Functional connectivity of reward processing in the brain

Controversial results have been reported concerning the neural mechanisms involved in the processing of rewards and punishments. On the one hand, there is evidence suggesting that monetary gains and losses activate a similar fronto-subcortical network. On the other hand, results of recent studies imply that reward and punishment may engage distinct neural mechanisms. Using functional magnetic resonance imaging (fMRI) we investigated both regional and interregional functional connectivity patterns while participants performed a gambling task featuring unexpectedly high monetary gains and losses. Classical univariate statistical analysis showed that monetary gains and losses activated a similar fronto-striatallimbic network, in which main activation peaks were observed bilaterally in the ventral striatum. Functional connectivity analysis showed similar responses for gain and loss conditions in the insular cortex, the amygdala, and the hippocampus that correlated with the activity observed in the seed region ventral striatum, with the connectivity to the amygdala appearing more pronounced after losses. Larger functional connectivity was found to the medial orbitofrontal cortex for negative outcomes. The fact that different functional patterns were obtained with both analyses suggests that the brain activations observed in the classical univariate approach identifi es the involvement of different functional networks in the current task. These results stress the importance of studying functional connectivity in addition to standard fMRI analysis in reward-related studies.

Early auditory processing

ABSTRACT (English)An accurate processing of the order between sensory events at the millisecond time scale is crucial for both sensori-motor and cognitive functions. Temporal order judgment (TOJ) tasks, is the ability of discriminating the order of presentation of several stimuli presented in a rapid succession. The aim of the present thesis is to further investigate the spatio-temporal brain mechanisms supporting TOJ. In three studies we focus on the dependency of TOJ accuracy on the brain states preceding the presentation of TOJ stimuli, the neural correlates of accurate vs. inaccurate TOJ and whether and how TOJ performance can be improved with training.In "Pre-stimulus beta oscillations within left posterior sylvian regions impact auditory temporal order judgment accuracy" (Bernasconi et al., 2011), we investigated if the brain activity immediately preceding the presentation of the stimuli modulates TOJ performance. By contrasting the electrophysiological activity before the stimulus presentation as a function of TOJ accuracy we observed a stronger pre-stimulus beta (20Hz) oscillatory activity within the left posterior sylvian region (PSR) before accurate than inaccurate TOJ trials.In "Interhemispheric coupling between the posterior sylvian regions impacts successful auditory temporal order judgment" (Bernasconi et al., 2010a), and "Plastic brain mechanisms for attaining auditory temporal order judgment proficiency" (Bernasconi et al., 2010b), we investigated the spatio-temporal brain dynamics underlying auditory TOJ. In both studies we observed a topographic modulation as a function of TOJ performance at ~40ms after the onset of the first sound, indicating the engagement of distinct configurations of intracranial generators. Source estimations in the first study revealed a bilateral PSR activity for both accurate and inaccurate TOJ trials. Moreover, activity within left, but not right, PSR correlated with TOJ performance. Source estimations in the second study revealed a training-induced left lateralization of the initial bilateral (i.e. PSR) brain response. Moreover, the activity within the left PSR region correlated with TOJ performance.Based on these results, we suggest that a "temporal stamp" is established within left PSR on the first sound within the pair at early stages (i.e. ~40ms) of cortical processes, but is critically modulated by inputs from right PSR (Bernasconi et al., 2010a; b). The "temporal stamp" on the first sound may be established via a sensory gating or