Editorial: «Interventional Neuroradiology: a Neuroscience sub-specialty?¼.

Interventional Neuroradiology (INR) is not bound by the classical limits of a speciality, and is not restricted by standard formats of teaching and education. Open and naturally linked towards neurosciences, INR has become a unique source of novel ideas for research, development and progress allowing new and improved approaches to challenging pathologies resulting in better anatomo-clinical results. Opening INR to Neurosciences is the best way to keep it alive and growing. Anchored in Neuroradiology, at the crossroad of neurosciences, INR will further participate to progress and innovation as it has often been in the past.

«Interventional Neuroradiology: a neuroscience sub-specialty?¼.

Interventional Neuroradiology (INR) is not bound by the classical limits of a specialty, and is not restricted by standard formats of teaching and education. Open and naturally linked towards neurosciences, INR has become a unique source of novel ideas for research, development and progress allowing new and improved approaches to challenging pathologies resulting in better anatomo-clinical results. Opening INR to Neurosciences is the best way to keep it alive and growing. Anchored in Neuroradiology, at the crossroad of neurosciences, INR will further participate to progress and innovation as it has often been in the past.

Oxytocin facilitates protective responses to aversive social stimuli in males.

The neuropeptide oxytocin (OXT) can enhance the impact of positive social cues but may reduce that of negative ones by inhibiting amygdala activation, although it is unclear whether the latter causes blunted emotional and mnemonic responses. In two independent double-blind placebo-controlled experiments, each involving over 70 healthy male subjects, we investigated whether OXT affects modulation of startle reactivity by aversive social stimuli as well as subsequent memory for them. Intranasal OXT potentiated acoustic startle responses to negative stimuli, without affecting behavioral valence or arousal judgments, and biased subsequent memory toward negative rather than neutral items. A functional MRI analysis of this mnemonic effect revealed that, whereas OXT inhibited amygdala responses to negative stimuli, it facilitated left insula responses for subsequently remembered items and increased functional coupling between the left amygdala, left anterior insula, and left inferior frontal gyrus. Our results therefore show that OXT can potentiate the protective and mnemonic impact of aversive social information despite reducing amygdala activity, and suggest that the insula may play a role in emotional modulation of memory.

Cerebral lesions can impair fMRI-based language lateralization.

PURPOSE: Several small patient studies and case reports raise concerns that the reliability of functional magnetic resonance imaging (fMRI) may be impaired in the vicinity of cerebral lesions. This could affect the clinical validity of fMRI for presurgical language lateralization. The current study sets out to identify if a systematic effect of lesion type and localization on fMRI exists. METHODS: We classify lesions typically occurring in epilepsy patients according to (1) their potential to disturb blood oxygenation level dependent (BOLD)-effect generation or detection or to disturb spatial brain normalization, and (2) the proximity of lesions to protocol-specific volumes of interest (VOIs). The effect of lesions is evaluated through the examination of 238 epilepsy patients and a subgroup of 37 patients with suspected unilateral left-language dominance according to the Wada test. RESULTS: Patients with fMRI-critical lesions such as cavernomas, gliomas, and mass defects close to VOIs, or with severe atrophy, show lower lateralization indices (LIs) and more often discordant language lateralization with the Wada test than do patients without such lesions. DISCUSSION: This study points seriously toward fMRI-language lateralization being sensitive to cerebral lesions. Some lesion types and locations are more critical than others. Our results question the noncritical application of fMRI in patients with cerebral lesions.

Strongly lateralized activation in language fMRI of atypical dominant patients-implications for presurgical work-up.

PURPOSE: Functional magnetic resonance imaging (fMRI) is being used increasingly for language dominance assessment in the presurgical work-up of patients with pharmacoresistant epilepsy. However, the interpretation of bilateral fMRI-activation patterns is difficult. Various studies propose fMRI-lateralization index (LI) thresholds between +/-0.1 and +/-0.5 for discrimination of atypical from typical dominant patients. This study examines if these thresholds allow identifying atypical dominant patients with sufficient safety for presurgical settings. METHODS: 65 patients had a tight comparison, fully controlled semantic decision fMRI-task and a Wada-test for language lateralization. According to Wada-test, 22 were atypical language dominant. In the remaining, Wada-test results were compatible with unilateral left dominance. We determined fMRI-LI for two frontal and one temporo-parietal functionally defined, protocol-specific volume of interest (VOI), and for the least lateralized of these VOIs ("low-VOI") in each patient. RESULTS: We find large intra-individual LI differences between functionally defined VOIs irrespective of underlying type of language dominance (mean LI difference 0.33+/-0.35, range 0-1.6; 15% of patients have inter-VOI-LI differences >1.0). Across atypical dominant patients fMRI-LI in the Broca's and temporo-parietal VOI range from -1 to +1, in the "remaining frontal" VOI from -0.93 to 1. The highest low-VOI-LI detected in atypical dominant patients is 0.84. CONCLUSIONS: Large intra-individual inter-VOI-LI differences and strongly lateralized fMRI-activation in patients with Wada-test proven atypical dominance question the value of the proposed fMRI-thresholds for presurgical language lateralization. Future studies have to develop strategies allowing the reliable identification of atypical dominance with fMRI. The low-VOI approach may be useful.

