Integrated global power from the primary structures that composed the Default Mode Network (DMN) and from a random collection of other structures were measured by sLORETA (standardized low-resolution electromagnetic tomography) for young university volunteers who had completed an inventory that contained a subscale by which egocentricity has been inferred. Subjects who exhibited higher scores for egocentricity displayed significantly more power within the DMN structures relative to comparison areas. This was not observed for individuals whose egocentricity scores were lowest where the power differences between the DMN and comparison structures were not significant statistically. DMN power was greater in the right hemisphere than the left for men but greater in the left hemisphere than the right for women. The results are consistent with our operating metaphor that elevation of power or activity within the DMN is associated with greater affiliation with the self and its cognitive contents.
Default mode network; Egocentricism; Gender differences; Psychometric Measurement; Quantitative electroencephalography; sLORETA.
Brain tumours that are associated with cerebral aneurysms are rare occurrences, whereas the coexistence of brain tumours and intra-tumoural aneurysms is even rarer. There have been 12 brain tumour cases that have been reported in the literature that describe an aneurysm within a brain tumour, with 4 of these tumours being meningiomas.
A 34-year-old male patient presented with sudden-onset headache, and an inter-hemispheric meningioma with intra-tumoural bleeding was found due to a ruptured embedded anterior cerebral artery aneurysm. The aneurysm was diagnosed incidentally on the third cerebral angiogram, while the initial 2 angiograms were negative. The patient was treated with endovascular aneurysm embolisation that was followed by tumour resection.
This paper is the first case report to describe the coexistence of a meningioma and an aneurysm, which presented with intra-tumoural haemorrhage that was negative on the initial cerebral angiogram. Unlike previous case reports, the aneurysm in this case was located with an anterior cerebral artery distribution.
Meningioma; Haemorrhage; subarachnoid haemorrhage (SAH); aneurysms; computed tomography; Brain magnetic resonance imaging (MRI).
The ability to predict an impending threat during Pavlovian conditioning diminishes the emotional response
that is produced once the threat is encountered. Diminution of the threat response appears to be mediated by somewhat
independent associative learning and expectancy-related processes. Therefore, the present study was designed to better
understand the neural mechanisms that support associative learning processes, independent of expectancy, that influence
the emotional response to a threat. Healthy volunteers took part in a Pavlovian conditioning procedure during which trait
anxiety, expectation of the unconditioned stimulus (UCS), skin conductance response (SCR), and functional magnetic
resonance imaging (fMRI) signal were assessed. The results showed no evidence for associative learning that was
independent of expectation. Threat-related SCR expression was diminished on predictable trials vs. unpredictable trials of
the UCS (i.e. conditioned UCR diminution). Similar to SCR, conditioned UCR diminution was observed within the left
dorsolateral PFC, dorsomedial PFC, ventromedial PFC, and left anterior insula. In contrast, potentiation of the threat-related
fMRI signal response was observed within left dorsolateral PFC, inferior parietal lobule (IPL), and posterior
insula. A negative relationship was observed between UCS expectancy and UCR expression within the dorsomedial PFC,
ventromedial PFC, and anterior insula. Finally, the anticipatory fMRI signal responses within the PFC, posterior
cingulate, and amygdala showed an inverse relationship with threat-related activation within the brain regions that showed
UCR diminution. The current findings suggest that the PFC and amygdala support learning-related processes that impact
the magnitude of the emotional response to a threat.
fMRI; conditioning; unconditioned response; prefrontal cortex; emotion; fear; anxiety; skin conductance.