prior entry mechanism.Behavioral and brain responses to identical stimuli can vary due to attention modulation, vary with experimental and task parameters or "internal noise". In a fourth experiment (Bernasconi et al., 2011b) we investigated where and when "neural noise" manifest during the stimulus processing. Contrasting the AEPs of identical sound perceived as High vs. Low pitch, a topographic modulation occurred at ca. 100ms after the onset of the sound. Source estimation revealed activity within regions compatible with pitch discrimination. Thus, we provided neurophysiological evidence for the variation in perception induced by "neural noise".ABSTRACT (French)Un traitement précis de l'ordre des événements sensoriels sur une échelle de temps de milliseconde est crucial pour les fonctions sensori-motrices et cognitives. Les tâches de jugement d'ordre temporel (JOT), consistant à présenter plusieurs stimuli en succession rapide, sont traditionnellement employées pour étudier les mécanismes neuronaux soutenant le traitement d'informations sensorielles qui varient rapidement. Le but de cette thèse est d'étudier le mécanisme cérébral soutenant JOT. Dans les trois études présentées nous nous sommes concentrés sur les états du cerveau précédant la présentation des stimuli de JOT, les bases neurales pour un JOT correct vs. incorrect et sur la possibilité et les moyens d'améliorer l'exécution du JOT grâce à un entraînement.Dans "Pre-stimulus beta oscillations within left posterior sylvian regions impact auditory temporal order judgment accuracy" (Bernasconi et al., 2011),, nous nous sommes intéressé à savoir si l'activité oscillatoire du cerveau au pré-stimulus modulait la performance du JOT. Nous avons contrasté l'activité électrophysiologique en fonction de la performance TOJ, mesurant une activité oscillatoire beta au pré-stimulus plus fort dans la région sylvian postérieure gauche (PSR) liée à un JOT correct.Dans "Interhemispheric coupling between the posterior sylvian regions impacts successful auditory temporal order judgment" (Bernasconi et al., 2010a), et "Plastic brain mechanisms for attaining auditory temporal order judgment proficiency" (Bernasconi et al., 2010b), nous avons étudié la dynamique spatio-temporelle dans le cerveau impliqué dans le traitement du JOT auditif. Dans ses deux études, nous avons observé une modulation topographique à ~40ms après le début du premier son, en fonction de la performance JOT, indiquant l'engagement des configurations de générateurs intra- crâniens distincts. La localisation de source dans la première étude indique une activité bilatérale de PSR pour des JOT corrects vs. incorrects. Par ailleurs, l'activité dans PSR gauche, mais pas dans le droit, est corrélée avec la performance du JOT. La localisation de source dans la deuxième étude indiquait une latéralisation gauche induite par l'entraînement d'une réponse initialement bilatérale du cerveau. D'ailleurs, l'activité dans la région PSR gauche corrèlait avec la performance de TOJ.Basé sur ces résultats, nous proposons qu'un « timbre-temporel » soit établi très tôt (c.-à-d. à ~40ms) sur le premier son par le PSR gauche, mais module par l'activité du PSR droite (Bernasconi et al., 2010a ; b). « Le timbre- temporel » sur le premier son peut être établi par le mécanisme neuronal de type « sensory gating » ou « prior entry ».Les réponses comportementales et du cerveau aux stimuli identiques peut varier du à des modulations d'attention ou à des variations dans les paramètres des tâches ou au bruit interne du cerveau. Dans une quatrième expérience (Bernasconi et al. 2011B), nous avons étudié où et quand le »bruit neuronal« se manifeste pendant le traitement des stimuli. En contrastant les AEPs de sons identiques perçus comme aigus vs. grave, nous avons mesuré une modulation topographique à env. 100ms après l'apparition du son. L'estimation de source a révélé une activité dans les régions compatibles avec la discrimination de fréquences. Ainsi, nous avons fourni des preuves neurophysiologiques de la variation de la perception induite par le «bruit neuronal».

Trace element chemistry and U-Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

