Manipulation of Pre-Target Activity on the Right Frontal Eye Field Enhances Conscious Visual Perception in Humans

The right Frontal Eye Field (FEF) is a region of the human brain, which has been consistently involved in visuo-spatial attention and access to consciousness. Nonetheless, the extent of this cortical site’s ability to influence specific aspects of visual performance remains debated. We hereby manipulated pre-target activity on the right FEF and explored its influence on the detection and categorization of low-contrast near-threshold visual stimuli. Our data show that pre-target frontal neurostimulation has the potential when used alone to induce enhancements of conscious visual detection. More interestingly, when FEF stimulation was combined with visuo-spatial cues, improvements remained present only for trials in which the cue correctly predicted the location of the subsequent target. Our data provide evidence for the causal role of the right FEF pre-target activity in the modulation of human conscious vision and reveal the dependence of such neurostimulatory effects on the state of activity set up by cue validity in the dorsal attentional orienting network

New approaches to the study of human brain networks underlying spatial attention and related processes

Cognitive processes, such as spatial attention, are thought to rely on extended networks in the human brain. Both clinical data from lesioned patients and fMRI data acquired when healthy subjects perform particular cognitive tasks typically implicate a wide expanse of potentially contributing areas, rather than just a single brain area. Conversely, evidence from more targeted interventions, such as transcranial magnetic stimulation (TMS) or invasive microstimulation of the brain, or selective study of patients with highly focal brain damage, can sometimes indicate that a single brain area may make a key contribution to a particular cognitive process. But this in turn raises questions about how such a brain area may interface with other interconnected areas within a more extended network to support cognitive processes. Here, we provide a brief overview of new approaches that seek to characterise the causal role of particular brain areas within networks of several interacting areas, by measuring the effects of manipulations for a targeted area on function in remote interconnected areas. In human participants, these approaches include concurrent TMS-fMRI and TMS-EEG, as well as combination of the focal lesion method in selected patients with fMRI and/or EEG measures of the functional impact from the lesion on interconnected intact brain areas. Such approaches shed new light on how frontal cortex and parietal cortex modulate sensory areas in the service of attention and cognition, for the normal and damaged human brain

Efficacia a breve e lungo termine del protocollo Spector, presso la residenza protetta

Aimee Spector dal 2001, attraverso una serie di studi randomizzati controllati, sviluppa e dimostra l’efficacia di un protocollo di stimolazione cognitiva per persone affette da demenza di grado lieve-moderato (Spector et al., 2006). Il presente studio, i cui dati preliminari sono stati presentati lo scorso anno, si è proposto di verificare in un campione di 39 grandi vecchi con demenza l’efficacia del protocollo Spector e confermare quanto già riportato in letteratura (Woods et al., 2012). Si è però inteso ovviare ai limiti metodologici degli studi precedenti comparando l’efficacia del protocollo con un gruppo di controllo attivo impiegato in attività alternative ma comparabili, per numero di sessioni, a quelle svolte dal gruppo sperimentale. Sono state poi introdotte prove volte ad indagare l’eventuale miglioramento in aree quasi o completamente nuove nell’ambito della stimolazione cognitiva in anziani con demenza come il linguaggio. Nello specifico, quindi, è stata valutata l’efficacia a breve e lungo termine (follow-up a 3 mesi) in prove volte ad indagare il funzionamento cognitivo globale, il tono dell’umore, aspetti comportamentali, qualità di vita e abilità di produzione linguistica. Si riportano i risultati ormai definitivi dello studio e vengono discussi ex novo i risultati relativi al mantenimento nel tempo (follow-up a tre mesi) dei benefici ottenuti

ELEMENTAL COMPOSITION DETERMINED BY PIXE ANALYSIS OF THE INSOLUBLE AEROSOL PARTICLES IN EPICA-DOME C ICE CORE SAMPLES REPRESENTING THE LAST 27000 YEARS

107 samples from the first 581 m of the EPICA ice core, Dome C, East Antarctica, representing a 27000 year record, were analysed by the PIXE technique. The concentrations of several elements (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, Mn, Fe) were determined in the insoluble particles, collected by filtration from the melted ice samples. The average elemental ratios for Holocene and LGM are in agreement with continental crust values. The element depositional fluxes, evaluated from PIXE concentration data by means of the EPICA ice accumulation rate, are smaller in the Holocene than during Glacial times, confirming the differences in dust loads in the atmosphere during the contrasting climatic conditions. In Holocene, the fraction of the insoluble particle mass (estimated as the sum of the measured element oxides) agrees well with the total dust mass as determined from Coulter Counter measurements, but during the LGM the particle counting shows a larger dust mass

Three-dimensional speckle tracking echocardiography in the assessment of right ventricular dysfunction after surgical repair of tetralogy of Fallot.

