Search

Though diel variations are geographically widespread phenomena among phytoplankton and zooplankton, knowledge is limited regarding diel variations in planktonic ciliate (microzooplankton) community structure. In this study, we analyzed diel variations in community structure of planktonic ciliates in the northern South China Sea (nSCS) and tropical Western Pacific (tWP). Hydrological characteristics during day and night were slightly different over both the nSCS and tWP, while ciliate average abundance at night was clearly higher than in the day in the upper 200 m. In both the nSCS and tWP, abundance proportions of large size-fraction (> 30 μm) aloricate ciliates at night were higher than in the day. While for tintinnids, abundance proportion of large lorica oral diameter at night were lower than in the day. The relationship between environmental factors and ciliate abundance pointed out that depth and temperature were main factors influencing aloricate ciliate and tintinnid in both day and night. For some dominant tintinnid species, chlorophyll a was another important factor influencing their diel vertical distribution. Our results provide fundamental data for better understanding the mechanisms of planktonic ciliate community diel variation in the tropical Western Pacific Ocean. [ABSTRACT FROM AUTHOR]

The short term (hourly scale) variability of heterotrophic prokaryote (HP) vertical distribution and respiratory activity, was investigated in the north-western (NW) Mediterranean Sea. HP vertical distribution was determined on board by flow cytometry analysis of seawater samples collected by series of CTD casts. Cell counts and viability were determined for all samples. HP respiratory rates were determined later in the laboratory from filtered seawater samples (23 dm3) from 300–1 150-m depth. The average cell viability was 94.8%±2.2% (n=240). There was no accumulation of dead cells, due to quick decay of damaged cells. In the epipelagic layer, three HP groups were distinguished, two (HNA1, HNA2) whose cells exhibited a high nucleic acid content and one (LNA) with low nucleic acid content cells. HNA2 was most populated at 50 m but not detected at 90 m and below, presumably aerobic anoxygenic photoheterotrophic bacteria (AAPs). The variability in HP abundance was mainly confined in the upper 80 m. A few secondary peaks of HP abundance were observed (80–150 m) in connection with abundance troughs in the surface layer. HP cells were continuously present in a wide layer around 500 m (mean 191×103 cells/cm3). Below this layer, HP abundance randomly exhibited peaks, coupled to respiratory rate peaks. The HP abundance and variability in the water column was suppressed during a strong wind event. The observed sporadic variability was tentatively interpreted through a pulsed carbon-export mechanism induced by the microorganism production of dissolved polysaccharides, followed by flocculation and rapid sinking. This mechanism would thus contribute to (i) preventing organic matter accumulation in the epipelagic layer, (ii) seeding the water column with live HP cells, and (iii) supplying the aphotic water column with fresh and labile organic matter. This important vertical flux mechanism needs further observations and modelling. [ABSTRACT FROM AUTHOR]

In the eutrophic Ghar El Melh Lagoon (GML, Tunisia), the distribution of heterotrophic prokaryotes, pico- and nanophytoplankton was studied at five stations in November 2012 at the single cell level, along with environmental factors. Flow cytometry analysis of ultraplankton (<10 μm) resolved (i) two heterotrophic prokaryote groups, low and high nucleic acid contents (LNA and HNA, respectively), and (ii) eight to nine ultraphytoplankton groups (cryptophyte-like cells, two nanoeukaryote subgroups, two picoeukaryote subgroups and three Synechococcus-like cells subgroups). Prochlorococcus was not detected. According to redundancy analysis (RDA), a significant difference was found in the distribution of the ultraplankton between stations ( F = 2.61, p < 0.05); maximum proliferations of heterotrophic prokaryotes were observed in the inner parts of the lagoon at stations 3, 4 and 5 affected by urban, agricultural and industrial discharges. Ultraphytoplankton concentrations were the highest near the outlet of the lagoon at stations 1 and 2 influenced by freshwater outflow and oligotrophic Mediterranean water inflow, respectively. At station 1, the large ultraphytoplankton concentration derives from the high abundance of cryptophyte-like cells favoured by the freshwater outflow whereas at station 2, the input of oligotrophic Mediterranean water enhanced the abundance of Synechococcus and picoeukaryotes at the expense of nanoeukaryotes. Two trophic regimes were thus differentiated in GML. [ABSTRACT FROM AUTHOR]

