Biomedical subjects

W Lang

Publications and source records attributed to W Lang.

At least 73 records · Page 4Linked to original sources

PubMed2000

Reduced activation of midline frontal areas in human elderly subjects: a contingent negative variation study.

Contingent negative variation (CNV) was recorded from electrodes F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P7, P3, Pz, P4 and P8 in 19 young (mean age: 23 years) and 15 elderly (mean age: 66 years) healthy right-handed subjects, using a S2-choice paradigm. Young subjects showed early peak negativity shortly after the warning stimulus over mid-frontal areas, whereas for the remaining electrodes the negativity increased continuously. The amplitude of the early CNV was selectively reduced in elderly subjects over midline but not lateral frontal areas. We conclude that the activation of frontal midline areas as pre-supplementary motor area or anterior cingulate might be impaired in higher age.

Acoustic Stimulation↗

PubMed2000

A dominant role for the c-Jun NH2-terminal kinase in oncogenic ras-induced morphologic transformation of human lung carcinoma cells.

Oncogenic (activated) Ras is a signal transducer that activates multiple effector-mediated signaling pathways leading to altered cell morphology, growth and differentiation, and neoplastic transformation. Activating mutations of Ras family genes have been detected in many types of human cancers, including lung cancer. However, the signaling mechanisms by which oncogenic Ras controls cancer cell growth is poorly characterized. This study evaluates the role of two specific signaling pathways, the c-Jun NH2-terminal kinase (JNK) pathway, and the extracellular signal-regulated kinase (ERK) pathway, in oncogenic Ras-induced morphological transformation of NCI-H82 human small cell lung cancer cells. In the NCI-H82 cell line, oncogenic Ras causes a marked and sustained activation of JNK but only has a modest effect on activation of the ERK pathway. The persistent JNK activation is associated with Ras-induced changes in cell morphology and enhanced transforming activity. Furthermore, JNK activation correlates with the induction of c-Jun expression, c-Jun phosphorylation on serines 63 and 73, and increased AP-1 activity. Deregulation of the JNK pathway using a dominant-negative mutant of JNK1, JNK1(APF), completely reverses the oncogenic Ras-induced transformed phenotype, including morphological reversion and inhibition of anchorage-independent growth and low-serum growth. Moreover, expression of JNK1(APF) leads to a decrease in c-Jun/AP-1 activity. In contrast, inhibition of ERK activation via a pharmacological approach using a mitogen-activated protein kinase/ERK kinase-specific inhibitor 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one is unable to reverse the Ras-induced transformed morphology and c-Jun/AP-1 induction. These results demonstrate that the JNK/c-Jun/AP-1 pathway plays an essential role in mediating oncogenic Ras function in lung carcinoma cells.

Carcinoma, Small Cell↗

PubMed2000

Isolation and identification of metabolites of porfiromycin formed in the presence of a rat liver preparation.

The isolation and identification of the major metabolites of porfiromycin formed in the presence of a rat liver preparation under aerobic conditions were performed with high-performance liquid chromatography and electrospray ionization mass spectrometry. Porfiromycin was extensively metabolized by the rat liver preparation in an aqueous 0.1 M potassium phosphate buffer (pH 7.4) containing an NADPH generating system at 37 degrees C. A total of eight metabolites was identified as mitosene analogs. Of these, three primary metabolites are 2-methylamino-7-aminomitosene, 1,2-cis and 1,2-trans-1-hydroxy-2-methylamino-7-aminomitosene, which are consistent with those previously observed in hypoxia using purified rat liver NADPH-cytochrome c reductase. Interestingly, 2-methylamino-7-aminomitosene is a reactive metabolite, which undergoes further activation at the C-10 position by the loss of carbamic acid and then links with the 7-amino group of the primary metabolites to yield two dimeric adducts. In addition, three phosphate adducts, 10-decarbamoyl-2-methylamino-7-aminomitosene-10-phosphate, 1,2-cis and 1,2-trans-2-methylamino-7-aminomitosene-1-phosphate, were also identified in the incubation system. The configurations of the diastereoisomeric metabolites were determined with (1)HNMR and phosphatase digestion. On the basis of the metabolite profile, we propose in vitro metabolic pathways for porfiromycin. The findings provide direct evidence for understanding the reactive nature and hepatic metabolism of the drug currently in phase III clinical trials.

Acetylcysteine↗

PubMed2000

[The indications and embolism monitoring in lumen-opening therapies of the a. carotis].

