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1.  A Schizophrenia-Like Psychotic Disorder Secondary to an Arachnoid Cyst Remitted with Neurosurgical Treatment of the Cyst 
We describe a case of delusional psychosis that was terminated by neurosurgical removal of a large arachnoid cyst. The patient was suffering his first psychotic episode and had symptoms typical of schizophrenia.
The case underscores the importance of considering that an arachnoid cyst can induce psychopathological symptoms, even those of schizophrenia. Indeed, such symptoms may be the cyst's only clinical manifestation.
In addition, the case highlights the importance of doing a structural imaging test when confronted with a first episode of psychosis, especially if the episode is relatively late in appearance. Such imaging may lead to a diagnosis that in turn can enable a definitive neurosurgical resolution of the psychosis.
PMCID: PMC3959176  PMID: 24653786
Arachnoid cysts; neurosurgery; psychosis; psychiatry.
2.  Enhanced Power Within the Default Mode Network in Normal Subjects with Elevated Scores on an Egocentric Scale 
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.
PMCID: PMC4238028  PMID: 25419254
Default mode network; Egocentricism; Gender differences; Psychometric Measurement; Quantitative electroencephalography; sLORETA.
3.  Increasing Neuroradiology Exam Volumes On-Call Do Not Result in Increased Major Discrepancies in Primary Reads Performed by Residents 
Background and Purpose:
A common perception is that increased on-call workload leads to increased resident mistakes. To test this, we evaluated whether increased imaging volume has led to increased errors by residents.
Materials and Methods:
A retrospective review was made of all overnight neuroradiology CT exams with a primary resident read from 2006-2010. All studies were over-read by staff neuroradiologists next morning. As the volume is higher on Friday through Sunday nights, weekend studies were examined separately. Discrepancies were classified as either minor or major. “Major” discrepancy was defined as a discrepancy that the staff radiologist felt was significant enough to potentially affect patient care, necessitating a corrected report and phone contact with the ordering physician and documentation. The total number of major discrepancies was recorded by quarter. In addition, the total number of neuroradiology CT studies read overnight on-call was noted.
The mean number of cases per night during the weekday increased from 3.0 in 2006 to 5.2 in 2010 (p<0.001). During the weekend, the mean number of cases per night increased from 5.4 in 2006 to 7.6 in 2010 (p<0.001). Despite this increase, the major discrepancy rate decreased from 2.7% in 2006 to 2.3% in 2010 (p=0.34).
Despite an increase in neuroradiology exam volumes, there continues to be a low major discrepancy rate for primary resident interpretations. While continued surveillance of on-call volumes is crucial to the educational environment, concern of increased major errors should not be used as sole justification to limit autonomy.
PMCID: PMC4311384  PMID: 25646138
Discrepancy; education; error; on-call; resident.
4.  Hippocampal Morphology in a Rat Model of Depression: The Effects of Physical Activity 
Accumulating in vivo and ex vivo evidences show that humans suffering from depression have decreased hippocampal volume and altered spine density. Moreover, physical activity has an antidepressant effect in humans and in animal models, but to what extent physical activity can affect hippocampal volume and spine numbers in a model for depression is not known.
In this study we analyzed whether physical activity affects hippocampal volume and spine density by analyzing a rodent genetic model of depression, Flinders Sensitive Line Rats (FSL), with Magnetic Resonance Imaging (MRI) and ex vivo Golgi staining.
We found that physical activity in the form of voluntary wheel running during 5 weeks increased hippocampal volume. Moreover, runners also had larger numbers of thin spines in the dentate gyrus. Our findings support that voluntary wheel running, which is antidepressive in FSL rats, is associated with increased hippocampal volume and spine numbers.
PMCID: PMC4319211
Animal model; dendrite morphology; flinders sensitive line rats; hippocampus; major depression; MRI; volume based morphometry.
5.  Long-Wave Infrared Functional Brain Imaging in Human: A Pilot Study 
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
PMCID: PMC3565228  PMID: 23400426
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.
PMCID: PMC3580904  PMID: 23459141
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.
