Category: brain size

Not a surprising headline until you consider that Dr Erhan Genç and Christoph Fraenz at Ruhr-Universität Bochum are reported as suggesting that people with higher scores on an intelligence test were found to have smaller brain structures.

Brains are extremely complex organs and many aspects of their function and structure are not yet fully understood. However, we do know that neurons usually gather data from adjacent (presynaptic) neurons through complex tree-like structures containing many dendrites. The dendrites communicate with their own neuron’s cell body. Based on the messages received through the dendrites, a cell may fire (create an action potential) or not. When an action potential is generated, a message is then sent out to other neurons (postsynaptic) through the axon terminal. The reports of this study (I haven’t read the actual paper yet) is suggestive that people with fewer dendrites feeding into certain neurons in the cerebral cortex had higher IQ scores.

There are typically large numbers of dendrites communicating with each neuron in the cerebral cortex. There is a putative logic which could argue that smaller dendrite trees could be more efficient. Leading to a greater number of relevant action potentials being created more quickly. Given our limitations in understanding the mechanisms that lead to the generation and maintenance of dendrites, some caution needs to be expressed here. Without an appreciation of what the extra dendrites (in the participants with lower IQ scores) do, and why they are there, the picture is incomplete. Intelligence tests in general and IQ tests, in particular, are regarded by many experts as being reductive. It is possible that people with a history of IQ testing could have developed dendritic structures able to support this activity. But has anything been lost in the process? Are the extra dendrites in the lower IQ scored participants simply inefficient, and of no real benefit?

So what has this got to do with meditation? I wrote recently about structural changes in the brains of meditators. A conclusion from my own investigations was that increases and decreases in brain structures are likely to be the result of intense and sustained meditation practice. So the demonstration that neurological structures become bigger or smaller is probably an unhelpful oversimplification. The relationship between the alteration in structural size in different (interrelated) regions of the brain needs to be understood and then correlated to cognitive functionality if the understanding of the significance of changes is to be approached.

Rather than increasing or decreasing brain structures, meditators should probably think about their practice in terms of its deliverable goals in relation to behaviour. Brain imaging technology is still in its infancy and there are many significant problems still to overcome. We are probably decades away for being certain of the impact of complex human behaviours (like meditation) on brain structure, but we have for centuries been able to relate certain practices with behavioural changes. There are two obvious exceptions to these generalizations, age-related structural decline and changes due to neurodegeneration.

It should reiterate that I haven’t seen the full report of the Genç and Fraenz paper but a report is available at Eureka Alert.