Carotid endarterectomy (CEA) is proven to be beneficial in symptomatic patients with high-grade carotid stenosis (70% to 99%; residual lumen as a percentage of the normal distal internal carotid artery) on condition that the peri-operative risk for mortality and morbidity is less than 6%. A minority of the "leading experts" in North America (48%) and Western Europe (28%) recommends carotid endarterectomy in asymptomatic patients in general. Most experts suggest to perform surgery only in asymptomatic patients who are at risk for carotid occlusion in the near future or embolism. At its present state, angioplasty and stenting is an experimental although promising technique which will have to be compared to carotid endarterectomy. Criteria for duplex grading of internal carotid stenosis have been established and systematically validated to results of angiography. Pre-surgical use of angiography will more and more be restricted to selected patients in whom the results of duplex sonography remain inconclusive. The detection of microemboli with transcranial doppler sonography seems to be of particular importance before and during carotid angioplasty and stenting.

Angioplasty, Balloon↗

PubMed2000

Out-of-hospital diagnosis of cerebral infarction versus intracranial hemorrhage.

OBJECTIVE: To establish a model based on clinical and anamnestic data easily available in the out-of-hospital setting, which facilitates the differential diagnosis between cerebral infarction and intracranial hemorrhage. DESIGN: Retrospective study that simulates a prospective approach. SETTING: Emergency Department of the University Hospital in Vienna, Austria. PATIENTS AND PARTICIPANTS: Data of 224 patients with either intracranial hemorrhage or cerebral infarction were prospectively collected. Uni-and multivariate analysis was performed to identify neurological symptoms and anamnestic data, which were associated with either intracranial hemorrhage or cerebral infarction. MEASUREMENTS AND RESULTS: Unilateral weakness or sensory loss was observed more frequently in patients with infarction compared to hemorrhage (69.8 % vs 11.9 %, P < 0.001). The frequency of patients with impaired level of consciousness was significantly higher in the hemorrhage group compared to the infarction group (59.3 % vs 3.8 %, P < 0.001). A multivariate logistic regression analysis showed that hypertension (OR = 0.31, 95 % CI = 0.12-0.76, P = 0.01), diabetes (OR = 0.17, 95% CI = 0.04-0.68, P = 0.01), and unilateral weakness or sensory loss (OR = 0.10, 95 % CI = 0.04-0.26, P < 0.001) were significantly associated with cerebral infarction. Impaired level of consciousness was significantly related to hemorrhage (OR = 13.41, 95 % CI = 3.92-45.91, P < 0.001). On the basis of the logistic regression analysis, we generated a scoring system for the out-of-hospital diagnosis between infarction and hemorrhage. The values of the score lay between -3 and +3. The probability of infarction increases when the score becomes negative, and the probability for hemorrhage increases when the score becomes positive. CONCLUSION: Our model is a useful guideline for the differential diagnosis between cerebral infarction and intracranial hemorrhage in the out-of-hospital setting, as it is based on easily available clinical and anamnestic parameters.

Aged↗

PubMed2000

High resolution DC-EEG mapping of the Bereitschaftspotential preceding simple or complex bimanual sequential finger movement.

The present set of experiments investigated the Bereitschaftspotential (BP) preceding voluntary bimanual sequential simple (task 1) and complex movements (task 2) in supplementary/cingulate and primary motor areas (SCMA, MIs) using 64-channel direct current electroencephalography analysis in 16 right-handed healthy subjects. The results showed that: (1) onset times of BPs preceding the two tasks were significantly earlier at Cz than at C3 and C4, (2) the complex task induced significantly larger amplitudes than the simple task over the SCMA 1.1 s before EMG onset (BPI period), over the SCMA and both MIs for the BP2 period, extending from the SCMA and MIs to all frontocentral, central, centroparietal, and frontal areas during the motor potential period, (3) task difference prior to 0.96 s mainly appeared in the SCMA rather than in either MI, (4) the BP had a significantly larger amplitude in the SCMA than in the MIs, the differences being asymmetric between the left and the right hemisphere motor areas, and (5) the sinks of BP current source density (CSD) preceding the two tasks were found in the frontocentral midline; and the regions and intensities of CSD maps were larger and stronger in task 2 than they were in task I at the same times of the epoch. The results suggested that: (1) the SCMA and MIs participate in bimanual sequential simple or complex movements, (2) the SCMA appears to not only serve as a trigger command for voluntary movement but also seems to design the different motor modes, (3) the amplitude, duration, onset time, CSD region, and intensity of BP all increase with the level of complexity of the movement, (4) the greater the complexity of the action, the earlier the preparation and the larger the extent of activated neuronal populations in the SCMA, (5) activation of the SCMA occurred prior to that of the MI, and (6) the activation suggests an asymmetry between left and right MIs in simultaneous bilateral finger movement, but this asymmetry seems to be less pronounced for complex movements.

