The digestive system of xenacoelomorphs

Interest in the study of Xenacoelomorpha has recently been revived due to realization of its key phylogenetic position as the putative sister group of the remaining Bilateria. Phylogenomic studies have attracted the attention of researchers interested in the evolution of animals and the origin of novelties. However, it is clear that a proper understanding of novelties can only be gained in the context of thorough descriptions of the anatomy of the different members of this phylum. A considerable literature, based mainly on conventional histological techniques, describes different aspects of xenacoelomorphs' tissue architecture. However, the focus has been somewhat uneven; some tissues, such as the neuro-muscular system, are relatively well described in most groups, whereas others, including the digestive system, are only poorly understood. Our lack of knowledge of the xenacoelomorph digestive system is exacerbated by the assumption that, at least in Acoela, which possess a syncytial gut, the digestive system is a derived and specialized tissue with little bearing on what is observed in other bilaterian animals. Here, we try to remedy this lack of attention by revisiting the different studies of the xenacoelomorph digestive system, and we discuss the diversity present in the light of new evolutionary knowledge.

[Differences between the neuropsychological profiles of Asperger's syndrome and non-verbal learning disorder]

INTRODUCTION

The validity of the Asperger syndrome (AS) diagnose continues to be debated due to the lack of consensus on its definition, specially regarding higher-functioning autism. Previous research has suggested that the neuropsychological profile of the non verbal learning syndrome (NVLS) might be utilized to sustain a differential diagnose of the AS with other diseases associated with development.

AIM

To analyze the neuropsychological profile of children diagnosed with AS and compare with those obtained from children with NVLS.

SUBJECTS AND METHODS

All cognitive domains from 15 children have been evaluated with an extensive variety of tests; 5 were diagnosed with AS and 5 with NVLS, all of them submitted to the Nino Jesus Children's University Hospital. As a control group, another 5 children with no pathology were evaluated.

RESULTS

Obtained data shows significant differences between the two groups under study. Profile from individuals under AS shows deficit in linguistic as well as non verbal skills and, when compared to the control group, executive functions seem to be generally more altered.

CONCLUSIONS

Further investigation is suggested to determine that the NVLS could be an explanation model for AS. On the other hand, we stress the need to deepen the study of the executive functions and their relationship with the mind's theory, as an hypothesis to explain the AS.