PMCID: PMC3636485  PMID: 23750187
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.
PMCID: PMC3722534  PMID: 23894262
Magnetic resonance imaging; cochlea; vestibular; semicircular canals; Tesla.
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.
Case description:
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.
PMCID: PMC3812785  PMID: 24179557
Meningioma; Haemorrhage; subarachnoid haemorrhage (SAH); aneurysms; computed tomography; Brain magnetic resonance imaging (MRI).
Langerhans cell histiocytosis (LCH) is a rare histiocytic disorder with an unpredictable clinical course and highly varied clinical presentation ranging from single system to multisystem involvement. Although head and neck involvement is common in LCH, isolated bilateral temporal bone involvement is exceedingly rare. Furthermore, LCH is commonly misinterpreted as mastoiditis, otitis media and otitis externa, delaying diagnosis and appropriate therapeutic management. To improve detection and time to treatment, it is imperative to have LCH in the differential diagnosis for unusual presentations of the aforementioned infectious head and neck etiologies. Any lytic lesion of the temporal bone identified by radiology should raise suspicion for LCH. We hereby describe the radiologic findings of a case of bilateral temporal bone LCH, originally misdiagnosed as mastoiditis.
PMCID: PMC3905351  PMID: 24478812
Langerhans cell histiocytosis; Bilateral temporal bone; Mastoiditis; CT; 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.
PMCID: PMC3905352  PMID: 24478811
fMRI; conditioning; unconditioned response; prefrontal cortex; emotion; fear; anxiety; skin conductance.
We report a case of a benign notochordal cell tumor (BNCT) of the sacrum with atypical imaging features, which was incidentally discovered in a 74-year-old man undergoing evaluation for progressively worsening hip and back pain. It is important for radiologists, pathologists and orthopedic surgeons to be aware of the diagnosis of BNCT and be familiar with its radiographic features to avoid unnecessary treatment. This case illustrates the advantage of percutaneous computed tomography (CT)-guided biopsy as a minimally invasive technique for definitive diagnosis of a BNCT with atypical imaging features.
PMCID: PMC3905355  PMID: 24478810
Benign notochordal cell tumor; Benign chordoma; Giant notochordal hamartoma; Giant notochordal rest and Needle biopsy.
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.
PMCID: PMC3905356  PMID: 24478813
fMRI; mental navigation; retinotopic maps; five visual streams; far periphery.
In this work we combine machine learning methods and graph theoretical analysis to investigate gender associated differences in resting state brain network connectivity. The set of all correlations computed from the fMRI resting state data is used as input features for classification. Two ensemble learning methods are used to perform the detection of the set of discriminative edges between groups (males vs. females) of brain networks: 1) Random Forest and 2) an ensemble method based on least angle shrinkage and selection operator (lasso) regressors. Permutation testing is used not only to assess significance of classification accuracy but also to evaluate significance of feature selection. Finally, these methods are applied to data downloaded from the Connectome Project website. Our results suggest that gender differences in brain function may be related to sexually dimorphic regional connectivity between specific critical nodes via gender-discriminative edges.
PMCID: PMC3271304  PMID: 22312418
Resting state fMRI; Machine learning; Graph theory; Regularization; GLMNET; Random forest.
Certain Acute Clinical presentations are highly suggestive of stroke caused by specific mechanisms. One example of this would be the sudden onset of aphasia without hemiparesis often reflecting cerebral embolism, frequently from a cardiac source. Posterior reversible encephalopathy syndrome (PRES) describes a usually reversible neurologic syndrome with a variety of presenting symptoms from headache, altered mental status, seizures, vomiting, diminished spontaneity and speech, abnormalities of visual perception and visual loss. We report a patient presenting with elevated blood pressure, CT characteristics of PRES but a highly circumscribed neurologic syndrome (Wernicke's Aphasia without hemiparesis) suggestive of a cardioembolic stroke affecting the left MCA territory. That is, PRES mimicked a focal stroke syndrome. The importance of recognizing this possibility is that his deficits resolved with blood pressure control, while other treatments, such as intensifying his anticoagulation would have been inappropriate. In addition, allowing his blood pressure to remain elevated as is often done in the setting of an acute stroke might have perpetuated the underlying pathophysiology of PRES leading to a worse clinical outcome. For this reason PRES needs to be recognized quickly and treated appropriately.