A novel, self-expanding, nitinol stent in medically refractory intracranial atherosclerotic stenoses: the Wingspan study.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the safety and performance of the Wingspan stent system and Gateway percutaneous transluminal angioplasty balloon catheter in the treatment of high-grade, intracranial atherosclerotic lesions in patients who had failed medical therapy. METHODS: In this prospective, multicenter, single-arm study, medically refractory patients with a modified Rankin score < or =3 and recurrent symptoms attributable to angiographically demonstrated intracranial stenosis > or =50% in a vessel 2.5 to 4.5 mm in diameter were enrolled. Intracranial lesions were predilated with an undersized Gateway balloon catheter to 80% of the native vessel diameter, followed by deployment of the self-expanding Wingspan stent to facilitate further remodeling of the atherosclerotic plaque and to maintain vessel patency. Neurologic examinations and angiograms were performed at 6 months after the procedure. RESULTS: Among the 45 patients enrolled, the degree of stenosis was reduced from a baseline of 74.9+/-9.8% to 31.9+/-13.6% after stenting and 28+/-23.2% at the 6-month follow-up. The 30-day composite ipsilateral stroke/death rate was 4.5% (2/44); at the 6-month follow-up, the ipsilateral stroke/death rate was 7.0%, the rate for all strokes was 9.7%, and all-cause mortality was 2.3%. Physician-reported follow-up in 43 patients (average of 13 months) conducted outside the study protocol (not adjudicated by the clinical event committee) reported 1 additional ipsilateral stroke. CONCLUSIONS: In medically refractory patients with high-grade intracranial atherosclerotic stenoses, a new treatment paradigm involving predilation with an undersized Gateway percutaneous transluminal angioplasty balloon catheter and placement of a self-expanding Wingspan stent system appears to be safe, may facilitate remodeling, and may contribute to favorable angiographic outcomes.

"Soundmorphing": a new approach to studying speech perception in humans.

A problem in current studies of brain activation in speech perception is that most studies use stimuli that are sampled from different categories. This study presents a new approach in creating acoustic stimuli by filtering real words in different ways, thus this enables one to 'morph' the sounds gradually from something like tones to real words while preserving temporal characteristics ("soundmorphing"). This will make it possible to explore steps between tone and speech processing on a gradual scale. This study aimed to investigate more closely the network, involved in the perception of speech and the decoding of auditory (speech-)stimuli. Sets of auditory stimuli were created by dividing real words into several frequency-bands and creating a randomised rearrangement of these components. Four different sets of stimuli were used, containing 1, 2, 3 or 4 frequency bands (total range: 0-2500 Hz). Only the latter one contained intelligible words. During the fMRI session, these four trial types were presented pseudo-randomised. In all conditions, significant activations of auditory cortex were observed. The number of activated voxels and their significance increased over the four trial types. In addition, Broca's area, SMA, left thalamus, and right cerebellum were activated in the most complex and most speech-like condition. Comparing these complexes with the tone-like trials, only the left auditory cortex, left SMA, and cingulate gyrus became significant. These activations reflect the bilateral processing of the auditory stimuli, but only the left temporal areas demonstrated an increasing BOLD response with an increasing number of presented frequency components.

Differences of cerebral activation between superior and inferior learners during motor sequence encoding and retrieval.