Adult↗

PubMed2000

Dissociation of motor preparation from memory and attentional processes using movement-related cortical potentials.

The EEG activity preceding self-paced voluntary movements (movement-related cortical potential, MRCP) is smaller if subjects make the same movement each time (regular task) compared with when different movements are made each time (random task). To test whether extra activity in the random task is due to increased motor preparation needed to switch between different movements, or to memory/attentional processes needed to select movements randomly, we compared regular and random movements with an additional alternating task. This alternating task required subjects to make different movements each time as in the random task, but since the task was very simple, the memory/attentional load was similar to that in the regular task. The MRCP was equally large over motor areas in both random and alternating tasks, suggesting that the extra activity over sensorimotor areas reflected processes involved in motor preparation rather than memory/attention. We speculate that, in the regular task, some part of the instructions for the previous movement remains intact, reducing the amount of preparation needed for the next repetition. Thus the MRCP is smaller than in the alternating and random tasks. Although the MRCPs in alternating and random tasks were similar over the motor areas, the random task had more activity than the alternating task in contralateral frontal areas. This part of the MRCP may therefore be related to memory/attentional processes required to randomize the sequence of movements. We conclude that the MRCP contains dissociable components related to motor preparation and memory/attention.

Adult↗

PubMed2000

Dedicated phased-array coil for peripheral MRA.

In this paper we introduce a phased-array coil dedicated for MRA of peripheral arteries which covers the upper and lower legs. The structure of this coil includes a solid cabinet with four flexible wings forming a "T." The flexibility of the wings allows adaptation to the individual leg size. There are eight circularly polarized channels, four on each side. This coil is compatible with other surface coils. For MRA of peripheral arteries, it is combined with the body phased-array coil and the spine array coil which cover the lower abdomen and the pelvis. We examined six patients using this coil combination. The image quality, the signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of these examinations were compared with that of peripheral MRA examinations obtained with the body resonator. Image quality with the array coil was considerably improved in comparison with the body resonator examinations. The SNR and CNR increased approximately 100%. The handling of this coil was very quick and simple, similar to the procedure with other surface coils. The use of dedicated phased-array coils for peripheral MRA may be an important step toward the establishment of MR digital subtraction angiography (DSA) as a non-invasive alternative to intra-arterial DSA in the visualization of peripheral arteries. Its potential has to be evaluated in future studies.

Aged↗

PubMed2000

Fluoroscopically triggered contrast-enhanced 3D MR DSA and 3D time-of-flight turbo MRA of the carotid arteries: first clinical experiences in correlation with ultrasound, x-ray angiography, and endarterectomy findings.

The aim of this article was to obtain initial experiences with fluoroscopically triggered contrast-enhanced (CE) 3D MR DSA with elliptical centric k-space order and 3D time-of-flight (TOF) turbo MRA of the carotid arteries. In this prospective study we examined 16 consecutive patients with suspicion of atherosclerotic disease involving the carotid arteries. Ultrasound was available in all, x-ray angiography in 12, surgical correlation in 9, and intraoperative x-ray angiography in 4 patients. All examinations were done on a 1.5 T unit applying: transverse plain 3D TOF turbo MRA and coronal CE MRA with fluoroscopic triggering. Combining head and neck array coils allowed the visualization of supraaortic arteries from the aortic arch to the circle of Willis. MRA results (maximum intensity projections) were compared with x-ray angiography, ultrasound, and inspection of endarterectomy specimens. Volume rendering was performed in selected cases additionally. Agreement between CE MRA, 3D TOF turbo MRA and x-ray angiography regarding stenoses of the internal and external carotid artery was very good. CE MRA was able to detect correctly intracranial stenoses, but delineation of the aortic arch and proximal common carotid arteries was sometimes reduced. Volume rendering was suited for visualization of MRA images providing a realistic three-dimensional impression. In conclusion, high-resolution fluoroscopically triggered CE MRA as non-invasive technique is another important step on the way to replace invasive x-ray angiography for the evaluation of atherosclerotic carotid artery disease. High resolution 3D TOF turbo MRA might be a helpful adjunct to increase the diagnostic reliability for the carotid bifurcation.

