Spatial and temporal variation in algal-assemblage structure in isolated dryland river waterholes, Cooper Creek and Warrego River, Australia

The scale at which algal biodiversity is partitioned across the landscape, and the biophysical processes and biotic interactions which shape these communities in dryland river refugia was studied on two occasions from 30 sites in two Australian dryland rivers. Despite the waterholes studied having characteristically high levels of abiogenic turbidity, a total of 186 planktonic microalgae, 253 benthic diatom and 62 macroalgal species were recorded. The phytoplankton communities were dominated by flagellated cryptophytes, euglenophytes and chlorophytes, the diatom communities by cosmopolitan taxa known to tolerate wide environmental conditions, and the macroalgal communities by filamentous cyanobacteria. All algal communities showed significant differences between catchments and sampling times, with a suite of between 5 and 12 taxa responsible for similar to 50% of the observed change. In general, algal assemblage patterns were poorly correlated with the measured environmental variables. Phytoplankton and diatom assemblage patterns were weakly correlated with several waterhole geomorphic measures, whereas macroalgal assemblage patterns showed some association with variability in ionic concentration.

A political analysis of the PRSP initiative: Social struggles and the organization of persistent relations of inequality

The current global development project appears to be premised on the assumption that underlying political debates over development have been settled. An upshot of this is that development is reduced to the theoretical, ideological and legal framework of a neo-liberal political order. However, implicit, and sometimes explicit, political dynamics of development can be rendered from a perspective that foregrounds social struggles. I offer a political analysis of the PRSP initiative by examining its evolution and implications considered within social and political contexts, and by specific reference to the 'poverty reduction' interventions that emerged in the 1980s. I argue that the PRSP initiative is best understood as the formation of a comprehensive extension of neo-liberal strategic responses that emerged in the 1980s. In this context, I discuss the example of microcredit schemes in relation to the PRSP process and demonstrate the analytical significance of micro-political social relations for political analyses of development. The approach I adopt reveals social struggles as relationally constitutive of formations of a hegemonic development discourse otherwise ostensibly rendered in de-contextualized terms. From the perspective of critical development analysis such struggles are the concrete expressions of the contradictions immanent to the dialectic of development through inequality and immiseration in the (re)production of social power.

Electronic dance music culture and religion: An Overview

This article provides a comprehensive and critical overview of existing research that investigates (directly and indirectly) the religio-spiritual dimensions of electronic dance music culture (EDMC) (from disco, through house, to post-rave forms). Studies of the culture and religion of EDMC are explored under four broad groupings: the cultural religion of EDMC expressed through 'ritual' and 'festal'; subjectivity, corporeality and the phenomenological dance experience (especially 'ecstasy' and 'trance'); the dance community and a sense of belonging (the 'vibe' and 'tribes'); and EDMC as a new 'spirituality of life'. Moving beyond the cultural Marxist approaches of the 1970s, which held youth (sub)cultural expressions as 'ineffectual' and 'tragic', and the postmodernist approaches of the early 1990s, which held rave to be an 'implosion of meaning', recent anthropological and sociological approaches recognise that the various manifestations of this youth cultural phenomenon possess meaning, purpose and significance for participants. Contemporary scholarship thus conveys the presence of religiosity and spirituality within contemporary popular cultural formations. In conclusion, I suggest that this and continuing scholarship can offer useful counterpoint to at least one recent account (of clubbing) that overlooks the significance of EDMC through a restricted and prejudiced apprehension of 'religion'.

Laminar distribution of the pathological changes in frontal and temporal cortex in 8 patients with progressive supranuclear palsy

OBJECTIVE: To determine the laminar distribution of the pathological changes in the cerebral cortex in progressive supranuclear palsy (PSP). METHOD: The distribution of the abnormally enlarged neurons (EN), surviving neurons, neurofibrillary tangles (NFT), glial inclusions (GI), tufted astrocytes (TA), and neuritic plaques (NP) were studied across the cortex in tau immunolabeled sections of frontal and temporal cortex in 8 cases of PSP. RESULTS: The distribution of the NFT was highly variable with no consistent pattern of laminar distribution. The GI were distributed either in the lower laminae or uniformly across the cortex. Surviving neurons exhibited either a density peak in the upper laminae or a bimodal distribution was present with density peaks in the upper and lower laminae. The EN and glial cell nuclei were distributed primarily in the lower cortical laminae. There were positive correlations between the densities of the EN and glial cell nuclei and negative correlations between the surviving neurons and glial cells. No correlations were present between the densities of the NFT and GI. CONCLUSION: Cortical pathology in PSP predominantly affects the lower laminae but may spread to affect the upper laminae in some cases. The NFT and GI may have different laminar distributions and gliosis occurs concurrently with neuronal enlargement.

