giovedì 13 febbraio 2014

Un possibile modello biofisico cerebrale per la presa di decisione

di Alberto Carrara, LC

Pubblicato online il 9 febbraio 2014 sulla prestigiosa rivista scientifica Nature Neuroscience, l’articolo intitolato: Aneural mechanism underlying failure of optimal choice with multiplealternatives, sembra sostenere una visione contro-intuitiva, una sorta di “giro di boa” nel campo neurobioetico che concerne la presa di decisione (decision-making), strettamente connessa a tematiche quali il libero arbitrio, la libertà soggettiva e la responsabilità personale e interpersonale.

Bolton K. H. Chau e colleghi del Department of Experimental Psychology e del FMRIB Centre dell’University of Oxford (John Radcliffe Hospital, Oxford, UK), sostengono che, mentre la comune ricerca sulla presa di decisione generalmente si basa su un modello di “decisione” tra due opzioni, il loro modello a tre variabili, fornirebbe un risultato sorprendente. Così lo esprimono: “greater difficulty choosing between two options in the presence of a third very poor, as opposed to very good, alternative”.



“Decision-making research has often focused on decisions between two options. The authors adapt a decision-making model to account for a third, unavailable option and find that decision-making is more difficult with a poorer, and not better, third alternative. Ventromedial prefrontal cortex activity predicts individual variation in decision-making with multiple options”.

Ecco l’abstract dell’articolo pubblicato:

Abstract
Despite widespread interest in neural mechanisms of decision-making, most investigations focus on decisions between just two options. Here we adapt a biophysically plausible model of decision-making to predict how a key decision variable, the value difference signal—encoding how much better one choice is than another—changes with the value of a third, but unavailable, alternative. The model predicts a surprising failure of optimal decision-making: greater difficulty choosing between two options in the presence of a third very poor, as opposed to very good, alternative. Both investigation of human decision-making and functional magnetic resonance imaging–based measurements of value difference signals in ventromedial prefrontal cortex (vmPFC) bore out this prediction. The vmPFC signal decreased in the presence of low-value third alternatives, and vmPFC effect sizes predicted individual variation in suboptimal decision-making in the presence of multiple alternatives. The effect contrasts with that of divisive normalization in parietal cortex.

Link alla rivista.

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