Aged↗

PubMed2000

False recognition in a verbal memory task: an event-related potential study.

Brain potentials were recorded from 15 healthy young subjects during the performance of a word recognition task. During the study phase, subjects had to intentionally memorise a series of words. These words were presented again together with the same number of new words in a following test phase where the instruction was to discriminate between repeated words and new words. We compared event-related potentials (ERPs) evoked by correctly identified repeated words (hits) and ERPs evoked by incorrectly classified new words (false alarms). Although both types of words were thought to be repeated the ERPs indicated differences between these two conditions starting at about 450 ms after the stimulus onset. These differences were mostly pronounced over frontal scalp locations but occurred also over parietal scalp locations (false alarms produced significantly more negative going ERPs than hits). We interpret that frontal and parietal brain areas show greater activation during false recognition because of a more intensive search for item representations.

Adult↗

PubMed2000

Duplex ultrasonography in the diagnosis of incompetent Cockett veins.

OBJECTIVE: Incompetent perforating veins of the medial calf, i.e. those of the Cockett groups, play a major role in the developement of chronic venous insufficiency. The aim of the present study was to test the value of duplex ultrasonography (DUS) in the diagnosis of function and localisation of those veins. METHODS: Eighty-nine legs with incompetent perforating veins of the medial calf selected for subfascial endoscopic perforator surgery (SEPS) were included in a prospective study. Preoperative DUS was used to determine the number and localisation of the perforator veins. Findings were compared with preoperative ascending phlebography and intraoperative endoscopy during SEPS. RESULTS: Nearly equal numbers of insufficient Cockett veins at each level were detected by DUS and ascending phlebography (Cockett III: n, 76 vs. n, 76, P, 1.0; Cockett: II n=84 vs. n=82, P=0.569; Cockett I: n, 36 vs. n, 37, P=1.0; chi(2)-test). Findings were confirmed intraoperatively. CONCLUSION: The accuracy of DUS is comparable to phlebography for the diagnosis of incompetent perforating veins of the lower leg. DUS is non-invasive and avoids the potential risks of radiologic imaging.

Chronic Disease↗

PubMed2000

High resolution spatiotemporal analysis of the contingent negative variation in simple or complex motor tasks and a non-motor task.

OBJECTIVES: Since the characteristics of the Bereitschaftspotential (BP) - voluntary movement paradigm of internally-driven movements - have been established recently by our group using high resolution DC-EEG techniques, it was of great interest to apply similar techniques to the other slow brain potential--contingent negative variation (CNV) of externally-cued movements--with the same motor tasks using the same subjects. METHODS: The CNV for simple bimanual sequential movements (task 1), complex bimanual sequential movements (task 2) and a non-motor condition (task 3) was recorded on the scalp using a 64 channel DC-EEG in 16 healthy subjects, and the data were analyzed with high resolution spatiotemporal statistics and current source density (CSD). RESULTS: (1) The CNV was distributed over frontal, frontocentral, central and centroparietal regions; a negative potential was found at the frontal pole and a positive potential was found over occipital regions. (2) CNV amplitudes were higher for task 2 than for task 1, and there was no late CNV for task 3. (3) A high resolution spatiotemporal analysis revealed that during the early CNV component, statistical differences existed between the motor tasks (tasks 1 and 2) and the non-motor task (task 3), which occurred at frontocentral, central, centroparietal, parietal and parieto-occipital regions. During the late CNV component, additional significant differences were found not only between the motor tasks and the non-motor task but also between motor task 1 and task 2 at frontocentral, central and centroparietal regions. (4) Comparison of the CNV between the frontomesial cortex (situated over the supplementary/cingulate areas, SCMA) and both lateral pre-central areas (situated over the primary motor areas, MIs) showed that there was no statistically significant difference between the two cortical motor areas except for the early CNV. (5) Comparison of the CNV between the 3 tasks over the cortical motor areas showed that there were significant differences between the motor tasks and the non-motor task regarding the auditory evoked potential (AEP) and the early CNV component, and between all 3 tasks in the late CNV, the visual evoked potential (VEP(2)) and the N-P component. (6) The ranges and the densities of the CSD maps were larger and higher for complex than for simple tasks. The current sinks of the AEP and the early CNV were located at Fz, the late CNV at FCz and surrounding regions. As to be expected, current sources of the VEPs were located at the occipital lobes. The CNV was a current sink (negative) except for the VEP's main component which was a current source (positive). CONCLUSIONS: (1) The CNV topography over the scalp varied with the complexity of motor tasks and between motor and non-motor conditions. (2) The origin of the early CNV may rest in the frontal lobes, while the late CNV may stem from more extensive cortical areas including SCMA, MIs, etc. (3) The late CNV component is not identical with the BP.

