Is the Brain a Discovery Network?

We have substantial understanding of the biophysics of neuronal responses – that is, how a neural signal is generated in the brain, how it is transmitted and how it is received by another neuron. However, much less is known about neural coding – which is, how information is processed by the neurons and why the neural signals travel in the brain in the way they do. The BRAIN initiative by the Obama administration provided a big boost to the neuroscience research to address this issue. In an effort to contribute to the neural coding research, this thesis attempts to analyze the human brain network and the communication in the brain, using probabilistic algorithms to understand the way neural signals travel in the brain. Specifically, we were interested in exploring whether the neural signals in the brain are traveling in search for some resources (e.g. protein, cell, subgraph, etc.). In other words, we tested whether the brain is a “Discovery Network”. To test our hypothesis, we implemented a family of resource search algorithms and its variants on 37 subjects (18 healthy and 19 depressed). The results, even though do not prove the hypothesis, provide enough evidence to not reject this hypothesis. At the end of the thesis, we provide some future directions and ideas, some of which improve upon our current algorithms, as ways to proceed further in this research.