Characteristics of interhemispheric relationships in the absence or presence of a skill

A comparative analysis of the time and amplitude characteristics of the negative N200 and positive P300 components of visual evoked potentials recorded at symmetric points of the frontal, parietal, temporal, and occipital areas of the right and left hemispheres of the cerebral cortex has been performed in subjects with or without the skill of operating a computer. Subjects inexperienced in an operator’s work exhibited an interhemispheric difference in the time and amplitude characteristics of the studied components. In subjects that had the skill of operating a computer, the interhemispheric difference was little, which suggests that the cortex plays only a small role in the cerebral control of this activity.     

Meeusella and the origin of stamens

Meeusella gen. nov. is a strobilate pollen organ from the Lower Cretaceous of Transbaikalie (east of the Lake Baikal); the branched lateral branches (paracladia), if fully developed, bear a subterminal pair of stalked synangial heads. In some cases the latter are reduced to a pair of sessile heads or the paracladia are sterile. It is suggested that the synangial heads might be further reduced to a pair of bisporangiate thecae, while the paracladium apex between them might form a prominent connective of a typical stamen. ▭ Androecium, androclade, angiosperms, proangiesperms, stamen, evolutionary morphology.