Autism is a severe developmental disorder marked by a triad of deficits, including impairments in reciprocal social interaction, delays in early language and communication, and the presence of ...restrictive, repetitive and stereotyped behaviors. In this review, it is argued that the search for the neurobiological bases of the autism spectrum disorders should focus on the social deficits, as they alone are specific to autism and they are likely to be most informative with respect to modeling the pathophysiology of the disorder. Many recent studies have documented the difficulties persons with an autism spectrum disorder have accurately perceiving facial identity and facial expressions. This behavioral literature on face perception abnormalities in autism is reviewed and integrated with the functional magnetic resonance imaging (fMRI) literature in this area, and a heuristic model of the pathophysiology of autism is presented. This model posits an early developmental failure in autism involving the amygdala, with a cascading influence on the development of cortical areas that mediate social perception in the visual domain, specifically the fusiform “face area” of the ventral temporal lobe. Moreover, there are now some provocative data to suggest that visual perceptual areas of the ventral temporal pathway are also involved in important ways in representations of the semantic attributes of people, social knowledge and social cognition. Social perception and social cognition are postulated as normally linked during development such that growth in social perceptual skills during childhood provides important scaffolding for social skill development. It is argued that the development of face perception and social cognitive skills are supported by the amygdala–fusiform system, and that deficits in this network are instrumental in causing autism.
While well-represented on clinical measures, co-speech gesture production has never been formally studied in autistic adults. Twenty-one verbally fluent autistic adults and 21 typically developing ...controls engaged in a controlled conversational task. Group differences were observed in both semantic/pragmatic and motoric features of spontaneously produced co-speech gestures. Autistic adults prioritized different functions of co-speech gesture. Specifically, they used gesture more than controls to facilitate conversational turn-taking, demonstrating a novel nonverbal strategy for regulating conversational dynamics. Autistic adults were more likely to gesture unilaterally than bilaterally, a motoric feature of gesture that was individually associated with autism symptoms. Co-speech gestures may provide a link between nonverbal communication symptoms and known differences in motor performance in autism.
The present study investigated the relationship between infant temperament characteristics and autism spectrum disorder (ASD) risk status. Temperament was examined at 6, 12, and 24 months in 282 ...infants at high familial risk for ASD and 114 low-risk controls using the Infant Behavior Questionnaire-Revised and Early Childhood Behavior Questionnaire. Infants were divided into three groups at 24 months: High-Risk Positive—classified as ASD (HR Pos), High-Risk Negative (HR Neg), and Low-Risk Negative (LR Neg). At 6 and 12 months HR Pos infants exhibited lower Surgency and Regulatory Capacity than LR Neg infants. By 12 months they also demonstrated increased Negative Affect. Group differences remained, when early signs of ASD were controlled for, suggesting that temperament differences could be useful targets for understanding the development of ASD.
To evaluate the efficacy and safety of risperidone in children and adults with Tourette syndrome.
This was an 8-week, randomized, double-blind, placebo-controlled trial. The primary outcome measure ...was the Total Tic score of the Yale Global Tic Severity Scale (YGTSS).
Thirty-four medication-free subjects (26 children and 8 adults) ranging in age from 6 to 62 years (mean = 19.7 +/- 17.0 years) participated. YGTSS Total Tic scores were similar at baseline (26.0 +/- 5.1 for risperidone vs 27.4 +/- 8.5 for placebo). After 8 weeks of treatment (mean daily dose of 2.5 +/- 0.85), the 16 subjects on risperidone showed a 32% reduction in tic severity from baseline, compared to a 7% reduction for placebo patients (n = 18) (F2,64 = 6.07; p = 0.004). The 12 children randomized to risperidone showed a 36% reduction in tic symptoms compared to an 11% decrease in the 14 children on placebo (F2,48 = 6.38; p = 0.004). Two children on risperidone showed acute social phobia, which resolved with dose reduction in one subject but resulted in medication discontinuation in the other. A mean increase in body weight of 2.8 kg was observed in the risperidone group compared to no change in placebo (F2,64 = 10.68; p = 0.0001). No extrapyramidal symptoms and no clinically significant alterations in cardiac conduction times or laboratory measures were observed.
