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The d.c. electrical conductivity of polyacrylate sodium salt and poly(acrylic acid) aqueous solutions of different molecular weights from 2 to 200 kD has been investigated in a wide range of polymer concentration, covering both the semidilute (unentangled and entangled) and concentrated regimes. The data have been analyzed on the basis of a modified version of the Manning theory of counterion condensation, to cover the semidilute regime, taking into account scaling arguments recently proposed by Dobrynin et al. (Macromolecules 1995, 28, 1859). This analysis, on the basis of the conductivity model we have adopted, provides evidence for a fraction of free counterions that increases with the polymer concentration until the semidilute-concentrated crossover concentration is reached, suggesting that, in the concentration range investigated, the effective charge on the polyion is dependent on the polymer concentration. Moreover, at the higher concentrations investigated, our data suggest that a regime is attain...

Introduction Several studies have already shown that transcranial direct current stimulation (tDCS) is an useful tool to enhance recovery in aphasia. However, no reports to date have investigated functional connectivity changes on cortical activity due to tDCS language treatment. Objectives The present study explored whether bilateral tDCS over the frontal regions would improve language performance in a group of aphasic patients. We also wanted to assess the impact of dual tDCS language treatment on functional connectivity reorganization through rs-fMRI. Materials & methods Nine aphasic persons with articulatory disorders underwent an intensive language therapy in two different conditions: bilateral anodic stimulation over the left Broca’s area and cathodic contralesional stimulation over the right homologue of Broca’s area and a sham condition. The language treatment lasted three weeks (Monday to Friday – fifteen daily sessions). In all patients, language measures were collected before (T0) and at the end of treatment (T15). Before and after each treatment condition (real vs.sham), each subject underwent a resting state fMRI (rsfMRI). Results Results showed that, after real stimulation, patients exhibited the greatest recovery not only in terms of better accuracy in articulating the treated stimuli but also for untreated items on different tasks of the language test (picture description, noun and verb naming, word repetition, word reading). Moreover, while after the sham condition connectivity changes were confined into the right brain hemisphere, bilateral stimulation yielded to stronger functional connectivity increase in the left hemisphere. Conclusion In conclusion, our data provide converging evidence from behavioural and functional imaging data that bilateral tDCS determines functional connectivity changes into the lesioned hemisphere enhancing language recovery process in stroke patients.

Despite their routine use during surgical procedures, no consensus has yet been reached on the precise mechanisms by which hypnotic anesthetic agents produce their effects. Molecular, animal and human studies have suggested disruption of thalamocortical communication as a key component of anesthetic action at the brain systems level. Here, we used the anesthetic agent, propofol, to modulate consciousness and to evaluate differences in the interactions of remote neural networks during altered consciousness. We investigated the effects of propofol, at a dose that produced mild sedation without loss of consciousness, on spontaneous cerebral activity of 15 healthy volunteers using functional magnetic resonance imaging (fMRI), exploiting oscillations (

A consistent and prominent feature of brain functional magnetic resonance imaging (fMRI) data is the presence of low-frequency (2+ signaling. Specifically, neurotransmission induces pulses of Ca2+ concentration in astrocytes, resulting in increased cerebral perfusion and neuroactive transmitter release by these cells (i.e., gliotransmission), which in turn stimulates neuronal activity. Noticeably, the level of neuron-astrocyte cross talk regulates the periodic behavior of the Ca2+ wave-induced BOLD fluctuations. Our results suggest that the spontaneous ongoing activity of neuroglial networks is a potential source of the observed slow fMRI signal oscillations.

