Neurobiological model of visuo-spatial cognition in young Williams Syndrome children: measures of dorsal-stream and frontal function

We examine hypotheses for the neural basis of the profile of visual cognition in young children with Williams syndrome (WS). These are: (a) that it is a consequence of anomalies in sensory visual processing; (b) that it is a deficit of the dorsal relative to the ventral cortical stream; (c) that it reflects deficit of frontal function, in particular of fronto-parietal interaction; (d) that it is related to impaired function in the right hemisphere relative to the left. The tests reported here are particularly relevant to (b) and (c). They form part of a more extensive programme of investigating visual, visuospatial, and cognitive function in large group of children with WS children, aged 8 months to 15 years. To compare performance across tests, avoiding floor and ceiling effects, we have measured performance in children with WS in terms of the ‘age equivalence’ for typically developing children. In this paper the relation between dorsal and ventral function was tested by motion and form coherence thresholds respectively. We confirm the presence of a subgroup of children with WS who perform particularly poorly on the motion (dorsal) task. However, such performance is also characteristic of normally developingchildren up to 5 years: thus the WS performance may reflect an overall persisting immaturity of visuospatial processing which is particularly evident in the dorsal stream. Looking at the performance on the global coherence tasks of the entire WS group, we find that there is also a subgroup who have both high form and motion coherence thresholds, relative to the performance of children of the same chronological age and verbal age on the BPVS, suggesting a more general global processing deficit. Frontal function was tested by a counterpointing task, ability to retrieve a ball from a ‘detour box’, and the Stroop-like ‘day-night’ task, all of which require inhibition of a familiar response. When considered in relation to overall development as indexed by vocabulary, the day-night task shows little specific impairment, the detour box shows a significant delay relative to controls, and the counterpointing task shows a marked and persistent deficit in many children. We conclude that frontal control processes show most impairment in WS when they are associated with spatially directed responses, reflecting a deficit of fronto-parietal processing. However, children with WS may successfully reduce the effect of this impairment by verbally mediated strategies. On all these tasks we find a range of difficulties across individual children and a small subset of WS who show very good performance, equivalent to chronological age norms of typically developing children. Neurobiological models of visuo-spatial cognition in children with WS p.4 Overall, we conclude that children with WS have specific processing difficulties with tasks involving frontoparietal circuits within the spatial domain. However, some children with WS can achieve similar performance to typically developing children on some tasks involving the dorsal stream, although the strategies and processing may be different in the two groups.

Comparison of genetic and morphological methods to detect the presence of American lobsters, Homarus americanus H. Milne Edwards, 1837 (Astacidea: Nephropidae) in Norwegian waters

American lobsters (Homarus americanus H. Milne Edwards, 1837) are imported live to Europe and should according regulations be kept in land-based tanks until sold. In spite of the strict regulations aimed specifically at preventing the introduction of this species into the NE Atlantic, several specimens of H. americanus have been captured in the wild, especially in Oslofjord, Norway since 1999. One of the great concerns is interbreeding between the introduced American species and the local European lobster, H. gammarus (Linnaeus, 1758). For this reason an awareness campaign was launched in 2000 focusing on morphologically "unusual" lobsters caught in local waters. Morphological characters have been based on colour and sub-ventral spines on the rostrum. Two samples of H. americanus were used for comparisons, as well as samples of European lobster from Oslofjord collected in 1992. Previous genetic analyses (allozymes, mtDNA and microsatellite DNA) have demonstrated that the American lobster is distinct from its European counterpart, with several additional alleles at many loci in addition to different allelic frequency distribution of alleles of "shared" alleles. During the present study, thirteen microsatellite loci were tested in the initial screening, and the three most discriminating loci (Hgam98, Hgam197b and Hgam47b) were used in a detailed comparison between the two species. A total of 45 unusual lobsters were reported captured from Ålesund (west) to Oslofjord (southeast) from 2001 to 2005 and these were analysed for the three microsatellite loci. Nine specimens were identified as American lobsters. Comparisons between morphological and genetic characteristics revealed that morphological differences are not reliable in discrimination the two species, or to identify hybrids. Further, some loci display almost no overlapping in allele frequency distribution for the reference samples analysed, thus providing a reliable tool to identify hybrids.

