Electrophysiological Advances on Multiple Object Processing in Aging

EEG research conducted in the past five years on multiple object processing has begun to define how the aging brain tracks the numerosity of the objects presented in the visual field for different goals. We review the recent EEG findings in healthy older individuals (age range: 65-75 years approximately) on perceptual, attentional and memory mechanisms- reflected in the N1, N2pc and Contralateral Delayed Activity components of the EEG, respectively- during the execution of a variety of cognitive tasks requiring simultaneous processing of multiple elements. The findings point to multiple loci of neural changes in multi-object analysis, and suggest the involvement of early perceptual mechanisms, attentive individuation and WM operations in the neural and cognitive modification due to aging. However, the findings do not simply reflect early impairments with a cascade effect over subsequent stages of stimulus processing, but in fact highlight interesting dissociations between the effects occurring at the various stages of stimulus processing. Finally, the results on older adults indicate the occurrence of neural overactivation in association to good levels of performance in easy perceptual contexts, thus providing some hints on the existence of compensatory phenomena that are associated with the functioning of early perceptual mechanisms

Формирование изображения нарушителя в радиолучевых системах охраны

В статье рассмотрены вопросы улучшения информационных характеристик двухпозиционных радио- лучевых технических систем охраны. В качестве первого приближения сигналообразования использована лучевая модель формирования интерференционной картины ЭМ-волны. Разработан метод формирования двумерного изображения нарушителя в виде теневого силуэта. Получено обратное преобразование Кирхгофа, связывающее функцию пропускания объекта с распределением комплексной амплитуды ЭМ-волны в плоскости приема.У статті розглянуті питання поліпшення інформаційних характеристик двопозиційних радіопроменевих технічних систем охорони. Як перше наближення сигналостворення використана променева модель формування інтерференційної картини ЕМ-хвилі. Розроблено метод формування двовимірного зображення порушника у вигляді тіньового силуету. Отримано зворотне перетворення Кірхгофа, що зв’язує функцію пропускання об’єкта з розподілом комплексної амплітуди ЕМ-хвилі в площині прийому.The article deals with the issues of improving information characteristics of two-position radio-beam technical protection systems. The beam model of forming EM wav interference pattern is used as the first approximation of signal forming. The method of forming the intruder’s two-dimensional image as a shadow silhouette has been developed. The author has drawn the Kirchhoff inversion connecting the object’s transmission function with the distribution of the EM wave complex amplitude in the reception plane

Influence of frontal-to-parietal connectivity in pseudoneglect: A cortico-cortical paired associative stimulation study

Pseudoneglect is a set of visuospatial biases that entails a behavioral advantage for stimuli appearing in the left hemifield compared to the right one. Although right hemisphere dominance for visuospatial processing has been invoked to explain this phenomenon, its neurophysiological mechanisms are still debated, and the role of intra- and inter-hemispheric connectivity is yet to be defined. The present study explored the possibility of modulating pseudoneglect in healthy participants through a cortico-cortical paired associative stimulation protocol (ccPAS): a non-invasive brain stimulation protocol that manipulates the interplay between brain regions through the repeated, time-locked coupling of two transcranial magnetic stimulation (TMS) pulses. In the first experiment, healthy participants underwent a frontal-to-parietal (FP) and a parietal-to-frontal (PF) ccPAS. In the FP protocol, the first TMS pulse targeted the right frontal eye field (FEF), and the second pulse the right inferior parietal lobule (IPL), two critical areas for visuospatial and attentional processing. In the PF condition, the order of the pulses was reversed. In both protocols, the inter-stimulus interval (ISI) was 10 ms. Before and after stimulation, pseudoneglect was assessed with a landmark task and a manual line bisection task. A second experiment controlled for ccPAS timing dependency by testing FP-ccPAS with a longer ISI of 100 ms. Results showed that after administering the FP-ccPAS with the ISI of 10 ms, participants' leftward bias in the landmark task increased significantly, with no effects in the manual line bisection task. The other two protocols tested were ineffective. Our findings showed that ccPAS could be used to modulate pseudoneglect by exploiting frontal-to-parietal connectivity, possibly through increased top-down attentional control. FP-ccPAS could represent a promising tool to investigate connectivity properties within visuospatial and attentional networks in the healthy and as a potential rehabilitation protocol in patients suffering from severe visuospatial pathologies