Previous studies suggest that the clinical manifestations of Alzheimer's disease (AD) are not only associated with regional gray matter damage but also with abnormal functional integration of different brain regions by disconnection mechanisms. A measure of anatomical connectivity (anatomical connectivity mapping or ACM) can be obtained by initiating diffusion tractography streamlines from all parenchymal voxels and then counting the number of streamlines passing through each voxel of the brain. In order to assess the potential of this parameter for the study of disconnection in AD, we computed it in a group of patients with AD (N=9), in 16 patients with amnestic mild cognitive impairment (a-MCI, which is considered the prodromal stage of AD) and in 12 healthy volunteers. All subjects had an MRI scan at 3T, and diffusion MRI data were analyzed to obtain fractional anisotropy (FA) and ACM. Two types of ACM maps, absolute count (ac-ACM) and normalized by brain size count (nc-ACM), were obtained. No between group differences in FA surviving correction for multiple comparison were found, while areas of both decreased (in the supramarginal gyrus) and increased (in the putamen) ACM were found in patients with AD. Similar results were obtained with ac-ACM and nc-ACM. ACM of the supramarginal gyrus was strongly associated with measures of short-term memory in healthy subjects. This study shows that ACM provides information that is complementary to that offered by FA and appears to be more sensitive than FA to brain changes in patients with AD. The increased ACM in the putamen was unexpected. Given the nature of ACM, an increase of this parameter may reflect a change in any of the areas connected to it. One intriguing possibility is that this increase of ACM in AD patients might reflect processes of brain plasticity driven by cholinesterase inhibitors.

The hemocompatibility of standard surgical treatment of carotid artery disease through the insertion of metallic stents is investigated by means of radio wave dielectric spectroscopy technique that allows the measurements of the electrical parameters of the red blood cell membrane. Our measurements suggest that both the membrane permittivity and the membrane conductivity, which characterize the overall electrical behavior of the cell membrane, undergo an appreciable alteration of their standard values as a consequence of the stent insertion. These alterations persist over long period of time, up to 4 weeks. Even if these effects could not cause any evident damage at physiological or clinical level to the patient, the presence of a host response to the stent implant suggests that a full hemocompatibility has not yet reached, and a word of caution is necessary.

Multimodality imaging plays a significant role on specific diagnosis of prostate cancer. An endorectal PET-TOF MRI probe, designed here, allows for improved SNR and NECR with respect to standard imagers, providing better functional diagnosis of prostate diseases.

Objective To assess the contribution of regional grey matter (GM) atrophy and functional disconnection in determining the level of cognitive decline in patients with Alzheimer9s disease (AD) at different clinical stages. Methods Ten patients with amnesic mild cognitive impairment (a-MCI), 11 patients with probable AD and 10 healthy controls were recruited. T1 volumes were obtained from each subject and postprocessed according to an optimised voxel based morphometry protocol. Resting state functional MRI data were also collected from the same individuals and analysed to produce connectivity maps after identification of the default mode network (DMN) by independent component analysis. Results Compared with healthy controls, both AD and a-MCI patients showed a similar regional pattern of brain disconnection between the posterior cingulate cortex (PCC) and the medial prefrontal cortex and the rest of the brain. Conversely, the distribution of GM atrophy was significantly more restricted in a-MCI than in AD patients. Interestingly, the PCC showed reduced connectivity in a-MCI patients in the absence of GM atrophy, which was, in contrast, detectable at the stage of fully developed AD. Conclusions This study indicates that disconnection precedes GM atrophy in the PCC, which is a critical area of the DMN, and supports the hypothesis that GM atrophy in specific regions of AD brains likely reflects a long term effect of brain disconnection. In this context, our study indicates that GM atrophy in PCC accompanies the conversion from MCI to AD.

One of the main limitations for BNCT effectiveness is the insufficient intake of (10)B nuclei within turnout cells. This work was aimed at investigating the use Of L-DOPA as enhancer for boronophenylalanine (BPA) uptake in the C6 glioma model. The investigation was first performed in vitro, and then extended in vivo to the animal model. BPA accumulation in C6 glioma cells was assessed, using radiowave dielectric spectroscopy (RDS), with and without L-DOPA preloading. C6 glioma cells were also implanted in the brain of 25 rats, randomly assigned to two experimental branches: (1) intra-carotid BPA infusion; (2) intra-carotid BPA infusion after pre-treatment with L-DOPA, administrated 24 h before BPA infusion. All animals were sacrificed, and assessment of BPA concentrations in turnout tissue, normal brain, and blood samples was performed using high performance liquid chromatography (HPLC). L-DOPA preloading induced a massive increase of BPA concentration either in vitro on C6 glioma cells or in vivo in the animal model tumour. Moreover, no significant difference was found in the normal brain and blood samples between the two animal groups. This study suggests the potential use of L-DOPA as enhancer for EIPA accumulation in malignant gliomas eligible for BNCT.

