Neural correlates of visuospatial working memory in the 'at-risk mental state'.

BACKGROUND: Impaired spatial working memory (SWM) is a robust feature of schizophrenia and has been linked to the risk of developing psychosis in people with an at-risk mental state (ARMS). We used functional magnetic resonance imaging (fMRI) to examine the neural substrate of SWM in the ARMS and in patients who had just developed schizophrenia. METHOD: fMRI was used to study 17 patients with an ARMS, 10 patients with a first episode of psychosis and 15 age-matched healthy comparison subjects. The blood oxygen level-dependent (BOLD) response was measured while subjects performed an object-location paired-associate memory task, with experimental manipulation of mnemonic load. RESULTS: In all groups, increasing mnemonic load was associated with activation in the medial frontal and medial posterior parietal cortex. Significant between-group differences in activation were evident in a cluster spanning the medial frontal cortex and right precuneus, with the ARMS groups showing less activation than controls but greater activation than first-episode psychosis (FEP) patients. These group differences were more evident at the most demanding levels of the task than at the easy level. In all groups, task performance improved with repetition of the conditions. However, there was a significant group difference in the response of the right precuneus across repeated trials, with an attenuation of activation in controls but increased activation in FEP and little change in the ARMS. CONCLUSIONS: Abnormal neural activity in the medial frontal cortex and posterior parietal cortex during an SWM task may be a neural correlate of increased vulnerability to psychosis.

Neural correlates of movement generation in the 'at-risk mental state'.

OBJECTIVE: People with 'prodromal' symptoms have a very high risk of developing psychosis. We examined the neurocognitive basis of this vulnerability by using functional MRI to study subjects with an at-risk mental state (ARMS) while they performed a random movement generation task. METHOD: Cross-sectional comparison of individuals with an ARMS (n = 17), patients with first episode schizophreniform psychosis (n = 10) and healthy volunteers (n = 15). Subjects were studied using functional MRI while they performed a random movement generation paradigm. RESULTS: During random movement generation, the ARMS group showed less activation in the left inferior parietal cortex than controls, but greater activation than in the first episode group. CONCLUSION: The ARMS is associated with abnormalities of regional brain function that are qualitatively similar to those in patients who have recently presented with psychosis but less severe.

Economic impact of early intervention in people at high risk of psychosis.

BACKGROUND: Despite the increasing development of early intervention services for psychosis, little is known about their cost-effectiveness. We assessed the cost-effectiveness of Outreach and Support in South London (OASIS), a service for people with an at-risk mental state (ARMS) for psychosis. METHOD: The costs of OASIS compared to care as usual (CAU) were entered in a decision model and examined for 12- and 24-month periods, using the duration of untreated psychosis (DUP) and rate of transition to psychosis as key parameters. The costs were calculated on the basis of services used following referral and the impact on employment. Sensitivity analysis was used to test the robustness of all the assumptions made in the model. RESULTS: Over the initial 12 months from presentation, the costs of the OASIS intervention were pound1872 higher than CAU. However, after 24 months they were pound961 less than CAU. CONCLUSIONS: This model suggests that services that permit early detection of people at high risk of psychosis may be cost saving.

Delusion formation and reasoning biases in those at clinical high risk for psychosis.

BACKGROUND: Cognitive models propose that faulty appraisal of anomalous experiences is critical in developing psychosis, particularly delusions. A data gathering bias may be fundamental to abnormal appraisal. AIMS: To examine whether there is a data gathering bias in people at high risk of developing psychosis. METHOD: Individuals with an at-risk mental state (n=35) were compared with a matched group of healthy volunteers (n=23). Participants were tested using a modified version of the 'beads' reasoning task with different levels of task difficulty. RESULTS: When task demands were high, the at-risk group made judgements on the basis of less information than the control group (P<0.05). Within both groups, jumping to conclusions was directly correlated with the severity of abnormal beliefs and intolerance of uncertainty (P<0.05). In the at-risk group it was also associated with impaired working memory (P<0.05), whereas in the control group poor working memory was associated with a more conservative response style (P<0.05). CONCLUSIONS: People with an at-risk mental state display a jumping to conclusions reasoning style, associated with impaired working memory and intolerance of uncertainty. This may underlie a tendency to develop abnormal beliefs and a vulnerability to psychosis.

Armored Scales and Their Parasitoids on Commercial Avocados Grown in California or Imported from Mexico.

Levels of armored scales (Hemiptera: Diaspididae) on Mexican Hass avocados imported into California over May 2008-June 2009 were monitored on 135 trucks entering the state via the Blythe border station, the entry point receiving the highest volume of fruit. Levels of live sessile scales were 3.9-fold higher than indicated in a previous survey (September 2007-April 2008) although levels of live eggs and crawlers were similar to previous levels. A survey of avocado fruit in California infested with armored scales detected four species known to be endemic but failed to find any of the seven exotic Diaspididae entering the state on Mexican fruit. Monitoring of Mexican armored scales on imported avocados from September 2007 to December 2010 recovered 10 species of parasitoids predominated by two species of Signiphora Ashmead (Hymenoptera: Signiphoridae). One of these species, Signiphora flavopalliata Ashmead, comprised 36% of all collected Mexican parasitoids and is a known hyperparasitoid. A survey of armored scale parasitoids present on commercial California avocados detected 17 genetic signatures, with only four of these in common with those detected on imported Mexican fruit. The implications of these findings are discussed.