The authors investigated the microbial composition of phototrophic biofilms proliferating in a show cave using flow cytometry for the first time in such a context. Results are based on several biofilms sampled in the Moidons Caves (France) and concern both heterotrophic prokaryotes and autotrophic microorganisms. Heterotrophic microorganisms with low nucleic acid content were dominant in biofilms, as can be expected from the oligotrophic conditions prevailing within the cave. Analysis of the biofilm autotrophic components revealed the presence of several taxa, particularly the unicellular green algae Chlorella minutissima, specifically well adapted to this cave. Relationships between flow cytometry results and environmental variables determined in the cave were established and discussed so as to better understand biofilm proliferation processes in caves. [ABSTRACT FROM AUTHOR]

In the frame of the Taparura Project, we studied the distribution of pico-, nano- and microphytoplankton communities in relation to environmental variables at 18 stations sampled during four coastal cruises conducted between October 2009 and July 2010 at the bottom, on the north coast of Sfax (Tunisia, Eastern Mediterranean Sea). The restoration effect on coastal ultraphytoplankton (<10 μm) and microphytoplankton (<200 μm) was investigated using conventional flow cytometry and inverted microscopy. Flow cytometry analysis of ultraphytoplankton resolved six groups ( Prochlorococcus, Synechococcus, nanoeukaryotes and three distinct subgroups within picoeukaryotes). In addition to these autotrophic groups, two unknown groups were characterised on the north coast. Picophytoplankton abundance shifted from a summer dominance of Synechococcus to a dominance of picoeukaryotes and Prochlorococcus during spring. Nanoeukaryotes were the most abundant in spring. Microphytoplankton was resolved into five groups, labelled Bacillariophyceae, Dinophyceae, Cyanobacteriae, Euglenophyceae and Chlorophyceae. A total of 90 microphytoplankton species were identified in all stations, with an overwhelming abundance of large diatoms, a typical trait of benthic communities ( Coscinodiscus sp., Grammatophora sp., Navicula sp., Pleurosigma sp., Striatella unipunctata ...). Results collected in this study are favouring a beneficial impact on the ecosystem of the Sfax north coast restoration achieved by the Taparura Project. [ABSTRACT FROM AUTHOR]

Picoplankton distribution was investigated in different water masses of the East China Sea in November, 2006 and February, 2007. The autumn and winter cruises crossed three major water masses: the coastal water mass (CWM), the mixed water mass (MWM), which forms on the continental shelf, and the Kuroshio water mass (KWM). Picoplankton composition was resolved into four main groups by flow cytometry, namely Synechococcus, Prochlorococcus, picoeukaryotes, and heterotrophic bacteria. The average abundances of Synechococcus, picoeukaryotes, and heterotrophic bacteria were (0.63±10.88)×10, (1.61±1.16)×10, (3.39±1.27)×10 cells/mL in autumn and (6.45±8.60)×10, (3.23±2.63)×10, (3.76±1.37)×10 cells/mL in winter, respectively. Prochlorococcus was not found in the CWM and seldom observed in surface samples in either season. However, Prochlorococcus was observed in the MWM and KWM (approximately 10 cells/mL) in both autumn and winter. Synechococcus distribution varied considerably among water masses, with the highest levels in KWM and lowest levels in CWM. The depth-averaged integrated abundance of Synechococcus was approximately 5-fold higher in KWM than in CWM, which may be due primarily to water temperature. In the MWM, Synechococcus was resolved as two subgroups; the presence of both subgroups was more common in autumn. Picoeukaryote abundance varied less among water masses than Synechococcus, and heterotrophic bacteria depth-averaged integrated abundance exhibited the smallest seasonal variations with respect to water mass. Correlation analysis showed that relationships between picoplankton abundances and environmental factors (temperature, nutrients, and chlorophyll a) differed among the three water masses, suggesting that the three water masses have different effects on picoplankton distribution (particularly Synechococcus). [ABSTRACT FROM AUTHOR]