Cerebral activation during memory encoding and retrieval might depend on subjects' learning capacity, either by corresponding to better performance in superior learners or by reflecting increased effort in inferior learners. To investigate these alternative hypotheses, the study compared cerebral activation during encoding and retrieval of a motor sequence in groups of subjects with superior and inferior learning performances. Ten healthy subjects underwent functional magnetic resonance imaging (fMRI) while performing a motor sequence encoding paradigm (i.e. finger tapping sequence) and a retrieval paradigm (i.e. reproduction of the learned sequence). Subjects were divided into superior and inferior learners according to the correctness of sequence reproduction during retrieval. During encoding, there was strong bilateral activation in the middle frontal gyrus, the supplementary motor area (SMA), the lateral parietal lobe and the cerebellum. During retrieval, again strong activation was found in identical areas of the prefrontal cortex, the parietal lobe and the cerebellum. During encoding, inferior learners showed more left-sided activations in the left middle frontal and inferior parietal gyri. Superior learners showed increased activation in the corresponding right-sided brain areas during encoding as well as during retrieval. Differences of cerebral activations in the prefrontal and parietal cortex during encoding and retrieval were found to be related to retrieval performance, i.e. success and effort. Further intervention studies are needed to assess whether these interindividual differences are the cause or the consequence of differences in memory performance.

Evidence for a dysfunctional retrosplenial cortex in patients with schizophrenia: a functional magnetic resonance imaging study with a semantic-perceptual contrast.

We investigated whether the retrosplenial and the posterior cingulate cortex (RS-PCC) is functionally impaired in schizophrenia patients. Therefore, we measured functional magnetic resonance imaging (fMRI) signal changes associated with a synonym-judgment task known to activate, among other areas, the RS-PCC. Compared to 12 matched control subjects, 12 schizophrenia patients exhibited reliably weaker activations in the RS-PCC, the dorsolateral prefrontal cortex and the left orbitofrontal cortex (P < 0.05, corrected). Differences in frontal activations are in line with previous studies showing a structurally and functionally affected prefrontal cortex in schizophrenia. The impaired RS-PCC functionality in a semantic task may relate to verbal memory deficits frequently observed in schizophrenia patients, because this region is pivotal for gating information into the medial temporal lobe memory system.

Cranial magnetic resonance imaging in genetically proven myotonic dystrophy type 1 and 2.

Cranial magnetic resonance imaging (MRI) in 19 German patients with genetically proven myotonic dystrophy Type 1 (DM1, n = 10) or Type 2 (DM2, n = 9) showed pathological findings consisting of white matter lesions (WML) and/or brain atrophy in 9/10 DM1 and 8/9 DM2 patients. Anterior temporal WML (ATWML) were exclusively seen in DM1 patients. Our findings indicate a high frequency of central nervous system (CNS) involvement in both disorders. However, temporopolar pathology, previously associated with intellectual dysfunction, seems to be restricted to DM1.

Using visual advance information: an event-related functional MRI study.

Our event-related functional MRI (efMRI) study investigates whether visual advance information (AI) affects rather perceptual or central response-related processing areas. Twelve subjects were required to make a go/no-go decision to a conjunction of a specific color and motion direction. The stimuli were preceded by a cue, providing 100% valid advance information about motion direction. Partial and full advance information (PAI and FAI) predicted possible targets, respectively, certain nontargets, neutral cues (NAI) gave no prediction. The time between cue and stimulus (stimulus onset asynchrony, SOA) was varied. A response benefit was found after PAI as compared with NAI. The benefit was small with a short SOA (150 ms), increased with intermediate SOA (450 ms) and sustained with long SOA (750 ms). Perceptual and central processing areas were more active with increasing SOA, but only central response-related processing areas were selectively modulated by cue information. In particular, supplementary motor area and bilateral inferior parietal lobe were more active with PAI than with NAI. If comparing NAI with FAI, more errors were made and activity was larger in central processing areas. Our results suggest that, depending on the processing time, cues providing perceptual information modulate central response-related processes.

Temporal and cerebellar brain regions that support both declarative memory formation and retrieval.

Using event-related fMRI, we scanned young healthy subjects while they memorized real-world photographs and subsequently tried to recognize them within a series of new photographs. We confirmed that activity in the medial temporal lobe (MTL) and inferior prefrontal cortex correlates with declarative memory formation as defined by the subsequent memory effect, stronger responses to subsequently remembered than forgotten items. Additionally, we confirmed that activity in specific regions within the parietal lobe, anterior prefrontal cortex, anterior cingulate and cerebellum correlate with recognition memory as measured by the conventional old/new effect, stronger responses for recognized old items (hits) than correctly identified new items (correct rejections). To obtain a purer measure of recognition success, we introduced two recognition effects by comparing brain responses to hits and old items misclassified as new (misses). The positive recognition effect (hits > misses) revealed prefrontal, parietal and cerebellar contributions to recognition, and in line with electrophysiological findings, the negative recognition effect (hits < misses) revealed an anterior medial temporal contribution. Finally, by inclusive masking, we identified temporal and cerebellar brain areas that support both declarative memory formation and retrieval. For matching operations during recognition, these areas may re-use representations formed and stored locally during encoding.