"Purpose: Boron neutron capture therapy (BNCT) is a radiotherapeutic modality based on B-10(n, alpha)Li-7 reaction, for the treatment of malignant gliomas. One of the main limitations for BNCT effectiveness is the insufficient intake of B-10 nuclei in the tumor cells. This work was aimed at investigating the use of L-DOPA as a putative enhancer for B-10-drug 4-dihydroxy-borylphenylaianine (BPA) uptake in the C6-glioma model. The investigation was first performed in vitro and then extended to the animal model. Methods and Materials: BPA accumulation in C6-glioma cells was assessed using radiowave dielectric spectroscopy, with and without L-DOPA preloading. Two L-DOPA incubation times (2 and 4 hours) were investigated, and the corresponding effects on BPA accumulation were quantified. C6-glioma cells were also implanted in the brain of 32 rats, and tumor growth was monitored by magnetic resonance imaging. Rats were assigned to two experimental branches: (1) BPA administration; (2) BPA administration after pretreatment with L-DOPA. All animals were sacrificed, and assessments of BPA concentrations in tumor tissue, normal brain, and blood samples were performed using high-performance liquid chromatography. Results: L-DOPA preloading induced a massive increase of BPA concentration in C6-glioma cells only after a 4-hour incubation. In the animal model, L-DOPA pretreatment produced a significantly higher accumulation of BPA in tumor tissue but not in normal brain and blood samples. Conclusions: This study suggests the potential use of L-DOPA as enhancer for BPA accumulation in malignant gliomas eligible for BNCT. L-DOPA preloading effect is discussed in terms of membrane transport mechanisms. (C) 2008 Elsevier Inc."

In this paper we present a new approach directed to ascertain the full hemo-compatibility of aortic endograft prostheses based on the measurement of the passive electrical parameters of the erythrocyte cell membrane. The red blood cell membrane, from an electric point of view, is characterized by an electrical permittivity, is an element of(s), which takes into account the structural charged organization of the lipid double layer, and by the electrical conductivity, ss, which accounts for the ionic transport processes across the membrane. These parameters can be easily measured by means of a radiowave dielectric spectroscopy technique, analyzing the dependence of the electrical impedance of an erythrocyte suspension on the frequency of the applied electric field. In this preliminary report, we investigate the alterations induced, at a membrane level, by two different devices commonly employed for endovascular abdominal aortic aneurysm exclusion, i.e., Excluder((R)) and Zenith((R)) devices, implanted in ten patients. We observe, in all the cases investigated, a statistically significant increase of both the permittivity is an element of(s) and electrical conductivity sigma(s) of the erythrocyte membrane upon the prosthesis implant, this increase being higher than about 20% of the un-treated values. Moreover, these alterations remain roughly unaffected 30 days after surgery. These findings suggest that a complete hemo-compatibility of these prostheses is lacking, even if the observed alterations may not have a clinical relevance.

The aging of water suspension of the synthetic clay Laponite has been studied by liquid-state triple-quantum filter nuclear magnetic resonance techniques, in a range of clay weight concentration (C-w = 0.012-0.028) known as the isotropic phase. Counterions dynamic parameters (rotational correlation time tau(c) and quadrupolar coupling constant e(2)qQ/h) have been extracted from sodium triple-quantum filtered experimental data within the multi-exponential quadrupolar relaxation theory in the fast exchange approximation. By monitoring quadrupolar sodium ions dynamical (tau(c) and e(2)qQ/h) and static (counterion concentration p(b)) properties during the aging, we find two different mechanisms of transition toward an arrested state. Our experimental findings match with the description which states, at low concentration, the formation of clusters of Laponite disks trigger the reaching of the arrested state, while at high concentration, single disks are the basic units of the arrested phase. The procedure proposed in this paper, based on multiple quantum filtered NMR data analysis, results to be a useful means to study the routes to arrested states in aqueous colloidal dispersions.