Navigating complex routes and finding objects of interest are challenging tasks for the visually impaired. The project NAVIG (Navigation Assisted by artificial VIsion and GNSS) is directed toward increasing personal autonomy via a virtual augmented reality system. The system integrates an adapted geographic information system with different classes of objects useful for improving route selection and guidance. The database also includes models of important geolocated objects that may be detected by real-time embedded vision algorithms. Object localization (relative to the user) may serve both global positioning and sensorimotor actions such as heading, grasping, or piloting. The user is guided to his desired destination through spatialized semantic audio rendering, always maintained in the head-centered reference frame. This paper presents the overall project design and architecture of the NAVIG system. In addition, details of a new type of detection and localization device are presented. This approach combines a bio-inspired vision system that can recognize and locate objects very quickly and a 3D sound rendering system that is able to perceptually position a sound at the location of the recognized object. This system was developed in relation to guidance directives developed through participative design with potential users and educators for the visually impaired. [ABSTRACT FROM AUTHOR]

Here, we combined flow cytometry (FCM) and phylogenetic analyses after cell sorting to characterize the dominant groups of the prokaryotic assemblages inhabiting two ponds of increasing salinity: a crystallizer pond (TS) with a salinity of 390 g/L, and the non-crystallizer pond (M1) with a salinity of 200 g/L retrieved from the solar saltern of Sfax in Tunisia. As expected, FCM analysis enabled the resolution of high nucleic acid content (HNA) and low nucleic acid content (LNA) prokaryotes. Next, we performed a taxonomic analysis of the bacterial and archaeal communities comprising the two most populated clusters by phylogenetic analyses of 16S rRNA gene clone library. We show for the first time that the presence of HNA and LNA content cells could also be extended to the archaeal populations. Archaea were detected in all M1 and TS samples, whereas representatives of Bacteria were detected only in LNA for M1 and HNA for TS. Although most of the archaeal sequences remained undetermined, other clones were most frequently affiliated to Haloquadratum and Halorubrum. In contrast, most bacterial clones belonged to the Alphaproteobacteria class ( Phyllobacterium genus) in M1 samples and to the Bacteroidetes phylum ( Sphingobacteria and Salinibacter genus) in TS samples. [ABSTRACT FROM AUTHOR]

The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigen-presenting cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage of responding T cells were of the CD8 memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8 subset bearing memory cell markers (CD45A, CD45RO), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for the prevention of mastitis caused by S. uberis. [ABSTRACT FROM AUTHOR]

utomated in situ flow cytometry, high-pressure liquid chromatography (HPLC), optical microscopy and fluorometry were combined to monitor phytoplankton over two summer periods (2005 and 2006). In 2006, temperature was higher and nutrients lower than in 2005, generating differences in the phytoplankton assemblages (i.e., abundance and structure). Pigment-size classes based on daily HPLC analysis provided evidence for higher proportions of picoplankton and nanoplankton with higher biomass in 2005 and a dominance of microplankton with lower biomass in 2006, the latter with lower specific diversity, as evidenced by weekly microscopy analyses. Total chlorophyll a estimations from fluorometry measurements recorded every 30 min were higher in 2005 than in 2006, as for the HPLC chlorophyll a concentrations. An automated in situ flow cytometer (Thyssen et al., J Plankton Res 30(9):1027-1040, ) sampled seawater every 30 min. Data analysis yielded the resolution of seven clusters based on light scatter and fluorescence. In 2006, an increase in abundance of the largest cells was observed, confirming pigment and microscopy data. The results suggest that the ecosystem was on a constant renewing process in summer 2005 due to a strong wind event and on a highly productive and recycling way in summer 2006 due to stratification of the upper water layer. Automated submersible flow cytometry confirms to be a powerful tool providing high-resolution data by monitoring phytoplankton at the single cell level. This technology gives access to the shape of the light scatter and fluorescence signals generated by each cell passing through a laser beam and that are linked to size, structure and pigment content of the target cell. When combined with conventional techniques, it further improves our understanding of phytoplankton assemblages. [ABSTRACT FROM AUTHOR]