Adult↗

PubMed2000

Does weight loss maintenance become easier over time?

OBJECTIVE: Studies of health-related behaviors, including weight loss, have shown that risk of relapse decreases over time, although reasons for this relationship are unclear. The purpose of this cross-sectional study was to determine if subjects who have maintained weight losses for varying periods of time report different strategies for weight loss maintenance or differences in the effort and pleasure associated with weight maintenance behaviors. RESEARCH METHODS AND PROCEDURES: Subjects were 758 women and 173 men who had maintained losses of at least 30 lb (mean = 60 lb) for 2 years or longer (mean = 6.8 +/- 7.0 years). Self-administered questionnaires assessed subjects' use of weight maintenance strategies in the past year and their perceptions of the effort, attention, and pleasure associated with weight maintenance. RESULTS: Subjects who had maintained weight losses longer used fewer weight maintenance strategies and reported that less effort was required to diet and maintain weight and that less attention was required to maintain weight. The pleasure derived from exercise, low-fat eating, and maintaining weight was unrelated to duration of weight loss maintenance. DISCUSSION: As duration increases, a shift in the balance between the effort and pleasure of weight maintenance may occur. This shift may increase the likelihood of continued maintenance.

Adult↗

PubMed2000

A case-control study of successful maintenance of a substantial weight loss: individuals who lost weight through surgery versus those who lost weight through non-surgical means.

OBJECTIVE: To determine if method of weight loss (surgery; non-surgery) is associated with current levels of psychosocial functioning or current weight maintenance behaviors in individuals who have lost large amounts of weight. DESIGN: Subjects were 67 cases and 67 controls selected from the National Weight Control Registry, a longitudinal study of individuals successful at long-term maintenance of weight loss. Cases had initially lost weight through bariatric surgery while controls had lost weight through non-surgical means. The current psychosocial functioning and weight maintenance behaviors of cases and controls were assessed and compared. RESULTS: Cases and controls were matched on gender, current weight and total weight loss. Surgical cases reported significantly higher fat intake and lower physical activity levels. There were no differences in cases' and controls' reports of the impact of weight loss on other areas of their lives, neither were there differences on measures of depression or binge-eating. CONCLUSIONS: Reported improvement in psychosocial functioning did not depend upon how weight was initially lost, but cases and controls appear to be using very different behaviors to maintain their weight losses.

Adult↗

PubMed2000

[A hybrid technique for the automatic floating table MRA of peripheral arteries using a dedicated phased-array coil combination].

PURPOSE: We introduce a hybrid technique which allows a high resolution MRA of the peripheral arteries with a dedicated phased-array coil using the floating table technique. MATERIALS AND METHODS: Five patients with peripheral arterial occlusive disease were examined within one week with i.a. DSA and MRA using the hybrid technique. MRA examinations were done on a 1.5 T system. At first, pelvic arteries were examined in a single step mode applying the CareBolus technique. Subsequently, thighs and lower legs were examined using the floating table mode. 125 vascular segments were evaluated. RESULTS: The hybrid technique proved to be robust and could be performed in each case. Mean examination time was about 30 min. For 117 vascular segments no difference was found between i.a. DSA and MRA. Three segments revealed a higher grade of stenosis in DSA than in MRA, five segments were graded higher in MRA than in DSA. Occlusions were visualized identically in both methods. Venous overlap had no relevant effects on image evaluation. CONCLUSIONS: This hybrid technique in combination with phased-array coils allows a high resolution MRA of the peripheral arteries with very good image quality. If future studies confirm reduced venous overlap, this method may be an alternative also for users of the floating table MRA with the body resonator.

Arterial Occlusive Diseases↗

PubMed2000

Inhibitory effects of silibinin on cytochrome P-450 enzymes in human liver microsomes.