The U-Pb ages and the trace element content of zircon U-Pb along with major and trace element whole rock data on gabbroic dikes from the Lanzo lherzolitic massif, N-Italy, have been determined to constrain crustal accretion in ocean-continent transition zones. Three Fe-Ti gabbros were dated from the central and the southern part of the massif providing middle Jurassic ages of 161 +/- 2, 158 +/- 2 and 163 +/- 1 Ma, which argue for magmatic activity over few millions of years. Zircon crystals are characterized by high but variable Th/U ratios, rare earth element patterns enriched in heavy rare earths, pronounced positive Ce and negative Eu-anomalies consistent with crystallization after substantial plagioclase fractionation. The zircon trace element composition coupled with whole rock chemistry was used to reconstruct the crystallization history of the gabbros. A number of gabbros crystallized in situ, and zircon precipitated from trapped, intercumulus liquid, while other gabbros represent residual liquids that were extracted from a cumulus pile and crystallized along syn-magmatic shear zones. We propose a model in which the emplacement mechanism of gabbroic rocks in ocean-continent transition zones evolves from in situ crystallization to stratified crystallization with efficient extraction of residual liquid along syn-magmatic shear zones. Such an evolution of the crystallization history is probably related to the thermal evolution of the underlying mantle lithosphere.

Influence of the implanted pulse generator as reference electrode in finite element model of monopolar deep brain stimulation.

Electrical deep brain stimulation (DBS) is an efficient method to treat movement disorders. Many models of DBS, based mostly on finite elements, have recently been proposed to better understand the interaction between the electrical stimulation and the brain tissues. In monopolar DBS, clinically widely used, the implanted pulse generator (IPG) is used as reference electrode (RE). In this paper, the influence of the RE model of monopolar DBS is investigated. For that purpose, a finite element model of the full electric loop including the head, the neck and the superior chest is used. Head, neck and superior chest are made of simple structures such as parallelepipeds and cylinders. The tissues surrounding the electrode are accurately modelled from data provided by the diffusion tensor magnetic resonance imaging (DT-MRI). Three different configurations of RE are compared with a commonly used model of reduced size. The electrical impedance seen by the DBS system and the potential distribution are computed for each model. Moreover, axons are modelled to compute the area of tissue activated by stimulation. Results show that these indicators are influenced by the surface and position of the RE. The use of a RE model corresponding to the implanted device rather than the usually simplified model leads to an increase of the system impedance (+48%) and a reduction of the area of activated tissue (-15%).

Threading libraries performance when applied to image acquisition and processing in a forensic application

Peer-reviewed

The cAMP response element binding protein-2 (CREB-2) can interact with the C/EBP-homologous protein (CHOP).

cAMP response element binding protein-2 (CREB-2) is a basic leucine zipper (bZIP) factor that was originally described as a repressor of CRE-dependent transcription but that can also act as a transcriptional activator. Moreover, CREB-2 is able to function in association with the viral Tax protein as an activator of the human T-cell leukemia virus type I (HTLV-I) promoter. Here we show that CREB-2 is able to interact with C/EBP-homologous protein (CHOP), a bZIP transcription factor known to inhibit CAAT/enhancer-dependent transcription. Cotransfection of CHOP with CREB-2 results in decreased activation driven by the cellular CRE motif or the HTLV-I proximal Tax-responsive element, confirming that CREB-2 and CHOP can interact with each other in vivo.

Taking on new challenges in multi-word unit processing for Machine Translation

This paper discusses the qualitativecomparative evaluation performed on theresults of two machine translation systemswith different approaches to the processing ofmulti-word units. It proposes a solution forovercoming the difficulties multi-word unitspresent to machine translation by adopting amethodology that combines the lexicongrammar approach with OpenLogos ontologyand semantico-syntactic rules. The paper alsodiscusses the importance of a qualitativeevaluation metrics to correctly evaluate theperformance of machine translation engineswith regards to multi-word units.

Normative Topographic ERP Analyses of Speed of Speech Processing and Grammar Before and After Grammatical Treatment.

Typically developing (TD) preschoolers and age-matched preschoolers with specific language impairment (SLI) received event-related potentials (ERPs) to four monosyllabic speech sounds prior to treatment and, in the SLI group, after 6 months of grammatical treatment. Before treatment, the TD group processed speech sounds faster than the SLI group. The SLI group increased the speed of their speech processing after treatment. Posttreatment speed of speech processing predicted later impairment in comprehending phrase elaboration in the SLI group. During the treatment phase, change in speed of speech processing predicted growth rate of grammar in the SLI group.