Isolation and preliminary biological assessment of AADGAPLIRFamide and SVPGVLRFamide from Caenorhabditis elegans

To date, 9 FMRFamide-related peptides (FaRPs) have been structurally characterised from Caenorhabditis elegans. Radioimmunometrical screening of an ethanolic extract of C. elegans revealed the presence of two additional FaRPs that were purified by reverse-phase HPLC and subjected to Edman degradation analysis and gas-phase sequencing. Unequivocal primary structures for the two FaRPs were determined as Ala-Ala-Asp-Gly-Ala-Pro-Leu-Ile-Arg-Phe-NH2 and Ser-Val-Pro-Gly-Val-Leu-Arg-Phe-NH2. Using MALDI-TOF mass. spectrometry, the molecular masses of the peptides were found to be 1032 Da (MH) and 875 Da (MH)(+), respectively. Two copies of AADGAPLIRFamide are predicted to be encoded on the precursor gene termed flp-13, while one copy of SVPGVLRFamide is located on flp-18. Synthetic replicates of the peptides were tested on Ascaris suum somatic muscle to assess bioactivity. ADDGAPLIRFamide had inhibitory effects on A. suum muscle strips, which occurred over a range of concentrations from a threshold for activity of 10 nM to 10 muM. SVPGVLRFamide was excitatory on A. suum somatic musculature from a threshold concentration for activity of 1 nM to 10 muM. The inhibitory and excitatory effects of AADGAPLIRFamide and SVPGVLRFamide, respectively, were the same for dorsal and ventral muscle strips as well as innervated and denervated preparations, suggesting that these physiological effects are not nerve cord dependent. Addition of ADDGAPLIRFamide (10 muM) to muscle strips preincubated in high-K+ and -Ca2+-free medium resulted in a normal inhibitory response. Peptide addition to muscle strips preincubated in Cl--free medium showed no inhibitory response, suggesting that the inhibitory response of the peptide may be chloride mediated. A normal excitatory response was noted following the addition of 10 muM SVPGVLRFamide to muscle strips preincubated in high-K+, Ca2+- and Cl--free media. (C) 2001 Academic Press.

Organization of the musculature of schistosome cercariae

Phalloidin-fluorescein isothiocyanate staining of filamentous actin was used to identify muscle systems within the cercariae of Schistosoma mansoni. Examination of labeled cercariae by confocal scanning laser microscopy revealed distinct organizational levels of myofiber arrangements within the body wall, anterior cone, acetabulum, and esophagus. The body wall throughout showed a typical latticelike arrangement of outer circular and inner longitudinal myofibers, with an additional innermost layer of diagonal fibers in the anterior portion of the body. Circular and longitudinal fibers were also evident in the anterior organ and esophagus and. to some extent, the ventral acetabulum. Most striking was the striation of the cercarial tail musculature.

Microscopical evaluation of neural connectivity between paired stages of Eudiplozoon nipponicum (Monogenea : Diplozoidae)

Diplozoidae monogeneans are fish-gill ectoparasites comprising 2 individuals fused in so-called permanent copula. This unique situation occurs when 2 larvae (diporpae) make contact on the host gill, such that their union triggers maturation into an individual adult worm. The present study examined paired stages of Eudiplozoon nipponicum microscopically to ascertain whether somatic fusion involves neural connectivity between these 2 heterogenic larvae. Neuronal pathways were demonstrated in whole-mount preparations of the worm, using indirect immunocytochemical techniques interfaced with confocal scanning laser microscopy for peptidergic and serotoninergic innervations and enzyme cytochemical methodology and light microscopy for cholinergic components. Elements of the central nervous systems of paired worms are connected by commissures the region of fusion so that the 2 systems are in structural continuity. Interindividual connections were most apparent between corresponding ventral nerve cords. All 3 classes of neuronal mediators were identified throughout both central and peripheral connections of the 2 nervous systems. The anatomical complexity and apparent plasticity of the diplozoon nervous system suggest that it has a pivotal role not only in motility, feeding, and reproductive behaviors but also in the events of larval pairing and somatic fusion.