When people scan mental images, their response times increase linearly with increases in the distance to be scanned, which is generally taken as reflecting the fact that their internal representations incorporate the metric properties of the corresponding objects. In view of this finding, we investigated the structural properties of spatial mental images created from nonvisual sources in three groups (blindfolded sighted, late blind, and congenitally blind). In Experiment 1, blindfolded sighted and late blind participants created metrically accurate spatial representations of a small-scale spatial configuration under both verbal and haptic learning conditions. In Experiment 2, late and congenitally blind participants generated accurate spatial mental images after both verbal and locomotor learning of a full-scale navigable space (created by an immersive audio virtual reality system), whereas blindfolded sighted participants were selectively impaired in their ability to generate precise spatial representations from locomotor experience. These results attest that in the context of a permanent lack of sight, encoding spatial information on the basis of the most reliable currently functional system (the sensorimotor system) is crucial for building a metrically accurate representation of a spatial environment. The results also highlight the potential of spatialized audio-rendering technology for exploring the spatial representations of visually impaired participants. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including one about the interrelationship of map learning, verbal learning and spatial recognition, and another which analyzes spatial updating after scene rotation and concomitant physical rotation of the observer.

Mental image scanning is generally assumed to be a single process that allows people to shift attention across visualized objects. However, this implicit assumption is open to question. We report a set of three experiments based on the tasks originally designed by Kosslyn, Ball, and Reiser (1978) and Finke and Pinker (1982). Participants scanned the identical images of an array of dots in the two tasks. Nevertheless, the participants required more time to shift their focus over the imaged stimulus in the Kosslyn et al. (1978) paradigm. Moreover, correlational analyses revealed no consistent relationship between the slopes of the increases in scanning times with increasing distances in the two paradigms. We conclude that in the Kosslyn et al. (1978) paradigm, the participants draw primarily on transformational processes to scan, whereas in the Finke and Pinker (1982) paradigm, they draw primarily on attentional processes. Both processes, transforming the image and shifting an attention window, produce linear increases in time with increases in distance, but for different reasons. [ABSTRACT FROM AUTHOR]

The vertical distribution of heterotrophic bacteria and four ultraphytoplanktonic (<10 µm) groups (Prochlorococcus, Synechococcus, pico- and nanoeukaryotes) was investigated by flow cytometry at three process stations located in three different sub-systems belonging to the Antarctic Circumpolar Current frontal zone and to the Southern Indian Ocean (60–66°E, 43–46°S; ANTARES 4 cruise, January-February 1999): the Subtropical Zone (STZ), the Convergence Zone and the Polar Frontal Zone (PFZ). In each sub-system, short-term variability of cell abundance and flow cytometric parameters (right-angle light scatter and chlorophyll autofluorescence) was assessed through a times series of up to 24 h with a 2 h sampling frequency. The ultraphytoplankton vertical distribution exhibited a high spatial variability, with dominance of Prochlorococcus in the STZ (mean: 762.85×1010 cells m-2), whereas picoeukaryotes (<3 µm) were dominant in the PFZ (55.46×1010 cells m-2), a typically high-nutrient low-chlorophyll zone. Heterotrophic bacteria abundance was maximum (9.84×1013 cells m-2) in the frontal zone, between the Agulhas Front and the Subtropical Front. Nanoeukaryotes showed the largest (up to 80%) variations between two consecutive sampling periods (2 h). Abundance variations could not be assigned to the same water mass during the time series due to the highly variable hydrodynamics of the study area. Trends of short-term abundance variations were opposite between the PFZ (lowest at night) and north of the Subtropical Front (highest at night). The observed spatial and short-term variations illustrate the complexity of the water masses in the Indian sector of the Southern Ocean, and highlight the challenge of extrapolating discrete measurements over space and time for use in evaluating carbon budgets in such dynamic areas. [ABSTRACT FROM AUTHOR]