A two-dimensional doppler-radiometer for earth observation

Compared to synthetic aperture radars (SARs), the angular resolution of microwave radiometers is quite poor. Traditionally, it has been limited by the physical size of the antenna. However, the angular resolution can be improved by means of aperture synthesis interferometric techniques. A narrow beam is synthesized during the image formation processing of the cross-correlations measured at zero-lag between pairs of signals collected by an array of antennas. The angular resolution is then determined by the maximum antenna spacing normalized to the wavelength (baseline). The next step in improving the angular resolution is the Doppler-Radiometer, somehow related to the super-synthesis radiometers and the Radiometer-SAR. This paper presents the concept of a three-antenna Doppler-Radiometer for 2D imaging. The performance of this instrument is evaluated in terms of angular/spatial resolution and radiometric sensitivity, and an L-band illustrative example is presented.

Via-configurable transistor array: a regular design technique to improve ICs yield

Process variations are a major bottleneck for digital CMOS integrated circuits manufacturability and yield. That iswhy regular techniques with different degrees of regularity are emerging as possible solutions. Our proposal is a new regular layout design technique called Via-Configurable Transistors Array (VCTA) that pushes to the limit circuit layout regularity for devices and interconnects in order to maximize regularity benefits. VCTA is predicted to perform worse than the Standard Cell approach designs for a certain technology node but it will allow the use of a future technology on an earlier time. Ourobjective is to optimize VCTA for it to be comparable to the Standard Cell design in an older technology. Simulations for the first unoptimized version of our VCTA of delay and energy consumption for a Full Adder circuit in the 90 nm technology node are presented and also the extrapolation for Carry-RippleAdders from 4 bits to 64 bits.

Occupational exposure to diisononyl phthalate (DiNP) in polyvinyl chloride processing operations

PURPOSE: Diisononyl phthalate (DiNP) is primarily used as a plasticizer in polyvinyl chloride (PVC) materials. While information is available on general population exposure to DiNP, occupational exposure data are lacking. We present DiNP metabolite urinary concentrations in PVC processing workers, estimate DiNP daily intake for these workers, and compare worker estimates to other populations. METHODS: We assessed DiNP exposure in participants from two companies that manufactured PVC materials, a PVC film manufacturer (n = 25) and a PVC custom compounder (n = 12). A mid-shift and end-shift urine sample was collected from each participant and analyzed for the DiNP metabolite mono(carboxy-isooctyl) phthalate (MCiOP). Mixed models were used to assess the effect on MCiOP concentrations of a worker being assigned to (1) a task using DiNP and (2) a shift where DiNP was used. A simple pharmacokinetic model was used to estimate DiNP daily intake from the MCiOP concentrations. RESULTS: Creatinine-adjusted MCiOP urinary concentrations ranged from 0.42-80 μg/g in PVC film and from 1.11-13.4 μg/g in PVC compounding. PVC film participants who worked on a task using DiNP (n = 7) had the highest MCiOP geometric mean (GM) end-shift concentration (25.2 μg/g), followed by participants who worked on a shift where DiNP was used (n = 11) (17.7 μg/g) as compared to participants with no task (2.92 μg/g) or shift (2.08 μg/g) exposure to DiNP. The GM end-shift MCiOP concentration in PVC compounding participants (4.80 μg/g) was comparable to PVC film participants with no task or shift exposure to DiNP. Because no PVC compounding participants were assigned to tasks using DINP on the day sampled, DiNP exposure in this company may be underestimated. The highest DiNP intake estimate was 26 μg/kg/day. CONCLUSION: Occupational exposure to DiNP associated with PVC film manufacturing tasks were substantially higher (sixfold to tenfold) than adult general population exposures; however, all daily intake estimates were less than 25% of current United States or European acceptable or tolerable daily intake estimates. Further characterization of DiNP occupational exposures in other industries is recommended.

