New brain wave theory explains cognition and consciousness
· News-MedicalProfessor Earl K. Miller, member of MIT's Brain and Cognitive Sciences facultyCircuits and synapses are important and fundamental, that's the start. But there is more going on. The brain generates waves, and wave dynamics are a highly efficient way to coordinate and perform computation"
While digital circuits make calculations one step at a time through sequential switches and gates, analog computation, which can be performed via the interference of waves, processes multiple calculations in parallel. That's not only more efficient, but also locally focused traveling waves happen to be a ubiquitous feature of the brain, the scientists note.
"The brain exploits its own physics," wrote Miller and co-authors Scott L. Brincat and Jefferson E. Roy, who are research scientists in Miller's lab.
The new theory is important not only because it provides an explanation of cognition and consciousness, but also because it asserts the potential importance of considering waves in clinical treatment. Conveniently, waves can be manipulated non-invasively.
Building the analog argument
To make the case that the brain uses waves to coordinate neurons to produce cognition and consciousness, the scientists begin with the now well-established observation that many neurons don't just do one job. Instead, they respond to multiple cues and contexts, essentially participating in multiple functional networks at once, a property called "mixed selectivity." Miller and colleagues have argued for years that this gives the brain immense computational horsepower, but it also initially raised the question of how the brain organizes these multiple overlapping networks with such speed and flexibility to produce the nimble thought we all depend on.
"Synapses store representations, while wave dynamics help determine which representations are active at any given time," the authors wrote.
Miller acknowledges that his lab's next step should be to provide direct evidence that the analog computations are taking place.
Connection to consciousness
The article asserts that consciousness "emerges when these dynamic wave patterns bring the cortex in an organized, globally integrated state, one that naturally links and influences widespread activity."
"Consciousness depends less on specific receptors or cell types and more on the integrity of large-scale wave organization," the authors write in the review.
In other words, much like cognition, consciousness depends on how the brain efficiently organizes itself with brain waves.
"Electric field dynamics offer a low-overhead substrate for organizing and coordinating information across cortical networks," they conclude. "Given strong evolutionary pressure to maximize computation per unit energy, it would be surprising if evolution did not exploit such a built-in analog computing substrate."
The Freedom Together Foundation, The Picower Institute for Learning and Memory, the Army Research Office, Office of Naval Research, A MURI grant, The National Institutes of Health, and The Simons Center for the Social Brain supported the research.
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