Communication costs are 35-fold computational costs in the human brain (2021)
I have friends who are non-science PhDs and absolutely believe anything published in a science journal must be absolutely sound.<p>Before I started reading I thought, &quot;alas, its going to be pseudo-science again right?&quot;.... and as far as I can see, yes, basically it is.<p>1. Logical bits are not thermodynamic bits, so a thermodynamic analysis of the brain can only be compared to a thermodynamic analysis of CPUs (if one wishes to compare at all)<p>2. Every phrase which begins &quot;suppose, assume, conjecture&quot; introduces fatal assuptions into the whole project, extremely few are defensible. The idea that a single neurone is &quot;computing&quot; whilst its &quot;communication&quot; with others is non-computational in a <i>logical</i> sense is clearly false. One can make a thermodynmic distinction between energy &quot;of the neurone&quot; and &quot;of thier &#x27;communication&#x27;&quot; this distinction has no relevance to a computational-logical model of the brain as a computational system.<p>3. The frequent reference to thermodynamic limits of &quot;computation&quot; (in a logical sense) as a baseline for comparison with (abitary) parts of the brain, is meaningless. The thermodynamic efficiency of the brain is <i>interesting</i> only insofar as any possible logical model of the brain seems to imply vastly more &quot;computational resources&quot;. And vastly more thermodynamic resources than CPUs have. Physical limits on theoretical computation pertain, if they are even themsevles coherent (which is disputed), to the absolute minimal possible &quot;piece&quot; of reality, not even, i&#x27;d say, to any <i>measurable</i> phenomenon. As soon as a system has to engage in measurement, i&#x27;d say it would be millions+ times less &quot;efficient&quot; than &#x27;physical limit&#x27;s would suggest.<p>One &quot;trick&quot; to see through the pseudoscience of computational neurobiology is simply to apply its methods to actual CPUs and computers. With the above assumptions, this paper would conclude that only one operation in a transistor  is &quot;computing&quot; anything, the energy required to do that is &quot;the energy of computation&quot;... and the rest of the energy used across CPU(-RAM-etc.) was &quot;merely communication&quot;.<p>As-if all algorithms were <i>logically</i> specified as a purely parallel series of switch-flips. No, algorithms (in a computation-logic) sense have nothing to do with switch flips. And their implementation on digital computers requires <i>many</i>, serial and parallel and &quot;thermodynamic communication&quot; between them <i>to perform the computation in question</i>.