Connectivity alterations underlying the breakdown of pseudoneglect: New insights from healthy and pathological aging

A right-hemisphere dominance for visuospatial attention has been invoked as the most prominent neural feature of pseudoneglect (i.e., the leftward visuospatial bias exhibited in neurologically healthy individuals) but the neurophysiological underpinnings of such advantage are still controversial. Previous studies investigating visuospatial bias in multiple-objects visual enumeration reported that pseudoneglect is maintained in healthy elderly and amnesic mild cognitive impairment (aMCI), but not in Alzheimer's disease (AD). In this study, we aimed at investigating the neurophysiological correlates sustaining the rearrangements of the visuospatial bias along the progression from normal to pathological aging. To this aim, we recorded EEG activity during an enumeration task and analyzed intra-hemispheric fronto-parietal and inter-hemispheric effective connectivity adopting indexes from graph theory in patients with mild AD, patients with aMCI, and healthy elderly controls (HC). Results revealed that HC showed the leftward bias and stronger fronto-parietal effective connectivity in the right as compared to the left hemisphere. A breakdown of pseudoneglect in patients with AD was associated with both the loss of the fronto-parietal asymmetry and the reduction of inter-hemispheric parietal interactions. In aMCI, initial alterations of the attentional bias were associated with a reduction of parietal inter-hemispheric communication, but not with modulations of the right fronto-parietal connectivity advantage, which remained intact. These data provide support to the involvement of fronto-parietal and inter-parietal pathways in the leftward spatial bias, extending these notions to the complex neurophysiological alterations characterizing pathological aging

A simultaneous modulation of reactive and proactive inhibition processes by anodal tDCS on the right inferior frontal cortex

Proactive and reactive inhibitory processes are a fundamental part of executive functions, allowing a person to stop inappropriate responses when necessary and to adjust performance in in a long term in accordance to the goals of a task. In the current study, we manipulate, in a single task, both reactive and proactive inhibition mechanisms, and we investigate the within-subjects effect of increasing, by means of anodal transcranial direct current stimulation (tDCS), the involvement of the right inferior frontal cortex (rIFC). Our results show a simultaneous enhancement of these two cognitive mechanisms when modulating the neural activity of rIFC. Thus, the application of anodal tDCS increased reaction times on Go trials, indicating a possible increase in proactive inhibition. Concurrently, the stop-signal reaction time, as a covert index of the inhibitory process, was reduced, demonstrating an improvement in reactive inhibition. In summary, the current pattern of results validates the engagement of the rIFC in these two forms of inhibitory processes, proactive and reactive inhibition and it provides evidence that both processes can operate concurrently in the brain

Enhancing cognitive training effects in Alzheimer's disease: rTMS as an add-on treatment.

The treatment of Alzheimer's disease (AD) in the field of non-pharmacological interventions is a challenging issue, given the limited benefits of the available drugs. Cognitive training (CT) represents a commonly recommended strategy in AD. Recently, repetitive transcranial magnetic stimulation (rTMS) has gained increasing attention as a promising therapeutic tool for the treatment of AD, given its ability of enhancing neuroplasticity. In the present randomized, double-blind, sham-controlled study, we aimed at investigating the add-on effect of a high frequency rTMS protocol applied over the left dorsolateral prefrontal cortex (DLPFC) combined with a face-name associative memory CT in the continuum of AD pathology. Fifty patients from a very early to a moderate phase of dementia were randomly assigned to one of two groups: CT plus real rTMS or CT plus placebo rTMS. The results showed that the improvement in the trained associative memory induced with rTMS was superior to that obtained with CT alone. Interestingly, the extent of the additional improvement was affected by disease severity and levels of education, with less impaired and more educated patients showing a greater benefit. When testing for generalization to non-trained cognitive functions, results indicated that patients in CT-real group showed also a greater improvement in visuospatial reasoning than those in the CT-sham group. Interestingly, this improvement persisted over 12 weeks after treatment beginning. The present study provides important hints on the promising therapeutic use of rTMS in AD

