I had some free time last week to conduct a web search on the human cerebellum. I was looking for published papers describing the known anatomical connections between the cerebellum and other areas of the brain. My motivation for doing so arose from a couple of predictions I made recently regarding the role of the cerebellum. I am claiming, based on my ongoing research, that the cerebellum contributes absolutely nothing to the production and processing of speech and language. So I went looking for evidence to either corroborate or falsify my claim. My research is unorthodox, to say the least. I am a non-fundamentalist Christian and I believe that the Bible contains amazing scientific knowledge that will transform the world. I am basing my claims regarding the cerebellum on my interpretation of various metaphorical passages in the book of Revelation. As always, if you are uncomfortable with my religious beliefs, this blog is not for you, sorry.
Since I am claiming that the cerebellum has nothing to do with language and speech, it follows that I am also predicting that there should be no connections between the cerebellum and Broca’s area, the part of the left hemisphere of the brain that produces speech. So I did a Google search for “cerebellar connections "Broca’s area"” and I stumbled on this abstract of a 1989 article on the cerebellum at the American Psychological Association's web site:
Whereas the cerebellar connections to frontal motor areas enable the cerebellum to improve motor skills, cerebellar connections to adjacent association areas of the prefrontal cortex can enable the cerebellum to improve mental skills, and cerebellar connections to Broca's area can enable the cerebellum to improve language skills.
I almost fell out of my chair. My reaction was, “Absolutely no way! This has got to be complete baloney.” I realize that I am biased and I am not that smart but what I lack in wits I make up for in tenacity. I then scoured the net for information on Henrietta and Alan Leiner, the authors of the article. I soon found out that they are a retired neuroscientist couple in their eighties who started out as computer scientists/mathematicians and then decided to pursue careers in neuroscience. Judging from their published work, it is obvious that the Leiners were obsessed with one goal, showing that the cerebellum participates in all sorts of cognitive tasks in addition to the well-known motor functions. Question is, did the Leiners rely on hard neuro-anatomical evidence showing that there is a two-way bundle of fibers connecting the cerebellum and Broca’s area? Nope. The only anatomical “evidence” provided by the Leiners that I could find is this:
The anatomical evidence derives from the modularity of the cerebellum, whose cortical nerve cells are organized into longitudinal micro-modules, which are arrayed perpendicular to the cortical surface and parallel to each other. The number of these micro-modules increased when the cerebellum enlarged, which enlarged the computing capabilities of the network. (From principles underlying the processing of information, it is known that when modules with modest processing capabilities are assembled in large numbers in parallel, the resulting network can achieve remarkably powerful computing capabilities.)
Say what? That's not anatomical evidence. Where is the evidence for a pathway between the cerebellum and Broca’s area, pray tell? Anything else is wishful thinking at best and deception at worst. I immediately smelled a fish.
Playing the Darwinian Card
It has been close to twenty years since the Leiners first published their original articles on the cerebellum (they have published several more articles on the same theme in the nineties) but I could not find a single reference on the net to any study that showed that a bi-directional pathway connects the cerebellum and the speech areas. The entire basis behind the supposed involvement of the cerebellum in higher cognitive tasks, such as language processing, is flimsy circumstantial evidence. The Leiners based their work mainly on the supposed evolution of the human cerebellum and suggested that future researchers use fMRI (functional magnetic resonance imaging) to support their hypothesis. At this point I knew that I had caught me a live one. The Leiners were essentially playing the Darwinian card, a smart career move that, I'm sure, guaranteed continued funding for their work. Their work on the cerebellum has been cited many times in the literature even though its veracity has never been questioned or corroborated by anybody that I could find. This is the reason that I maintain that neo-Darwinism is an insidious curse, a detriment to progress in neuroscience and elsewhere.
I hereby accuse the neuroscience community of shoddy workmanship. I accuse Henrietta and Alan Leiner of promulgating pseudoscientific bullshit with regard to the supposed language and cognitive functions of the cerebellum. I accuse the neo-Darwinists of imposing an incomplete, erroneous and inadequate evolutionary model on the soft sciences. I accuse neuroscientists and biologists of practicing pseudoscience based on their unquestioning faith in Darwinian evolution.
I challenge the neuroscience community to show any hard neuro-anatomical evidence for a bi-directional pathway between the cerebellum and Broca’s area. It should not be hard to prove. I predict that there is none. It is incumbent on those who insist that the cerebellum participates in speech production to put their money where their mouths are. I am not hiding behind ambiguous words and double entendres. I am making a precise anatomical and functional prediction about the human cerebellum. Prove me wrong with actual anatomical evidence, not circumstantial evidence that is open to subjective and/or erroneous interpretation.