Risperidone appears to be safe and effective for short-term treatment of tics in children or adults with Tourette syndrome. Longer-term studies are needed to evaluate the durability of efficacy and safety over time.
Abstract The neuropeptide oxytocin has become a subject of great interest in studies investigating human social cognition. Single intranasal administration of the hormone has been reported to have ...positive behavioral effects, such as increasing trust or facilitating social approach, 45–80 min after administration. However, little is still known about the long-term pharmacokinetics of oxytocin nasal spray application in humans. This study addressed the question how long oxytocin plasma levels remain elevated following nasal spray administration. Another goal was to examine the influence of oxytocin administration on endogenous steroid hormones since such alterations might modulate social behavior via an indirect way. Eight healthy Caucasian men were challenged with a single intranasal application of 26 international units of oxytocin. Changes in oxytocin blood plasma levels, as well as steroid hormone levels of progesterone, testosterone and estradiol were assessed at 5 consecutive time points over a period of 3.5 h (−5, +30, +90, +150, +210 min relative to oxytocin administration). Results gave evidence for a substantial rise of oxytocin plasma levels 30 min after intranasal administration, observed in 7 of 8 participants. Group mean oxytocin plasma level was found to have returned to baseline already 90 min post administration, though in some individuals the plasma levels was still elevated relative to sampling at post 150 min. Steroid hormone analyses yielded a slight augmentation of endogenous testosterone levels 210 min after oxytocin administration. Our data confirms previous findings that oxytocin administered as a nasal spray enters the blood circulation, elevating oxytocin plasma levels for a limited time. Our findings suggest that this time window differs between individuals, but that, for the used dose, it does not extend beyond 150 min post administration. The data further provides preliminary evidence that intranasal oxytocin has an enhancing effect on testosterone in healthy men.
Canonical babbling-producing syllables with a mature consonant, full vowel, and smooth transition-is an important developmental milestone that typically occurs in the first year of life. Some studies ...indicate delayed or reduced canonical babbling in infants at high familial likelihood for autism spectrum disorder (ASD) or who later receive an ASD diagnosis, but evidence is mixed. More refined characterization of babbling in the first year of life in infants with high likelihood for ASD is needed.
Vocalizations produced at 6 and 12 months by infants (n = 267) taking part in a longitudinal study were coded for canonical and non-canonical syllables. Infants were categorized as low familial likelihood (LL), high familial likelihood diagnosed with ASD at 24 months (HL-ASD) or not diagnosed (HL-Neg). Language delay was assessed based on 24-month expressive and receptive language scores. Canonical babble ratio (CBR) was calculated by dividing the number of canonical syllables by the number of total syllables. Generalized linear (mixed) models were used to assess the relationship between group membership and CBR, controlling for site, sex, and maternal education. Logistic regression was used to assess whether canonical babbling ratios at 6 and 12 months predict 24-month diagnostic outcome.
No diagnostic group differences in CBR were detected at 6 months, but HL-ASD infants produced significantly lower CBR than both the HL-Neg and LL groups at 12 months. HL-Neg infants with language delay also showed reduced CBR at 12 months. Neither 6- nor 12-month CBR was significant predictors of 24-month diagnostic outcome (ASD versus no ASD) in logistic regression.
Small numbers of vocalizations produced by infants at 6 months may limit the reliability of CBR estimates. It is not known if results generalize to infants who are not at high familial likelihood, or infants from more diverse racial and socioeconomic backgrounds.
Lower canonical babbling ratios are apparent by the end of the first year of life in ASD regardless of later language delay, but are also observed for infants with later language delay without ASD. Canonical babbling may lack specificity as an early marker when used on its own.
EVOLUTION OF AGRICULTURE IN INSECTS Mueller, U.G; Gerardo, N.M; Aanen, D.K ...