Finding a path between locations is a routine task in daily life. Mental navigation is often used to plan a route
to a destination that is not visible from the current location. We first used functional magnetic resonance imaging (fMRI)
and surface-based averaging methods to find high-level brain regions involved in imagined navigation between locations
in a building very familiar to each participant. This revealed a mental navigation network that includes the precuneus,
retrosplenial cortex (RSC), parahippocampal place area (PPA), occipital place area (OPA), supplementary motor area
(SMA), premotor cortex, and areas along the medial and anterior intraparietal sulcus. We then visualized retinotopic maps
in the entire cortex using wide-field, natural scene stimuli in a separate set of fMRI experiments. This revealed five
distinct visual streams or ‘fingers’ that extend anteriorly into middle temporal, superior parietal, medial parietal,
retrosplenial and ventral occipitotemporal cortex. By using spherical morphing to overlap these two data sets, we showed
that the mental navigation network primarily occupies areas that also contain retinotopic maps. Specifically, scene-selective
regions RSC, PPA and OPA have a common emphasis on the far periphery of the upper visual field. These
results suggest that bottom-up retinotopic organization may help to efficiently encode scene and location information in
an eye-centered reference frame for top-down, internally generated mental navigation. This study pushes the border of
visual cortex further anterior than was initially expected.
fMRI; mental navigation; retinotopic maps; five visual streams; far periphery.
Although some authors suggest to use Long-Wave Infrared (LWIR) sensors to evaluate brain functioning, the link between emissions of LWIR and mental effort is not established. The goal of this pilot study was to determine whether frontal LWIR emissions vary during execution of neuropsychological tasks known to differentially activate the pre-frontal cortex (simple color presentations, induction of the Stroop effect, and a gambling task with real money). Surprisingly, LWIR emissions as measured with bilateral frontal sensors in 47 participants significantly differed between tasks, in the supposed direction (Color
Long-wave; passive; infrared; brain imaging.
To characterize the progression of injured tissue resulting from a permanent focal cerebral ischemia after the acute phase, Magnetic Resonance Imaging (MRI) monitoring was performed on adult male C57BL/6J mice in the subacute stages, and correlated to histological analyses.
Material and methods:
Lesions were induced by electrocoagulation of the middle cerebral artery. Serial MRI measurements and weighted-images (T2, T1, T2* and Diffusion Tensor Imaging) were performed on a 9.4T scanner. Histological data (Cresyl-Violet staining and laminin-, Iba1- and GFAP-immunostainings) were obtained 1 and 2 weeks after the stroke.
Two days after stroke, tissues assumed to correspond to the infarct core, were detected as a hyperintensity signal area in T2-weighted images. One week later, low-intensity signal areas appeared. Longitudinal MRI study showed that these areas remained present over the following week, and was mainly linked to a drop of the T2 relaxation time value in the corresponding tissues. Correlation with histological data and immuno-histochemistry showed that these areas corresponded to microglial cells.
The present data provide, for the first time detailed MRI parameters of microglial cells dynamics, allowing its non-invasive monitoring during the chronic stages of a stroke. This could be particularly interesting in regards to emerging anti-inflammatory stroke therapies.
Mouse; permanent cerebral ischemia; stroke; microglia; NMR Imaging.
We studied the imaginary coherence (IC) of gamma frequency oscillations between brain regions of male schizophrenia patients during an auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG).
Subjects were 10 right-handed male schizophrenia patients, evaluated by the positive and negative symptom scale (PANSS), and 10 healthy controls. Functional connectivity during the auditory oddball task was reconstructed in low (30-50 Hz) and high (50-100 Hz) gamma bands, and represented by imaginary coherence (IC) based on significant oscillatory power changes. We calculated correlations between PANSS scores and IC.
In the high gamma band, IC between left occipital and right prefrontal lobe areas during the time window 750-1000 ms from stimulus onset showed negative correlations with total negative scores, total positive scores, the sum of positive and negative scores in PANSS, conceptual disorganization, and social avoidance scores. In the low gamma band, IC between the same areas from 250-500 ms also showed a negative correlation with the conceptual disorganization score. In the same time window, IC between left occipital and right frontoparietal lobe areas in the low gamma band showed a positive correlation with hallucinatory behavior; IC between right temporal pole and left prefrontal lobe areas showed a positive correlation with delusion scores, although these ICs were decreased relative to controls.
Functional disconnection of high and low gamma bands in auditory oddball task may play an important role in the auditory processing in schizophrenia patients.
Magnetoencephalography; gamma band; functional connectivity; PANSS; schizophrenia; P300.