PMCID: PMC3282886  PMID: 22371821
Posterior reversible encephalopathy syndrome; Stroke; Embolism; Wernicke's aphasia.
We report the case of an 11 year old boy who presented with nausea, vomiting and ataxia. He was evaluated with computed tomography (CT) and magnetic resonance imaging (MRI). Imaging demonstrated minimal enhancement and hemorrhage of a cerebellar mass. Cerebellar glioblastoma multiforme (GBM) is extremely rare in the cerebellum at any age but especially in children. The atypical findings of minimal enhancement, cerebellar location and hemorrhagic presentation combine to make the prospective diagnosis of GBM a difficult one. This rare combination of findings has not been previously reported.
PMCID: PMC3296109  PMID: 22423307
Glioblastoma multiforme; pediatric; cerebellum.
Hypovitaminosis D is associated with cognitive decline in the elderly, but the issue of causality remains unresolved. Definitive evidence would include the visualization of brain lesions resulting from hypovitaminosis D. The aim of the present article is to determine, through a literature review, the location and nature of possible brain disorders in hypovitaminosis D. We found limited brain-imaging data, which reported ischemic infarcts and white matter hyperintensities in hypovitaminosis D, though did not provide their specific location or report any focal atrophy. Based on the finding of executive dysfunctions (i.e., mental shifting and information updating impairments) in the presence of hypovitaminosis D, we suggest that hypovitaminosis D is associated with a dysfunction of the frontal-subcortical neuronal circuits, particularly the dorsolateral circuit. Further imaging studies are required to corroborate this assumption and to determine whether hypovitaminosis D results in degenerative and / or vascular lesions.
PMCID: PMC3296113  PMID: 22423308
Vitamin D; brain mapping; cognition; older adults.
The polymorphism of variable number of tandem repeat (VNTR) in dopamine receptor D4 (DRD4) gene exon III has been linked to various neuro-psychiatric conditions with disinhibition/impulsivity as one of the core features. This study examined the modulatory effects of long-allele variant of DRD4 VNTR on the regional neural activity as well as inter-regional neural interactions in a young female population. Blood sample and resting state eyes-closed EEG signals were collected in 233 healthy females, stratified into two groups by polymerase chain reaction: long-allele carriers (>4- repeat) and non-carriers (<=4-repeat/<=4-repeat). The values of mean power of 18 electrodes and mutual information of 38 channel pairs across theta, alpha, and beta frequencies were analyzed. Our connectivity analysis was based on information theory, which combined Morlet wavelet transform and mutual information calculation. Between-group differences of regional power and connectivity strength were quantified by independent t-test, while between-group differences in global trends were examined by non-parametric analyses. We noticed that DRD4 VNTR long-allele was associated with decreased global connectivity strength (from non-parametric analysis), especially over bi-frontal, biparietal and right fronto-parietal and right fronto-temporal connections (from independent t-tests). The between-group differences in regional power were not robust. Our findings fit with the networks of response inhibition, providing evidence bridging DRD4 long-allele and disinhibition/impulsivity in neuropsychiatric disorders. We suggest future DRD4 studies of imaging genetics incorporate connectivity analysis to unveil its impact on cerebral network.
PMCID: PMC3308261  PMID: 22448208
Electroencephalography (EEG); mutual information; connectivity; power spectrum; DRD4; polymorphism.
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.
PMCID: PMC3409351  PMID: 22870167
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.
PMCID: PMC3412199  PMID: 22870168
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.
PMCID: PMC3419863  PMID: 22905075
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.
PMCID: PMC3426773  PMID: 22927897
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 revised.
PMCID: PMC3428632  PMID: 22930669
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.
PMCID: PMC3431563  PMID: 22942925
Bullet; dystrophic calcification; spinal cord trauma.

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