Modeling the biochemical network that does dopamine signalling in the striatum

<p>The ability to sense and react-to external environment is a crucial element of life. Transformation</p><p>of environmental stimuli to organismal response involves complex computations</p><p>which become increasingly sophisticated as an organism is higher up the tree of life. In</p><p>the animal kingdom starting from lower level phyla except for Porifera the elements involved</p><p>in these computations show a functional organization to form the nervous system</p><p>with varying degree of complexity possibly to increase the repertoire and efficiency of the</p><p>stimulus-response transformation. Given the dynamic nature of the external environment</p><p>it is crucial that animals should be able to associate novel environmental stimuli to appropriate</p><p>responses and also reconfigure the existing stimuli-response transformations in the</p><p>light of newer environmental realities. Learning encapsulates these abilities of an organism</p><p>to create novel association or update existing associations. One of the various forms</p><p>of learning is reward learning and it is fundamental to several animal behaviors. In reward</p><p>learning if a stimulus or a stimulus-response pair is followed by a rewarding experience</p><p>then its perceived salience increases and this results in an association between the stimulus</p><p>response and the reward. Using such associations built upon past experiences an organism</p><p>could predict a possible reward if a specific stimulus is present in a given environmental</p><p>context and how it should respond to achieve this reward. In other words reward learning is</p><p>a process of creating or updating stimuli-response transformations that is guided by reward</p><p>as a teaching signal.</p>