Annual review of ecology, evolution, and systematics,
01/2005, Letnik:
36, Številka:
1
Journal Article
Recenzirano
Agriculture has evolved independently in three insect orders: once in ants, once in termites, and seven times in ambrosia beetles. Although these insect farmers are in some ways quite different from ...each other, in many more ways they are remarkably similar, suggesting convergent evolution. All propagate their cultivars as clonal monocultures within their nests and, in most cases, clonally across many farmer generations as well. Long-term clonal monoculture presents special problems for disease control, but insect farmers have evolved a combination of strategies to manage crop diseases: They (a) sequester their gardens from the environment; (b) monitor gardens intensively, controlling pathogens early in disease outbreaks; (c) occasionally access population-level reservoirs of genetically variable cultivars, even while propagating clonal monocultures across many farmer generations; and (d) manage, in addition to the primary cultivars, an array of "auxiliary" microbes providing disease suppression and other services. Rather than growing a single cultivar solely for nutrition, insect farmers appear to cultivate, and possibly "artificially select" for, integrated crop-microbe consortia. Indeed, crop domestication in the context of coevolving and codomesticated microbial consortia may explain the 50-million year old agricultural success of insect farmers.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, INZLJ, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK, ZRSKP
8.
evolution of agriculture in ants Mueller, U.G; Rehner, S.A; Schultz, T.R
Science (American Association for the Advancement of Science),
09/1998, Letnik:
281, Številka:
5385
Journal Article
Recenzirano
Cultivation of fungi for food by fungus-growing ants (Attini: Formicidae) originated about 50 million years ago. The subsequent evolutionary history of this agricultural symbiosis was inferred from ...phylogenetic and population-genetic patterns of 553 cultivars isolated from gardens of "primitive" fungus-growing ants. These patterns indicate that fungus-growing ants succeeded at domesticating multiple cultivars, that the ants are capable of switching to novel cultivars, that single ant species farm a diversity of cultivars, and that cultivars are shared occasionally between distantly related ant species, probably by lateral transfer between ant colonies.
Language delay is extremely common in children with autism spectrum disorder (ASD), yet it is unclear whether measurable variation in early language is associated with genetic liability for ASD. ...Assessment of language development in unaffected siblings of children with ASD can inform whether decreased early language ability aggregates with inherited risk for ASD and serves as an ASD endophenotype.
We implemented two approaches: (1) a meta-analysis of studies comparing language delay, a categorical indicator of language function, and language scores, a continuous metric, in unaffected toddlers at high and low familial risk for ASD, and (2) a parallel analysis of 350 unaffected 24-month-olds in the Infant Brain Imaging Study (IBIS), a prospective study of infants at high and low familial risk for ASD. An advantage of the former was its detection of group differences from pooled data across unique samples; an advantage of the latter was its sensitivity in quantifying early manifestations of language delay while accounting for covariates within a single large sample.
Meta-analysis showed that high-risk siblings without ASD (HR-noASD) were three to four times more likely to exhibit language delay versus low-risk siblings without ASD (LR-noASD) and had lower mean receptive and expressive language scores. Analyses of IBIS data corroborated that language delay, specifically receptive language delay, was more frequent in the HR-noASD (n = 235) versus LR-noASD group (n = 115). IBIS language scores were continuously and unimodally distributed, with a pathological shift towards decreased language function in HR-noASD siblings. The elevated inherited risk for ASD was associated with lower receptive and expressive language scores when controlling for sociodemographic factors. For receptive but not expressive language, the effect of risk group remained significant even when controlling for nonverbal cognition.
Greater frequency of language delay and a lower distribution of language scores in high-risk, unaffected toddler-aged siblings support decreased early language ability as an endophenotype for ASD, with a more pronounced effect for receptive versus expressive language. Further characterization of language development is warranted to refine genetic investigations of ASD and to elucidate factors influencing the progression of core autistic traits and related symptoms.
Rapid identification of behaviorally relevant objects is important for survival. In humans, the neural computations for visually discriminating complex objects involve inferior temporal cortex (IT). ...However, less detailed but faster form processing may also occur in a phylogenetically older subcortical visual system that terminates in the amygdala. We used binocular rivalry to present stimuli without conscious awareness, thereby eliminating the IT object representation and isolating subcortical visual input to the amygdala. Functional magnetic resonance imaging revealed significant brain activation in the left amygdala but not in object-selective IT in response to unperceived fearful faces compared to unperceived nonface objects. These findings indicate that, for certain behaviorally relevant stimuli, a high-level cortical representation in IT is not required for object discrimination in the amygdala.
PDF