Low frequency fluctuations (LFFs) of the BOLD signal are a major discovery in the study of the resting brain with functional magnetic resonance imaging (fMRI). Two fMRI-based measures, functional connectivity (FC), a measure of signal synchronicity, and the amplitude of LFFs (ALFF), a measure of signal periodicity, have been proved to be sensitive to changes induced by several neurological diseases, including degenerative dementia. In spite of the increasing use of these measures, whether and how they are related to each other remains to be elucidated. In this work we used voxel-wise FC and ALFF computed in different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; and full-band: 0.01-0.073 Hz), in order to assess their relationship in healthy elderly as well as the relevant changes induced by Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI). We found that in healthy elderly subjects FC and ALFF are positively correlated in anterior and posterior cingulate cortex (full-band, slow-4 and slow-5), temporal cortex (full-band and slow-5), and in a set of subcortical regions (full-band and slow-4). These correlation patterns between FC and ALFF were absent in either AD or MCI patients. Notably, the loss of correlation between FC and ALFF in the AD group was primarily due to changes in FC rather than in ALFF. Our results indicate that degenerative dementia is characterized by a loss of global connection rather than by a decrease of fluctuation amplitude.

We have studied the complexation process taking place in cationic liposomes in the presence of anionic polyelectrolytes, in the polyion concentration range from the dilute to the concentrated regime, by combining dynamic light scattering and transmission electron microscopy techniques. We employed as the cationic lipid a two-chained amphiphile (Dioleoyltrimethylammoniumpropane) and sodium polyacrylate salt as the flexible anionic polyelectrolyte. The results evidence a variety of different structures, mainly depending on the liposome-polyion charge ratio, whose peculiar dynamical and structural features are briefly described. In particular, three different polyion concentration regions are found, within which a monomodal or bimodal distribution of aggregates, with a well-defined time evolution, is present. At low polyion content, close to the isoelectric point, large aggregates are formed, deriving from the collapse of the liposomal bilayers into extended charged surfaces, where adsorbed polyions form a two-dimensional strongly correlated array and organize into a two-dimensional Wigner liquid. At high polyion content, above a critical concentration, the size distributions of the complexes are clearly bimodal and a large-component aggregate, continuously increasing with time, coexists with a population of smaller-size aggregates. At an intermediate polyion concentration, spherical, small-size vesicular structures are reformed, connected in a network by polymer chains. A brief discussion tries to summarize our results into a consistent picture.

The dielectric properties of polyelectrolytes in solvent of different quality have been measured in an extended frequency range and the dielectric parameters associated with the polarization induced by counterion fluctuation over some peculiar polyion lengths have been evaluated. Following the scaling theory of polyelectrolyte solutions and the recent models developed by Dobrynin and Rubinstein that explicitly take into account the quality of the solvent on the polyion chain conformation, we have reviewed and summarized a set of scaling laws that describe the dielectric behavior of these systems in the dilute and semidilute regime. Moreover, for poorer solvents, where theory of hydrophobic polyelectrolytes predicts, and computer simulation confirms, a particular chain structure consisting of partially collapsed monomers (beads) connected by monomer strings, we derived a scaling law. These predictions are compared with the results obtained from the dielectric parameters (the dielectric increment delta epsilon and the relaxation time tau(ion)) of the "intermediate" frequency relaxation of two partially charged polymers, which possess a carbon-based backbone for which water is a poor solvent and ethylene glycol is a good solvent. By varying the solvent composition (a water-ethylene glycol mixture), we have tuned the quality of the solvent, passing from poor to good condition and have observed the predicted scaling for all the systems investigated. These findings give a further support to the scaling theory of polyelectrolyte solutions and to the necklace model for hydrophobic polyelectrolytes in poor solvents.

We have investigated molecular interactions between a charged monolayer of different lipid compositions with a polyelectrolyte at the air–water interface by means of Langmuir isotherm measurements and between charged liposomes in an aqueous suspension by means of light scattering measurements, respectively. The condensing effect of the ionic character of the subphase the stability of the mixed monolayers at the appropriate lipid composition and the aggregation processes in the liposome suspension induced by an oppositely charged polyelectrolyte are briefly discussed.

The effects of added salt on the electrical conductivity behavior of a polyelectrolyte solution are described in light of the scaling approach recently proposed by Dobrynin and Rubinstein [Macromolecules 28, 1859 (1995); 32, 915 (1999)], taking into account the influence of the solvent quality factor. The coupling between the conformation of the chain and the local charge distribution, giving rise to different conductometric behaviors, has been investigated under different conditions, in a wide concentration range of added salt. The polyion equivalent conductances ${\ensuremath{\lambda}}_{p}$ have been evaluated in different concentration regimes for a hydrophilic polyion in good solvent condition and compared with the experimental values obtained from electrical conductivity measurements. The agreement is rather good in the wide range of concentration of the added salt investigated. In the case of poor solvent conditions, we find the appropriate expressions for the electrical conductivity when the polyion chain consists into collapsed beads alternating with stretched segments in the framework of the necklace globule model.