PHYLOGENY OF THE SUBFAMILIES OF THE FAMILY BRACONIDAE (HYMENOPTERA: ICHNEUMONOIDEA): A REASSESSMENT.

Abstract- The recently published phylogeny of Braconidae by Quicke and van Achterberg is reassessed. Character-state definitions and character polarities are evaluated, and more rigorous methods are suggested. Our results indicate that there are many more parsimonious solutions to their data set, the consensus of which differs substantially from their results. Based on our reassessment, little can be said about the relationships among braconid subfamilies. Consensus trees show the cyclostomes as a largely unresolved basal grade. The two other major lineages which have been proposed, the helconoids and microgastroids, are somewhat better resolved, but not consistently so. Relationships among the helconoids vary considerably depending on the parameters used for parsimony analysis.

Prefrontal function at presentation directly related to clinical outcome in people at ultrahigh risk of psychosis.

BACKGROUND: The prodromal phase of psychosis is characterized by impaired executive function and altered prefrontal activation. The extent to which the severity of these deficits at presentation predicts subsequent clinical outcomes is unclear. METHODS: We employed functional magnetic resonance imaging in a cohort of subjects at clinical risk for psychosis and in healthy controls. Images were acquired at clinical presentation and again after 1 year, using a 1.5-T Signa MRI scanner while subjects were performing a verbal fluency task. SPM5 was used for the analysis of imaging data. Psychopathological assessment of the "at-risk" symptoms was performed by using the Comprehensive Assessment for the At-Risk Mental State (CAARMS) and the Positive and Negative Symptom Scale (PANSS). RESULTS: In the at-risk mental state (ARMS) group, between presentation and follow-up, the CAARMS (perceptual disorder and thought disorder subscales) and the PANSS general scores decreased, while the Global Assessment of Functioning (GAF) score increased. Both the ARMS and control groups performed the verbal fluency task with a high degree of accuracy. The ARMS group showed greater activation in the left inferior frontal gyrus but less activation in the anterior cingulate gyrus than controls. Within the ARMS group, the longitudinal normalization of neurofunctional response in the left inferior frontal gyrus was positively correlated with the improvement in severity of hallucination-like experiences. CONCLUSIONS: The normalization of the abnormal prefrontal response during executive functioning is associated with 12-month psychopathological improvement of prodromal symptoms.

Altered brain function directly related to structural abnormalities in people at ultra high risk of psychosis: longitudinal VBM-fMRI study.

BACKGROUND: Several studies have indicated that people with prodromal signs of psychosis show alterations in the structure and function of the brain when they first present to clinical services. However, the longitudinal course of these abnormalities, and how they relate to subsequent clinical and functional outcome is relatively unclear. METHODS: A cohort of subjects at ultra high risk of psychosis were studied using functional magnetic resonance imaging (fMRI) in conjunction with the N-Back task, and volumetric MRI at first clinical presentation and again after one year. Levels of psychopathology and global functioning were assessed at the same time points using the CAARMS, PANSS, and the GAF scale. RESULTS: At baseline, the high risk group showed reduced activation during the task in the left middle frontal gyrus, supramarginal gyrus and inferior parietal lobule, and reduced gray matter volume in the left middle and medial frontal gyri, left insula and the right anterior cingulate gyrus. Within the high-risk group, there was a positive correlation between the magnitude of the functional and structural alterations in the left middle frontal gyrus. Between presentation and follow up, the severity of perceptual disorder and thought disorder (rated by the CAARMS), and of general psychopathology (rated by the PANSS general score) decreased, and the level of global functioning improved. This clinical and functional improvement was associated with a longitudinal increase in activation in the anterior cingulate and right parahippocampal gyrus. The change in anterior cingulate response was directly correlated with the improvement in the GAF score. CONCLUSIONS: In subjects presenting with prodromal signs of psychosis, reduced prefrontal activation during a working memory task is associated with a reduction in gray matter volume in the same area. Changes in anterior cingulate activation were correlated with functional improvement in this group, consistent with the role of this region in multiple cognitive and social processes.

Spatial working memory in individuals at high risk for psychosis: longitudinal fMRI study.

