Summary of the approach: The scientist were able to collect an information-rich multidimensional data set from human subjects including single cell physiology, neuronal morphology, MRI and IQ test scores. Both the size and dendritic complexity of the cells, as well as their electrical signals – so called action potentials – were measured in the lab and compared with the IQ scores. These samples still contained living cells that the scientists studied. To access the diseased part deep in the brain, surgeons commonly have to remove small undamaged samples of temporal lobe. Each patient took an IQ test before the operation, as part of a presurgery assesment.

The Dutch team studied 46 people who needed surgery for brain tumors or epilepsy. Huib Mansvelder, an expert for cellular neuroscience who is working within the Human Brain Project. “The study is the first to take the single cell perspective and link cellular properties to human intelligence”, explains senior author Prof. Theoretical studies additionally predicted that larger dendrites may help cells to initiate electrical signals faster.īut because of the very difficult access to human living neurons it was an open question until now whether any of these cellular properties could be proven to actually relate to human intelligence.Ī collaboration of basic neuroscientists at the Free University Amsterdam with neurosurgeons and clinical psychologists at Amsterdam University Medical Center now made it possible to find out whether smarter brains are indeed better equipped with faster and bigger cells. In these brain areas the cortex, where most of the neurons are, is also thicker in people with higher IQ. Some evidence had suggested that the size of so-called dendrites, the long branched out protrusions through which each neuron receives signals from thousands of other cells, might play a role: Especially in brain areas that integrate different types of information, such as the frontal and temporal lobes, brain cells have bigger dendrites. But so far, not much had been known about how the differences in the properties of these cells from person to person matter for human cognitive abilities like intelligence.

Our brain works through the activity of its almost 100 billion neurons that each collect, process and pass on information in the form of electrical signals.

Neurons in the brain