Microbial respiration in the ocean is considered as the major process representative of the organic matter biological oxidation.The corresponding metabolic CO2 production was estimated to be about 22 Pg C y−1 [24]. However, the in situ respiration rate is generally too low (by several orders of magnitude) to be accessible to the available direct measurement methods. Some fluorescent probes, such as DiOC6(3) (Molecular Probes, USA) have been shown to be very sensitive to changes in the proton electrochemical potential difference (Δμ~H+), characterising mitochondrial and plasmic membranes bearing the cell respiratory system in eukaryotic and prokaryotic cells respectively [22, 37]. In mitochondria, Δμ~H+ is linked to the flux of oxygen uptake by a linear relationship [32]. To our knowledge, no such relationship has been established in the case of whole marine cells. In the present work, we addressed the dark respiration rate of the Chlorophyceae Dunaliella tertiolecta (Butcher) in axenic cultures, both directly by using a highly sensitive oxygraph (Oroboros) and by staining cells with DiOC6(3). We found and standardized a linear relationship between oxygen uptake by D. tertiolecta and its green fluorescence inducedby DiOC6(3), enabling the determination by flow cytometry of the respiration rate of D. tertiolecta. [ABSTRACT FROM AUTHOR]

Abstract Do mental imagery and perception involve common processing mechanisms? Imagery researchers have devoted a great deal of effort to establishing the functional and structural similarities between images and perceptual events. Recent studies have focused on the comparison of images that are reconstructions of previous perceptual experience and images constructed from verbal descriptions. This article reports the findings of a research program based on the mental scanning paradigm; they reveal the similarities and differences between the two kinds of mental images. Neuroimaging studies have also provided evidence that the parieto-occipital cortex is involved in the processing of visual images, whether they are based on perceptual experience or constructed from linguistic inputs. However, the PET studies conducted by our research groups provide no evidence that the primary visual cortex is engaged in the generation of visual images. As there is contradictory evidence about this, further research is needed to clarify the role of the early visual areas in mental visual imagery. [ABSTRACT FROM AUTHOR]

In a series of four experiments, reading time of texts and memory for their informational content were studied in relation to readers' imagery abilities. The main prediction was that if high imagers (HIs) tend to elaborate images expressing the semantic content of the text while reading, then they should require more time to read imageable material than low imagers (LIs). And in fact, when subjects read a descriptive/narrative text, HIs not only read more slowly, but remembered the text better than LIs. In contrast, when subjects read abstract, nonimageable material, there was no difference between the two groups in reading times or memory. Additional experiments provided further support for the claim that HIs spent more time elaborating images while they read descriptive/narrative text. [ABSTRACT FROM AUTHOR]

Six experiments were conducted to test whether the spatial properties of cognitive maps constructed from verbal descriptions are similar to those of representations derived from visual experience. Data from spatial priming, distance comparison, and mental scanning experiments all suggest that people are able to convert verbal descriptions of configurations into mental representations that reflect the spatial extension of these configurations. In addition, cognitive maps constructed from descriptions exhibit reliable metric properties which make them structurally isomorphic to the corresponding spatial configurations. [ABSTRACT FROM AUTHOR]

In two experiments, three modes of action encoding were compared: overt enactment, self-imagination, and imagination of another person performing the actions. Overt enactment and imagining self-performance of an action are mainly assumed to involve motor-kinesthetic representations, whereas imagining another person is thought to place more demands on the visual representational system. Previous paired-associate learning data on memory of action verbs showed that motor-kinesthetic imagery hinders pair integration, but that pair integration is facilitated by visual imagery. The comparison of free and cued recall of actions learned from lists of concrete nouns supports the assumption that the representational properties of overt enactment and self-imagination differ from those involved in the imagining of another person. [ABSTRACT FROM AUTHOR]

