Flux balance analysis (FBA) is a constraint-based approach widely used to study the metabolic capabilities of cellular or check details subcellular systems. FBA problems are highly under determined and many different phenotypes can satisfy any set of constraints through which the metabolic system is represented. Two of the main concerns in FBA are exploring the space of solutions for a given metabolic network and finding a specific phenotype which is representative for a given task such as maximal
growth rate. Here, we introduce a recursive algorithm suitable for overcoming both of these concerns. The method proposed is able to find the alternate optimal patterns of active reactions of an FBA problem and identify the minimal subnetwork able to perform a specific task as optimally as the whole. Our method represents an alternative to and an extension of other approaches conceived for exploring the space of solutions of an FBA problem. It may also be particularly helpful in defining a scaffold of reactions upon which to build up a dynamic model, when the important pathways of the system have not yet been well-defined. (C) 2009 Elsevier Ltd. All rights reserved.”
“Peripersonal space processing in monkeys’ brain relies on visuo-tactile neurons activated by objects near, not touching, the animal’s skin. Multisensory interplay in peripersonal space
is now well documented also in humans, in brain damaged patients presenting cross-modal extinction as well as in healthy subjects and typically takes the form of stronger visuo-tactile interactions in peripersonal than far space. We recently showed in healthy humans the existence of a functional link between Plasmin voluntary object-oriented actions DNA Damage inhibitor (Grasping) and the multisensory coding of the space around us (as indexed by visual-tactile interaction). Here, we investigated whether performing different actions towards the same object implies differential modulations of peripersonal space. Healthy subjects were asked to either grasp or point towards a target object. In addition, they discriminated whether tactile stimuli were delivered on their
right index finger (up), or thumb (down), while ignoring visual distractors. Visuo-tactile interaction was probed in baseline Static conditions (before the movement) and in dynamic conditions (action onset and execution). Results showed that, compared to the Static baseline both actions similarly strengthened visuo-tactile interaction at the action onset, when Grasping and Pointing were kinematically indistinguishable. Crucially, Grasping induced further enhancement than Pointing in the execution phase, i.e., when the two actions kinematically diverged. These findings reveal that performing actions induce a continuous remapping of the multisensory peripersonal space as a function of on-line sensory-motor requirements, thus supporting the hypothesis of a role for peripersonal space in the motor control of voluntary actions. (C) 2009 Elsevier Ltd.