Previous in vivo experimental magnetic resonance imaging (MRI) investigations of the mammalian inner ear at 4.7 Tesla have indicated that intravenously injected gadolinium (Gd) penetrates the perilymphatic labyrinth, but not the endolymphatic membranous labyrinth. In the present study, high field MRI at 9.4T was used to visualize the in vivo mouse vestibulo-cochlea system, and to determine whether the endolymphatic system is permeable to a Gd complex.
A 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with maximum gradient strength of 600 mT/m, a millipede coil (Varian design) and a Gd contrast agent were used for image acquisition in the normal C57 BL-6 mouse.
High-resolution 2D and 3D images of the mouse cochlea were acquired within 80 minutes following intravenous injection of Gd. Gd initially permeated the perilymphatic scala tympani and scala vestibuli, and permitted visualization of both cochlear turns from base to apex. The superior, inferior and lateral semicircular canals were subsequently visualized in 3 planes. The membranous endolymphatic labyrinth was impermeable to intravenously injected Gd, and thus showed no apparent uptake of Gd at 9.4T.
The 9.4T field strength MRI permitted acquisition of high resolution images of anatomical and physiological features of the normal, wild type mouse perilymphatic inner ear in vivo, and provided further evidence that the endolymphatic system is impermeable to intravenously injected Gd.
Magnetic resonance imaging; cochlea; vestibular; semicircular canals; Tesla.
We studied differences in the spatiotemporal dynamics of cortical oscillation across brain regions of patients with schizophrenia and normal subjects during the auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG).
Ten right-handed male schizophrenia patients were studied. We used a newly developed adaptive spatial filtering algorithm optimized for robust source time-frequency reconstruction of MEG and EEG data, and obtained consecutive images in functional maps of event-related desynchronization (ERD) and synchronization (ERS) in theta, lower alpha (8–10 Hz), upper alpha (10–13 Hz), and beta bands.
Beta ERD power at 750–1000 ms in patients was significantly increased in large right upper temporal and parietal regions and small upper portions of bilateral dorsal frontal and dorsal-medial parietal regions. Theta ERS power in schizophrenic patients during the oddball task was significantly increased in the left temporal pole at 250–500 ms, and was significantly increased in dorsal, medial frontal, and anterior portions of the anterior cingulate cortex in both hemispheres, and the left portion of lateral temporal regions at 500–750 ms, compared to the control group (family-wise error correction p<0.05). Lower alpha ERS power was significantly decreased in the right occipital region at 500–750 ms and in the right midline parietal and bilateral occipital regions at 750–1000 ms. Upper alpha ERS power was significantly decreased in right midline parietal and left occipital regions at 750–1000 ms.
ERD/ERS changes were noted in the left temporal pole and midline frontal and anterior cingulate cortex in theta ERS, occipital lobe in alpha ERS, and right temporal-frontal-parietal, midline frontal, and anterior cingulate cortex in beta ERD. These findings may reflect disturbances in interaction among active large neuronal groups and their communication with each other that may be related to abnormal cognitive and psychopathological function.
Study of ERD and ERS by time-frequency analyses using MEG is useful to clarify data processing dysfunction in schizophrenia.
Magnetoencephalography; event-related desynchronization; event-related synchronization; schizophrenia; oddball task; P300.
Quantifiable modification of standardized low-resolution brain electromagnetic tomography (sLORETA-qm), which is one of the non-adaptive beamformer spatial filtering techniques, has been applied to source localization and quantification of evoked field or oscillatory changes in magnetoencephalography (MEG). Here, we extended this technique to induced oscillatory brain activity changes, so-called event-related desynchronization or event-related synchronization. For localizing of significantly activated brain areas at the whole-brain level, permutation tests and multiple comparison corrections with false discovery rate were applied. Induced β- and γ-band oscillatory changes by right hand clenching task were demonstrated as an example of simple induced brain activity.
Magnetoencephalography; sLORETA-qm; quantitative analysis; ERD/ERS; oscillatory change; induced activity.