Structural Basis of Teneurin-Latrophilin Interaction in Repulsive Guidance of Migrating Neurons

Teneurins are ancient metazoan cell adhesion receptors that control brain development and neuronal wiring in higher animals. The extracellular C terminus binds the adhesion GPCR Latrophilin, forming a trans-cellular complex with synaptogenic functions. However, Teneurins, Latrophilins, and FLRT proteins are also expressed during murine cortical cell migration at earlier developmental stages. Here, we present crystal structures of Teneurin-Latrophilin complexes that reveal how the lectin and olfactomedin domains of Latrophilin bind across a spiraling beta-barrel domain of Teneurin, the YD shell. We couple structure-based protein engineering to biophysical analysis, cell migration assays, and in utero electroporation experiments to probe the importance of the interaction in cortical neuron migration. We show that binding of Latrophilins to Teneurins and FLRTs directs the migration of neurons using a contact repulsion-dependent mechanism. The effect is observed with cell bodies and small neurites rather than their processes. The results exemplify how a structure-encoded synaptogenic protein complex is also used for repulsive cell guidance

Subdomain-mediated axon-axon signaling and chemoattraction cooperate to regulate afferent innervation of the lateral habenula

A dominant feature of neural circuitry is the organization of neuronal projections and synapses into specific brain nuclei or laminae. Lamina-specific connectivity is controlled by the selective expression of extracellular guidance and adhesion molecules in the target field. However, how (sub)nucleus-specific connections are established and whether axon-derived cues contribute to subdomain targeting are largely unknown. Here, we demonstrate that the lateral subnucleus of the habenula (lHb) determines its own afferent innervation by sending out efferent projections that express the cell adhesion molecule LAMP to reciprocally collect and guide dopaminergic afferents to the lHb-a phenomenon we term subdomain-mediated axon-axon signaling. This process of reciprocal axon-axon interactions cooperates with lHb-specific chemoattraction mediated by Netrin-1, which controls axon target entry, to ensure specific innervation of the lHb. We propose that cooperation between pretarget reciprocal axon-axon signaling and subdomain-restricted instructive cues provides a highly precise and general mechanism to establish subdomain-specific neural circuitry

Niñas y mujeres con síndrome X frágil en España. Estudio sobre sus necesidades y las de sus familiares

Los objetivos de este estudio sobre niñas y mujeres con síndrome X frágil en España son los siguientes: - conocer cuáles son las necesidades de esas niñas o mujeres afectadas, según la experiencia y percepción de los propios padres y madres, - conocer las características psico-sociales de este colectivo, - conocer cuáles son las necesidades específicas de los padres y madres de las afectadas, - conocer su nivel de satisfacción con los apoyos sociales existentes y sus peticiones a las administraciones públicas

Controle do nematóide Aphelenchoides besseyi das sementes de arroz

Six trials were carried out at Lorena and Pindamonhangaba, SP, Brazil, to study the control of the rice nematode Aphelenchoides besseyi Christie 1942, for irrigated conditions. Some chemicals and one thermal treatment were effective in decreasing nematode density; nevertheless, there was no association with yield increases. The cultivars IR 841, IAC 435, IAC 120 and IAC 899 were very tolerant to nematode with yields prominence of IAC 899. Em seis experimentos conduzidos nos municípios de Lorena e Pindamonhangaba, SP, procurou-se verificar o efeito de tratamentos químicos e térmico de sementes sobre o nematóide Aphelenchoides besseyi Christie 1942, em condições de cultivo irrigado. Alguns produtos e o tratamento térmico reduziram o nível populacional do nematóide, porém não houve associação entre os dados de redução e aumento na produção. As cultivares utilizadas, IR 841, IAC 435, IAC 120 e IAC 899, demonstraram elevada tolerância ao nematóide, com destaque de produtividade da IAC 899