Morphofunctional experience-dependent plasticity in the honeybee brain.

Repeated or prolonged exposure to an odorant without any positive or negative reinforcement produces experience-dependent plasticity, which results in habituation and latent inhibition. In the honeybee (Apis mellifera), it has been demonstrated that, even if the absolute neural representation of an odor in the primary olfactory center, the antennal lobe (AL), is not changed by repeated presentations, its relative representation with respect to unfamiliar stimuli is modified. In particular, the representation of a stimulus composed of a 50:50 mixture of a familiar and a novel odorant becomes more similar to that of the novel stimulus after repeated stimulus preexposure. In a calcium-imaging study, we found that the same functional effect develops following prolonged odor exposure. By analyzing the brains of the animals subjected to this procedure, we found that such functional changes are accompanied by morphological changes in the AL (i.e., a decrease in volume in specific glomeruli). The AL glomeruli that exhibited structural plasticity also modified their functional responses to the three stimuli (familiar odor, novel odor, binary mixture). We suggest a model in which rebalancing inhibition within the AL glomeruli may be sufficient to elicit structural and functional correlates of experience-dependent plasticity.

Homology and evolution of the antenna in podocopid ostracods from the perspective of aesthetascs.

Antennal podomere homology has not been well documented in podocopid ostracods. Difficulties associated with describing this homology are compounded by the occurrence of specialised podomeres in both cytheroids and bairdioids. Our research establishes the existence of two kinds of aesthetascs shared among multiple higher taxa. Overgrowth "t-setae" are present in males in Cytheroidea, Cypridocopina and Darwinuloidea, and "aesthetasc yc" is found in both sexes in Cytheroidea and Bairdioidea. Homology of the antennal podomeres among all podocopid superfamilies was determined by using the chaetotaxy of these aesthetascs, leading to a description of evolutionary modifications of the podocopid antenna, which suggests that changes in function of the articulation were prompted by the temporal demands of copulatory behavior in each lineage.

Bariatric barosensor: a new paired structure in the paravetebral region of the iliac crest.

A new anatomical entity, which we have decided to name bariatric borosensor, is described. It represents a paired structure under the skin, supero-lateral to the posterior superior iliac spine, overlying the iliac crest at the level of the fourth lumbar vertebra. Each of the paired structure is about the size of an enlarged lymph node; 0.5-2.0 cm in the largest diameter, spherical or ovoid in shape and firm in consistency. They are easily palpated clinically and can be demonstrated objectively by ultrasound examination. A hypothesis is put forth, conjecturing that this new structure may have relevance to the problem of obesity in modern, civilised western societies.