Roles for the subiculum in spatial information processing, memory, motivation and the temporal control of behaviour

The subiculum is in a pivotal position governing the output of the hippocampal formation. Despite this, it is a rather under-explored and sometimes ignored structure. Here, we discuss recent data indicating that the subiculum participates in a wide range of neurocognitive functions and processes. Some of the functions of subiculum are relatively well-known-these include providing a relatively coarse representation of space and participating in, and supporting certain aspects of, memory (particularly in the dynamic bridging of temporal intervals). The subiculum also participates in a wide variety of other neurocognitive functions too. however. Much less well-known are roles for the subiculum, and particularly the ventral subiculum, in the response to fear, stress and anxiety, and in the generation of motivated behaviour (particularly the behaviour that underlies drug addiction and the response to reward). There is an emerging suggestion that the subiculum participates in the temporal control of behaviour. It is notable that these latter findings have emerged from a consideration of instrumental behaviour using operant techniques; it may well be the case that the use of the watermaze or similar spatial tasks to assess subicular function (on the presumption that its functions are very similar to the hippocampus proper) has obscured rather than revealed neurocognitive functions of subiculum. The anatomy of subiculum suggests it participates in a rather subtle fashion in a very broad range of functions, rather than in a relatively more isolated fashion in a narrower range of functions, as might be the case for

Using time-to-contact information to assess potential collision modulates both visual and temporal prediction networks

Accurate estimates of the time-to-contact (TTC) of approaching objects are crucial for survival. We used an ecologically valid driving simulation to compare and contrast the neural substrates of egocentric (head-on approach) and allocentric (lateral approach) TTC tasks in a fully factorial, event-related fMRI design. Compared to colour control tasks, both egocentric and allocentric TTC tasks activated left ventral premotor cortex/frontal operculum and inferior parietal cortex, the same areas that have previously been implicated in temporal attentional orienting. Despite differences in visual and cognitive demands, both TTC and temporal orienting paradigms encourage the use of temporally predictive information to guide behaviour, suggesting these areas may form a core network for temporal prediction. We also demonstrated that the temporal derivative of the perceptual index tau (tau-dot) held predictive value for making collision judgements and varied inversely with activity in primary visual cortex (V1). Specifically, V1 activity increased with the increasing likelihood of reporting a collision, suggesting top-down attentional modulation of early visual processing areas as a function of subjective collision. Finally, egocentric viewpoints provoked a response bias for reporting collisions, rather than no-collisions, reflecting increased caution for head-on approaches. Associated increases in SMA activity suggest motor preparation mechanisms were engaged, despite the perceptual nature of the task.

Echinostoma caproni: Differential tegumental responses to growth in compatible and less compatible hosts

The topography of the tegument of Echinostoma caproni adults collected from high (mice) and low (rats) compatible hosts was compared by SEM. In the oral (OS) and the ventral sucker (VS) areas, a worm age-host species interaction was found with regard to the density of spines. There was a decrease in the density of spines in the adults collected from mice, whereas an increase occurred in the OS area in worms from rats over time. The tegumentary spines in adults from mice became larger and blunter. Some spines from the VS area in adults from mice at 4 wpi were multipointed. The spines of adults from rats were sharper, not covered by the tegument and no multipointed spines were observed. We detected a greater level of actin gene expression in the adults collected from rats. These facts suggest that the low compatible host induces an increased turnover of tegumentary spines. (C) 2010 Elsevier Inc. All rights reserved.

How information guides movement: Intercepting curved free kicks in soccer

Previous studies have shown that balls subjected to spin induce large errors in perceptual judgements (Craig et al, 2006; Craig et al 2009) due to the additional accelerative force that causes the ball’s flight path to deviate from a standard parabolic trajectory. A recent review however, has suggested that the findings from such experiments may be imprecise due to the decoupling of perception and action and the reliance on the ventral system (Van der Kamp et al, 2008). The aim of this study was to present the same curved free kick trajectory simulations from the perception only studies (Craig et al, 2006; Craig et al, 2009) but this time allow participants to move to intercept the ball. By using immersive, interactive virtual reality technology participants were asked to control the movement of a virtual effector presented in a virtual soccer stadium so that it would make contact with a virtual soccer ball as it crossed the goal-line. As in the perception only studies the direction of spin had a significant effect on the participants’ responses (F(2,12)=222.340; p

