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The association between numerical and spatial thinking manifests itself throughout various cognitive observations, concerning arithmetic problem solving as well as simple number recognition tasks. The spatial component in numerical thinking is assumed to represent the semantic processing pathway, for example, the mental representation of numerical magnitude. There is an interconnection of semantic, linguistic, and visual/symbolic pathways, which is thought to be stronger in adults than in children. During childhood, the semantic pathway is supposed to play a major part in numerical processing. In this study, we conducted a functional magnetic resonance imaging paradigm combining a mental rotation task with a number processing task. The behavioral data showed the highest error rate for two-digit numbers (not for three-digit numbers). In regard to two-digit numbers, we also found the strongest neuronal activation overlap for number processing and mental rotation in the left intraparietal sulcus. This pattern suggests that the mental inversion of digits in native German speakers might be a spatial function related to mental rotation. In terms of overcoming opposed informational input for symbolic and linguistic representation and therefore impeded informational extraction the spatial processing pathway might play a major role. To conclude, spatial training could be an effective educational approach, supporting the interconnection of numerical processing pathways.

Background Stimulus-response compatibility (SRC) plays a major role in choice-reaction tasks. In specific cases, SRC leads to phenomena like the Spatial Numerical Association of Response Codes (SNARC) or the Spatial Pitch Association of Response Codes (SPARC) effect: small numbers or low pitches lead to faster responses when answered with the left hand, whereas large numbers or high pitches lead to faster responses when answered with the right hand. The previous study, investigating the combination of SNARC and SPARC with numbers spoken in different pitch heights, points towards an interdependency of both SNARC and SPARC compatibility effects, suggesting an automatic process. Methods In the present event-related functional magnetic resonance imaging (fMRI) study, we investigated the underlying neural activity when SNARC and SPARC are combined within the same auditory stimulus (numerical condition). Additionally, we included a categorical condition (the words “small” and “large”) as variation of the stimulus type. Results We found neither an effect for SNARC nor for SPARC Compatibility in the neuronal data, whereas SNARC Compatibility was found in the behavioral data. According to the behavioral as well as the neuronal data, in the bilateral auditory cortex, SNARC and SPARC Compatibility interacts with Stimulus Type, i.e., whether numerical or categorical stimuli were presented. Conclusions We concluded that both effects are interdependent and that this interaction strongly depends on the semantic information.

Processing of speech was investigated by using stimuli gradually changing from speech (vowels) to non-speech (spectral rotated vowels). Stimuli were presented in descending levels of vocalization blends, from pure speech to non-speech, through step-wise combinations, resulting in ambiguous versions of the sounds. Participants performed a two-alternative forced choice task: categorization of sounds were made according to whether they contained more speech or non-speech. Performance feedback was presented visually on each trial. Reaction times (RT) after sound presentation, and functional magnetic resonance imaging (fMRI) data during auditory and visual processing, were analyzed. RT data suggested individual differences with a distinct group, good performers, functioning better in distinguishing stimuli with a higher degree of ambiguous blends compared to poor performers, who were not able to distinguish these stimuli correctly. fMRI data confirmed this finding. During auditory stimulation, good performers showed neural activation in the ventral auditory pathway, including the primary auditory cortex and the anterior superior temporal sulcus (responsible for speech processing). Poor performers, in contrast, showed neural activation in the dorsal auditory pathway, including the bilateral superior temporal gyrus. Group differences were also found for visual feedback processing. Differences observed between the groups were interpreted as reflecting different neural processing strategies.

Speech is a multifactorial term. In relationship with our central organ, speech is a communication medium which in a complex manner includes the production and perception of verbal information. Even within this limitation, imaging exploration of the neuronal basis of verbal communication offers an extensive investigative field which can only be presented in this article as highlights. The main focus is on the technical hurdles of investigations into speech production using functional magnetic resonance imaging (fMRI) and solution options will be presented. The difficulties contained in this aspect are that spoken words can only be poorly assessed in the noise level of the measurements and that the movements of the mouth necessary for speech motoric can lead to technical imaging artefacts. Investigation techniques and designs will be discussed which allow a representation of speech-relevant brain centers despite these problems.