The default mode network (DMN) has been consistently activated across a wide variety of self-related tasks, leading to a proposal of the DMN’s role in self-related processing. Indeed, there is limited fMRI evidence that the functional connectivity within the DMN may underlie a phenomenon referred to as self-awareness. At the same time, none of the known studies have explicitly investigated neuronal functional interactions among brain areas that comprise the DMN as a function of self-consciousness loss. To fill this gap, EEG operational synchrony analysis [1, 2] was performed in patients with severe brain injuries in vegetative and minimally conscious states to study the strength of DMN operational synchrony as a function of self-consciousness expression. We demonstrated that the strength of DMN EEG operational synchrony was smallest or even absent in patients in vegetative state, intermediate in patients in minimally conscious state and highest in healthy fully self-conscious subjects. At the same time the process of ecoupling of operations performed by neuronal assemblies that comprise the DMN was highest in patients in vegetative state, intermediate in patients in minimally conscious state and minimal in healthy fully self-conscious subjects. The DMN’s frontal EEG operational module had the strongest decrease in operational synchrony strength as a function of selfconsciousness loss, when compared with the DMN’s posterior modules. Based on these results it is suggested that the strength of DMN functional connectivity could mediate the strength of self-consciousness expression. The observed alterations similarly occurred across EEG alpha, beta1 and beta2 frequency oscillations. Presented results suggest that the EEG operational synchrony within DMN may provide an objective and accurate measure for the assessment of signs of self-(un)consciousness in these challenging patient populations. This method therefore, may complement the current diagnostic procedures for patients with severe brain injuries and, hence, the planning of a rational rehabilitation intervention.
EEG alpha and beta rhythms; brain operations; metastability; neurophysiological pattern; resting state; default mode; DMN; synchronization; functional connectivity; (un)consciousness of self.
While the neural network encompassing the processing of the mother tongue (L1) is well defined and has revealed the existence of a bilateral ventral pathway and a left dorsal pathway in which 3 loops have been defined, the question of the processing of a second language (L2) is still a matter of debate. Among variables accounting for the discrepancies in results, the degree of L2 proficiency appears to be one of the main factors. The present study aimed at assessing both pathways in L2, making it possible to determine the degree of mastery of the different speech components (prosody, phonology, semantics and syntax) that are intrinsically embedded within connected speech and that vary according to the degree of proficiency using high degrees of prosodic information. Two groups of high and moderate proficiency in L2 performed an fMRI comprehension task in L1 and L2. The modifications in brain activity observed within the dorsal and the ventral pathways according to L2 proficiency suggest that different processes of L2 are supported by differences in the integrated activity within distributed networks that included the left STSp, the left Spt and the left pars triangularis.
Bilingualism; connected speech perception; degree of proficiency; ventral and dorsal pathways; fMRI.
1 Hz repetitive Transcranial Magnetic Stimulation (rTMS) is considered to have an inhibitory effect in
healthy people because it suppresses the excitability of the motor or visual cortex that is expressed as an increase in
the motor or the phosphene threshold (PT), respectively. However, the underlying mechanisms and the brain structures
involved in the action of rTMS are still unknown. In this study we used two sessions of simultaneous TMS-functional
magnetic resonance imaging (fMRI), one before and one after, 15 minutes of 1Hz rTMS to map changes in
brain function associated with the reduction in cortical excitability of the primary visual cortex induced by 1 Hz
rTMS, when TMS was applied on the occipital area of healthy volunteers. Two groups were evaluated, one group
composed of people that can see phosphenes, and another of those lacking this perception. The inhibitory effect, induced
by the 1 Hz rTMS, was observed through the increase of the PT, in the first group, but did not lead to a global
reduction in brain activation, instead, showed change in the activation pattern before and after rTMS. Conversely, for
the second group, changes in brain activation were observed just in few brain areas, suggesting that the effect of 1 Hz
rTMS might not be inhibitory for everyone and that the concept of inhibitory/excitatory effect of rTMS may need to be
TMS-functional magnetic resonance imaging; phosphene threshold.
We report the case of a 24 year old male who had a retained bullet within his thoracic spine from a gunshot
wound resulting in paraplegia. After 7 months he began experiencing painful dysesthesias at his sensory level. Repeat
imaging demonstrated migration of the bullet as well as the development of intramedullary dystrophic calcification
associated with the bullet. This case demonstrates not only the ability for retained bullets to migrate within the spinal
canal but also demonstrates they can lead to remote symptoms due to the development of dystrophic calcification.