It is suggested that visual-imaginal encoding of actions, i.e., imagining seeing somebody else performing a described action, should be distinguished from motor-imaginal encoding, i.e., imagining how one performs the action oneself. While both kinds of encoding should provide good item-specific information, only visual-imaginal encoding should also lead to good relational encoding of word pairs. In three experiments in which subjects had to learn verb pairs, we obtained supporting data for this assumption. Although CR performance was equal to FR performance under visual-imaginal encoding, under motorimaginal encoding CR performance was worse than FR performance. In principle, this finding parallels results obtained with imagined noun pairs and with performed verb pairs. [ABSTRACT FROM AUTHOR]

Subjects were asked to read sentences which described scenes containing objects. In the scene described in each sentence, a specific part of a particular object was necessarily implied as having an important role. The object was named but none of its parts were. The assumption was that the subjects, while processing the sentence and immediately afterward, would cognitively 'center' on the important part, as a function of the context created by the sentence. Immediately after reading the sentence, the subjects were probed with a picture of either the important part, or of an unimportant part of the object. Judgments of the compatibility of this picture probe with the sentence were faster for pictures of important parts than for pictures of other parts. This was taken as supporting the hypothesis of cognitive centration. In a second experiment, in which words were used as probes instead of pictures, a purely verbal process to account for the results was ruled out. In a third experiment, subjects were given instructions to intentionally form visual images of the scenes described by the sentences. In this case, overall response times to the picture probes were shorter than in the absence of such instructions, but this decrease was greater for pictures of unimportant parts. This finding was interpreted as showing that imagery instructions increase the rate of activation of features to varying degrees as a function of the previous level of activation. [ABSTRACT FROM AUTHOR]

Within the framework of a featural approach to conceptual representations, 'figurative features' were defined as cognitive entities reflecting the sensory properties of objects in the human mind. In conceptual hierarchies such as taxonomies, 'primary concepts' were defined as the most abstract concepts which could still be characterized by their richness in figurative features. The present experiment demonstrated that when subjects were required to form visual images in response to nouns, imagery latencies were shorter to nouns designating primary concepts than to nouns designating either more abstract or more specific concepts. Furthermore, when subjects were subsequently presented with a pictured object and were asked to categorize it as illustrating or not the previously designated concept, it took less time to decide that the object corresponded to a primary concept than to either more abstract or more specific concepts. Subjects classified as high imagers had shorter imagery latencies than low imagers to all kinds of nouns, but decision times in the picture-categorization task did not significantly differ in both groups. These data are discussed in reference to current models of mental imagery. [ABSTRACT FROM AUTHOR]

Previous research has found a linear relation between distance and scanning times for spatial configurations when the spatial configurations were learned perceptually and when they were constructed from well-structured verbal descriptions. The current research replicated the time-distance relation when the images were constructed from repetitions of wel1 structured descriptions but not when the images were generated from three repetitions of a description that presented information in a random order. Six exposures to the randomly ordered information yielded the expected time-distance relation in image scanning. We posited that additional exposure to the poorly structured information allowed the image to develop the structural coherence and resolution needed to support consistent scanning. Thus, the structure of descriptions can affect the intrinsic structure of images of described objects and hence the mental operations performed subsequently on these images. Another experiment indicated that image coherence and resolution improves even after the verbal description is accurately recalled. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 38 year old pregnant woman with fever, chills, cough, vomiting and weakness. A nasopharyngeal swab specimen was positive for influenza A (H1N1) virus and treatment started with oseltamivir. However, the patient developed severe acute respiratory distress syndrome (ARDS). Noninvasive positive pressure ventilation (NIPPV) was administered and the patient recovered after a cesarean delivery was performed and the infant was born with no influenza infection.