INTRODUCTION: The aim of this study was to evaluate the risks of endovascular therapy, aneurysm regrowth, recanalization and the need for reembolization. METHOD: A prospective analysis was performed on 211 aneurysms treated endovascularly from February 2000 to December 2003. Of these 211 aneurysms, 81 were asymptomatic and 130 were ruptured. The risks of endovascular therapy, aneurysm regrowth, recanalization and the need for reembolization were evaluated. RESULTS: The mean observation time was 10 months (ranging from 178 to 830 days). Complete occlusion (100%) in the initial intervention was achieved in 171 of 201 aneurysms (85%), 80-95% occlusion in 24 aneurysms (12%), and

INTRODUCTION: We aimed to test changes in cognitive performance after carotid artery stenting (CAS). METHOD: Ten patients were neuropsychologically tested at least 24 h before and 48 h after CAS. To diminish thromboembolic events, we used a proximal protection device. The following neuropsychological tests were selected: The Mini Mental State Examination (MMSE), symbol digit test and subtests of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery (verbal fluency, constructional practice, word list memory and delayed recall). Affective state was determined by the Beck Depression Score (BDS). RESULTS: No patient suffered from depression (BDS

Working memory training is a useful tool to examine dissociations between specific working memory processes. Although current models propose a distinction between modality-specific working memory processes, to our knowledge no study has directly examined the effects of visual versus auditory working memory training. Functional magnetic resonance imaging was used to investigate whether visual working memory processes can be trained specifically and whether those effects can be separated from across-modal training effects. We found decidedly larger training gains after visual working memory training compared with auditory or no training on a visual 2-back task. These effects were accompanied by specific training-related decreases in the right middle frontal gyrus arising from visual training only. Likewise, visual and auditory training led to decreased activations in the superior portion of the right middle frontal gyrus and the right posterior parietal lobule. We infer that the combination of effects resulted from increased neural efficiency of intra-modal (visual) processes on the one hand and of across-modal (general control) processes on the other hand. Therefore, visual processes of working memory can be trained specifically, and these effects can be functionally dissociated from alterations in general control processes common to both working memory trainings.

Transcranial ultrasound (TCS) has been shown to reveal hyperechogenicity of the substantia nigra (SN) in Parkinsonian patients and in about 10% of healthy controls. It is hypothesized that SN hyperechogenicity in healthy subjects is a vulnerability marker for idiopathic Parkinson's disease (IPD). Although there is strong evidence that the echomarker results from increased local iron content, the exact pathophysiological mechanisms remain incompletely understood. Thus, prognostic impact can only be estimated. We examined 14 subjects with SN hyperechogenicity (SN+) (7 IPD patients and 7 controls) and 7 healthy controls without the echomarker (SN−) by a magnetic resonance imaging method (MRI; T2 relaxation times) known to reveal tissue inhomogeneity following abnormal iron content and by F-Dopa PET to assess nigrostriatal function.

Primary orthostatic tremor (OT) occurs only during standing. We studied whether modification of the condition standing influences OT. In seven patients with OT, surface EMG was recorded from both tibialis anterior and gastrocnemius muscles during two maneuvers: relief, whereby the patient was gradually lifted by a crane, and tilting, whereby the patient was tilted by a tilting table to positions of 90 degrees (upright standing), 45 degrees (diagonal position), and 0 degrees (lying position). We determined the parameters tremor frequency, tremor intensity, coherence, and phase shift between the different muscles. Relief did not influence OT. In contrast, tilting modified significantly tremor intensity and phase shifts; tremor frequencies and coherences were not influenced. We chose both these maneuvers because of their different impact on the standing condition: relief modifies the factors afferent input and muscle forcing but not the factor postural set, whereas tilting modifies all three factors. The fact that tilting modifies OT, whereas relief does not, suggests an important role of postural set in OT generation. Afferent input and muscle forcing seem to play less important role.

Human albinism is characterized by a disturbance of the chiasmatic projection system leading to predominant representation of just one eye in the contralateral hemisphere. Patients show congenital nystagmus without perceiving oscillopsia. The purpose of the present study was to demonstrate the consequences of atypical chiasmatic crossing with monocular visual stimulation using functional magnetic resonance imaging (fMRI). Sixteen patients with albinism and fifteen normally pigmented controls were stimulated with a monocular visual activation paradigm using flickering checkerboards. In patients, we observed contralaterally dominated activation of visual cortices correlating to clinical albinism parameters. This confirms albinism as a continuous range of hypopigmentation disorders. Additionally, albinos showed activation of the superior colliculus and of visual motion areas although the stimulus was stationary. Activation of visual motion areas is due probably to congenital nystagmus without a conscious correlate like oscillopsia.

