Fifth, this power-of-two mathematical logic confines the total numbers of distinct inputs ( i ) coming into a given microcircuit in order to best utilize the available cell resources. For instance, as a result of its exponential growth, at a mere i = 40, the total number of neurons ( n ) required to cover all possible connectivity patterns within a microcircuit would be more than 10^12 (already exceeding the total number of neurons in the human brain). For Caenorhabditis elegans – which has only 302 neurons, limiting i to 8 or less at a given neural node makes good economic sense. Furthermore, by employing a sub-modular approach (e.g., using a set of four or fi ve inputs per subnode), a given circuit can greatly increase the input types it can process with the same number of neurons. ′
He also mentions cortical layering. It seems like he’s envisioning the brain as a forest of smaller, relatively shallow networks following the principles he describes, rather than one tree where all neurons are wired together in a uniform way.
From a paper by Dr. Tsien, retrieved from http://www.augusta.edu/mcg/discovery/bbdi/tsien/documents/theoryofconnectivity.pdf
He also mentions cortical layering. It seems like he’s envisioning the brain as a forest of smaller, relatively shallow networks following the principles he describes, rather than one tree where all neurons are wired together in a uniform way.