More complex than we can imagine

My Phd back in the 1980's dealt with the possible role of inefficient interhemispheric transfer in specific learning disabilities. The models from which I worked were the effects of commissurotomies and agenesis of the corpus callosum and other commissures. In neuropsychology much was made of the localization of function and double dissociation was the gold standard. Norman Geschwind's disconnection theories were very influential in both neurology and neuropsychology.

Image from Wikipedia Commons file authored by Thomas Schultz.

It was also the time that simplistic pop-psychology ideas about whole brain stimulation proliferated. Neuroscientists tried to stop the flow of whole brain half-wittery to no avail. The trainers, the teachers, the mystics, the quacks and the charlatans latched on to the left-brain right-brain whole-brain idea like leeches and never let go again. The fact that neuroscience soon proved these simplistic ideas wrong was merely a mild inconvenience.

Two quotes from a recent post "Connectomics" by Steven Novella over at Neurologica shows just how ridiculously oversimplified the left-brain right-brain concept is:

"There are approximately 100 billion neurons in the adult human brain. Each neuron makes thousands of connections to other neurons, resulting in an approximate 150 trillion connections in the human brain. The pattern of those connections is largely responsible for the functionality of the brain – everything we sense, feel, think, and do. Neuroscientists are attempting to map those connections – in an effort known as connectomics."

and

"... the connections among neurons in the brain are not the only feature that contributes to brain function. The astrocytes and other “support” cells also contribute to brain function. There is also a biochemical level to brain function – the availability of specific neurotransmitters, for example. So even if we could completely reproduce the neuronal connections in the brain, there are other layers of complexity superimposed upon this."