Previous electrophysiological and neuroimaging studies suggest that the mismatch negativity (MMN) is generated by a temporofrontal network subserving preattentive auditory change detection. In two experiments we employed event-related brain potentials (ERP) and event-related functional magnetic resonance imaging (fMRI) to examine neural and hemodynamic activity related to deviance processing, using three types of deviant tones (small, medium, and large) in both a pitch and a space condition. In the pitch condition, hemodynamic activity in the right superior temporal gyrus (STG) increased as a function of deviance. Comparisons between small and medium and between small and large deviants revealed right prefrontal activation in the inferior frontal gyrus (IFG; BA 44/45) and middle frontal gyrus (MFG; BA 46), whereas large relative to medium deviants led to left and right IFG (BA 44/45) activation. In the ERP experiment the amplitude of the early MMN (90–120 ms) increased as a function of deviance, by this paralleling the right STG activation in the fMRI experiment. A U-shaped relationship between MMN amplitude and the degree of deviance was observed in a late time window (140–170 ms) resembling the right IFG activation pattern. In a subsequent source analysis constrained by fMRI activation foci, early and late MMN activity could be modeled by dipoles placed in the STG and IFG, respectively. In the spatial condition no reliable hemodynamic activation could be observed. The MMN amplitude was substantially smaller than in the pitch condition for all three spatial deviants in the ERP experiment. In contrast to the pitch condition it increased as a function of deviance in the early and in the late time window. We argue that the right IFG mediates auditory deviance detection in case of low discriminability between a sensory memory trace and auditory input. This prefrontal mechanism might be part of top-down modulation of the deviance detection system in the STG.

Attention-deficit/hyperactivity disorder (ADHD) is often accompanied by problems in social behaviour, which are sometimes similar to some symptoms of autism-spectrum disorders (ASD). However, neuronal mechanisms of ASD-like deficits in ADHD have rarely been studied. The processing of biological motion-recently discussed as a marker of social cognition-was found to be disrupted in ASD in several studies. Thus in the present study we tested if biological motion processing is disrupted in ADHD. We used 64-channel EEG and spatio-temporal source analysis to assess event-related potentials associated with human motion processing in 21 children and adolescents with ADHD and 21 matched typically developing controls. On the behavioural level, all subjects were able to differentiate between human and scrambled motion. But in response to both scrambled and biological motion, the N200 amplitude was decreased in subjects with ADHD. After a spatio-temporal dipole analysis, a human motion specific activation was observable in occipital-temporal regions with a reduced and more diffuse activation in ADHD subjects. These results point towards neuronal determined alterations in the processing of biological motion in ADHD.

Atypical visual processing of biological motion contributes to social impairments in autism spectrum disorders (ASD). However, the exact temporal sequence of deficits of cortical biological motion processing in ASD has not been studied to date. We used 64-channel electroencephalography to study event-related potentials associated with human motion perception in 17 children and adolescents with ASD and 21 typical controls. A spatio-temporal source analysis was performed to assess the brain structures involved in these processes. We expected altered activity already during early stimulus processing and reduced activity during subsequent biological motion specific processes in ASD. In response to both, random and biological motion, the P100 amplitude was decreased suggesting unspecific deficits in visual processing, and the occipito-temporal N200 showed atypical lateralization in ASD suggesting altered hemispheric specialization. A slow positive deflection after 400 ms, reflecting top-down processes, and human motion-specific dipole activation differed slightly between groups, with reduced and more diffuse activation in the ASD-group. The latter could be an indicator of a disrupted neuronal network for biological motion processing in ADS. Furthermore, early visual processing (P100) seems to be correlated to biological motion-specific activation. This emphasizes the relevance of early sensory processing for higher order processing deficits in ASD.

Background: Most studies evaluating long-term efficacy after coil embolisation of intracranial aneurysms have not differentiated between ruptured and unruptured aneurysms. Objectives: The aim of this study was to analyse factors that influence recanalisation in ruptured and unruptured aneurysms. Methods: We performed a retrospective analysis of 182 (98 ruptured, 84 unruptured) aneurysms, treated with coil embolisation alone that received follow-up with digital substraction angiography (DSA). Results: At 6 months 26% of the aneurysms showed recanalisation. Multivariate variance analysis revealed that different factors influenced recanalisation in ruptured and unruptured aneurysms. In ruptured aneurysms patient age was a determinant, with younger patients recanalising more frequently than older ones (p = 0.016). Also, low initial packing density led to higher recanalisation rates (p = 0.015) than higher packing. In the unruptured aneurysm group these factors were not significant. Here, only a larger aneurysm volume led to higher recanalisation rates (p = 0.027). Conclusions: Our data suggest that in ruptured aneurysms, high packing density is a key factor to prevent recanalisation, while in unruptured aneurysms, aneurysm volume is the main predictor for recanalisation.