Functional segregation of the temporal lobes into highly differentiated subsystems for auditory perception: an auditory rapid event-related fMRI-task.

With this study, we explored the blood oxygen level-dependent responses within the temporal lobe to short auditory stimuli of different classes. To address this issue, we performed an attentive listening event-related fMRI study, where subjects were required to concentrate during the presentation of different types of stimuli. Because the order of stimuli was randomized and not predictable for the subject, the observed differences between the stimuli types were interpreted as an automatic effect and were not affected by attention. We used three types of stimuli: tones, sounds of animals and instruments, and words. We found in all cases bilateral activations of the primary and secondary auditory cortex. The strength and lateralization depended on the type of stimulus. The tone trials led to the weakest and smallest activations. The perception of sounds increased the activated network bilaterally into the superior temporal sulcus mainly on the right and the perception of words led to the highest activation within the left superior temporal sulcus as well as in left inferior frontal gyrus. Within the left temporal sulcus, we were able to distinguish between different subsystems, showing an extending activation from posterior to anterior for speech and speechlike information. Whereas posterior parts were involved in analyzing the complex auditory structure of sounds and speech, the middle and anterior parts responded strongest only in the perception of speech. In summary, a functional segregation of the temporal lobes into several subsystems responsible for auditory processing was visible. A lateralization for verbal stimuli to the left and sounds to the right was already detectable when short stimuli were used.

In vivo voxel-based morphometry in multiple system atrophy of the cerebellar type.

BACKGROUND: Multiple system atrophy (MSA) is a sporadic neurodegenerative disease. According to the clinical presentation a parkinsonian type and a cerebellar type (MSA-C) are distinguished. OBJECTIVE: To study the morphological alterations of MSA-C-affected brains in vivo using voxel-based morphometric analysis of magnetic resonance images. SETTING: University hospital. PATIENTS: Fourteen patients (5 men and 9 women) with MSA-C (mean age [SD], 59.4 [7.4] years; mean [SD] disease duration, 3.7 [1.4] years) and 13 healthy control subjects (5 men and 8 women) (mean [SD] age, 55.1 [6.9] years) were studied. METHODS: T1-weighted magnetic resonance images were normalized to a common stereotaxic space and segmented into gray and white matter. Data were analyzed using statistical parametric mapping (SPM99). RESULTS: Gray matter was reduced in the brainstem and the anterior lobe of the cerebellum. Reduction of white matter was observed in the middle cerebellar peduncles, cerebellar white matter, and brainstem. The inverted comparison revealed an increase of white matter density along the pyramidal tracts. CONCLUSIONS: Voxel-based morphometry revealed a significant loss of cerebellar and brainstem tissue in MSA-C. It allowed a precise anatomical localization and a distinction between gray and white matter densities. In addition, our data point to a particular involvement of the pyramidal tract in MSA-C.

Menstrual cycle-dependent neural plasticity in the adult human brain is hormone, task, and region specific.

In rodents, cyclically fluctuating levels of gonadal steroid hormones modulate neural plasticity by altering synaptic transmission and synaptogenesis. Alterations of mood and cognition observed during the menstrual cycle suggest that steroid-related plasticity also occurs in humans. Cycle phase-dependent differences in cognitive performance have almost exclusively been found in tasks probing lateralized neuronal domains, i.e., cognitive domains such as language, which are predominantly executed by one hemisphere. To search for neural correlates of hormonally mediated neural plasticity in humans, we thus conducted a functional magnetic resonance imaging study measuring brain activity related to a semantic decision task in the language domain. This was contrasted with a letter-matching task in the perceptual domain, in which we expected no steroid hormone-mediated effect. We investigated 12 young healthy women in a counterbalanced repeated-measure design during low-steroid menstruation and high-steroid midluteal phase. Steroid serum levels correlated with the volume and lateralization of particular brain activations related to the semantic task but not with brain activity related to the perceptual task. More specifically, bilateral superior temporal recruitment correlated positively with progesterone and medial superior frontal recruitment with both progesterone and estradiol serum levels, whereas activations in inferior and middle frontal cortex were unaffected by steroid levels. In contrast to these specific interactions, testosterone levels correlated nonselectively with overall activation levels by neural and/or vascular factor(s). In conclusion, our data demonstrate steroid hormone responsivity in the adult human brain by revealing neural plasticity in the language domain, which appears hormone, task, and region specific.