Multiple system atrophy: laminar distribution of the pathological changes in frontal and temporal neocortex--a study in ten patients

OBJECTIVE: To determine the distribution of the pathological changes in the neocortex in multiple-system atrophy (MSA). METHOD: The vertical distribution of the abnormal neurons (neurons with enlarged or atrophic perikarya), surviving neurons, glial cytoplasmic inclusions (GCI) and neuronal cytoplasmic inclusions (NI) were studied in alpha-synuclein-stained material of frontal and temporal cortex in ten cases of MSA. RESULTS: Abnormal neurons exhibited two common patterns of distribution, viz., density was either maximal in the upper cortex or a bimodal distribution was present with a density peak in the upper and lower cortex. The NI were either located in the lower cortex or were more uniformly distributed down the cortical profile. The distribution of the GCI varied considerably between gyri and cases. The density of the glial cell nuclei was maximal in the lower cortex in the majority of gyri. In a number of gyri, there was a positive correlation between the vertical densities of the abnormal neurons, the total number of surviving neurons, and the glial cell nuclei. The vertical densities of the GCI were not correlated with those of the surviving neurons or glial cells but the GCI and NI were positively correlated in a small number of gyri. CONCLUSION: The data suggest that there is significant degeneration of the frontal and temporal lobes in MSA, the lower laminae being affected more significantly than the upper laminae. Cortical degeneration in MSA is likely to be secondary to pathological changes occurring within subcortical areas.

Laminar degeneration of the frontal and temporal cortex in neuronal intermediate filament inclusion disease (NIFID): a study using a-internexin immunohistochemistry

Objective: To determine the laminar distribution of the pathological changes in the frontal and temporal lobe in neuronal intermediate filament inclusion disease (NIFID). Method: The distribution of the alpha-intenexin-positive neuronal cytoplasmic inclusions (NCI), surviving neurons, swollen achromatic neurons (SN) and glial cell nuclei was studied across the cortex in gyri of the frontal and temporal lobe in 10 cases of NIFID. Results: The distribution of the NCI was highly variable within different gyri, a peak in the upper cortex, a bimodal distribution with peaks of density in the upper and lower laminae, or no significant variation in density across the cortex. The surviving neurons were either bimodally distributed or exhibited no significant change in density across the cortex. The SN and glial cell nuclei were most abundant in the lower cortical laminae. In half of the gyri, variations in density of the NCI across the cortex were positively correlated with the SN. In some gyri, the surviving neurons were positively correlated with the SN and negatively correlated with the glial cell nuclei. In addition, the SN and glial cell nuclei were positively correlated in over half the gyri studied. Conclusion: The data suggest that frontal and temporal lobe degeneration in NIFID characterized by NCI, SN, neuronal loss and gliosis extends across the cortical laminae with considerable variation between cases and gyri. alpha-internexin-positive neurons in the upper laminae appear to be particularly vulnerable. The gliosis appears to be largely correlated with the appearance of SN and with neuronal loss and not related to the NCI.

Spatial and temporal dependencies of cross-orientation suppression in human vision.

A well-known property of orientation-tuned neurons in the visual cortex is that they are suppressed by the superposition of an orthogonal mask. This phenomenon has been explained in terms of physiological constraints (synaptic depression), engineering solutions for components with poor dynamic range (contrast normalization) and fundamental coding strategies for natural images (redundancy reduction). A common but often tacit assumption is that the suppressive process is equally potent at different spatial and temporal scales of analysis. To determine whether it is so, we measured psychophysical cross-orientation masking (XOM) functions for flickering horizontal Gabor stimuli over wide ranges of spatio-temporal frequency and contrast. We found that orthogonal masks raised contrast detection thresholds substantially at low spatial frequencies and high temporal frequencies (high speeds), and that small and unexpected levels of facilitation were evident elsewhere. The data were well fit by a functional model of contrast gain control, where (i) the weight of suppression increased with the ratio of temporal to spatial frequency and (ii) the weight of facilitatory modulation was the same for all conditions, but outcompeted by suppression at higher contrasts. These results (i) provide new constraints for models of primary visual cortex, (ii) associate XOM and facilitation with the transient magno- and sustained parvostreams, respectively, and (iii) reconcile earlier conflicting psychophysical reports on XOM.

