Nature has recently published two reports that strongly suggest individual neurons are sensitive.

Given that each neuron, or brain nerve, has an electrical bridge between other brain cells, and that some 225,000,000,000, 000,000 (225 million billion) different types of brain connections, given some are active, some not, this is very exciting news.

Why? Well, in the history of neuropsychology there have been three significant approaches to understanding how the neurons which Santiago Ramón y Cajal first isolated in 1897, (for which he got a Nobel prize in 1906) work to create cognition.

Firstly, Structuralism. Wundt, Tichener and others tried to break down the structure of the cognitive brain, and then secondly, the gestalt school, led by Max Wertheimer of the 1920s - moved away from neurobiology to suggest the brain created the mind, our thoughts, by combining many parts and then producing something new. It was the first major theory to suggest how how we emerge, construct, and generate multiple ideas.

Then in the 1950s, functionalism emerged from the ideas of Turing and developed by Putnam, Block, and Fodor in the 1980s that suggested the brain is like a computer and works in large arrays. These three, and seperately the amazing work done with fMRI research and neural pathways has lead to a common position that it takes thousands of neurons, via the cat ions of potassium in electrical exchange, to make the brain work.

That is: it takes thousands of neurons working together to do anything in the brain.Not so. At least that’s what two studies in December’s Nature show. Two teams one lead by Karel Svoboda, at the Janelia Farm research campus at Howard Hughes Medical Institute in Ashburn, Virginia, and the other led by Michael Brecht at Humboldt University Germany conducted elegant experiments on the barrel cortex in rats. This is the part that the whiskers connects to. Whiskers in rats are so sensitive that blind rats can get around in tests as competently as sighted rats.

By observing how the brain acts, via diodes and light, in the barrel cortex, and then reducing the number of activated neurons both teams observed that it takes a lot less neurons than previously thought to produce a reaction. In the experiments single neurons produced the sensation of touch.Even though Newsome conducted similar work at MIT ten years ago it did not have the sophistication of these new studies. The question is then what does it mean?

Well, firstly and importantly it may not take 1000s of neurons to perform an action, on the contrary, there is strong evidence to suggest that different electrical activity is possible within a single neuron. Each nerve can complete different functions. This fits into our current ideas about the brain functioning like an array, but it also complicates it, can a single neuron be its own array?

Further, these studies and others may produce some real results for our understanding of the neuron and the role of sparse coding in the brain. Sparse coding works on the theory that we do not build massive arrays for many simple tasks.

All of this helps us to understand the structure and function of the brain. But is also does have implications for our own brains and the understanding of thought and the mind. As well as understanding how much neurons need to interact with others it helps us to understand the role of the neuron and if we can understand how the neuron functions better this will have meaning for long-term brain health, in particular for stroke and Alzheimers, and this is only good news.