Background: The combined effects of preoperative hypertrophy and hypoxia, possible intraoperative myocardial damage, type of reconstruction, and acquired postoperative lesions such as pulmonary regurgitation may result in impaired RV deformation in post-operative tetralogy of Fallot (TF). Recently 3D speckle tracking echocardiography (3DSTE) has been proposed to assess mechanical dyssynchrony in these patients but the role of electromechanical dysfunction is not completely clear. Methods: Sixteen patients after TF repair (aged 17-53years) with dilated right ventricle, right bundle branch block (QRS >120ms), and NYHA class I or greater were studied with twodimensional and three-dimensional speckle tracking echocardiography. Right ventricular enddiastolic and end-systolic volumes were measured from three-dimensional datasets and right ventricular ejection fraction (3D-RVEF) was obtained. Right intraventricular dyssynchrony was determined as the difference between the longest and shortest electromechanical coupling times in the basal septal and lateral RV segments. Interventricular dyssynchrony was determined as the difference between electromechanical coupling times in the basal lateral LV segment and the most delayed RV segment. Sixteeen age-matched healthy subjects were selected as controls. Results: Right intraventricular dyssynchrony (77.1+/-24.2ms vs 13.1+/-8.9ms) and interventricular dyssynchrony (74.7+/-22.2ms vs 11.4+/-7.9ms) were shown in patients compared to normal controls. Right intraventricular dyssynchrony correlated with RV longitudinal strain (r=0.62, p<0.005), 3D RV end-systolic volume (r=0.47, p=0.02), and QRS duration (r=0.39, p=0.03). Interventricular dyssynchrony correlated with RV longitudinal strain (r=0.73, p<0.001), RV systolic pressure (r=0.59, p<0.005), 3D-RVEF (r=0.53, p=0.003), and QRS duration (r=-0.44, p=0.031). Reduced RV strain, 3D-RVEF and prolonged QRS duration were the main determinant factors predicting RV dyssynchrony by multivariate analysis. On ROC curves RV strain and 3DRVEF had optimal predictive accuracy of the NYHA functional class and a larger area under the receiver operating characteristic curve than the QRS duration. Conclusions: In patients with repaired TF RV dyssynchrony is associated with reduced 3D-RVEF and RV 3DSTE parameters

Right ventricular function in acute pulmonary embolism: a combined assessment by three-dimensional and speckle tracking echocardiography

Background. We aimed to assess changes in right ventricular (RV) parameters determined by three-dimensional echocardiography (3DE) and speckle tracking echocardiography (STE) in patients with acute pulmonary embolism and RV dysfunction without systemic hypotension (submassive PE). Methods. We prospectively studied 66 patients at the onset of the acute episode and after a median follow-up of 30 days and six months. Sixty-six controls were selected. RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE) and myocardial performance index (MPI) were determined. RV systolic pressure (RVSP) was assessed by continuous wave Doppler echocardiography. Three-dimensional right ventricular ejection fraction (3D-RVEF) was calculated. Two-dimensional peak systolic RV longitudinal strain (RVLS) was measured in the basal, mid and apical segments of free wall (BFW, MFW, AFW) and septum. Results. TAPSE and FAC were smaller and MPI was larger compared to controls (p<0.05). Global RVLS (p<0.05), MFW-RVLS (p<0.001), and 3D-RVEF (p<0.001) were lower in PE patients than controls. There was earlier reversal of MFW-RVLS values on a 30-day follow-up and longer reversal of 3D-RVEF and RVSP values on a 6-month follow-up. ROC analysis showed that changes in 3D-RVEF and MFW-RVLS were the most sensitive predictors of adverse events. By multivariate analysis, RVSP (p=0.007), MFW-RVLS (p=0.002) and 3D-RVEF (p=0.001) were independently associated with adverse outcomes. Conclusions. Acute submassive PE has a significant impact on RV function as assessed by 3DE and STE. Decrease in MFW-RVLS and 3D-RVEF may persist during short and long-term follow-up and correlate with unfavorable outcome