hint on a higher sensitivity for alcoholtoxic effects in non-comorbid subjects. This study was supported by EUSARNAD (Marie Curie International Research Staff Exhange Scheme Program).

POE03 EEG and imaging correlates of insular seizures

BackgroundInsular epilepsy is an uncommon and frequently overlooked condition, causing a rare type of seizures which is still not included by The International League Against epilepsy (ILAE) in its current...

A Neurological Cause of Recurrent Choking During Sleep

We describe a case of nocturnal choking episodes caused by insular seizures. Recurrent choking spells from sleep showed no response to treatment for sleep apnea or gastroesophageal reflux. Laryngoscopy revealed no abnormalities. Although continuous EEG monitoring during events was normal, ictal SPECT imaging showed increased radiotracer uptake in the left insular region, an area involved in sensation of the upper gastrointestinal tract. The episodes remitted after initiation of an antiepileptic drug. Obstructive sleep apnea is the most common cause for presentation to a sleep center, but seizures should remain in the differential diagnosis of nocturnal choking episodes.

Brain perfusion correlates of medial temporal lobe atrophy and white matter hyperintensities in mild cognitive impairment

To assess the association of Medial Temporal lobe Atrophy (MTA) and White Matter Hyperintensities (WMHs) with gray matter perfusion in Mild Cognitive Impairment (MCI). 56 MCI patients (age = 69.3 +/- 7.0, 32 females) underwent brain MR scan and (99m)Tc ECD SPECT. We evaluated MTA according to Scheltens' fivepoint scale on T1 MR images, and assessed WMHs using the rating scale for age-related white matter changes on T2-weighted and FLAIR MR images. We divided MCI into age-matched subgroups with high and low MTA and high and low WMHs load. We processed SPECT images with SPM2 following an optimized protocol and performed a voxel-based statistical analysis comparing high vs. low MTA and high vs. low WMHs, setting p-value at 0.001 uncorrected, thresholding cluster extent at 100 voxels, using proportional scaling and entering age and WMHs or MTA respectively as nuisance covariates. MCI with high compared with low MTA showed hypoperfusion in the left hippocampus and in the left parahippocampal gyrus. MCI with high compared with low WMHs showed a hypoperfusion area in the left insular region and superior temporal gyrus. MTA in MCI is associated with hippocampal gray matter hypoperfusion while WMHs is associated with gray matter hypoperfusion in areas of the insula and temporal neocortex. These results confirm that MTA is associated with local functional changes and suggest that WMHs may be associated with remote brain cortical dysfunction.

Sylvian meningioma without dural attachment in an adult

This paper presents a rare case of a sylvian meningioma in a 35-year-old male. The patient visited our hospital because of a 10-year history of simple partial seizures. Magnetic resonance imaging revealed a 3.5-cm, well-circumscribed, homogenously enhanced, circular mass without dural attachments in the left insular region. The tumor was not stained on angiogram. The tumor was located in the extra-axial space of the sylvian fissure without any dural attachment, and was strongly attached to the middle cerebral artery. The tumor was excised, and a histological diagnosis of a transitional meningioma without a malignancy was made. A Sylvian meningioma without dural attachment is quite rare, and a preoperative differentiation of this lesion is generally difficult. This paper discusses the characteristics and possible pathogenesis of meningiomas without a dural detachment.

Disseminated Multifocal Herpes Zoster Leukoencephalitis and Subcortical Hemorrhage in an Immunosuppressed Child

We describe a rare case of multifocal varicella-zoster leukoencephalitis in an immunosuppressed adolescent boy who developed a herpetiform rash on his groin and subsequently presented with a subacute encephalopathy, aphasia, and hemiparesis. Magnetic resonance imaging scan of the brain revealed multifocal bi-hemispheric target-like lesions predominantly in the white matter. A magnetic resonance imaging scan 2 weeks later showed a subcortical hemorrhage in the left insular region. He received long-term high-dose intravenous acyclovir and had significant improvement in his neurologic status.