Spatial filtering for pilot-aided WCDMA systems: a semi-blind subspace approach

This paper proposes a spatial filtering technique forthe reception of pilot-aided multirate multicode direct-sequencecode division multiple access (DS/CDMA) systems such as widebandCDMA (WCDMA). These systems introduce a code-multiplexedpilot sequence that can be used for the estimation of thefilter weights, but the presence of the traffic signal (transmittedat the same time as the pilot sequence) corrupts that estimationand degrades the performance of the filter significantly. This iscaused by the fact that although the traffic and pilot signals areusually designed to be orthogonal, the frequency selectivity of thechannel degrades this orthogonality at hte receiving end. Here,we propose a semi-blind technique that eliminates the self-noisecaused by the code-multiplexing of the pilot. We derive analyticallythe asymptotic performance of both the training-only andthe semi-blind techniques and compare them with the actual simulatedperformance. It is shown, both analytically and via simulation,that high gains can be achieved with respect to training-onlybasedtechniques.

Enhanced MDIR receiver for space-time dispersive channels

A particular property of the matched desiredimpulse response receiver is introduced in this paper, namely,the fact that full exploitation of the diversity is obtained withmultiple beamformers when the channel is spatially and timelydispersive. This particularity makes the receiver specially suitablefor mobile and underwater communications. The new structureprovides better performance than conventional and weightedVRAKE receivers, and a diversity gain with no needs of additionalradio frequency equipment. The baseband hardware neededfor this new receiver may be obtained through reconfigurabilityof the RAKE architectures available at the base station. Theproposed receiver is tested through simulations assuming UTRAfrequency-division-duplexing mode.

Conditional maximum likelihood timing recovery: estimators and bounds

This paper is concerned with the derivation of new estimators and performance bounds for the problem of timing estimation of (linearly) digitally modulated signals. The conditional maximum likelihood (CML) method is adopted, in contrast to the classical low-SNR unconditional ML (UML) formulationthat is systematically applied in the literature for the derivationof non-data-aided (NDA) timing-error-detectors (TEDs). A new CML TED is derived and proved to be self-noise free, in contrast to the conventional low-SNR-UML TED. In addition, the paper provides a derivation of the conditional Cramér–Rao Bound (CRB ), which is higher (less optimistic) than the modified CRB (MCRB)[which is only reached by decision-directed (DD) methods]. It is shown that the CRB is a lower bound on the asymptotic statisticalaccuracy of the set of consistent estimators that are quadratic with respect to the received signal. Although the obtained boundis not general, it applies to most NDA synchronizers proposed in the literature. A closed-form expression of the conditional CRBis obtained, and numerical results confirm that the CML TED attains the new bound for moderate to high Eg/No.

Smart antennas in software radio base stations

The application of adaptive antenna techniques to fixed-architecture base stations has been shown to offer wide-ranging benefits, including interference rejection capabilities or increased coverage and spectral efficiency.Unfortunately, the actual implementation ofthese techniques to mobile communication scenarios has traditionally been set back by two fundamental reasons. On one hand, the lack of flexibility of current transceiver architectures does not allow for the introduction of advanced add-on functionalities. On the other hand, theoften oversimplified models for the spatiotemporal characteristics of the radio communications channel generally give rise toperformance predictions that are, in practice, too optimistic. The advent of software radio architectures represents a big step toward theintroduction of advanced receive/transmitcapabilities. Thanks to their inherent flexibilityand robustness, software radio architecturesare the appropriate enabling technology for theimplementation of array processing techniques.Moreover, given the exponential progression ofcommunication standards in coexistence andtheir constant evolution, software reconfigurabilitywill probably soon become the only costefficientalternative for the transceiverupgrade. This article analyzes the requirementsfor the introduction of software radio techniquesand array processing architectures inmultistandard scenarios. It basically summarizesthe conclusions and results obtained withinthe ACTS project SUNBEAM,1 proposingalgorithms and analyzing the feasibility ofimplementation of innovative and softwarereconfigurablearray processing architectures inmultistandard settings.