At the 35th meeting of the Society for Neuroscience in Washington, DC, the Dalai Lama gave the inaugural “Dialogues between Neuroscience and Society” lecture. Delivered to an overflow crowd at a meeting of some 30,000 neuroscientists, the talk was a remarkable display of the areas of convergence between Buddhist thought and modern neuroscience. It may come as no surprise that there was controversy over his being invited to deliver this lecture insofar as he is both a head of state and a religious leader, and for that reason he largely stuck to his prepared text. But at least at one point he strayed, telling the audience that he was an enthusiastic proponent of new technology, even though he was computer illiterate. Elaborating, he told the audience that meditating was hard work for him (even though he meditates for 4 hours every morning), and that if neuroscience found a way to put electrodes in his brain and give him the same result as he gets from meditating, he would be an enthusiastic volunteer. A recent experiment moves us closer to making his wish a reality. Before delving into the new paper, a bit of background is appropriate.
The Dalai Lama’s interest in neuroscience has been reciprocated by at least some members of the neuroscience community who have reasoned that studying the brains of people who meditate might lead to novel insights about the human brain. Some of the most remarkable observations have come from Richard Davidson’s laboratory at the University of Wisconsin. In one particularly notable experiment, Davidson’s team studied the EEG of long-time (10,000 – 50,000 hours of practice) meditators practicing ‘open monitoring meditation’. Remarkably, Lutz et al. found that these individuals exhibited much more gamma-synchrony than naive meditators. Indeed, these long-time meditators were able to produce sustained gamma-activity in a manner that has never previously been observed in any other humans. Although the precise significance of the gamma oscillations remains to be discerned in detail (an important point indeed), sustained gamma activity has emerged as a proxy for at least some aspects of the meditative state.
The strongest hypothesis for generation of the gamma rhythm is that it is due to the activation of fast-spiking interneurons in the cerebral cortex. In two new papers to be published in Nature, the laboratories of Christopher Moore and Li-Huei Tsai at MIT collaborated with Karl Deisseroth’s group at Stanford to test this hypothesis directly. Using an elegant set of recombinant techniques, they used custom-designed viruses to infect only the fast-spiking interneurons of the cerebral cortex with genetically-engineered light-sensitive cation channels. Using fine optical fibres, the experimenters delivered light to the cortex, activating only the fast-spiking interneurons. The experimenters knew what they were after, for they did not inject just any part of the cortex, but rather the specific part of the cortex to which the mouse’s vibrissae project – the barrel cortex. Essentially the mouse equivalent to our visual system, the barrel cortex is highly specialized for acquiring information about the outside world for mice (who are nearly blind). When the experimenters evoked gamma oscillations, the tuning of the neurons in the barrel cortex was sharpened, precisely what one would predict were one’s attention to be focused. It is hard to ignore the fact that the sustained gamma-oscillation in the mice was highly reminiscent of the type of electrical activity recorded from the long-time meditators.
There are numerous caveats about this conclusion, the most important of which is that despite the elegant experimental paradigm utilized by the investigators, sustained gamma-activity is not identical to mediation. For these reasons, I doubt that the Dalai Lama would accept this experiment as satisfying his call to the neuroscience community to develop a technological replacement for meditation. But given the growing body of evidence which suggests that meditation improves several measures of attention, it is fair to conclude that the field of cognitive enhancement has just undergone a seismic shift; the prospect of using advanced technology to mimic states that require many years of practice on the mat is certainly now one that merits consideration. It is humbling to note that the hypothesis that gamma oscillation is due to activation of fast-spiking interneurons has been around since 1995, but only now have we developed the technology to test the hypothesis directly. How long will it be before a new version of this technology is available for human consumption? I think I will have to meditate on that.