The dorsomedial visual areas in New World and Old World monkeys: homology and function

The extrastriate cortex near the dorsal midline has been described as part of an 'express' pathway that provides visual input to the premotor cortex. This pathway is considered important for the integration of sensory information about the visual field periphery and the skeletomotor system, especially in relation to the control of arm movements. However, a better understanding of the functional contributions of different parts of this complex has been hampered by the lack of data on the extent and boundaries of its constituent visual areas. Recent studies in macaques have provided the first detailed view of the topographical organization of this region in Old World monkeys. Despite differences in nomenclature, a comparison of the visuotopic organization, myeloarchitecture and connections of the relevant visual areas with those previously studied in New World monkeys reveals a remarkable degree of similarity and helps to clarify the subdivision of function between different areas of the dorsomedial complex. A caudal visual area, named DM or V6, appears to be important for the detection of coherent patterns of movement across wide regions of the visual field, such as those induced during self-motion. A rostral area, named M or V6A, is more directly involved with visuomotor integration. This area receives projections both from DM/V6 and from a separate motion analysis channel, centred on the middle temporal visual area (or V5), which detects the movement of objects in extrapersonal space. These results support the suggestion, made earlier on the basis of more fragmentary evidence, that the areas rostral to the second visual area in dorsal cortex are homologous in all simian primates. Moreover, they emphasize the importance of determining the anatomical organization of the cortex as a prerequisite for elucidating the function of different cortical areas.

Dendritic branching patterns of pyramidal cells in the visual cortex of the new world marmoset monkey, with comparative notes on the old world macaque monkey

The basal dendritic arbors of 442 supragranular pyramidal cells in visual cortex of the marmoset monkey were compared by fractal analyses. As detailed in a previous study,(1) individual cells were injected with Lucifer Yellow and processed for a DAB reaction product. The basal dendritic arbors were drawn, in the tangential plane, and the fractal dimension (D) determined by the dilation method. The fractal dimensions were compared between cells in ten cortical areas containing cells involved in visual processing, including the primary visual area (Vi), the second visual area (V2), the dorsoanterior area (DA), the dorsomedial area (DM), the dorsolateral. area (DL), the middle temporal area (MT), the posterior parietal area (PP), the fundus of the superior temporal area (FST) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively). Of 45 pairwise interareal comparisons of the fractal dimension of neurones, 20 were significantly different. Moreover, comparison of data according to previously published visual processing pathways revealed a trend for cells with greater fractal dimensions in higher cortical areas. Comparison of the present results with those in homologous cortical areas in the macaque monkey(2) revealed some similarities between the two species. The similarity in the trends of D values of cells in both species may reflect developmental features which, result in different functional attributes.

Pyramidal cell heterogeneity in the visual cortex of the nocturnal new world owl monkey (aotus trivirgatus)

Recent studies have revealed marked variation in pyramidal cell structure in the visual cortex of macaque and marmoset monkeys. In particular, there is a systematic increase in the size of, and number of spines in, the arbours of pyramidal cells with progression through occipitotemporal (OT) visual areas. In the present study we extend the basis for comparison by investigating pyramidal cell structure in visual areas of the nocturnal owl monkey. As in the diurnal macaque and marmoset monkeys, pyramidal cells became progressively larger and more spinous with anterior progression through OT visual areas. These data suggest that: 1. the trend for more complex pyramidal cells with anterior progression through OT visual areas is a fundamental organizational principle in primate cortex; 2. areal specialization of the pyramidal cell phenotype provides an anatomical substrate for the reconstruction of the visual scene in OT areas; 3. evolutionary specialization of different aspects of visual processing may determine the extent of interareal variation in the pyramidal cell phenotype in different species; and 4. pyramidal cell structure is not necessarily related to brain size. Crown Copyright (C) 2003 Published by Elsevier Science Ltd on behalf of IBRO. All rights reserved.

Improving fECG signal acquisition in the evaluation of fetal well-being

The ability to monitor fetal heart rate is vital during late pregnancy and labor in order to evaluate fetal well-being. Current monitoring practice is essentially based on external cardiotocography and, less frequently, during labor, invasive fetal scalp electrocardiography. Many current and envisaged applications could benefi t from simpler devices using a 3-lead ECG confi guration. We are designing a maternity support belt with an embedded wireless 3-lead ECG sensor, and have investigated the infl uence of the ground electrode position on signal quality. Data from over 100 pregnant women was collected with the ground electrode placed in 3 locations in order to determine optimum electrode placement and belt form factor.

Cultural tourism in Northwest Portugal – the case of the world heritage site of Guimarães

A cidade de Guimarães, no noroeste português, é um espaço imbuído de um forte significado simbólico e cultural. A acreditação pela U.N.E.S.C.O. do seu centro histórico como Património Cultural da Humanidade, em Dezembro de 2001, contribuiu significativamente para aumentar o seu potencial em termos turísticos. Na realidade, desde aquela data, tem-se assistido a um aumento sustentado do número de visitantes. O presente capítulo debruça-se sobre a análise de alguns resultados de um inquérito por questionário aplicado aos residentes do município de Guimarães com o objetivo de avaliar a sua perceção dos benefícios que a atividade turística pode trazer. O inquérito foi implementado entre Janeiro e Março de 2010. Os resultados mostram que aqueles revelam uma perceção favorável dos impactos do turismo e que esta perceção está correlacionada com a idade e o nível de instrução dos inquiridos.

The host-tourist interaction in a world heritage site: the case of Guimarães

Guimarães, in the northwest of Portugal, is a city of strong symbolic and cultural significance and its nomination by UNESCO as world heritage, in 2001, enlarged its tourism potential. In this paper we present a few results of a survey that envisaged capturing the Guimarães residents’ perceptions of tourism impacts and their attitudes towards tourists. Specifically, one analyzes the type of relationship that exists between some socio-demographic groups and the perceived tourism impacts, as well as their socio-characteristics and the existing level of interaction between residents and tourists. The survey was implemented between January and March 2010 to a convenience sample of 540 inhabitants of the municipality of Guimarães resulting in 400 questionnaires with complete data. For this, we made use of various statistical techniques. Using a factorial analysis, we can conclude that the three factors used explain 52.3% of the variance contained in the original variables obtained from the survey. By another side, using a logit model in the analysis and taking as the dependent variable the frequent or very frequent contact with tourists, we found that only the variables referred to perceived positive impacts of tourism, education and the place of residence in urban areas have shown to be statistically significant. We are aware of the multiple ways the issue of residents’ perceptions and attitudes towards tourism can be approached and of the difficulties to get useful policy-oriented insights. This paper is a step in that trail.