Title:
Toward the Origin of Intelligence: Neurobiology of Mental Simulation

Abstract:
Decision making requires assessment of the values resulting from possible action candidates. While this can be done in a model-free manner, simply by updating a scalar value for each action in each state, many of our decisions are model-based, involving explicit prediction or mental simulation of what will happen, when, and how probably. Which brain areas support such mental simulation? What neural circuit mechanism realizes it? What is the control mechanism for harnessing it? Here we report our efforts toward answering these critical questions.
We performed a functional MRI experiment in which subjects performed simple but non-trivial task that requires multi-step prediction of the cursor movements on the screen after key presses. Analysis of the brain activity during the planning period before finger motion showed that different brain areas are involved in such planning depending on the degree of the learning of internal models.
In order to understand the neural circuit mechanism of mental simulation, we are performing two-photon imaging of the mouse cortex during a task that required prediction of the position of a moving sound source. Our data suggest that the neurons in the posterior parietal cortex neurons are involved in such predictions.
An important issue in predicting the future is how far ahead one should take into account. Our series of recording and manipulation experiments with rats and mice suggests that the serotonergic projection from the dorsal raphe nucleus plays a key role in the regulation of the patience of an animal, and that the effect of serotonin is dependent on the confidence of the animal.

Background (by Piet Hut):
Together with Jun Makino and me, Prof. Kenji Doya and others are preparing for a summer school on an Integrative Approach to the Study of Awareness. This will include consciousness in general as well as self-awareness, and responsiveness of autonomous agents in complex systems to each other and to their environment. Starting with origins of life studies, and more widely origins of life-like processes, origins of intelligence is another example of the spontaneous emergence of complex autonomous behavior.