Evidence of long-term allocentric spatial memory in the Terrestrial Hermit Crab Coenobita compressus.

Spatial learning is a complex cognitive skill and ecologically important trait scarcely studied in crustaceans. We investigated the ability of the Pacific (Ecuadorian) hermit crab Coenobita compressus, to learn an allocentric spatial task using a palatable novel food as reward. Crabs were trained to locate the reward in a single session of eleven consecutive trials and tested subsequently, for short- (5 min) and long-term memory 1, 3 and 7 days later. Our results indicate that crabs were able to learn the location of the reward as they showed a reduction in the time required to find the food whenever it was present, suggesting a visuo-spatial and olfactory cue-guided task resolution. Moreover, crabs also remember the location of the reward up to 7 days after training using spatial cues only (without the food), as evidenced by the longer investigation time they spent in the learned food location than in any other part of the experimental arena, suggesting a visuo-spatial memory formation. This study represents the first description of allocentric spatial long-term memory in a terrestrial hermit crab.

Pathways to a Diagnosis of Autism Spectrum Disorder.

OBJECTIVE: This study aimed to analyze the pathways to obtaining a diagnosis of autism spectrum disorder (ASD) within the Mexican health system. METHODS: Parents of children with ASD (N=186) were approached at specialized health centers and interviewed about the sequence of professionals they contacted that led to a diagnosis. The authors established the pathway to diagnosis, time of first parental concerns, time of first consultation, age of the child at diagnosis, and other measures. A Sankey plot was used to illustrate the complexity of the pathway to diagnosis. Diagnostic delays among children with autism were compared with delays among subsamples of children with Asperger's syndrome. Regression analysis was used to evaluate the effect of socioeconomic and clinical variables on diagnostic delays. RESULTS: The median diagnostic delay was 27 months (interquartile range [IQR] 8-36), and three professional contacts (IQR 3-6) were needed to achieve a diagnosis. Patients switched between primary and tertiary care even in later stages of the pathway. Patients with Asperger's syndrome had longer delays than patients with autism, and girls and older patients took more time to receive a diagnosis. Parental concerns regarding language, developmental issues, and perceived developmental regression resulted in shorter diagnostic delays. CONCLUSIONS: Pathways to diagnosis of ASD are long and involve multiple contacts, with patients alternating between primary and specialized care. This pattern reflects failures in the diagnostic protocols and referral systems of clinical centers in Mexico, and such issues may be experienced in countries with similarly overwhelmed health care systems.