Bullet; dystrophic calcification; spinal cord trauma.
Inner speech involvement in self-reflection was examined by reviewing 130 studies assessing brain activation during self-referential processing in key self-domains: agency, self-recognition, emotions, personality traits, autobiographical memory, and miscellaneous (e.g., prospection, judgments). The left inferior frontal gyrus (LIFG) has been shown to be reliably recruited during inner speech production. The percentage of studies reporting LIFG activity for each self-dimension was calculated. Fifty five percent of all studies reviewed indicated LIFG (and presumably inner speech) activity during self-reflection tasks; on average LIFG activation is observed 16% of the time during completion of non-self tasks (e.g., attention, perception). The highest LIFG activation rate was observed during retrieval of autobiographical information. The LIFG was significantly more recruited during conceptual tasks (e.g., prospection, traits) than during perceptual tasks (agency and self-recognition). This constitutes additional evidence supporting the idea of a participation of inner speech in self-related thinking.
Self-awareness; self-reflection; self-referential activity; inner speech; self-talk; verbal labeling; left inferior frontal gyrus; language; conceptual self-domains; perceptual self-domains; brain-imaging.
We report the case of a 57-year-old male who presented with recurrent sinus infections and frequent nasal
irrigation. He was found at nasal endoscopy to have multiple outgrowths along his ethmoid and maxillary sinuses.
Computed tomography (CT) showed multiple bony exostoses along these sinuses. We report the imaging findings of
exostoses associated with sinonasal irrigation.
Exostoses; paranasal sinuses.
Targeting in deep brain stimulation (DBS) relies heavily on the ability to accurately localize particular anatomic brain structures. Direct targeting of subcortical structures has been limited by the ability to visualize relevant DBS targets.
Methods and Results:
In this work, we describe the development and implementation, of a methodology utilized to create a three dimensional deformable atlas for DBS surgery. This atlas was designed to correspond to the print version of the Schaltenbrand-Bailey atlas structural contours. We employed a smoothing technique to reduce artifacts inherent in the print version.
We present the methodology used to create a three dimensional patient specific DBS atlas which may in the future be tested for clinical utility.
Deep brain stimulation; Targeting; deep brain stimulation; atlas.
Intraosseous lipoma is a rare benign tumor, mostly occurring in lower limb especially in os calcis and the metaphyses of long bones. Intraosseous lipoma of the skull is even rarer, with 12 cases having been reported to involve the sphenoid bone in the literature. We present the third reported case of sphenoclival intraosseous lipoma in a 43-year-old man with headache, hyperprolactinemia and visual disturbance. Performed Magnetic Resonance Imaging (MRI) revealed pituitary macroadenoma as well as a mildly expansile lesion with high signal intensity on both T1- and T2-weighted sequences within the left greater wing of the sphenoid and the clivus. The patient refused to undergo surgical removal of pituitary macroadenoma and medical treatment was initiated instead; thereafter, follow up Computed Tomography (CT) and MRI scans revealed regression of the pituitary macroadenoma whereas the sphenoclival lesion was depicted as a welldefined fat-containing intraosseous lesion which showed no perceptible growth, 17 months later.
Intraosseous lipoma; Sphenoclival; Magnetic resonance imaging; Computed tomography.
Although human brain development continues throughout childhood and adolescence, it is a non-linear process
both structurally and functionally. Here we review studies of brain development in healthy children from the viewpoint of
structure and the perfusion of gray and white matter. Gray matter volume increases and then decreases with age, with the
developmental time of the peak volume differing among brain regions in the first and second decades of life. On the other
hand, white matter volume increase is mostly linear during those periods. As regards fractional anisotropy, most regions
show an exponential trajectory with aging. In addition, cerebral blood flow and gray matter volume are proportional at
similar developmental ages. Moreover, we show that several lifestyle choices, such as sleeping habits and breakfast staple,
affect gray matter volume in healthy children. There are a number of uninvestigated important issues that require future
Development; Children; Gray matter; White matter; Voxel-based morphometry; Diffusion tensor imaging; Magnetic resonance imaging; Arterial spin labeling.