Laminar distribution of Pick bodies, Pick cells and Alzheimer disease pathology in the frontal and temporal cortex in Pick's disease

Lesions in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) have distinct laminar distributions in the cortex. The objective of the present study was to test the hypothesis that the lesions characteristic of Pick's disease (PD) and AD have distinctly different laminar distributions in cases of PD. Hence, the laminar distribution of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) was studied in the frontal and temporal cortex in nine patients with PD. In 57% of analyses of individual cortical areas, the density of PB was maximal in the upper cortex while in 25% of analyses, the distribution of PB was bimodal with density peaks in the upper and lower cortex. The density of PC was maximal in the lower cortex in 77% of analyses while a bimodal distribution was present in 5% of analyses. The density of NFT was maximal in the upper cortex in 50% of analyses, in the lower cortex in 15% of analyses, with a bimodal distribution in 4% of analyses. The density of SP did not vary significantly with cortical depth in 86% of analyses. The vertical densities of PB and PC were negatively correlated in 12/21 (57%) of brain areas. The maximum density of PB in the upper cortex was positively correlated with the maximum density of PC in the lower cortex. In 17/25 (68%) of brain areas, there was no significant correlation between the vertical densities of PB and NFT. The data suggest that the pathogenesis of PB may be related to that of the PC. In addition, although in many areas PB and NFT occur predominantly in the upper cortex, the two lesions appeared to affect different neuronal populations.

Quantification of pathological lesions in the frontal and temporal lobe of ten patients diagnosed with Pick's disease

The densities of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) in the frontal and temporal lobe were determined in ten patients diagnosed with Pick's disease (PD). The density of PB was significantly higher in the dentate gyrus granule cells compared with the cortex and the CA sectors of the hippocampus. Within the hippocampus, the highest densities of PB were observed in sector CA1. PC were absent in the dentate gyrus and no significant differences in PC density were observed in the remaining brain regions. With the exception of two patients, the densities of SP and NFT were low with no significant differences in mean densities between cortical regions. In the hippocampus, the density of NFT was greatest in sector CA1. PB and PC densities were positively correlated in the frontal cortex but no correlations were observed between the PD and AD lesions. A principal components analysis (PCA) of the neuropathological variables suggested that variations in the densities of SP in the frontal cortex, temporal cortex and hippocampus were the most important sources of heterogeneity within the patient group. Variations in the densities of PB and NFT in the temporal cortex and hippocampus were of secondary importance. In addition, the PCA suggested that two of the ten patients were atypical. One patient had a higher than average density of SP and one familial patient had a higher density of NFT but few SP.

The spatial distribution and temporal dynamics of brain regions activated during the perception of object and non-object patterns

Both animal and human studies suggest that the efficiency with which we are able to grasp objects is attributable to a repertoire of motor signals derived directly from vision. This is in general agreement with the long-held belief that the automatic generation of motor signals by the perception of objects is based on the actions they afford. In this study, we used magnetoencephalography (MEG) to determine the spatial distribution and temporal dynamics of brain regions activated during passive viewing of object and non-object targets that varied in the extent to which they afforded a grasping action. Synthetic Aperture Magnetometry (SAM) was used to localize task-related oscillatory power changes within specific frequency bands, and the time course of activity within given regions-of-interest was determined by calculating time-frequency plots using a Morlet wavelet transform. Both single subject and group-averaged data on the spatial distribution of brain activity are presented. We show that: (i) significant reductions in 10-25 Hz activity within extrastriate cortex, occipito-temporal cortex, sensori-motor cortex and cerebellum were evident with passive viewing of both objects and non-objects; and (ii) reductions in oscillatory activity within the posterior part of the superior parietal cortex (area Ba7) were only evident with the perception of objects. Assuming that focal reductions in low-frequency oscillations (< 30 Hz) reflect areas of heightened neural activity, we conclude that: (i) activity within a network of brain areas, including the sensori-motor cortex, is not critically dependent on stimulus type and may reflect general changes in visual attention; and (ii) the posterior part of the superior parietal cortex, area Ba7, is activated preferentially by objects and may play a role in computations related to grasping. © 2006 Elsevier Inc. All rights reserved.