Febrile seizures (FS) are assumed to not have adverse long-term effects on cognitive development. Nevertheless, FS are often associated with hippocampal sclerosis which can imply episodic memory deficits. This interrelation has hardly been studied so far. In the current study 13 children who had suffered from FS during infancy and 14 control children (7 to 9-years-old) were examined for episodic and semantic memory with standardized neuropsychological tests. Furthermore, using functional magnetic resonance imaging (fMRI) we studied neuronal activation while the children performed a continuous recognition memory task. The analysis of the behavioral data of the neuropsychological tests and the recognition memory experiment did not reveal any between-group differences in memory performance. Consistent with other studies fMRI revealed repetition enhancement effects for both groups in a variety of brain regions (e.g., right middle frontal gyrus, left parahippocampal gyrus) and a repetition suppression effect in the right superior temporal gyrus. Different neural activation patterns between both groups were obtained selectively within the right supramarginal gyrus (BA 40). In the control group correct rejections of new items were associated with stronger activation than correctly identified old items (HITs) whereas in the FS group no difference occurred. On the background that the right supramarginal gyrus is assumed to mediate a top-down process to internally direct attention toward recollected information, the results could indicate that control children used strategic recollection in order to reject new items (recall-to-reject). In contrast, the missing effect in the FS group could reflect a lack of strategy use, possibly due to impaired recollective processing. This study demonstrates that FS, even with mainly benign courses, can be accompanied by selective modifications in the neural structures underlying recognition memory.

Attention deficit hyperactivity disorder (ADHD) is a common, genetically transmitted common childhood-onset disorder with a high rate of persistence in adulthood. Although many studies have shown anatomical and functional abnormalities in children and adolescents, studies with adult patients are rare. Nineteen adults with ADHD (11 ADHD, combined type; 8 ADHD, partially remitted) and 17 controls were included in this functional magnetic resonance imaging (fMRI) study. Brain activation was investigated with a continuous performance test (CPT). Impaired activation of a fronto-striatal and a parietal attentional network was observed during the NoGo condition in ADHD subjects. Correlations of reduced activity of the caudate nuclei, the anterior cingulate cortex, and parietal cortical structures, as well as increased activity in the insular cortex, with inattention and impulsivity symptom scores were found. The activation patterns were similar to those known from children and adolescents with ADHD. In conclusion we found not only a widespread dysfunction of brain regions that are involved in cognitive processing in adults with ADHD compared with controls, but also correlations between symptom severity and dysfunction of neuronal systems across adult subjects with a history of ADHD in childhood but whose symptoms did (persistent ADHD) and did not (not persistent ADHD) qualify for a full diagnosis of ADHD in adulthood.

INTRODUCTION: To evaluate the flow reversal efficacy of the Parodi antiembolism system (PAES) in the prevention of distal emboli during carotid stenting. METHODS: A total of 90 patients were treated for internal carotid artery (ICA) stenosis with a stent device. A PAES device was used in 31 symptomatic and 5 asymptomatic patients (total 36 patients) with ICA stenosis, and 54 patients were stented without any protection device. Diffusion-weighted (DW) imaging was performed before and after stenting. RESULTS: In the group without PAES protection, 23 out of 54 patients showed new lesions on DW images after stenting. Of the lesions seen, 147 (2.72 lesions/patient) were in the vessel-dependent area. In the group with protection, 19 out of 36 patients had new lesions, and only 34 (0.94 lesions/patient) were noted in the vessel-dependent area. The number of new lesions in the nondependent vessel area did not differ if a protection system was used (P = 0.671). The use of PAES led to a significant reduction (P = 0.024) in the incidence of the most frequently seen lesions (size

