Whose Brain Is It? [March 2012 – Leena Prasad]

Whose Brain Is It?

Presented within the flow of the lives of fictional characters, this is a monthly column with a journalist’s perspective on brain research.

 

“Are you nervous at all?” Sanjay says.

“Excited,” Dana responds to her husband. “Yes, nervous, but with excitement.”

She is having her brain examined today. Well, not exactly examined, but observed by a method called Positron-Emission Tomography (PET scan) which is used to measure changes in cerebral blood flow as a result of brain activity.

“It’s not too late for you to take part in this also, you know.”

“No, no, I’d rather watch.”

Since her decision to participate in the study, they have been reading up on how the brain controls muscular movements.  There is a region towards the back of the brain, appropriately called the posterior parietal cortex, which takes visual information as input and translates it into motor commands. These commands travel through a pipeline of several brain regions to the primary motor cortex, a region that sends neural impulses to the spinal cord resulting in muscle contractions.

Later that afternoon, Dana dresses as if she’s going out dancing.

“Does my primary motor cortex look ready for action?”

“I don’t know but I think my posterior parietal cortex is getting activated.” Her husband winks at her.

She is wearing a flowing jade silk skirt that comes up just above her knee, a silk shirt with just the amount of cleavage that her husband likes, and pencil heels. She has been told that she should prepare for tango dancing as if she was going out to a nightclub and not to a science lab.

Dana and Sanjay have been dancing for many years now. They won an amateur tango contest last year which is what brought them the attention that had led to her participation in this experiment.

When they arrive at the place where the study is to be conducted, she looks around for a dance floor, perhaps a live band. The place looks like an office with a few desks and computers. Through an open door, she sees some large machines. The professor, Dr. D, arrives soon and explains the procedure to her.

“So, I, uh, I’ll be lying down the whole time,” she says. How can they study tango dancing if she will be lying down the entire time? She looks over at Sanjay and he looks as skeptical as she feels.

Dr. D laughs. “I know it sounds very strange.”

“I thought someone said that I will be moving my legs, I mean, I was told to dress for dancing.”

“Yes, yes, the machine is designed so that there is a surface area for moving your legs as if you are dancing. That’s the idea, to watch what’s happening in your brain as your legs move to the music.”

Dana does not look convinced. But she has committed to this, trusts the scientist, and is curious about the outcome. She follows the professor to a room with a large intimidating machine. She has seen these machines on television. People usually lie down in them with their head placed inside the machine. The only difference is that this particular machine actually has an inclined bottom surface where here legs would rest.

“That surface is for you to move your legs,” Dr. D says. “You’ll be listening to tango music through headsets.”

As Dana moves her legs in rhythm to the tango music, sensory organs in her leg muscles will pass on data to the brain’ in terms of the location and orientation of her muscles. The brain will use this information to update the motor commands that it sends back to the muscles. Scientists understand the neural mechanisms of basic motor functions. They are curious, however, to observe how these same mechanisms scale up to handle the complexity of the motions of dance.

In a study at the University of Texas Health Science Center at San Antonio, scientists used PET scans to observe the brains of five male and five female tango dancers in an experiment that occurred as described for the fictional character Dana.

Once Dana is lying inside the scanner with her head immobilized, she is asked to execute the basic salida step of the Argentine tango as she hears the music through her headset. By restricting the legs to motions where the body could not actually move in space, the scientist were able to limit the study to the exact movement of the leg muscles without having to worry about the extra movements of the entire body moving from one location to another.

Sanjay is not allowed to be in the lab so he is unable to watch the results but the professor explains what he and his colleagues saw in the brains of Dana and the other participants.

“We were able to confirm a hypothesis about the parietal lobe,” he said. “That’s the area in the back part of your head.”

“That’s such a large area,” Dana says. “Was there a specific region that you were observing?”

“Yes, yes, the hypothesis is that the brain contains a representative image of the body in a specific area called the precuneus. This representation helps the precuneus to choreograph the movements of the muscles, with the help of other parts of the brain. Of course, we can’t exactly see the representation in the precuneus but we can see blood flow activity in the area with a PET scan.”

“So more blood flow means more activity?” Sanjay says.

“Yes. And the tango dancing created a high level of activity in this region.”

“What’s name of the region, again?” Dana asks.

“Precuneus. You can google it to see the location and the size.”

“But what’s the point of this study,” Sanjay says. “It’s just curiosity or does it provide some answers?’

“Well, possibly. This area is one of the least studied areas of the brain so the more we know about it, the better we can use the knowledge.”

“We were asked to do the steps with and without music. What was the reason for that?”

“Very good question. That was to subtract the affect of music on the brain and to confirm that the precuneus is still activated.”

As they are driving  home, Dana searches for precuneus on her iPhone and reads out parts of the Wikipedia definition to her husband:

The precuneus is…involved with episodic memory, visuospatial processing, reflections upon self, and aspects of consciousness.

“Precuneus,” Sanjay says. “Sounds like it’s a busy part of the brain.”

“Tango dancing will never be the same for me again.”

“Well, it will be, except now the precuneus will be helping to choreograph the dancing and also be aware of itself while you are dancing.”

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Please send feedback and suggestions for future columns to leena@fishridingabike.com. Go to WhoseBrainIsIt.com for links to past columns and to FishRidingABike.com for Leena’s writing portfolio. Leena has a journalism degree from Stanford University.

References:

Brown, Steven & Parsons, Lawrence M. “The Neuroscience of Dance.” Scientific American July 2008:78-83. Print.

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