June 9, 2010

Individual Brain Cells Can ID Both Cars And Cats

Certain 'multitasking' neurons are best at making correct IDs in multiple categories


Researchers have never been sure exactly how specialized cells in the brain can be. Do different neurons each contribute to unique thoughts or can some neurons be cognitive "generalists" and participate in multiple thoughts? To answer this, MIT researchers examined the prefrontal cortex, the brain's executive in charge of decision-making and planning.

In previous studies, Earl K. Miller, Picower Professor of Neuroscience, found that individual neurons in monkeys' brains can become tuned to the concept of "cat" and others to the concept of "dog."

This time, Miller and colleagues Jason Cromer and Jefferson Roy recorded activity in the monkeys' brains as the animals switched back and forth between distinguishing cats vs. dogs and sports cars vs. sedans. Although they found individual neurons that were more attuned to car images and others to animal images, to their surprise, there were many neurons active in both categories. In fact, these "multitasking" neurons were best at making correct identifications in both categories.

The study suggests that cognitive demands"”how much brainpower is needed for a particular task"”may determine whether neurons in the prefrontal cortex "multitask" or stick to specialized categories.

"This ability to 'multitask' allows the brain to re-utilize the same pool of neurons for different tasks. Without it, storage capacity for critical thought might be severely limited," Miller said. The work could lead to a better understanding of disorders such as autism and schizophrenia in which individuals become overwhelmed by individual stimuli. For instance, a person with autism, when asked to picture a dog, may be flooded with dozens of mental images of all the canines he had ever seen.


Next steps: Researchers hope to explore further whether individual prefrontal cortex neurons are true "cognitive generalists," able to categorize stimuli across multiple modalities.


On the Net: