The contribution of primary and secondary somatosensory cortices to the representation of body parts and body sides: an fMRI adaptation study

Although the somatosensory homunculus is a classically used description of the way somatosensory inputs are processed in the brain, the actual contributions of primary (SI) and secondary (SII) somatosensory cortices to the spatial coding of touch remain poorly understood. We studied adaptation of the fMRI BOLD response in the somatosensory cortex by delivering pairs of vibrotactile stimuli to the finger tips of the index and middle fingers. The first stimulus (adaptor) was delivered either to the index or to the middle finger of the right or left hand, whereas the second stimulus (test) was always administered to the left index finger. The overall BOLD response evoked by the stimulation was primarily contralateral in SI and was more bilateral in SII. However, our fMRI adaptation approach also revealed that both somatosensory cortices were sensitive to ipsilateral as well as to contralateral inputs. SI and SII adapted more after subsequent stimulation of homologous as compared with nonhomologous fingers, showing a distinction between different fingers. Most importantly, for both somatosensory cortices, this finger-specific adaptation occurred irrespective of whether the tactile stimulus was delivered to the same or to different hands. This result implies integration of contralateral and ipsilateral somatosensory inputs in SI as well as in SII. Our findings suggest that SI is more than a simple relay for sensory information and that both SI and SII contribute to the spatial coding of touch by discriminating between body parts (fingers) and by integrating the somatosensory input from the two sides of the body (hands).

Drivers of change in mountain farming in Slovakia: from socialist collectivisation to the Common Agricultural Policy

The transformations in Slovak agriculture from the 1950s to the present day, considering both the generic (National and EU) and site-specific (local) drivers of landscape change, were analysed in five mountain study areas in the country. An interdisciplinary approach included analysis of population trends, evaluation of land use and landscape change combined with exploration of the perceptions of local stakeholders and results of previous biodiversity studies. The generic processes active from the 1950s to 1970s were critical for all study areas with impacts lasting right up until the present day. Agricultural collectivisation, agricultural intensification and land abandonment had negative effects in all study areas. However, the precise impacts on the landscape were different in the different study areas due to site-specific attributes (e.g. population trends, geographic localisation and local attitudes and opportunities), and these played a decisive role in determining the trajectory of change. Regional contrasts in rural development between these territories have increased in the last two decades, also due to the imperfect preconditions of governmental support. The recent Common Agricultural Policy developments are focused on maintenance of intensive large-scale farming rather than direct enhancement of agro-biodiversity and rural development at the local scale. In this context, local, site-specific attributes can and must form an essential part of rural development plans, to meet the demands for management of the diversity of agricultural mountain landscapes and facilitate the multifunctional role of agriculture.

On the 'special' status of emotional faces... Comment on Yang, Hong, and Blake (2010)

A wealth of literature suggests that emotional faces are given special status as visual objects: Cognitive models suggest that emotional stimuli, particularly threat-relevant facial expressions such as fear and anger, are prioritized in visual processing and may be identified by a subcortical “quick and dirty” pathway in the absence of awareness (Tamietto & de Gelder, 2010). Both neuroimaging studies (Williams, Morris, McGlone, Abbott, & Mattingley, 2004) and backward masking studies (Whalen, Rauch, Etcoff, McInerney, & Lee, 1998) have supported the notion of emotion processing without awareness. Recently, our own group (Adams, Gray, Garner, & Graf, 2010) showed adaptation to emotional faces that were rendered invisible using a variant of binocular rivalry: continual flash suppression (CFS, Tsuchiya & Koch, 2005). Here we (i) respond to Yang, Hong, and Blake's (2010) criticisms of our adaptation paper and (ii) provide a unified account of adaptation to facial expression, identity, and gender, under conditions of unawareness

Resting tremor classification and detection in Parkinson's disease patients

Parkinson is a neurodegenerative disease, in which tremor is the main symptom. This paper investigates the use of different classification methods to identify tremors experienced by Parkinsonian patients.Some previous research has focussed tremor analysis on external body signals (e.g., electromyography, accelerometer signals, etc.). Our advantage is that we have access to sub-cortical data, which facilitates the applicability of the obtained results into real medical devices since we are dealing with brain signals directly. Local field potentials (LFP) were recorded in the subthalamic nucleus of 7 Parkinsonian patients through the implanted electrodes of a deep brain stimulation (DBS) device prior to its internalization. Measured LFP signals were preprocessed by means of splinting, down sampling, filtering, normalization and rec-tification. Then, feature extraction was conducted through a multi-level decomposition via a wavelettrans form. Finally, artificial intelligence techniques were applied to feature selection, clustering of tremor types, and tremor detection.The key contribution of this paper is to present initial results which indicate, to a high degree of certainty, that there appear to be two distinct subgroups of patients within the group-1 of patients according to the Consensus Statement of the Movement Disorder Society on Tremor. Such results may well lead to different resultant treatments for the patients involved, depending on how their tremor has been classified. Moreover, we propose a new approach for demand driven stimulation, in which tremor detection is also based on the subtype of tremor the patient has. Applying this knowledge to the tremor detection problem, it can be concluded that the results improve when patient clustering is applied prior to detection.

Architectonic subdivisions of the amygdalar complex of a primitive marsupial (Didelphis aurita)

The architecture of the amygdaloid complex of a marsupial, the opossum Didelphis aurita, was analyzed using classical stains like Nissl staining and myelin (Gallyas) staining, and enzyme histochemistry for acetylcholinesterase and NADPH-diaphorase. Most of the subdivisions of the amygdaloid complex described in eutherian mammals were identified in the opossum brain. NADPH-diaphorase revealed reactivity in the neuropil of nearly all amygdaloid subdivisions with different intensities, allowing the identification of the medial and lateral subdivisions of the cortical posterior nucleus and the lateral subdivision of the lateral nucleus. The lateral, central, basolateral and basomedial nuclei exhibited acetylcholinesterase positivity, which provided a useful chemoarchitectural criterion for the identification of the anterior basolateral nucleus. Myelin stain allowed the identification of the medial subdivision of the lateral nucleus, and resulted in intense staining of the medial subdivisions of the central nucleus. The medial, posterior, and cortical nuclei, as well as the amygdalopiriform area did not exhibit positivity for myelin staining. On the basis of cyto- and chemoarchitectural criteria, the present study highlights that the opossum amygdaloid complex shares similarities with that of other species, thus supporting the idea that the organization of the amygdala is part of a basic plan conserved through mammalian evolution. (C) 2008 Elsevier Inc. All rights reserved.

Chaotic synchronization in general network topology for scene segmentation

Chaotic synchronization has been discovered to be an important property of neural activities, which in turn has encouraged many researchers to develop chaotic neural networks for scene and data analysis. In this paper, we study the synchronization role of coupled chaotic oscillators in networks of general topology. Specifically, a rigorous proof is presented to show that a large number of oscillators with arbitrary geometrical connections can be synchronized by providing a sufficiently strong coupling strength. Moreover, the results presented in this paper not only are valid to a wide class of chaotic oscillators, but also cover the parameter mismatch case. Finally, we show how the obtained result can be applied to construct an oscillatory network for scene segmentation.

Chaotic synchronization in 2D lattice for scene segmentation

Synchronization and chaos play important roles in neural activities and have been applied in oscillatory correlation modeling for scene and data analysis. Although it is an extensively studied topic, there are still few results regarding synchrony in locally coupled systems. In this paper we give a rigorous proof to show that large numbers of coupled chaotic oscillators with parameter mismatch in a 2D lattice can be synchronized by providing a sufficiently large coupling strength. We demonstrate how the obtained result can be applied to construct an oscillatory network for scene segmentation. (C) 2007 Elsevier B.V. All rights reserved.

Acumulação tecnológica e aprimoramento de performance competitiva: evidências de diferenças e similaridades e médias empresas do setor metal-mecânico no estado do rio de janeiro

The main objective of this dissertation is to examine the implications of technological capacities in the improvement of technical performance indexes, specifically at the company level. These relationships were examined in a small sample of metal-working enterprises in the state of Rio de Janeiro (1960 to 2006). Although diverse studies on technological competences have been carried out in the last twenty years, a gap in empirical studies still exist that correlate the performance of companies in the context of developing countries, especially in Brazil. Aiming to contribute to a reduction of these gaps, this dissertation examines the questions by the light of available models in literature, which opting themselves to using operational indexes of companies. For drawing the accumulation of technological competences in this study, the metric proposal by Figueiredo (2000) shall be used indicating the levels of technological qualification in process, product, and equipment functions. The empirical evidence examined in this dissertation is both qualitative and quantitative in nature and were collected, first hand, through extensive field research involving informal interviews, meetings, direct-site observation and document analysis. In relation to the results, the evidence suggests that: - In terms of technological accumulation, a company reached Level 5 of technological capacity in process and organization of production as well as product and equipment. Three companies obtained Level 4 in the function process function while two others had reached the same technological level in the functions of product and equipment. Two companies had reached Level 3 in the product and equipment functions and one remained this level in the function of process; - In terms of the rate of accumulation of technological capacities, the observed companies had reached Level 4 needs 29 years in process function, 32 years in product function and 29 years in equipment function; - In terms of improvement performance pointers, a company which reached Level 5 of technological capacity improved in 70% of its indicators of performance, while the company that had achieved Level 4 had raised its pointers 60% and the other companies had gotten improved in the order of 40%. It was evidenced that the majority of the pointers of the companies with higher levels of technological capacities had obtained better performance. This dissertation contributes to advancing the strategic management of companies in metal-working segment to understanding internal accumulation of technological capacity and indicators of performance especially in the field of empirical context studied. This information offers management examples of how to improve competitive performance through the accumulation of technological capacities in the process, product and equipment functions.

Increase in Hippocampal Theta Oscillations during Spatial Decision Making

The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (5–12 Hz). However, in rats both the power and the frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations support decision-making processes. In this study, we investigated to what extent spatial decision making modulates hippocampal theta oscillations when controlling for variations in locomotion speed. We recorded local field potentials from the CA1 region of rats while animals had to choose one arm to enter for reward (goal) in a four-arm radial maze. We observed prominent theta oscillations during the decision-making period of the task, which occurred in the center of the maze before animals deliberately ran through an arm toward goal location. In speed-controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running toward goal location. In addition, theta activity was higher during decision periods preceding correct choices than during decision periods preceding incorrect choices. Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decision making

Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

Oscilações Teta no hipocampo do rato durante tarefa de tomada de decisão espacial

The processing of spatial and episodic information during memory tasks depends on hippocampal theta oscillations. In the present study, I investigated the relationship between theta power and choice selection during spatial decision-making. I recorded local field potentials from the CA1 region of rats retrieving reward locations in a 4-arm maze. In trained but not in naïve animals, I observed a significant increase in theta power during decision-making, which could not be explained by changes in locomotion speed. Furthermore, a Bayesian decoder based on theta power predicted choice outcomes in speed-matched trials. The decoding time course revealed that performance increased above chance before the decision moment exclusively for theta power, remaining flat for other frequency bands. These results occurred for trained animals, but no significant prediction could be made for naïve animals. Altogether, the data support a mnemonic function of theta rhythm during spatial decision-making, indicating that these oscillations correlate with the retrieval of memories required for successful decisions

Mass generation for Abelian spin-1 particles via a symmetric tensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sistema de agentes poligínicos para esteganálise de imagens digitais

In this work, we propose a multi agent system for digital image steganalysis, based on the poliginic bees model. Such approach aims to solve the problem of automatic steganalysis for digital media, with a case study on digital images. The system architecture was designed not only to detect if a file is suspicious of covering a hidden message, as well to extract the hidden message or information regarding it. Several experiments were performed whose results confirm a substantial enhancement (from 67% to 82% success rate) by using the multi-agent approach, fact not observed in traditional systems. An ongoing application using the technique is the detection of anomalies in digital data produced by sensors that capture brain emissions in little animals. The detection of such anomalies can be used to prove theories and evidences of imagery completion during sleep provided by the brain in visual cortex areas

