Blinking BOLD signal

Those that follow this blog know that one of the repeated messages is that the results of single experiments are not to be trusted. We should be convinced by those ideas that have been shown by a number of different people, methods and subjects. (Also nothing is falsified by single experiments.) Its is the fabric, not the thread, of results that is convincing. This is particularly important with new technical tools such as neural scans. We really don’t know how trustworthy they are; the equipment, the mathematical manipulations, the interpretations are in flux. But it is what we have for physical evidence and so we do the best we can with it.

Neuroskeptic (here) has posted on a paper by Hupe and others that shows that there is a BOLD signature from blinks of the eyes in the scans of the visual cortex. It appears that once the problem is known, it should be possible to avoid it affecting results.

it’s long been believed that blink suppression mechanisms in the eye and brain somehow block out the responses that would otherwise happen during a blink….Then they (Hupe etal) simply treated the blinks as events, and used standard analysis methods to find neural activation associated with them. Blinks caused a significant BOLD response over a number of “visual” areas….I don’t think we should be too worried yet….However, as the authors point out, there is a risk that alterations in blink rate, caused, perhaps, by emotional or cognitive stress, might be wrongly “found” to be causing visual cortex activation, which might call into question claims of “top-down” influences on early visual cortex… oh dear.

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