We report on the time evolution of the aggregation behaviour of cationic liposome–polyelectrolyte complexes studied by means of dynamic light scattering technique. Pure dioleoyltrimethilammoniumpropane (DOTAP) and mixed DOTAP–dipalmitoylphosphatidylcholine (DPPC) liposomes in polyacrylate sodium salt aqueous solutions in a wide concentration range have been investigated and the size and size distributions of the resulting aggregates evaluated from the intensity autocorrelation function of the scattered light. Under appropriate conditions, we found two discrete aggregation regimes, resulting in two different structural arrangements, whose time evolution depends on the charge ratio and the polyelectrolyte molecular weight. A first small component of average size in the 100–500 range nm coexists with a larger component, whose typical size increases with time, up to some micrometers. The cluster growth from a single liposome, 70 nm in diameter, to the formation of polymer-coated liposome aggregates has been briefly discussed in the light of steric stabilization of colloids. Moreover, it has been found that the kinetics of aggregation of the larger, time-dependent, component follows a dynamical scaling within the diffusion-limited cluster aggregation (DLCA) regime. The understanding of structures resulting from interactions between polyelectrolytes with oppositely charged liposomes may help towards formulation of “lipoplexes” (cationic lipid–DNA complexes) to use as non-viral gene carriers.

The conductometric properties of aqueous polyelectrolyte solutions in the absence of added salt are reviewed in the light of the dynamic scaling description of the polymer conformation in different concentration regimes, recently proposed by Dobrynin and Rubinstein [Macromolecules 28, 1859 (1995); 32, 915 (1999)]. The scaling approach to the transport properties of polyelectrolyte solutions allows us to separate contributions due to polymer conformation from those due to the ionic character of the chain, and offers the possibility to extend the validity of the Manning conductivity model to the dilute and semidilute regimes. Moreover, the quality of the solvent, influencing the polyion-counterion interactions, can be properly taken into account. The electrical conductivity predicted by this scaling approach compares reasonably well with the observed values for a model polyelectrolyte (polyacrylate sodium salt in aqueous solutions, good solvent condition) over an extended concentration range from the dilute to the semidilute regime.

The exposure of a biomaterial to blood gives rise to complex reactions playing an important role in many biological phenomena, such as the problem of biocompatibility and the mechanism of cardiovascular and thromboembolic diseases. In the present work, we use a frequency-domain dielectric spectroscopy approach to evaluate possible changes in the passive electrical parameters of the erythrocyte membrane, i.e., the membrane conductivity sigma(s) and the membrane permittivity epsilon(s), after the insertion of a prosthesis (mean implantation time 8 days) in the circulatory system of patients treated for aortic aneurysm and the consequent interactions of erythrocyte cells with the biomaterial surface. We observe an increase of both the membrane conductivity and membrane permittivity, indicating changes at molecular level in the structural organization of the membrane. These membrane alterations can be viewed as precursory events for the initiation of the complex sequence of enzymatic reactions that take place on the material surface. Our results, although preliminary imply that a direct interaction between erythrocyte cell membrane and vascular prostheses may occur, causing a marked alteration in the electrical properties of the cell membrane. These findings might have relevant clinical implications and might offer possibilities to predict biocompatibility of biomaterials and give some further suggestions to resolve the problem of biomaterial-associated thrombogenicity.

The distribution of two main Boron neutron capture therapy (BNCT) agents, borocaptate sodium ( BSH ) and borono-phenylalanine ( BPA ), in C6 rat glioma cells has been investigated by means of radiowave dielectric spectroscopy measurements. Significant differences between cells treated with the two different boron carriers were found in the magnitude of passive electrical cell parameters. This technique offers a new procedure for the measurement of boron compounds interactions with different biological environments at cellular level and is suggested to have the potentiality for becoming an attractive tool for biodistribution studies of BNCT compounds in biological tissues.