BACKGROUND: Neurocognitive impairments in executive and mnemonic domains are already evident in the pre-psychotic phases. The longitudinal dynamic course of the neurofunctional abnormalities underlying liability to psychosis and their relation to clinical outcomes is unknown. METHODS: In this study we used functional magnetic resonance imaging (fMRI) in a cohort of subjects at ultra high clinical risk for psychosis (with an "At Risk Mental State", ARMS) and in healthy controls. Images were acquired at baseline and again after one year on a 1.5 Tesla Signa, while patients were performing a visuospatial working memory task. Psychopathological assessment of the prodromal symptoms was conducted at the same time points by using the CAARMS and the PANSS instruments. RESULTS: There were no significant differences between the ARMS and control groups with respect to age or IQ. Although both groups performed the PAL task with a high degree of accuracy, the ARMS showed an increased latency in answers during the most demanding level of the task. At baseline, such cognitive impairment was associated with reduced activation in the left precuneus, left superior parietal lobule, right middle temporal gyrus in the ARMS as compared to controls. In addition, the ARMS failed to activate parietal areas with increasing difficulty of the task. Between presentation and follow-up the overall clinical status of the ARMS sample improved, despite 2 out of the 15 subjects having developed a full-blown psychosis: the CAARMS (perceptual disorder and thought disorder subscales) and the PANNS general scores decreased, while the GAF score increased. Such clinical amelioration was associated with a longitudinal compensatory increase in occipitoparietal regions. CONCLUSIONS: The prodromal phase of psychosis is associated with functional alterations in parietal and temporal networks subserving visuospatial working memory which are more evident under high cognitive loads. The clinical improvement at one year is associated with a compensatory increase in occipitoparietal regions.

Comparison of five allopatric fruit fly parasitoid populations (Psyttalia species) (Hymenoptera: Braconidae) from coffee fields using morphometric and molecular methods.

Morphometric studies of five allopatric parasitoid populations (genus Psyttalia Walker) from coffee plantations in Cameroon (Nkolbisson), Ghana (Tafo) and Kenya (Rurima, Ruiru and Shimba Hills) and one non-coffee population (from Muhaka, Kenya) were compared with individuals of Psyttalia concolor (Szépligeti), a species released in several biological control programmes in the Mediterranean Region since the 20th Century. Analyses of wing vein measurements showed the second submarginal cell of the fore wing and its adjoining veins had the heaviest principal component weights and served as the main contributing variables in the diagnostic differentiation of the populations. Two populations (Rurima and Ruiru) were found to be the closest to each other and with the strongest phenetic affinity toward P. concolor (and forming one cluster). Populations from Shimba Hills (of unknown identity), Nkolbisson (P. perproximus (Silvestri)) and Tafo formed a second cluster and were separated from P. concolor. Comparison using amplified fragment length polymorphism (AFLP) also showed the Shimba, Nkolbisson and Tafo populations forming a cluster in a dendrogram generated from their genetic distances, with the Shimba and Tafo populations placed as the most closely related species. Based on consistent morphological similarities, morphometric and ecological data coupled with the genetic evidence from AFLP data, the Shimba population is suggested as belonging to the P. perproximus group and, thus, represents a new occurrence record in Kenya. Our results also support earlier conclusion from cross mating data that populations from Rurima and Ruiru belong to the Psyttalia concolor species-group.

Evolution and behavioral ecology of heteronomous aphelinid parasitoids.

In almost all species of parasitic wasps in the Coccophaginae, a subfamily of Aphelinidae, males have host relationships different from females. In these "heteronomous" species, females are generally endoparasitoids of sternorrhynchous Hemiptera, such as scale insects, mealybugs, and whiteflies. In contrast, males may be hyperparasitoids, developing in or on conspecific females or other primary parasitoids. In other species, females are endoparasitoids of whiteflies, and males are primary endoparasitoids of eggs of Lepidoptera. Males and females may both be primary parasitoids on the same species of scale insect hosts, but females develop as endoparasitoids, whereas males are ectoparasitoids. Here we review these life histories, focusing on examples of sexually dimorphic host relationships, development, and morphology. Coccophagine species may be sexual or parthenogenetic; we discuss reproductive modes and the interaction of sex ratio distorters with sex-specific host relationships. Sex allocation in the species in which males are hyperparasitoids involves choices of not what sex egg to lay, but whether to accept or reject a host of a given type; study in this area is reviewed as well as research in kin discrimination and ovicide. Last, we present the current understanding of phylogenetic relationships within this lineage and discuss hypotheses for the evolutionary origin of heteronomy in the Aphelinidae.

Variation and the phylogenetic utility of the large ribosomal subunit of mitochondrial DNA from the insect order Hymenoptera.

Nucleotide sequence variation from a 573-bp region of the mitochondrial 16S rRNA gene was determined for representative hymenopteran taxa. An overall bias in the distribution of A and T bases was observed from all taxa; however, the terebrants (parasitoids) displayed significantly lower AT ratios as well as a higher degree of strand asymmetry. Moreover, a strong positive correlation was observed between relative AT richness and sequence divergence, suggesting selection at the nucleotide level for A and T bases as well as functionality. Overall sequence difference ranged from 2.3 to 53.4%, with the maximum divergence between members of the two Hymenopteran suborders. These data were used in a phylogenetic analysis to illustrate the utility and degree of resolution provided by this information at various hierarchical levels within this taxonomically diverse order. Parsimony analysis revealed strong evidence for monophyly of the aculeates and the terebrants. Most noteworthy was a strongly supported clade containing the two terebrant superfamilies Icheumonoidea and Chalcidoidea. Conversely, high sequence divergence values resulted in instability at the base of the tree and limited resolution at the higher taxonomic levels. Nevertheless, these results do identify those taxonomic levels for which 16S rRNA sequences are phylogenetically informative.