The biology and functional anatomy of Modiolarca tumida (Musculus marmoratus) Bivalvia: Mytilidae

Modiolarca tumida (Hanley, 1843) is a member of the sub-family Crenellinae (Mytilidae). The preferred habitat of the species is the test of certain ascidians. The shell is dorsally flattened, which prevents it from cutting into the test during dorso-ventral contraction of the byssal retractors. The use of the byssus enables it to surround itself completely with host tissue. Adoption of the feeding posture involves the anterior-posterior contraction of the byssal retractors, which elevates the posterior margin above the host's surface using the anterior margin as the fulcrum against the host. Modiolarca tumida are attracted by the tunicin of the host, a process probably facilitated by the host's feeding currents. The smallest individuals are found round the oral aperture. Colonization of other parts of the host may result from surface migration as M. tumida can be highly mobile, crawling by means of the very extensible foot. It is during this process that individuals may be swept away in local currents and be forced to adopt a free-living existence.

FMRFamide-like peptides in root knot nematodes and their potential role in nematode physiology

FMRFamide-like peptides (FLPs) are a diverse group of neuropeptides that are expressed abundantly in nematodes. They exert potent physiological effects on locomotory, feeding and reproductive musculature and also act as neuromodulators. However, little is known about the specific expression patterns and functions of individual peptides. The current study employed rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) to characterize flp genes from infective juveniles of the root knot nematodes, Meloidogyne incognita and Meloidogyne minor. The peptides identified from these transcripts are sequelogs of FLPs from the free-living nematode, Caenorhabditis elegans; the genes have therefore been designated as Mi-flp-1, Mi-flp-7, Mi-flp-12, Mm-flp-12 and Mi-flp-14. Mi-flp-1 encodes five FLPs with the common C-terminal moiety, NFLRFamide. Mi-flp-7 encodes two copies of APLDRSALVRFamide and APLDRAAMVRFamide and one copy of APFDRSSMVRFamide. Mi-flp-12 and Mm-flp-12 encode the novel peptide KNNKFEFIRFamide (a longer version of RNKFEFIRFamide found in C. elegans). Mi-flp-14 encodes a single copy of KHEYLRFamide (commonly known as AF2 and regarded as the most abundant nematode FLP), and a single copy of the novel peptide KHEFVRFamide. These FLPs share a high degree of conservation between Meloidogyne species and nematodes from other clades, including those of humans and animals, perhaps suggesting a common neurophysiological role which may be exploited by novel drugs. FLP immunoreactivity was observed for the first time in Meloidogyne, in the circumpharyngeal nerve ring, pharyngeal nerves and ventral nerve cord. Additionally, in situ hybridization revealed Mi-flp-12 expression in an RIR-like neuron and Mi-flp-14 expression in SMB-like neurons, respectively. These localizations imply physiological roles for FLP-12 and FLP-14 peptides, including locomotion and sensory perception.

A chiton without a foot

The palaeoloricate ‘polyplacophorans’ are an extinct paraphyletic group of basal chiton-like organisms known primarily from their fossilized valves. Their phylo- genetic placement remains contentious, but they are likely to include both stem-group Polyplacophora and stem- group Aplacophora. Candidates for the latter position include ‘Helminthochiton’ thraivensis from the Ordovician of Scotland, which we redescribe here through a combined optical and micro-CT (XMT) restudy of the type material. The 11 specimens in the type series are all articulated, presenting partial or complete valve series as well as moul- dic preservation of the girdle armature; they demonstrate a vermiform body plan. The valves are typically palaeolori- cate in aspect, but differ in detail from all existing palaeol- oricate genera; we hence erect Phthipodochiton gen. nov. to contain the species. The most notable feature of the fossils is the spicular girdle; this is impersistently preserved, but demonstrably wraps entirely around the ventral surface of the animal, implying that a ‘true’ (i.e. polyplacophoran like) foot was absent, although we do not exclude the pos- sibility of a narrow solenogastre-like median pedal groove having been present. Phthipodochiton thraivensis presents an apparent mosaic of aplacophoran and polyplacophoran features and as such will inform our understanding of the relationship between these groups of extant molluscs. An inference may also be drawn that at least some other pal- aeoloricates possessed an ‘armoured aplacophoran’ body plan, in contrast to the ‘limpet-like’ body plan of extant Polyplacophora.