Silibinin, the main constituent of silymarin, a flavonoid drug from silybum marianum used in liver disease, was tested for inhibition of human cytochrome P-450 enzymes. Metabolic activities were determined in liver microsomes from two donors using selective substrates. With each substrate, incubations were carried out with and without silibinin (concentrations 3.7-300 microM) at 37 degrees in 0.1 M KH2PO4 buffer containing up to 3% DMSO. Metabolite concentrations were determined by HPLC or direct spectroscopy. First, silibinin IC50 values were determined for each substrate at respective K(M) concentrations. Silibinin had little effect (IC50>200 microM) on the metabolism of erythromycin (CYP3A4), chlorzoxazone (CYP2E1), S(+)-mephenytoin (CYP2C19), caffeine (CYP1A2) or coumarin (CYP2A6). A moderate effect was observed for high affinity dextromethorphan metabolism (CYP2D6) in one of the microsomes samples tested only (IC50=173 microM). Clear inhibition was found for denitronifedipine oxidation (CYP3A4; IC50=29 microM and 46 microM) and S(-)-warfarin 7-hydroxylation (CYP2C9; IC50=43 microM and 45 microM). When additional substrate concentrations were tested to assess enzyme kinetics, silibinin was a potent competitive inhibitor of dextromethorphan metabolism at the low affinity site, which is not CYP2D6 (Ki.c=2.3 microM and 2.4 microM). Inhibition was competitive for S(-)-warfarin 7-hydroxylation (Ki,c=18 microM and 19 microM) and mainly non-competitive for denitronifedipine oxidation (Ki,n=9 microM and 12 microM). With therapeutic silibinin peak plasma concentrations of 0.6 microM and biliary concentrations up to 200 microM, metabolic interactions with xenobiotics metabolised by CYP3A4 or CYP2C9 cannot be excluded.

Cytochrome P-450 Enzyme Inhibitors↗

PubMed2000

Electrophysiological, neuropsychological and clinical findings in multiple sclerosis patients receiving interferon beta-1b: a 1-year follow-up.

We assessed serial event-related potentials (ERPs) as well as neuropsychological and clinical test findings in a group of multiple sclerosis (MS) patients (n = 14) treated with interferon beta-1b (INF-beta-1b) compared to normal controls (n = 14). All investigations were done within 1 week before INF-beta-1b therapy was started and 12 months later. An auditory oddball paradigm was employed. No significant differences in the N100, P200, N200 or P300 latencies between patients and control group were found, but 3 out of 14 MS patients developed abnormal P300 latencies (more than 2 standard errors from the mean) after 1 year of INF-beta-1b therapy. This was not reflected by the respective neurological impairment as assessed by the Expanded Disability Status Scale score. ERPs might be a useful tool in clinical studies in order to evaluate drug effects on cognition, but for a final statement, the analysis of ERPs in a larger group of patients is required.

Adjuvants, Immunologic↗

PubMed2000

Modulation of spatial orientation processing by mental imagery instructions: a MEG study of representational momentum.

Under appropriate conditions, an observer's memory for the final position of an abruptly halted moving object is distorted in the direction of the represented motion. This phenomenon is called "representational momentum" (RM). We examined the effect of mental imagery instructions on the modulation of spatial orientation processing by testing for RM under conditions of picture versus body rotation perception and imagination. Behavioral data were gathered via classical reaction time and error measurements, whereas brain activity was recorded with the help of magnetoencephalography (MEG). Due to the so-called inverse problem and to signal complexity, results were described at the signal level rather than with the source location modeling. Brain magnetic field strength and spatial distribution, as well as latency of P200m evoked fields were used as neurocognitive markers. A task was devised where a subject examined a rotating sea horizon as seen from a virtual boat in order to extrapolate either the picture motion or the body motion relative to the picture while the latter disappeared temporarily until a test-view was displayed as a final orientation candidate. Results suggest that perceptual interpretation and extrapolation of visual motion in the roll plane capitalize on the fronto-parietal cortical networks involving working memory processes. Extrapolation of the rotational dynamics of sea horizon revealed a RM effect simulating the role of gravity in rotational equilibrium. Modulation of the P200m component reflected spatial orientation processing and a non-voluntary detection of an incongruity between displayed and expected final orientations given the implied motion. Neuromagnetic properties of anticipatory (Contingent Magnetic Variation) and evoked (P200m) brain magnetic fields suggest, respectively, differential allocation of attentional resources by mental imagery instructions (picture vs. body tilt), and a communality of neural structures (in the right centro-parietal region) for the control of both RM and mental rotation processes. Finally, the RM of the body motion is less prone to forward shifts than that of picture motion evidencing an internalization of the implied mass of the virtual body of the observer.

Adult↗