Finding one’s way and remembering the location of objects in the world is essential for everyday living. This research addresses the issue of the impact of schizophrenia on visuo-spatial memory, focusing especially on the sequential spatial memory in schizophrenic patients. We conducted an experiment involving a set of four related tests. The experiment took place on the premises of a Parisian hospital, the “ Hôpital de la Salpêtrière”. Two groups of participants were set up: a schizophrenic patients group ( n = 20) and a healthy participants one ( n = 28). In the first two tests, the participants were requested to verbally describe the route they previously went all over, then to draw it in the form of a sketch map. Not surprisingly, due to their communication difficulties, schizophrenic patients produced shorter descriptions than the control participants’. Their descriptions were less prescriptive (they mentioned less actions to be done), and also less descriptive (they referred to a lesser number of landmarks). Conversely, they produced more comments than the control participants did. Regarding the sketch maps, in a same way as for the verbal descriptions, schizophrenic patients produced quite poor sketches, especially regarding the number of relevant landmarks (they ignored a large number of landmarks) and the number of errors regarding the reorientations (they forgot more crucial turns). In short, the patients’ route descriptions are obviously quite unlikely to help an addressee to find a route and their sketch maps reflect a real difficulty in memorizing the landmarks and the overall shape of the route. In the last two tests, the participants were shown a set of 32 photographs. For each of them, they had to identify whether the view belonged to the route or not. Thereafter, they were shown 28 pairs of photographs and asked to decide for each pair which view had been encountered before the other one on the route. The results show that in spite of their cognitive deficit, the schizophrenic patients are able to correctly memorize the views they have encountered on a route. They have preserved ability to distinguish a scene from a similar other one and to identify that it belongs to the route. But they had poorer performance on the order recognition task than the control participants. Schizophrenic patients show severe deficits regarding the chronology of the events encountered along the routes. They are fully able to recognize objects, but they cannot correctly localize these objects in space. They have difficulties in remembering the spatial relations among landmarks in the environment. When recalling routes previously learned, they are impaired in the recall of the sequence of turns and the sequence of visual landmarks. To summarize, to refer to the classic distinction (cf. Landau and Jackendoff), they can quite easily answer the “what” question, while experiencing much difficulty with the “where” one. [ABSTRACT FROM AUTHOR]

A considerable amount of empirical work documents the role of visual perception in spatial cognition and the mental representation of space, while only few studies have been conducted on the role of other senses, in particular auditory perception. The present investigation focuses on the role of audition in wayfinding and the construction of the mental representation of a spatial environment. Our experiments are conducted in a virtual environment (VE), where participants are invited to perform a navigation task in which they locate non-visual sound sources which occupy specific positions in the surrounding space. The VE is purely auditory with no visual feedback. The task is presented in a game form, where sources are virtual bombs emitting a count-down sound. Participants have to find and deactivate them before they explode (which stops the emission of the corresponding sound sources). The data of interest are the participants’ trajectories, their response times, and their performance during the game. Post-experimental tests are also conducted in an attempt to externalize the participants’ mental representation of space via subsequent reconstruction tasks. In the present experimental context, the value of virtual reality is to offer control over the modalities available to the participants, allowing easy comparison of natural and distorted perceptual information. Here, in order to focus on the importance of sound information and to avoid the possible use of sensorimotor contingency cues, the participants do not move physically throughout the scene, but they use a joystick to control translational movements in the VE. The sound scene is rendered over headphones using the 3D audio binaural technique. The sound scene is continually updated taking into account the position and orientation of the participant in the VE. We contrast two conditions for determining the orientation of the participant, either using the actual orientation in the VE, or via a head-tracker. The second option allows the participant to change the orientation of their listening perspective without altering their direction of motion controlled via the joystick. Previous studies have shown the importance of dynamic acoustic cues that the brain correlates with vestibular information for auditory localization (Minnaar 2001; Wightman and Kistler 1999), but such studies have always been conducted in set-ups where the participants’ position and orientation remain fixed in the sound scene. It is the special feature of our approach to investigate the role of head movements in a navigational context. The first data are collected with sighted participants in order to establish a baseline that will further be referred to when blind participants are examined. [ABSTRACT FROM AUTHOR]

Comments on the coverage and reputation of the periodical "Psychological Research." Links between the periodical and the very history of psychology; Cognition as a superordinate concept; Willingness of authors to ensure that cognitive psychology is well-represented in the periodical.