Famous First Words is a recurring LabKitty feature wherein we have a look at the opening line of a famous scientific article.
Scientists' view of the brain tends to track the popular tech of the day. Descartes, for example, knew about horses so he concluded the soul was riding the brain horse-wise and even identified an anatomical rein from which the habenula gets its name. Fast forward many years and birth of the computer got everyone certain the brain trafficked in the ones and zeros of these marvels. At various other times the brain was a state machine, or a control system, or an associative net, or a Hebbian steam engine. Who knows what models tomorrow will bring, perhaps something about dark matter or quantum foam or "rap" (I once overheard a student argue we should study the brains of "rappers" because -- and I quote -- they are the intellectuals of society.)
More to today's point, somewhere between the equine and the Boolean, psychology got enamored with operant conditioning, popularized by BF Skinner and namesake of the box that bears his name. You go in the box. You do something good and a reward (sugar pellet, whiskey, tenure) appears. You do something bad and a punishment (electrical shock, 1040, "rap") appears instead.
The effect was we came to view the brain as a passive lump existing in a kind of sensory miasma, waiting for and then responding to a never-ending parade of stimuli called life. Anyone in possession of this device might find such a description overly simplistic. If you are like LabKitty, and why wouldn't you be, your mental existence isn't a grey fog punctuated by external interruptions, but rather a rich internal tapestry of hopes, dreams, and revenge fantasies.
That is not to say the stimulus-response paradigm isn't useful. We have learned a great deal about the brain's inner workings from presenting a stimulus and measuring the response in everything from individual neurons to the whole shebang. Yet, there is more to the brain's story.
Signs of ceaseless gronkulation had appeared in the lab going back to the earliest measurements. Hans Berger's pioneering work on EEG revealed oscillatory activity seemingly unrelated to stimulation. Much later, PET established the brain's energy consumption was not much different during mental gymnastics compared to not. And there was more. Sure, parts lit up when doing a something that engaged them: visual cortex for visual stimuli, auditory for sound, motor for movement, and so on. That was expected. But during the downtime, when you're doing "nothing," a leisurely pattern of activity appears and fades in cortex. Hills and valleys of correlated and anti-correlated neural real estate rise and fall to your utter indifference. To coin a phrase: There's something moving in here and it ain't us.
So the stage was set for someone to begin connecting all this argle-bargle to brain function. Enter Bharat Biswal, F. Zerrin Yetkin, Victor Haughton, and James Hyde.
Their experiment was simplicity itself (overlooking the eleventy-million dollar hijacked clinical MRI scanner, a homemade receiver coil, and what must have been days of number crunching on 90's-era computer hardware): You have a subject do finger tapping whilst inside an MRI scanner in order to locate their motor cortex. Then you have them do "nothing" and record several minutes of resting state activity. Then, you pick a spot in motor cortex and identify brain regions correlated with it in the resting state fluctuations.
What Biswal et al. discovered is that brain regions correlated with MI aren't random, but rather form a network of areas involved in motor processing. The contralateral MI, yes, but also other classical motor regions like the SMA as well as islands in frontal cortex not activated by the tapping task.
The conclusion is that resting state activity connects functionally relevant brain regions -- neuron populations that tend to cooperate in processing tasks. The results convinced most (or at least many) that these fluctuations were not an epiphenomenon but rather a genuine and useful neurophysiological index.
Why the correlated activity exists or what it does are questions that are still being explored today. Also, many more correlated collections have been discovered since Biswal identified the motor network. But their paper was a watershed. From one resting state article published in 1995, thousands appear annually today, spawning specialized journals, conferences, and funding. (Academics are always quick to jump a bandwagon that might take them to fame mountain and resting state fMRI was no exception.) Heutzutage, rsfMRI is used for everything from studying brain function to identifying disease markers to mapping eloquent cortex prior to surgery.
This is how it all began:
Physiological fluctuations in resting brain have been observed by several groups using echo-planar magnetic resonance imaging (EPI, MRI).
Biswal B, Yetkin FZ, Haughton VM, Hyde JS. Functional Connectivity in the Motor Cortex of Resting Human Brain Using Echo-Planar MRI. Magn Reson Med. 1995 Oct; 34(4):537-41
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