Ultrastructural features of the epidermis of the planarian Artioposthia triangulata (Dendy)

The epidermis of the land planarian Arthioposthia triangulata was examined by scanning and transmission electron microscopy. This investigation revealed that the flatworm was covered entirely with cilia and was especially densely populated on the ventral surface. In all regions the epidermis consisted of a one-layered columnar epithelium resting on a prominent basement membrane, but lacking a terminal web. Various secretions were found in the epidermis together with epidermal rhabdoids. Below the basement membrane other secretory material was visible and this included the cytoplasmic lamellated granules and adenal rhabdites. The basement membrane consisted of fibrils with a beaded appearance and these were arranged parallel to the epidermal layer but did not display cross-banding. The secretory cells above and below the basement membrane were compared and their products characterized on the basis of shape, size and location. Their possible function is discussed.

Immunocytochemical localization of glutamate-like immunoreactivity within the nervous system of the cestode Mesocestoides corti and the trematode Fasciola hepatica

The localization and distribution of glutamate-like immunoreactivity (IR) in the nervous system of both the cestode Mesocestoides corti and the trematode Fasciola hepatica has been determined by an indirect immunofluorescent technique, in conjunction with confocal scanning laser microscopy (CSLM). Immunostaining was widespread in the central (CNS) and peripheral (PNS) nervous systems of both species examined. In the CNS, IR was evident in nerve cells and fibres in the cerebral ganglia, the cerebral commissure and the dorsal, ventral and longitudinal nerve cords. In the peripheral nervous system (PNS) of M. corti, IR was apparent in nerve plexuses associated with the subtegmental musculature and the musculature associated with the anteriorly positioned suckers. In F. hepatica, IR was evident in the innervation of both the oral and the ventral suckers, In the reproductive system of F. hepatica, glutamate-IR was observed around the ootype/Mehlis' gland complex.

FASCIOLA-HEPATICA - ULTRASTRUCTURAL-CHANGES TO THE TEGUMENT OF JUVENILE FLUKES FOLLOWING INCUBATION IN-VITRO WITH THE DEACETYLATED (AMINE) METABOLITE OF DIAMPHENETHIDE

Ultrastructural changes to the tegument of 5-week-old, 3-week-old and freshly-excysted Fasciola hepatica following in vitro incubation with the deacetylated (amine) metabolite of diamphenethide (DAMD, 10 mu gml(-1)) were examined by transmission electron microscopy, A similar sequence of tegumental changes occurred in all three age groups of fluke, although, with increasing fluke age, the time before onset increased and the damage became more extensive. The 5-week-old flukes showed an initial stress response after 3 h, typified by blebbing of the apical plasma membrane, formation of microvilli and an accumulation and accelerated release of secretory bodies at the tegumental apex, as well as swelling of the basal infolds, The swelling increased in extent with progressively longer periods of incubation in DAMD, leading to extreme edema and sloughing of the tegument after 9 h. The 3-week-old flukes showed a stress response and swelling of the basal infolds after only 1.5 h, although sloughing of the tegument did not occur until after 9 h. In the freshly-excysted metacercaria, a stress response and some sloughing of the tegument were evident after only 0.5 h. At all stages of development, the ventral tegument was more severely affected than the dorsal, Changes also occurred to the tegumental cells which were indicative of a disruption in the synthesis and release of tegumental secretory bodies: the amount of GER became reduced, the cisternae became swollen and their ribosomal covering decreased, the Golgi complexes disappeared from the cells and the numbers of secretory bodies in the cells also decreased, The heterochromatin content of the nuclei increased and eventually the tegumental cells began to break down, Again, the changes became apparent more rapidly at the earlier stages of development. The ultrastructural changes to the tegument are linked to a possible mode of action for diamphenethide as an inhibitor of protein synthesis. In turn, the results may help to explain the drug's high efficacy against juvenile stages of F. hepatica.