Electrode polarization effects in dielectric spectra of highly conductive biological cell suspensions cause a severe difficulty in the estimation of dielectric parameters of cells under physiological conditions. This problem becomes particularly serious with the increase of the electrical conductivity of the sample, preventing the use of low frequencies in the characterization of biological systems, especially aqueous biological systems. Although a variety of methods to correct the electrode polarization have been proposed in the past, no simple technique for its correction has been available so far. Since the magnitude of the polarization effect can be time-dependent owing to changes in the conductance of the suspending medium or to possible alteration in the electrode surface structure, it is clear that correction procedure should be based on a kind of "self-correction" method, avoiding the so-called "comparison methods" which, on the contrary, require time-independent effects. This note is aimed to address this problem considering an electrode polarization modelled by a constant phase angle (CPA) element in series with the sample admittance. A scaling-law frequency dependence has found to describe the a.c. response of the interface between the electrode and the bulk electrolyte solution. Although this approach has been extensively proposed in the past in the analysis of dielectric spectra of biological suspensions, we have somewhat modified the way it has been previously applied and have re-examined in detail its effectiveness in typical systems of biological interest. The results give support to the proposed analysis, allowing the complete low-frequency dielectric spectra characterization at frequencies of the order of 1 kHz for samples with a bulk ionic conductivity as large as that of the order of 1 mho/m. Typical examples with different dielectric behaviours are extensively discussed in order to show the applicability of the proposed method to biological samples.

We present a set of low-frequency electrical conductivity measurements of solutions of differently charged, salt-free polyelectrolytes in poor- and in good-solvent conditions, in the semidilute concentration regime. The data have been analyzed and discussed in light of the necklace model for hydrophobic polyelectrolytes recently proposed by Dobrynin et al. [Macromolecules 29, 2974 (1996)] that predicts the chains to collapse into spheroidal cores connected by narrow strings. By varying the quality of the solvent, we have measured the polyion equivalent conductance lambda(p) in an extended concentration range in the semidilute regime and have demonstrated that this parameter is influenced by the polyion chain conformation, giving further support, when the poor-solvent condition prevails, to the picture of a string of electrostatic blobs. On the contrary, in good-solvent condition, the electrical conductivity data are in reasonable good agreement with the picture of an extended chain consisting of a collection of electrostatic blobs. These electrical conductivity measurements, in light of scaling theory, furnish new experimental support for the necklace model for hydrophobic polyions in poor solvents.

The renormalization group is the cornerstone of the modern theory of universality and phase transitions, a powerful tool to scrutinize symmetries and organizational scales in dynamical systems. However, its network counterpart is particularly challenging due to correlations between intertwined scales. To date, the explorations are based on hidden geometries hypotheses. Here, we propose a Laplacian RG diffusion-based picture in complex networks, defining both the Kadanoff supernodes' concept, the momentum space procedure, \emph{\'a la Wilson}, and applying this RG scheme to real networks in a natural and parsimonious way., Comment: 7 pages, 4 figures, and Supplementary Information

Alterations in the electrical passive parameters of red blood cell membranes occurring during storage have been investigated by means of two different experimental approaches, i.e., radiowave dielectric spectroscopy measurements and flow-cytometric measurements. We observed a correlation between the appearance of phosphatidylserine molecules in the outer leaflet of the cell membrane and the occurrence of a change in the electrical passive membrane parameters. The electrical re-organization of the membrane, resulting in an increase of its conductivity and permittivity after 5 -7 days from blood storage, can be considered as a precursory event for the loss of asymmetry in the lipid distribution across red blood cell membrane.

Spontaneous low-frequency Blood–Oxygenation Level–Dependent (BOLD) signals acquired during resting state are characterized by spatial patterns of synchronous fluctuations, ultimately leading to the identification of robust brain networks. The resting-state brain networks, including the Default Mode Network (DMN), are demonstrated to persist during sustained task execution, but the exact features of task-related changes of network properties are still not well characterized. In this work we sought to examine in a group of 20 healthy volunteers (age 33±6 years, 8F/12M) the relationship between changes of spectral and spatiotemporal features of one prominent resting-state network, namely the DMN, during the steady-state execution of a sustained working memory n-back task. We found that the steady state execution of such a task impacted on both functional connectivity and amplitude of BOLD fluctuations within large parts of the DMN, but these changes correlated between each other only in a small area of the posterior cingulate. We conclude that combined analysis of multiple parameters related to connectivity, and their changes during the transition from resting state to steady-state task execution, can contribute to a better understanding of how brain networks rearrange themselves in response of a task.