Macrofauna de ambientes não consolidados adjacentes à recifes da área de proteção ambiental dos recifes de corais Rio Grande do Norte, Brasil

This study aimed to characterize, for the first time, the benthic invertebrates that inhabit the region of soft bottoms adjacent to the APARC reefs in order to situate them as an important component of infralittoral coastal areas of Northeast Brazil. Soft bottoms areas of APARC corresponds to infralittoral zones vegetated by seagrass Halodule wrightii and unvegetated infralittoral zones, both subjected to substantial hydrodynamic stress. Through scuba diving, biological and sedimentary samples of both habitats were analyzed, with a cylindrical sampler. We identified 6160 individuals belonging to 16 groups and 224 species. The most abundant macrofaunal group was Polychaeta (43%), followed by Mollusca (25%) and Crustacea (14%), what was expected for these environments. In the first chapter, regarding vegetated areas, we tested three hypotheses: the existence of differences in the faunal structure associated with H. wrightii banks submitted to different hydrodynamic conditions; the occurrence of minor temporal variations on the associated macrofauna of banks protected from hydrodynamic stress; and if the diversity of macrofauna is affected by both benthophagous predators and H. wrightii biomass. It was observed that macrofauna associated at the Exposed bank showed differences in structure when comparing the Protected bank, the granulometry of the sediments, that co-varies with the hydrodynamism, was the cause of these variations. The results also pointed to a lower temporal variation in the macrofaunal structure on the Protected bank and a negative relation between macrofaunal and benthophagous fish abundance. At the Exposed bank, a greater faunal diversity was observed, probably due to the higher seagrass biomass. The second chapter compares the vegetated and non-vegetated areas in order to test the hypothesis that due to greater seasonal stability in tropical environments, seagrass structure would act to distinguish the vegetated and non-vegetated areas macrofauna, over time. It was also expected that depositivores were the most representative invertebrates on non-vegetated environments, on the assumption that the seagrass bank would work as a source of debris to adjacent areas, enriching them. Considering all sampling periods, the total macrofauna abundance and diversity were higher in vegetated areas, when compared to non-vegetated ones. Seasonally, the structural complexity provided by Halodule differentiated more clearly the fauna from vegetated and non-vegetated areas, but only at the climatic extremes, i.e. Dry season (extreme climatic stability, with low hydronamism variation) and Rainy season (great hydrodynamism variation and probably vegetated bank burial). Furthermore, the high organic matter levels measured in the sandy banks coincided with an outstanding trophic importance of deposit feeders, proving the debris-carrying hypothesis. The last chapter focused on the non-vegetated areas, where we tested that the hypothesis infaunal halo in tropical reefs depending on local granulometry. In this context, we also tested the hypothesis that benthophagous fish predation would have an effect on the low abundance of macrofaunal groups due to the high hydrographic stress, thus allowing other predatory groups to have greater importance in these environments. Proving the hypothesis, no spatial variation, both on abundance families neither on community structure, occur along distance of the edge reefs. However, we found that complex combinations of physical factors (grain size and organic matter levels originated from local hydronamic conditions) covary with the distance from the reefs and has stronger influence on macrofauna than considered biological factors, such as predation by benthophagous fishes. Based on the main results, this study shows that unconsolidated areas around APARC reefs are noteworthy from an ecological and conservational point of view, as evidenced by the biota-environment and organismal relations, never before described for these areas

Collision of positronium with atoms, molecules and ions using a modified coupled-channel framework

Scattering of positronium (Ps) from atoms (H, He, Ne, Ar), molecule (H(2)) and ion (He(+)) have been investigated using a coupled-channel (CC) formalism with a regularised non-local exchange potential. The advantage of using such a regularized exchange potential in the close-coupling formalism and the normalizability aspect of the solution at low energies with a minimum effective coupling are discussed. Results for the elastic and total scattering cross-sections, resonance and binding energies in Ps-H, and pick-off annihilation results in Ps-He are found to be in excellent agreement with measurements and variational predictions. (C) 2000 Elsevier B.V. B.V. All rights reserved.