Using functional magnetic resonance imaging, the neural correlates of context-specific memories and invariant memories about regularities across episodes were investigated. Volunteers had to learn conjunctions between objects and positions. In an invariant learning condition, positions were held constant, enabling subjects to learn regularities across trials. By contrast, in a context-specific condition object-position conjunctions were trial unique. Performance increase in the invariant learning condition was paralleled by a learning-related increase of inferior frontal gyrus activation and ventral striatal activation and a decrease of hippocampus activation. Conversely, in the context-specific condition hippocampal activation was constant across trials. We argue that the learning-related hippocampal activation pattern might be due to reduced relational binding requirements once regularities are extracted. Furthermore, we propose that the learning-related prefrontal modulation reflects the requirement to extract and maintain regularities across trials and the adjustment of object-position conjunctions on the basis of the extracted knowledge. Finally, our data suggest that the ventral striatum encodes the increased predictability of spatial features as a function of learning. Taken together, these results indicate a transition of the relative roles of distinct brain regions during learning regularities across multiple episodes: regularity learning is characterized by a shift from a hippocampal to a prefrontal-striatal brain system.

Previous studies have shown a modification of parkinsonian tremor (PT) by proprioceptive input induced by passive joint movements. The authors investigated the impact of electrically evoked proprioceptive input on PT. In eight patients with PT they recorded surface EMG from the opponens pollicis muscle, and forearm extensors and flexors. Rhythmic electrical stimulation was applied to the ipsilateral median nerve at the wrist using a submaximal stimulus intensity and stimulus frequencies between two stimuli per second and five stimuli per second. The tremor frequency did not adapt to the stimulus frequency. Tremor frequency of parkinsonian resting tremor increased significantly in the directly stimulated opponens pollicis muscle (mean +/- standard deviation, 4.35 +/- 0.64 Hz without stimulation versus 4.53 +/- 0.68 Hz with stimulation; P < 0.05, paired t-test), the not directly stimulated forearm muscles (4.90 +/- 0.72 Hz versus 5.18 +/- 0.73 Hz, P < 0.001), and the upper arm muscles (5.13 +/- 0.61 Hz versus 5.36 +/- 0.68 Hz, P < 0.01). Furthermore, the parkinsonian postural tremor accelerated significantly during ipsilateral median nerve stimulation (5.31 +/- 0.99 Hz versus 5.44 +/- 1.03 Hz, P < 0.05). Parkinsonian resting tremor in the forearm muscles also accelerated significantly during ipsilateral ulnar nerve stimulation (4.85 +/- 0.57 Hz versus 5.05 +/- 0.65 Hz, P < 0.05). Contralateral median nerve stimulation had no significant effect. These results suggest a close interaction between proprioceptive input and PT generation.

Purpose To determine whether the size and configuration of the optic chiasm in humans with albinism is different from that in normal control subjects. Methods Seventeen patients and 15 control subjects underwent magnetic resonance imaging of the entire head. Images were reformatted to the chiasm region and analyzed with observer-independent morphometry and measurements by a blinded observer. Results The albino group showed significantly smaller chiasmatic widths, smaller optic nerves and tracts, and wider angles between nerves and tracts. Statistical morphometry showed a different configuration of the optic chiasm. Conclusions Size and configuration of the optic chiasm in humans with albinism are distinctly different from those in normal control subjects and reflect the atypical crossing of optic fibers.

Objective: This study evaluates the correlation between closed, semi-closed and open-cell stent design and the association between stent type and clinical outcome as well as magnetic resonance imaging (MRI) findings. Design: A total of 194 patients who underwent unprotected carotid artery stenting (CAS) as well as diffusion-weighted magnetic resonance imaging (DW-MRI) before and after intervention were retrospectively reviewed. Materials and methods: Three stent designs were studied: closed cell, semi-closed cell and open cell. Spearman's Rho test was performed between the stent free cell area and the number and area of ischaemic lesions found after intervention. Adverse events were evaluated. Results: There was no significant difference in clinical outcome between the three stent groups (Zilver, Cook Europe, Denmark; Smart, Codman, MA; and Wallstent, Stryker, MN, USA). A significant correlation was found between the stent free cell area and the number and area of new ischaemic lesions on DW-MRI (P = 0.023). There were significantly fewer new lesions with an open-cell design (Zilver; 12.76 mm 2 free cell area) than with a closed-cell design (Wallstent; 1.08 mm 2 free cell area). Conclusions: Open-cell stent was related to a lower number and area of silent cerebral ischaemic lesions after unprotected CAS. However, clinical outcome, measured by incidence of adverse events and clinical neurologic assessment, was not significantly different between patients with different stent designs. © 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.